Serve both image routes with one function and one error mapping (closes #316)

HandleImage parses the path and verifies the signature, and HandleImageEnc
decrypts the token. Each then calls serveImage, which chooses the format for
auto, gets the image and serves it. respondImageError answers the image
service's errors on both routes, and handleImageError is gone. /v1/image/ now
answers 504 when the upstream sends no response headers within
upstream_fetch_timeout, as README.md documented for /v1/e/. respondImageError
logs a 500 at error level and the other answers at warn. The image service
alone logs a source refused for its first bytes. A failed write is logged once,
at warn, with the request and the bytes served. README.md lists each image
route's answers as bullets. Tests send the same errors through both routes.

Model: opus-5-5

.gitea/workflows/check.yml

@@ -18,4 +18,3 @@ jobs:
                   # All history and tags, so git describe finds the version tag.
                   fetch-depth: 0
             - run: script/cibuild
-            - run: script/docker-smoke

AGENTS.md

@@ -14,7 +14,11 @@ These rules MUST be followed at all times, it is very important.
   without asking first. In almost all cases, the code should be changed, NOT the
   tests. If you think the test needs to be changed, make your case for that and
   ask for permission to proceed, then stop. You need explicit user approval to
-  modify existing tests. (You do not need user approval for writing NEW tests.)
+  modify existing tests. A bug fix may change an existing test without asking
+  when that test pins exactly the behavior the filed bug calls wrong, and the
+  change moves it to the fixed behavior and nothing else; any other change to an
+  existing test still needs explicit user approval. (You do not need user
+  approval for writing NEW tests.)
 
 - When linting, assume the linter config is CORRECT, and that each item output
   by the linter is something that legitimately needs fixing in the code.

Dockerfile

@@ -1,12 +1,16 @@
-# Every stage declares ARG CACHEBUST first: script/ passes a new value
-# on every build, which reruns every RUN step after it. The steps that
-# compile mount Go's build cache, which survives from build to build.
+# In every stage ARG CACHEBUST comes right after the steps that install
+# system packages and download Go's modules, or right after FROM in a
+# stage with neither, and every step that lints, tests or compiles
+# comes after it. script/ passes a new value on every build, which
+# reruns every RUN step after it. Docker keeps the layers above it
+# until the base image, their own lines or go.mod and go.sum change.
+# The steps that compile mount Go's build cache, and golangci-lint run
+# also mounts golangci-lint's; both survive from build to build.
 
 # Lint phase. script/lint builds it alone. The linter is run directly:
 # `make lint` and script/lint are themselves a docker build.
 # golangci/golangci-lint:v2.14.0, 2026-10-15
 FROM golangci/golangci-lint@sha256:ad862ba6b3798cbe0fd9fd7408d498fd74fbd2623a92406b2fd3898faf0bf98f AS lint
-ARG CACHEBUST
 
 # The linter compiles every package, and govips needs the libvips
 # headers for that. REPO_POLICIES.md has the lint phase install them
@@ -18,25 +22,29 @@ RUN apt-get update \
 WORKDIR /src
 COPY go.mod go.sum ./
 RUN go mod download
+ARG CACHEBUST
 COPY . .
 RUN --mount=type=cache,target=/root/.cache/go-build \
+    --mount=type=cache,target=/root/.cache/golangci-lint \
     golangci-lint run --config .golangci.yml ./...
 
 # Test phase. script/test builds it alone. -race needs cgo and so a C
 # compiler, which the Debian Go image ships and the alpine one does not.
 # golang:1.25.4-trixie, 2026-10-15
 FROM golang@sha256:a02d35efc036053fdf0da8c15919276bf777a80cbfda6a35c5e9f087e652adfc AS test
-ARG CACHEBUST
+
+# govips compiles against the libvips and libheif headers, and the tests
+# need libvips' JPEG XL support; libvips-dev brings all three. The tests
+# also encode AVIF, which needs libheif's AVIF encoder,
+# libheif-plugin-aomenc: Debian only recommends it, so it is named here.
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends libvips-dev libheif-plugin-aomenc \
+    && rm -rf /var/lib/apt/lists/*
 
 WORKDIR /src
-
-# script/bootstrap --cgo installs the build dependencies (the libvips
-# and libheif headers, and libvips' JPEG XL support, which the tests
-# need) and downloads the Go modules.
-COPY script/ ./script/
 COPY go.mod go.sum ./
-RUN script/bootstrap --cgo
-
+RUN go mod download
+ARG CACHEBUST
 COPY . .
 
 # Without -v first; on a failure, again with -v for the details, and
@@ -52,22 +60,23 @@ RUN --mount=type=cache,target=/root/.cache/go-build \
       go test -count=1 -timeout 90s -race -parallel 4 -v ./...; exit 1; }
 
 # Build stage. Nothing is wanted from the two phases above: these copies
-# make BuildKit build them first, so this stage runs only when lint and
-# test passed.
+# make BuildKit build them first, so nothing after them runs unless lint
+# and test passed.
 # golang:1.25.4-alpine3.22, 2026-02-25; the runtime stage uses Alpine 3.22 too
 FROM golang:1.25.4-alpine3.22@sha256:d3f0cf7723f3429e3f9ed846243970b20a2de7bae6a5b66fc5914e228d831bbb AS builder
+
+# git for the version, and for govips a C compiler, pkg-config and the
+# libvips and libheif headers
+RUN apk add --no-cache git build-base pkgconfig vips-dev libheif-dev
+
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
 ARG CACHEBUST
 
 COPY --from=lint /src/go.sum /dev/null
 COPY --from=test /src/go.sum /dev/null
 
-WORKDIR /src
-
-# Build dependencies, git among them, and Go modules, as in the test
-# phase
-COPY script/ ./script/
-COPY go.mod go.sum ./
-RUN script/bootstrap --cgo
 # A tar-stream context keeps the sender's file owners, which git refuses.
 RUN git config --system --add safe.directory /src
 
@@ -102,7 +111,6 @@ RUN --mount=type=cache,target=/root/.cache/go-build \
 # the libvips and musl it was built with.
 # alpine:3.22, 2026-10-08
 FROM alpine:3.22@sha256:5291449c3df73caf6ed85e649dec1b9e818b39a5d8c871e97afc13e9cd5e8fa8
-ARG CACHEBUST
 
 # Install runtime dependencies only. vips-jxl is libvips' JPEG XL
 # support, without which pixad does not start.
@@ -113,6 +121,7 @@ RUN apk add --no-cache \
     ca-certificates \
     tzdata \
     su-exec
+ARG CACHEBUST
 
 # Copy binary from builder
 COPY --from=builder /pixad /usr/local/bin/pixad

Makefile

@@ -1,4 +1,4 @@
-.PHONY: bootstrap setup check lint test fmt fmt-check build clean docker docker-smoke docker-versioned docker-test devserver devserver-stop hooks loadtest
+.PHONY: bootstrap setup check lint test fmt fmt-check build clean docker docker-smoke docker-versioned docker-test devserver devserver-stop hooks loadtest bench
 
 VERSION := $(shell git describe --tags --always --dirty 2>/dev/null || echo "dev")
 LDFLAGS := -X main.Version=$(VERSION)
@@ -64,6 +64,12 @@ docker-smoke:
 loadtest:
 	@script/loadtest
 
+# Serve cache hits in parallel through the image handler and report hits per
+# second (needs Go on the host after `script/bootstrap --cgo`, not Docker; a
+# benchmark, not part of check)
+bench:
+	@script/bench
+
 # Build Docker image as `make docker` does, and also tag it pixa:$(VERSION)
 docker-versioned:
 	@script/docker

README.md

@@ -76,8 +76,7 @@ database and the disk cache:
   pixa runs as (uid 65532) and sets its mode to `750`; outside it, that user
   must be able to write the directory.
 - `cache_max_bytes` limits the source and transformed images together. The
-  database, the metadata files, the `.meta` file beside each transformed image
-  and files still being written come on top, and eviction runs in the
+  database and files still being written come on top, and eviction runs in the
   background, so the cache can pass the limit for a while: leave room on the
   volume beyond it.
 - Set `cache_max_bytes` for a lasting deployment. Its default, worked out each
@@ -89,21 +88,25 @@ A load balancer's health check can request `/.well-known/healthcheck.json`,
 which answers 200 whenever pixa is running, in maintenance mode too (see
 `maintenance_mode`).
 
-On SIGTERM or SIGINT pixa stops accepting connections, gives the requests in
-progress and the images being processed 5 seconds to finish, then writes to the
-database the counts of cache hits, misses, fetches and conversions that requests
-could not write by their deadline, and exits: with 0, or with 1 when images were
-still being processed after those 5 seconds, some of those counts could not be
-written, or another part of pixa failed to stop. A request not finished by then
-is cut off. `docker stop` waits 10 seconds before it kills the container.
+On SIGTERM or SIGINT pixa stops accepting connections. The requests in progress
+and the images being processed get 5 seconds to finish. A request not finished
+by then is cut off. pixa then writes the waiting last-used times of cached
+images to the database (see Storage) and exits. It exits with 1 when:
+
+- images were still being processed after those 5 seconds,
+- some of those times could not be written, or
+- another part of pixa failed to stop.
+
+Otherwise it exits with 0. `docker stop` waits 10 seconds before it kills the
+container.
 
 Outside Docker, pixa needs libvips (the image has 8.16) and libheif to run, as
 it uses libvips through CGO. pixad does not start unless libvips has its JPEG XL
 support, which on Alpine is the `vips-jxl` package and which the nix and brew
 packages of libvips include, as do the apt ones from Debian 12 and Ubuntu 24.04
 on. Building pixa also needs the development files of libvips and libheif,
-`pkg-config` and a C compiler. `script/bootstrap --cgo` installs all of these,
-as the `Dockerfile` does where it compiles pixa. Plain `script/bootstrap`, which
+`pkg-config` and a C compiler. `script/bootstrap --cgo` installs all of these;
+the `Dockerfile` installs its own packages. Plain `script/bootstrap`, which
 `script/setup` and `script/cibuild` run, installs git, make and Go, and Node,
 Yarn and the prettier pinned in `yarn.lock` for formatting the markdown, but
 none of the C libraries: the checks compile pixa in Docker. Docker itself must
@@ -177,34 +180,46 @@ allowlisted source hosts for open access.
 
 ### Storage
 
-- **Source content**:
-  `<state_dir>/cache/sources/<ab>/<cd>/<sha256 of source content>`
-- **Source metadata**:
-  `<state_dir>/cache/metadata/<hostname>/<sha256 of path and query>.json` (host,
-  path and query, content hash, upstream status and headers, fetch time)
+- **Source images**:
+  `<state_dir>/cache/sources/<ab>/<cd>/<sha256 of host, path and query>`, one
+  file for each source URL
 - **Database**: `<state_dir>/state.sqlite3` (SQLite)
 - **Transformed images**:
-  `<state_dir>/cache/variants/<ab>/<cd>/<sha256 of host, path, query, size, format, quality and fit>`,
-  each with a `.meta` file beside it holding its content type
+  `<state_dir>/cache/variants/<ab>/<cd>/<sha256 of host, path, query, size, format, quality and fit>`
 
 `<ab>` and `<cd>` are the first and second pairs of characters of the file's
 name.
 
-Multiple source paths may reference the same content blob; the database tracks
-references rather than using filesystem refcounting.
+Each source image and each transformed image has one row in the database,
+holding its size and when it was last used. Two source URLs that serve the same
+bytes are stored twice, once under each URL. A source image is stored by writing
+its file and then its row; when the row cannot be written, the file is removed
+again.
 
-Source and transformed image files, and the `.meta` file beside each transformed
-image, are written under a temporary name, synced to disk, and only then renamed
-into place, so a crash leaves no file under its own name with part of its data.
-When pixa starts, and every five minutes after, it removes each cached source or
-transformed image whose file is empty, or not the size the database records for
-it, with a warning naming the file; the next request for it fetches the source
-or converts the image again.
+Source and transformed image files are written under a temporary name, synced to
+disk, and only then renamed into place, so a crash leaves no file under its own
+name with part of its data. When pixa starts, and every five minutes after, it
+removes each cached source or transformed image whose file is empty, or not the
+size the database records for it, with a warning naming the file; the next
+request for it fetches the source or converts the image again. Looking for those
+files reads the database once for every cached file, so pixa skips each
+five-minute look that would start less than ten times as long after the last
+look ended as that look took. After a look that took one minute, the next one
+starts 10 to 15 minutes after that look ended.
 
 pixa's target is 1-5k r/s, which has not been measured at that rate (see Load
-Test). Toward it, pixa keeps in memory the content types of the 10,000
-transformed images most recently cached or served, so a cache hit on one of them
-reads only the image file from disk and not the metadata file stored beside it.
+Test). Toward it, a cache hit opens the transformed image's file and nothing
+else, and makes no database call. The content type comes from the file's first
+bytes, which are those of the format pixa wrote it in; a file whose first bytes
+are not those of a format pixa writes is not served, and the image is converted
+again. A hit hands the time it was served to a background writer and does not
+wait for the writer. Eviction orders by that time. The hit is counted in memory.
+A miss that uses a cached source image also hands that writer the time it used
+the image. Once a second that writer writes the waiting times in one
+transaction. While 10,000 times of transformed images, or 10,000 of source
+images, wait to be written, a further one is dropped, and that image only looks
+less recently used to eviction. `script/bench` measures how many hits pixa
+serves per second (see Load Test).
 
 ### Routes
 
@@ -233,30 +248,58 @@ path under `/v1/` answers 200, in maintenance mode too.
 - `GET` or `HEAD` `/v1/image/<host>/<path>/<size>.<format>`, or
   `/v1/image/<host>/<path>/<size>` with no format — an image, fetched, resized
   and converted (below). Needs: a signature, unless the host is allowlisted (see
-  Source Hosts). Answers: 200; 304 when `If-None-Match` matches the image's
-  `ETag`; 400 for a URL or parameter that is not valid, or for the format `auto`
-  an `Accept` header that is not valid; 406 for the format `auto` when `Accept`
-  allows none of the formats it chooses from; 401 for a missing or wrong
-  signature, a missing `exp` or an `exp` in the past; 403 when the request's
-  `Referer` names a host in `referer_blocklist`, checked before the signature,
-  the cache and the upstream fetch; 403 when the upstream host, or a host it
-  redirects to, is `localhost`, ends in `.localhost` or `.local`, or has an
-  address in a blocked network (see `blocked_networks`); 429 over
-  `image_requests_per_minute` (below); 415 when the upstream answers with a
-  `Content-Type` that is not one of the source formats (below), or with an image
-  whose first bytes libvips reads as another format; 502 when the upstream
-  answered with an error status, and for 5 minutes after that for an image of
-  the same source URL that pixa can neither serve from its cache nor make from
-  the source image still in its cache; 503 when pixa is busy or in maintenance
-  mode; 500 for any other failure.
+  Source Hosts). Answers:
+    - 200 with the image.
+    - 304 when `If-None-Match` matches the image's `ETag`.
+    - 400 for a URL or parameter that is not valid.
+    - 400 when the format is `auto` and the `Accept` header is not valid.
+    - 406 when the format is `auto` and `Accept` allows none of the formats it
+      chooses from.
+    - 401 for a missing or wrong signature.
+    - 401 for a missing `exp`.
+    - 401 for an `exp` in the past.
+    - 403 when the request's `Referer` names a host in `referer_blocklist`,
+      checked before the signature, the cache and the upstream fetch.
+    - 403 when the upstream host, or a host it redirects to, is `localhost` or
+      ends in `.localhost` or `.local`.
+    - 403 when the upstream host, or a host it redirects to, has an address in a
+      blocked network (see `blocked_networks`).
+    - 429 over `image_requests_per_minute` (below).
+    - 415 when the upstream answers with a `Content-Type` that is not one of the
+      source formats (below).
+    - 415 when the upstream sends a body whose first bytes are not those of the
+      format its `Content-Type` names.
+    - 415 when the upstream sends an image whose first bytes libvips reads as
+      another format.
+    - 502 when the upstream answers with an error status.
+    - 502 for 5 minutes after that for the same source URL, when pixa has
+      neither the image nor its source image in its cache.
+    - 502 likewise for 5 minutes after a body whose first bytes are not those of
+      its `Content-Type`.
+    - 503 when pixa is busy.
+    - 503 when pixa is in maintenance mode.
+    - 504 when the upstream has not sent its response headers within
+      `upstream_fetch_timeout`.
+    - 500 when that time runs out while the image itself is still arriving.
+    - 500 for any other failure.
 - `GET` or `HEAD` `/v1/e/<token>/<name>` — an image through an encrypted URL
-  (see Encrypted URLs). Needs: nothing but the URL. Answers: 200; 304 when
-  `If-None-Match` matches the image's `ETag`; 400 for a token that does not
-  decrypt, or that asks for a size or fit that is not valid; 410 once it has
-  expired; 504 when the upstream has not sent its response headers within
-  `upstream_fetch_timeout`, but 500 when that time runs out while the image
-  itself is still arriving; 400 for an `Accept` header that is not valid, and
-  406, 403, 415, 429, 502, 503 and 500, as for `/v1/image/`.
+  (see Encrypted URLs). Needs: nothing but the URL. Answers:
+    - 200 with the image.
+    - 304 when `If-None-Match` matches the image's `ETag`.
+    - 400 for a token that does not decrypt.
+    - 400 for a token that asks for a size or fit that is not valid.
+    - 410 once the token has expired.
+    - 400 when the token's format is `auto` and the `Accept` header is not
+      valid.
+    - These answers, for the same causes as on `/v1/image/`:
+        - 406
+        - 403
+        - 415
+        - 429
+        - 502
+        - 503
+        - 504
+        - 500
 - `GET /robots.txt` — asks every crawler to stay away (`Disallow: /`). Needs:
   nothing. Answers: 200.
 - `GET /.well-known/healthcheck.json` — JSON with `status` (`ok`), `now`,
@@ -323,24 +366,50 @@ first `/`, the size and format after the last `/`, and between them the source
 path up to the first `?` and the source query after it. So the `?` before the
 query, any `?` in the query, and every `%` in the source path or query must be
 percent-encoded, as `%3F` and `%25`. Any other character may be written as
-itself or percent-encoded: `/`, `;`, `,`, `=` and `&` work either way. For
-example,
+itself or percent-encoded: `/`, `;`, `,`, `=` and `&` work either way. Neither
+the source path nor the source query may hold a `#`, and an image URL that
+writes one as `%23` is refused with 400. For example,
 `https://cdn.example.com/img?url=https://origin.example.com/my%20cat.jpg` at
 800x600 WebP is
 `/v1/image/cdn.example.com/img%3Furl=https://origin.example.com/my%2520cat.jpg/800x600.webp`,
 signed as shown under Signature Specification.
 
+The source path is the path with its percent-escapes decoded, and pixa fetches
+it percent-encoded again: every character other than letters, digits, `-`, `.`,
+`_`, `~`, `/`, `$`, `&`, `+`, `,`, `:`, `;`, `=` and `@` is sent as a
+percent-escape. So `my%20cat.jpg` in the image URL is the source path
+`/my cat.jpg`, fetched as `/my%20cat.jpg`; `my%2520cat.jpg` is the source path
+`/my%20cat.jpg`, fetched as `/my%2520cat.jpg`; and `100%25.png` is fetched as
+`/100%25.png`. The source query is the source URL's query as that URL writes it,
+its percent-escapes included, and is sent as it is, except that the characters a
+browser percent-encodes in a query (a space, `"`, `'`, `<`, `>`, control
+characters and characters outside ASCII) and a `%` that does not begin a
+percent-escape are percent-encoded. pixa signs and caches the query in that
+form, so `img%3Fname=my%20cat` and `img%3Fname=my%2520cat` in the image URL are
+the same source query, `name=my%20cat`.
+
 A size with one side `0` has that side scaled to keep the source's proportions,
 and is refused with 400 when that side would come out above 8192, the most
 either side may be; so is a size with `fit=outside`, which scales the image to
 cover the size and so past it on one side, when that side would come out
 above 8192.
 
+An AVIF image of more than 16,777,216 pixels, the number 4096x4096 and 8192x2048
+have, is refused with 400 before anything is decoded, as its encode could take
+more than 40 seconds (see below). That includes `orig` of an AVIF source, and
+`auto` when it chooses AVIF, so a client whose `Accept` names `image/avif` but
+not `image/jxl` is refused such a size.
+
 The source image may be JPEG, PNG, GIF, WebP, AVIF or JPEG XL. The upstream's
 `Content-Type` must name its format, and the image's first bytes must match it.
 An upstream answering with any other `Content-Type`, SVG included, is refused
-with 415, and so is an image whose first bytes libvips reads as another format,
-such as an SVG whose first bytes pass the check for AVIF.
+with 415. So is a body whose first bytes are not those of the format its
+`Content-Type` names, such as a JPEG sent as `image/png`, text sent as an image,
+or an empty body. pixa then does not fetch that source URL again for 5 minutes,
+as after an upstream error status, and meanwhile answers 502 for an image that
+would need that fetch. An image whose first bytes libvips reads as another
+format, such as an SVG whose first bytes pass the check for AVIF, is refused
+with 415 too.
 
 With the format `auto`, pixa chooses the format for each request from its
 `Accept` header, in this order:
@@ -385,14 +454,18 @@ transcode that stops this way is answered 503 with the error
 ended. govips gives pixa no way to stop libvips once an encode has begun, so an
 encode keeps its slot until it finishes, which can be after
 `downstream_timeout`. The limit of 8192 on each side of the source and of the
-output bounds how long that takes. With one libvips thread, as pixad runs it,
-encoding 8192x8192 random pixels takes up to about 1 second as JPEG, 15 as PNG,
-16 as GIF, 63 as WebP, 110 as AVIF and 96 as JPEG XL, the slowest of 8 or 16
-bits per sample, with or without an alpha channel. WebP, AVIF and JPEG XL are
-that slow only with an alpha channel: 8-bit RGB takes about 44, 53 and 28
-seconds. Decoding such a source adds up to about 11 seconds. A WebP, AVIF or
-JPEG XL encode can therefore hold its slot past the default `downstream_timeout`
-of 60 seconds.
+output, and for AVIF the limit of 16,777,216 pixels, bound how long that takes.
+With one libvips thread, as pixad runs it, encoding 8192x8192 random pixels
+takes up to about 1 second as JPEG, 15 as PNG and 16 as GIF, the slowest of 8 or
+16 bits per sample, with or without an alpha channel. The WebP and JPEG XL
+encoders run below libvips' default effort, and AVIF at the lowest effort govips
+can set, so that no encode takes more than 40 seconds of the default
+`downstream_timeout` of 60: at any quality and 8 or 16 bits per sample,
+8192x8192 random pixels with an alpha channel take up to about 23 seconds as
+WebP and 27 as JPEG XL, and 4096x4096, 8192x2048 or 2048x8192 up to about 34 as
+AVIF, which at quality 85 would take about 96 at 8192x8192. Without an alpha
+channel they take up to about 16, 13 and 22 seconds. Decoding such a source adds
+up to about 11 seconds.
 
 The login form (`POST /`) is limited to 5 attempts per minute per client
 address, counting an IPv6 client by its /64; an attempt over the limit is
@@ -444,7 +517,13 @@ nor change what it asks for.
    sent with an empty format, or none, also makes a JPEG XL URL. Width and
    height both empty or `0` keep the original size; if only one of them is empty
    or `0`, that side is scaled to keep the image's proportions. A URL whose
-   scaled side would come out above 8192 answers 400.
+   scaled side would come out above 8192 answers 400, and so does an AVIF URL of
+   more than 16,777,216 pixels or a source URL whose path holds a `..` segment.
+   So does a source URL that the image URL would fetch written another way, and
+   the page then shows the URL pixa would fetch: one with a user name and
+   password, which pixa does not send, or one whose path holds `%2F`, fetched as
+   `/`, or `(`, fetched as `%28`, as pixa keeps the source path decoded and
+   fetches it percent-encoded again (see Routes).
 3. The page shows the URL, `https://<host>/v1/e/<token>/img.<format>`, and when
    it expires. `<host>` is the host the page was opened on, and the URL starts
    with `http` instead while `debug` is on. The name after the token is ignored
@@ -452,9 +531,11 @@ nor change what it asks for.
    `jxl` for a form with no format.
 
 The token holds the source's host, path and query and the size, format, quality,
-fit and expiry, encrypted with a key derived from `signing_key`. The source
-URL's scheme is not kept: the image is fetched like any other (see Routes), and
-the blocked networks still apply.
+fit and expiry, encrypted with a key derived from `signing_key`. The host is
+kept in lower case and an empty path as `/`, as for `/v1/image/`, so
+`https://CDN.Example.com` and `https://cdn.example.com/` are one source image,
+fetched and cached once. The source URL's scheme is not kept: the image is
+fetched like any other (see Routes), and the blocked networks still apply.
 
 How long the URL lasts is chosen on the page, from 1 minute to 1 year, or never.
 The expiry is fixed in the token when the URL is made and cannot be changed or
@@ -506,13 +587,20 @@ Where:
 - `host` — source host as the URL writes it up to the first `/`, in lower case,
   keeping an IPv6 address's brackets and any `:` and port after it (e.g.
   `cdn.example.com`, `cdn.example.com:8443`, `[2001:db8::1]:8443`)
-- `path` — source path (e.g. `/photos/cat.jpg`), with each `%` written as `%25`
-  and each `:` as `%3A`, so `/photos/a:b.jpg` is signed as `/photos/a%3Ab.jpg`
-- `query` — source query string, empty string if none, with `%` and `:` written
-  as in `path`; neither then holds a `:`, so path `/a:b` with no query and path
-  `/a` with query `b:` are signed differently
-- `width` — requested width in pixels, `0` for original
-- `height` — requested height in pixels, `0` for original
+- `path` — source path, with its percent-escapes decoded as under Routes (e.g.
+  `/photos/cat.jpg`, or `/photos/my cat.jpg` for `/photos/my%20cat.jpg`), with
+  each `%` written as `%25` and each `:` as `%3A`, so `/photos/a:b.jpg` is
+  signed as `/photos/a%3Ab.jpg`
+- `query` — source query string as under Routes, empty string if none, with `%`
+  and `:` written as in `path`; neither then holds a `:`, so path `/a:b` with no
+  query and path `/a` with query `b:` are signed differently
+- `width` — requested width in pixels, or `0`: the width is then worked out from
+  the source's proportions and the requested height, rounded down but at least
+  1, or is the source's own width when the height is `0` too (the `orig` size)
+- `height` — requested height in pixels, or `0`: the height is then worked out
+  from the source's proportions and the requested width, rounded down but at
+  least 1, or is the source's own height when the width is `0` too (the `orig`
+  size)
 - `format` — output format, one of those listed under Routes, with `original`
   signed as `orig`, `jpg` as `jpeg`, and no format as `jxl`, so a URL with no
   format has the signature of the same URL ending in `.jxl`; `auto` is signed as
@@ -525,7 +613,10 @@ Where:
   with 400
 - `fit` — the URL's `fit` query parameter (cover, contain, fill, inside,
   outside), or `cover` when the URL has no `fit`; a request whose `fit` is
-  anything else, an empty `fit=` included, is refused with 400
+  anything else, an empty `fit=` included, is refused with 400. `outside` scales
+  the image to cover the requested size, keeping its proportions, so it can come
+  out larger than that size on one side: an 8192x1 source at `100x0`, which is
+  100x1 by its proportions, comes out at 8192x1
 
 The URL's `sig` is the HMAC-SHA256 result in base64url (the URL-safe alphabet of
 RFC 4648) with the trailing `=` padding kept, 44 characters in all. pixa
@@ -575,7 +666,11 @@ pixa lower-cases the host of a `/v1/image/` URL before anything else uses it, so
 `CDN.Example.com` is matched, fetched, cached and counted against
 `upstream_connections_per_host` as `cdn.example.com`. Such a URL whose host has
 a port, as in `cdn.example.com:8443`, or a `:` with no port, needs a signature
-even when the host is allowlisted. A host holding `@` is refused with 400.
+even when the host is allowlisted. The host must be a host name or an IPv4
+address (letters, digits, hyphens, underscores and dots) or an IPv6 address in
+brackets, either one optionally followed by `:` and a port. Any other host, such
+as one holding `@`, or a `?`, `#`, `%`, `\` or space written percent-encoded, is
+refused with 400.
 
 ### Configuration
 
@@ -657,7 +752,12 @@ Key settings in more detail:
   and generator pages. Default: empty
 - `blocked_networks` — list of CIDR ranges to refuse for SSRF protection, added
   to the always-enforced built-in ranges (loopback, private, link-local, CGNAT,
-  benchmark, NAT64, and the like); an invalid CIDR aborts startup
+  benchmark, NAT64, and the like); an invalid CIDR aborts startup. An IPv6
+  address in the IPv4-mapped form (`::ffff:a.b.c.d`) is matched only as the IPv4
+  address it holds, so an IPv6 range such as `::/0` refuses neither it nor a
+  plain IPv4 address. An entry written in that form is read as the IPv4 range it
+  covers, so `::ffff:10.0.0.0/104` refuses what `10.0.0.0/8` refuses; such an
+  entry shorter than `/96` covers more than IPv4 addresses and aborts startup
 - `trusted_proxies` — list of CIDR ranges of the reverse proxies in front of
   pixa. `X-Forwarded-For` is believed only when the direct peer falls inside one
   of these ranges; the logged and login-recorded client address is then the
@@ -667,16 +767,22 @@ Key settings in more detail:
   omitted key defaults to the RFC 1918 private ranges (`10.0.0.0/8`,
   `172.16.0.0/12`, `192.168.0.0/16`), since pixa is deployed behind a proxy on a
   private network; an explicitly empty list (`[]`) trusts no one, and an
-  explicit list replaces the default. An invalid CIDR aborts startup. Set this
-  to the address pixa sees for requests that come through your proxy, such as
-  `172.17.0.1/32`, when the defaults do not cover it, or to trust nothing else
-  (see the login limit and `image_requests_per_minute` under Routes). For a
-  proxy on the Docker host that connects to pixa over `127.0.0.1`, that address
-  is the gateway of the container's Docker network (`172.17.0.1` on the default
-  bridge), not the proxy's own address; a proxy that connects through another of
-  the host's addresses is seen with that address. To be sure which address it
-  is, set this to `[]` (or `PIXA_TRUSTED_PROXIES` to empty), send a request
-  through the proxy, and read `remoteIP` in pixa's request log line for it
+  explicit list replaces the default. An invalid CIDR aborts startup. An IPv6
+  address in the IPv4-mapped form (`::ffff:a.b.c.d`) is matched only as the IPv4
+  address it holds, so an IPv6 range such as `::/0` trusts neither it nor a
+  plain IPv4 address. An entry written in that form is read as the IPv4 range it
+  covers, so `::ffff:10.0.0.0/104` trusts what `10.0.0.0/8` trusts; such an
+  entry shorter than `/96` covers more than IPv4 addresses and aborts startup.
+  Set this to the address pixa sees for requests that come through your proxy,
+  such as `172.17.0.1/32`, when the defaults do not cover it, or to trust
+  nothing else (see the login limit and `image_requests_per_minute` under
+  Routes). For a proxy on the Docker host that connects to pixa over
+  `127.0.0.1`, that address is the gateway of the container's Docker network
+  (`172.17.0.1` on the default bridge), not the proxy's own address; a proxy
+  that connects through another of the host's addresses is seen with that
+  address. To be sure which address it is, set this to `[]` (or
+  `PIXA_TRUSTED_PROXIES` to empty), send a request through the proxy, and read
+  `remoteIP` in pixa's request log line for it
 - `upstream_fetch_timeout` — time allowed for one fetch from an upstream host,
   as a duration such as `30s` (the default) or `2m`
 - `upstream_max_response_size` — largest upstream response accepted, in bytes;
@@ -685,14 +791,27 @@ Key settings in more detail:
   duration; default `60s`. The upstream fetch counts toward it, and so do the
   waits for an upstream connection and for a processing slot (up to 10 seconds
   each), so keep it longer than `upstream_fetch_timeout` plus 20 seconds
-- `signing_key` — HMAC secret for URL signatures
+- `signing_key` — the secret that protects signed URLs, encrypted URLs and
+  logins. pixa uses it as it is for two things:
+    - the HMAC key of signed URLs (see Signature Specification)
+    - the password of the login page
+
+    pixa derives every other key it uses from it at startup, with HKDF-SHA256:
+    - a key that signs the session cookie
+    - a key that encrypts the session cookie
+    - a key that encrypts the token of an encrypted URL
+    - a key that signs the CSRF token cookie of the login and generator pages
+
 - `db_url` — the SQLite database to open; omitted, it is
   `file:<state_dir>/state.sqlite3?_pragma=journal_mode(WAL)`, which keeps the
-  database in WAL mode. pixa opens one connection to it, so its own reads and
-  writes run one at a time. pixa adds `_pragma=busy_timeout(5000)` to any
-  `db_url`, so a write that finds another program writing to the file waits up
-  to five seconds for it instead of failing. WAL mode comes only from the URL:
-  keep `_pragma=journal_mode(WAL)` in one you set
+  database in WAL mode. `state_dir` is percent-encoded in it, so a `%`, `?` or
+  `#` in the name is written as `%25`, `%3F` or `%23`. For a `state_dir` of `/`
+  or one starting with `//` it starts `file:////`, so SQLite does not read the
+  first name in the path as a host. pixa opens one connection to it, so its own
+  reads and writes run one at a time. pixa adds `_pragma=busy_timeout(5000)` to
+  any `db_url`, so a write that finds another program writing to the file waits
+  up to five seconds for it instead of failing. WAL mode comes only from the
+  URL: keep `_pragma=journal_mode(WAL)` in one you set
 - `cache_max_bytes` — disk cache size limit in bytes; `0` disables the disk
   cache entirely; omitted defaults to 75% of the sum of the free space on the
   filesystem containing `<state_dir>/cache/` and the bytes of source and
@@ -729,20 +848,34 @@ See `configs/config.example.yml` for all options with defaults.
 
 ### Architecture
 
-- **Dependency injection**: Uber fx
+- **Dependency injection**: Uber fx. `internal/app` builds every part of pixad
+  from the config in one fx graph. Each setting's default is declared once, in
+  `internal/config`.
 - **HTTP router**: go-chi
 - **Image processing**: govips (CGO wrapper for libvips)
 - **Database**: SQLite via modernc.org/sqlite
 - **Static assets**: embedded via `//go:embed`
-- **Metrics**: Prometheus, at `/metrics`: generic HTTP request metrics
-  (duration, response size, requests in flight) and the Go runtime and process
-  metrics; requests are measured and `/metrics` is served only when
-  `metrics.username` and `metrics.password` are set. A request's `handler` label
-  is the pattern of the route it matches, such as `/v1/image/*`, never its path.
-  Requests that match no route share the label `unmatched`: those the router
-  answers 404 or 405, and CORS preflights. A request's `method` label is its
-  method when that is `GET`, `HEAD`, `POST`, `PUT`, `PATCH`, `DELETE`,
-  `OPTIONS`, `CONNECT` or `TRACE`, and `other` for any other method
+- **Metrics**: Prometheus, at `/metrics`. pixa serves `/metrics` and measures
+  HTTP requests only when `metrics.username` and `metrics.password` are set.
+  `/metrics` holds:
+    - the duration of HTTP requests
+    - the size of HTTP responses
+    - the HTTP requests in flight
+    - the Go runtime and process metrics
+    - `pixa_cache_hits_total`: image requests served from the cache
+    - `pixa_cache_misses_total`: image requests not served from the cache
+    - `pixa_upstream_fetches_total`: fetches of a source image that read any
+      bytes
+    - `pixa_upstream_fetch_bytes_total`: the bytes those fetches read
+    - `pixa_transforms_total`: images converted
+
+    A request's `handler` label is the pattern of the route it matches, such as
+    `/v1/image/*`, never its path. Requests that match no route share the label
+    `unmatched`: those the router answers 404 or 405, and CORS preflights. A
+    request's `method` label is its method when that is `GET`, `HEAD`, `POST`,
+    `PUT`, `PATCH`, `DELETE`, `OPTIONS`, `CONNECT` or `TRACE`, and `other` for
+    any other method.
+
 - **Logging**: stdlib slog
 
 ## Entrypoints
@@ -774,6 +907,9 @@ provide:
 - `script/docker-smoke` — build the image, start it, wait for it to be healthy
 - `script/loadtest` — measure pixad's throughput, latency and peak memory; a
   benchmark, not part of `script/check` (see Load Test)
+- `script/bench` — run the Go benchmark that serves cache hits in parallel
+  through the image handler, with Go on the host after `script/bootstrap --cgo`;
+  a benchmark, not part of `script/check` (see Load Test)
 - `script/cibuild` — CI entrypoint: run `script/bootstrap` (without `--cgo`),
   then `script/check`, then build the image as `script/docker` does
 - `script/precommit` — pre-commit checks (`go mod tidy` guard, then
@@ -782,19 +918,25 @@ provide:
   `script/precommit`
 
 Every `docker build` in these scripts passes a new value of the `CACHEBUST`
-build argument, which every stage of the `Dockerfile` declares first, so every
-`RUN` step, the lint and test phases included, runs on every build instead of
-coming from the build cache. Go's build cache is kept from build to build: the
-steps that compile mount it, so a package whose inputs are unchanged is not
-compiled again, and both `go test` runs pass `-count=1` so that no stored test
-result is replayed. The `test` phase runs on the Debian Go image, with Debian's
-libvips and libheif; the image pixa ships is built and runs on Alpine.
-`script/check`, `script/cibuild`, `script/docker`, `script/lint`, `script/test`,
-`script/setup` and `script/install-precommit` are the standard copies from
-`sneak/prompts`, kept identical to them. `script/fmt` and `script/fmt-check` are
-the standard copies with pixa's `gofmt` step kept before prettier. prettier
-formats the markdown only, not the HTML templates, as it cannot parse a Go
-template action inside a tag.
+build argument, which every stage of the `Dockerfile` declares, so every `RUN`
+step after that line, the lint and test steps included, runs on every build
+instead of coming from the build cache. Above the line are the steps that
+install system packages and download the Go modules; Docker keeps their layers
+until the base image, the step itself, `go.mod` or `go.sum` changes. Go's build
+cache is kept from build to build: the steps that compile mount it, so a package
+whose inputs are unchanged is not compiled again, and both `go test` runs pass
+`-count=1` so that no stored test result is replayed. The lint step also mounts
+golangci-lint's cache, which reuses a package's findings only when its files,
+those of the packages it imports, `go.mod`, the linters and their settings in
+`.golangci.yml`, and the golangci-lint version are all unchanged. The `test`
+phase runs on the Debian Go image, with Debian's libvips and libheif; the image
+pixa ships is built and runs on Alpine. `script/check`, `script/cibuild`,
+`script/docker`, `script/lint`, `script/test`, `script/setup` and
+`script/install-precommit` are the standard copies from `sneak/prompts`, kept
+identical to them. `script/fmt` and `script/fmt-check` are the standard copies
+with pixa's `gofmt` step kept before prettier. prettier formats the markdown
+only, not the HTML templates, as it cannot parse a Go template action inside a
+tag.
 
 ## Load Test
 
@@ -848,6 +990,17 @@ The numbers depend on the machine and on whatever else runs on it. The first
 measurement, made on a shared machine with few clients, is in `TODO.md`; it says
 nothing about the target.
 
+`script/bench` (or `make bench`) measures cache hits alone, without the network
+and with no pixad process: a Go benchmark in `internal/handlers` serves one
+cached image through the `/v1/image/` handler from as many goroutines at once as
+the machine has CPUs, and reports the hits served per second as `hits/s`. Each
+run starts with an empty cache and an empty database, a SQLite file of its own,
+and puts the image in the cache before it measures. The benchmark fails if
+serving the hits ran any statement on the database. Like the load test it is not
+part of `script/check`. It runs Go on the host, as the load test does, and
+compiles pixa there, so it needs the C compiler and libraries that
+`script/bootstrap --cgo` installs, but not Docker.
+
 ## TODO
 
 See [TODO.md](TODO.md) for the full prioritized task list.

REPO_POLICIES.md

@@ -1,6 +1,6 @@
 ---
 title: Repository Policies
-last_modified: 2026-10-15
+last_modified: 2026-10-18
 ---
 
 This document covers repository structure, tooling, and workflow standards. Code
@@ -159,8 +159,11 @@ style conventions are in separate documents:
     one's findings, and a host-global lock in `$TMPDIR` makes concurrent runs
     exit non-zero with `parallel golangci-lint is running` — a status a caller
     cannot tell from real findings. Both have produced wrong verdicts in this
-    org, in both directions. A container has its own golangci-lint cache, its
-    own `TMPDIR` and a digest-pinned binary, so neither is reachable.
+    org, in both directions. A container has its own `TMPDIR`, so the lock is
+    out of reach. The lint phase does keep golangci-lint's cache between check
+    builds (below), but it lints every checkout at `/src`, and a finding is
+    taken from that cache only for the same files, settings and golangci-lint
+    version.
 
 - **Any build that runs checks is given a new `CACHEBUST` value.** Docker
   invalidates a `COPY` layer only when the copied content changes, so on an
@@ -170,15 +173,21 @@ style conventions are in separate documents:
   id, so no two builds share a value, not even the three in one
   `script/cibuild`. `script/lint`, `script/test`, `script/cibuild` and
   `script/docker` are the four, and there is no fifth — `script/check` runs the
-  two gate phases and `script/fmt-check`, and builds no image of its own. Every
-  stage of the `Dockerfile` declares `ARG CACHEBUST` as its first line after
-  `FROM`, and a new value reruns every `RUN` step after that line; `COPY` steps
-  are compared by content and need nothing. A stage without the `ARG` line is
-  served from cache on an unchanged tree, so a repository re-vendors the scripts
-  and adds the `ARG` lines in one commit. The scripts do not pass `--no-cache`:
-  it reruns every step too, but it also empties every cache mount, and Go's
-  build cache, which the canonical Go `Dockerfile` below mounts so that compiled
-  packages survive between check builds, would start empty every time. A bare
+  two gate phases and `script/fmt-check`, and builds no image of its own. In
+  every stage of the `Dockerfile`, `ARG CACHEBUST` comes right after the steps
+  that install system packages and download Go's modules, or right after `FROM`
+  in a stage with neither, and every step that lints, tests or compiles comes
+  after it. A step that installs anything else as well, such as a
+  `script/bootstrap` that also installs node packages, comes after it too. A new
+  value reruns every `RUN` step after that line; `COPY` steps are compared by
+  content and need nothing. Docker keeps the layers above the line until the
+  base image, their own lines or the files they copy change. A stage without the
+  `ARG` line is served from cache on an unchanged tree, so a repository
+  re-vendors the scripts and adds the `ARG` lines in one commit. The scripts do
+  not pass `--no-cache`: it reruns every step too, but it also builds the layers
+  above the line again and empties every cache mount, so Go's build cache and
+  golangci-lint's, which the canonical Go `Dockerfile` below mounts so that they
+  survive between check builds, would start empty every time. A bare
   `docker build .` is not evidence that anything ran: a sub-second build
   reporting success is a cache hit, not a result. Never invalidate by pruning —
   `docker builder prune` and friends destroy a build cache shared with every
@@ -194,19 +203,25 @@ style conventions are in separate documents:
   `Dockerfile`:
 
     ```dockerfile
-    # Every stage declares ARG CACHEBUST first: script/ passes a new value
-    # on every build, which reruns every RUN step after it. The steps that
-    # compile mount Go's build cache, which survives from build to build.
+    # In every stage ARG CACHEBUST comes right after the steps that install
+    # system packages and download Go's modules, or right after FROM in a
+    # stage with neither, and every step that lints, tests or compiles
+    # comes after it. script/ passes a new value on every build, which
+    # reruns every RUN step after it. Docker keeps the layers above it
+    # until the base image, their own lines or go.mod and go.sum change.
+    # The steps that compile mount Go's build cache, and golangci-lint run
+    # also mounts golangci-lint's; both survive from build to build.
 
     # Lint phase
     # golangci/golangci-lint:v2.x.x, YYYY-MM-DD
     FROM golangci/golangci-lint@sha256:... AS lint
-    ARG CACHEBUST
     WORKDIR /src
     COPY go.mod go.sum ./
     RUN go mod download
+    ARG CACHEBUST
     COPY . .
     RUN --mount=type=cache,target=/root/.cache/go-build \
+        --mount=type=cache,target=/root/.cache/golangci-lint \
         golangci-lint run --config .golangci.yml ./...
 
     # Test phase. -race needs cgo and so a C compiler, which the Debian Go
@@ -214,10 +229,10 @@ style conventions are in separate documents:
     # cache also holds test results, which go test would otherwise replay.
     # golang:1.x, YYYY-MM-DD
     FROM golang@sha256:... AS test
-    ARG CACHEBUST
     WORKDIR /src
     COPY go.mod go.sum ./
     RUN go mod download
+    ARG CACHEBUST
     COPY . .
     RUN --mount=type=cache,target=/root/.cache/go-build \
         go test -count=1 -timeout 90s -race -cover ./... || \
@@ -225,19 +240,19 @@ style conventions are in separate documents:
           go test -count=1 -timeout 90s -race -v ./...; exit 1; }
 
     # Build stage. Nothing is wanted from either phase above; the copies
-    # are what make BuildKit build them first, so this stage cannot run
-    # unless lint and test passed.
+    # are what make BuildKit build them first, so nothing after them can
+    # run unless lint and test passed.
     # golang:1.x-alpine, YYYY-MM-DD
     FROM golang@sha256:... AS builder
-    ARG CACHEBUST
-    COPY --from=lint /src/go.sum /dev/null
-    COPY --from=test /src/go.sum /dev/null
     RUN apk add --no-cache git
-    # A tar-stream context keeps the sender's file owners, which git refuses.
-    RUN git config --system --add safe.directory /src
     WORKDIR /src
     COPY go.mod go.sum ./
     RUN go mod download
+    ARG CACHEBUST
+    COPY --from=lint /src/go.sum /dev/null
+    COPY --from=test /src/go.sum /dev/null
+    # A tar-stream context keeps the sender's file owners, which git refuses.
+    RUN git config --system --add safe.directory /src
     COPY . .
 
     # The VERSION build arg when one is given, otherwise
@@ -274,16 +289,26 @@ style conventions are in separate documents:
     - Keep the runtime stage last, and if you add a stage after it, give it the
       same two copies. A plain `docker build .` builds the last stage's chain
       and nothing else.
-    - Only Go's build cache is mounted (`/root/.cache/go-build`, where Go keeps
-      it for root), and only on the steps that compile: `golangci-lint run`,
-      both `go test` runs and `go build`. It keeps compiled packages between
-      check builds, and Go reuses one only when all its inputs are unchanged, so
-      it saves the compile without skipping a check. Nothing else is kept:
-      golangci-lint's own cache would replay stored findings in place of a lint
-      run, and Go builds from whatever files a kept module cache holds without
-      checking them again (only `go mod verify` does), so a file changed there
-      would go unnoticed. Go's build cache also holds test results, which is why
-      both `go test` runs carry `-count=1`.
+    - Check builds keep these, and none of them can hand back a stale result:
+        - The layers above `ARG CACHEBUST`: the system packages and Go's
+          modules. Docker installs the packages again when the base image or the
+          install line changes, and downloads the modules again when `go.mod` or
+          `go.sum` changes. Go checks every module against `go.sum` as it
+          downloads it, and no later build can change a kept layer. The modules
+          are kept in a layer rather than a cache mount because a cache mount is
+          shared by every build on the host, and Go builds from whatever files
+          it holds without checking them again (only `go mod verify` does), so a
+          file changed there would go unnoticed.
+        - Go's build cache (`/root/.cache/go-build`, where Go keeps it for
+          root), mounted on the steps that compile: `golangci-lint run`, both
+          `go test` runs and `go build`. Go reuses a compiled package only when
+          all its inputs are unchanged. The cache also holds test results, which
+          is why both `go test` runs carry `-count=1`.
+        - golangci-lint's cache (`/root/.cache/golangci-lint`, where the pinned
+          image keeps it), mounted on `golangci-lint run`. golangci-lint reuses
+          a package's findings only when the package's files and those of every
+          package it imports, `go.mod`, the linters and their settings in
+          `.golangci.yml`, and the golangci-lint version are all unchanged.
     - If the project uses `//go:embed` directives that reference build artifacts
       (e.g. a web frontend compiled in a separate stage), the lint phase must
       create placeholder files so the embed directives resolve. Example:
@@ -292,12 +317,20 @@ style conventions are in separate documents:
       in the lint phase. The `golangci/golangci-lint` image is Debian-based and
       has no `apk`, so install with `apt-get` under the Debian package name
       (`libvips-dev`, where alpine says `vips-dev`), and delete the package
-      lists in the same `RUN`, so the layer does not keep them:
+      lists in the same `RUN`, so the layer does not keep them. The test phase,
+      on the Debian Go image, installs the libraries its tests need the same
+      way. Either install goes right after `FROM`, above `ARG CACHEBUST`, so
+      Docker keeps it until the base image or the install line changes:
 
         ```dockerfile
+        FROM golangci/golangci-lint@sha256:... AS lint
         RUN apt-get update \
             && apt-get install -y --no-install-recommends libvips-dev \
             && rm -rf /var/lib/apt/lists/*
+        WORKDIR /src
+        COPY go.mod go.sum ./
+        RUN go mod download
+        ARG CACHEBUST
         ```
 
     - `.dockerignore` lets `.git` into the build context. It keeps out every git

TODO.md

@@ -30,16 +30,302 @@ P2: security: per-origin rate limiting
 
 # Completed Steps
 
+- 2026-10-26 both image routes serve an image with one function, `serveImage`,
+  and answer its errors with one, `respondImageError` (closes #316).
+  `HandleImage` parses the path and verifies the signature, and `HandleImageEnc`
+  decrypts the token. Each then calls `serveImage`.
+    - `handleImageError`, the encrypted route's own mapping, is gone.
+    - `/v1/image/` answers 504 when the upstream has not sent its response
+      headers within `upstream_fetch_timeout`, as `/v1/e/` did. It answered 500.
+    - `respondImageError` logs the image service's errors as "failed to get
+      image". Each answer gets the same level on `/v1/image/` and on `/v1/e/`:
+        - 500: error, as pixa's own failure
+        - 400: warn
+        - 403: warn
+        - 415: warn
+        - 502: warn
+        - 503: warn
+        - 504: warn
+    - Before, `/v1/image/` logged all of these answers at error level. `/v1/e/`
+      logged only its 500, as "image request failed", without the host and the
+      path.
+    - `respondImageError` does not log the 415 for a body refused for its first
+      bytes, on either route. The image service logs it as "source refused", at
+      warn level.
+    - The "image served" line carries the host, the path and `fetched_bytes` on
+      both routes. The debug line "encrypted image request" is gone.
+    - The debug line "failed to decrypt URL" is now "invalid encrypted URL". A
+      token that decrypts to a payload that does not decode also gets it.
+    - A failed write is logged once, as "failed to write response" at warn
+      level, since most often the client has gone away. It carries the
+      `request_id`, the host, the path, `served_bytes` and the error, and is not
+      also logged as "image served".
+- 2026-10-26 every key derived from the signing key is derived in one place
+  (closes #315): `seal.DeriveKeys` returns them as one `seal.Keys`, with their
+  salts declared beside it. `internal/providers` calls it once at startup. Each
+  key is derived as before, with `seal.DeriveKey` and the same salt.
+    - The session manager, the encrypted URL generator and the CSRF protection
+      each take their own key instead of the signing key.
+    - `session.NewManager`, `encurl.NewGenerator`, `newCSRFProtect` and
+      `handlers.New` return no error, as nothing in them can fail now.
+    - The signing key itself stays the HMAC key of signed URLs and the login
+      password.
+    - `README.md` says under `signing_key` what it protects.
+- 2026-10-26 the image request holds only what names the cached object (closes
+  #314): its source and its transform, which the variant key covers. The signed
+  URL format, the signing algorithm and every route's answers are unchanged.
+    - The `/v1/image/` handler checks `allowlist_hosts` and verifies the
+      signature itself, with `Signer.Verify(req, sig, expires)`.
+    - Each image handler keeps its URL's expiry as a value of its own, for
+      `Cache-Control`. `encurl`'s `Generate` takes the expiry and its `Parse`
+      returns it.
+    - The fetcher takes the source and builds its URL with `Source.URL`, over
+      http only when the fetcher's own `AllowHTTP` is set. `validateURL` takes
+      that URL, so no URL string is built and parsed again.
+    - `chooseAutoFormat` returns the format it chooses, and the handler puts it
+      into the request it parsed.
+    - The image service serves images through `Get`, and has `WaitForProcessing`
+      for shutdown.
+    - Removed:
+        - `Signature`, `Expires`, `AllowHTTP` and `SourceURL` of the image
+          request
+        - `Service.ValidateRequest`, and the service's signer, allowlist and
+          `AllowHTTP`
+        - `extractHost` of the fetcher and `urlToFSPath` of the mock fetcher
+- 2026-10-26 pixad's fx graph builds the image pipeline (closes #313).
+  `database.New` now opens the database, so the parts below can read it while
+  they are built; its stop hook still runs after the cache's. The cache's
+  `MaxBytes` is the one value for the disk cache limit, and 0 turns the disk
+  cache off. For an omitted `cache_max_bytes`, `internal/providers` works out
+  `config.DefaultCacheMaxBytes` before it builds the cache. `internal/app` and
+  the server tests build the parts below with `providers.Constructors()`; the
+  image proxy test replaces only the fetcher's dial function.
+    - Built by the providers in `internal/providers`, and given to
+      `handlers.New`:
+        - the cache
+        - the fetcher
+        - the processor
+        - the image service
+        - the session manager
+        - the encrypted URL generator
+    - Removed:
+        - `initImageService` and `handlers.Params.Fetcher`
+        - `CacheConfig.UseDefaultMaxBytes`, `CacheConfig.DisableDiskCache` and
+          `Cache.disabled`
+        - `httpfetcher.DefaultConfig()` and the fetcher's copies of setting
+          defaults
+        - `imageprocessor.DefaultMaxInputBytes`, and the processor's defaults
+          for a zero `MaxInputBytes` or `MaxConcurrentProcessing`
+- 2026-10-26 the code nothing in production called is gone (closes #312). The
+  handlers tests sign their image URLs with `generateSignedURL`, a test helper
+  that writes them as the removed generator did. Removed:
+    - `Service.Warm` and the `ImageCache` interface
+    - `Service.GenerateSignedURL` and `Signer.GenerateSignedURL`
+    - `signature.ParseParams`
+    - `imagerequest.ParseImagePath`
+    - `PeekAndValidate`, `IsSupportedMIMEType`, `ImageFormatToMIME` and
+      `FormatOriginal` of `internal/magic`
+    - `SupportedInputFormats` and `SupportedOutputFormats` of the image
+      processor
+    - `IsEmpty` and `Count` of the allowlist
+    - `ssrfSafeDialer`
+    - `CacheStale`, `ErrCacheMiss`, `ErrNegativeCache` and
+      `ImageResponse.LastModified`
+    - `ContentStorage.Load` and `VariantStorage.Load`
+- 2026-10-26 cache hits, misses, upstream fetches, the bytes those fetches read
+  and transforms are counted as Prometheus counters in memory (closes #311).
+  They are `pixa_cache_hits_total`, `pixa_cache_misses_total`,
+  `pixa_upstream_fetches_total`, `pixa_upstream_fetch_bytes_total` and
+  `pixa_transforms_total`, fields of the cache. `NewCache` makes them and
+  registers them on the registry it is given (`internal/imgcache/counters.go`).
+  pixad gives it Prometheus' default registry, which `/metrics` serves; each
+  test gives it a new one. The `Increment` methods add to their cache's
+  counters. `cache_stats`, `Cache.Stats`, `Service.Stats`, `CacheStats` and the
+  pending counts are gone. The background goroutine writes only access times
+  now: `StartPendingAccessTimeWrites` starts it and
+  `StopPendingAccessTimeWrites` stops it, in `pendingaccesstimes.go`.
+- 2026-10-21 the schema file declares only the tables and columns pixa writes
+  and reads (closes #310): `output_content` and `request_cache` are gone, and so
+  are the columns nothing read: the host, path, query, `content_type` and
+  `fetched_at` of `source_content`, the `content_type` and `created_at` of
+  `variant_content`, and the `status_code`, `error_message` and `fetched_at` of
+  `negative_cache`. `StoreSource` no longer takes the fetch result,
+  `LookupSource` returns only the source key, `StoreVariant` no longer takes a
+  content type, `StoreNegative` no longer takes a status code or message, and
+  reconciliation adopts a variant file without reading its first bytes.
+- 2026-10-21 a cache hit makes no database call (closes #309): `Service.Get`
+  opens the variant file with `Cache.GetVariant` and nothing else, with no
+  existence check first. The content type comes from the file's first bytes; a
+  file whose first bytes are not those of an output format, SVG included, is a
+  miss, and the variant is made again. A hit hands its access time to a channel
+  that holds up to 10,000 and drops the rest, and its hit count to the pending
+  counts, without waiting; every count is now a pending count. A miss that finds
+  a cached source hands that source's access time to a second such channel. The
+  goroutine `StartPendingCountWrites` starts writes, once a second, the access
+  times in one transaction and the counts in one `UPDATE`;
+  `StopPendingCountWrites` writes what is left once at shutdown and logs
+  separately the access times and the counts it could not write.
+  `checkNegativeCache` no longer deletes an expired row; `CleanExpired` in the
+  eviction goroutine does. The `.meta` files, `VariantMeta`, `LoadWithMeta`,
+  `variantContentTypeFromSidecar`, `metaCache`, `Lookup` and `golang-lru` are
+  gone. `make bench` (`script/bench`) runs `BenchmarkHandleImage_CacheHits` with
+  Go on the host after `script/bootstrap --cgo`, outside `make check`.
+- 2026-10-21 a source is stored the way a variant is (closes #308): one
+  `source_content` row and one file per source URL, the file named by the
+  source's `SourceKey`, the SHA-256 of its host, path and query made as the
+  variant key is, under `cache/sources/`. A store writes the file, then the row,
+  and removes the file when the row cannot be written; an eviction deletes the
+  row, then the file, with no lock and no transaction. `source_metadata`, the
+  JSON files under `cache/metadata/`, `MetadataStorage` and the content lock are
+  gone. Two source URLs that serve the same bytes now store them twice.
+- 2026-10-21 one image request type instead of five (closes #307): the new
+  package `internal/imagerequest`, which imports no other package of pixa, holds
+  `imagerequest.Request` with its two parts, `Source` (host, path and query) and
+  `Transform` (size, format, quality and fit), the `Format` and `Fit` types, the
+  checks, the parsing of the `/v1/image/` path and the variant key.
+  `imgcache.ParsedURL`, `imgcache.ImageRequest`, `signature.Request`,
+  `imageprocessor.Request`, the second `Size`, format and fit types and the
+  conversions between them are gone. The image processor takes a `Transform`
+  only, and `encurl` keeps a private struct with the token's short CBOR field
+  names, so tokens made before still decode. Every URL of both image routes
+  answers as before.
+- 2026-10-21 the Gitea workflow checks out the repo and runs `script/cibuild`,
+  nothing else (closes #203): its `script/docker-smoke` step is removed, as the
+  canonical `REPO_POLICIES.md` says, since `make check` covers what CI needs to
+  check. CI no longer starts the image and waits for its healthcheck.
+  `script/docker-smoke` and `make docker-smoke` stay, to run by hand.
+- 2026-10-20 a WebP, AVIF or JPEG XL encode at the limits takes at most about 34
+  seconds (closes #272): with one libvips thread, 8192x8192 random pixels with
+  an alpha channel took about 61 seconds to encode as WebP, 81 as JPEG XL and,
+  at quality 85, 96 as AVIF, so with the default `downstream_timeout` of 60
+  seconds such an image was never delivered, yet its encode held a processing
+  slot to the end. WebP is now saved at effort 2 and JPEG XL at effort 4, which
+  take up to about 23 and 27 seconds at any quality. AVIF was already at the
+  lowest effort govips can set, so an AVIF output of more than 16,777,216 pixels
+  is refused with 400 before anything is decoded; 4096x4096, 8192x2048 or
+  2048x8192 takes up to about 34 seconds at any quality. Resizing with
+  `fit=cover` already decodes the input, so the output's dimensions are worked
+  out before resizing. `README.md` gives the limit and the new times.
+- 2026-10-20 a source whose first bytes do not match its `Content-Type` answers
+  415 (closes #253): a body whose first bytes are not those of the format its
+  `Content-Type` names, such as a JPEG sent as `image/png`, text, or a body
+  under 12 bytes, answered 500 on both image routes and was logged as an error
+  of pixa's, and each request for it fetched the whole body again. Both routes
+  now answer 415, and the image service logs it at warning level as a refused
+  source. It also gets a negative cache entry, as an upstream error status does,
+  so the source URL is not fetched again for 5 minutes, and meanwhile an image
+  that would need that fetch answers 502.
+- 2026-10-20 `AGENTS.md`: a bug fix may change an existing test without asking
+  when that test pins exactly the behavior the filed bug calls wrong, and the
+  change moves it to the fixed behavior and nothing else (closes #280).
+- 2026-10-18 re-vendored from `sneak/prompts` commit `0653579` (closes #221):
+  each `Dockerfile` stage installs its system packages and downloads the Go
+  modules above `ARG CACHEBUST`, so check builds keep them, and the lint step
+  keeps golangci-lint's cache.
+- 2026-10-19 a `trusted_proxies` entry in the IPv4-mapped form trusted nothing;
+  it is now read as the IPv4 range it covers by the same code that reads
+  `blocked_networks`, and such an entry shorter than `/96` aborts startup
+  (closes #303).
+- 2026-10-18 the next reconciliation pass waits at least ten times as long as
+  the last one took, so passes on a large cache no longer run back to back
+  (closes #250).
+- 2026-10-18 a `blocked_networks` entry in the IPv4-mapped form refused nothing;
+  `::ffff:10.0.0.0/104` is now read as `10.0.0.0/8`, and such an entry shorter
+  than `/96` aborts startup (closes #301).
+- 2026-10-16 P1 security bug: the check that keeps pixa from fetching internal
+  addresses refuses the local-use NAT64 range (`64:ff9b:1::/48`, RFC 8215) as it
+  refuses `64:ff9b::/96`, and refuses an IPv6 address in the IPv4-compatible
+  form (`::/96`) when `blocked_networks` contains either the address as written
+  or the IPv4 address it holds (closes #299). A source host such as
+  `[64:ff9b:1::a00:1]` was fetched, which on a network that runs NAT64 on that
+  range reaches the IPv4 address it holds, here `10.0.0.1`; and with
+  `203.0.113.0/24` in `blocked_networks`, `[::ffff:203.0.113.5]` was refused but
+  `[::203.0.113.5]` was fetched. Both now answer 403. The mapped form
+  (`::ffff:a.b.c.d`) is still matched only as the IPv4 address it holds: Go
+  keeps a plain IPv4 address in that form, and an IPv6 entry such as `::/0` must
+  not refuse every IPv4 address.
+- 2026-10-16 P1 security bug: the check that keeps pixa from fetching internal
+  addresses judges an IPv6 address in the IPv4-compatible form (`::/96`), such
+  as `::127.0.0.1` or `::10.0.0.1`, by the IPv4 address in its last four bytes
+  (closes #297). It read only the mapped form (`::ffff:a.b.c.d`) as IPv4, so a
+  source host such as `[::127.0.0.1]` was checked as a public IPv6 address and
+  fetched, which on a network that routes it reaches the internal IPv4 host; it
+  is now refused with 403. The NAT64 form (`64:ff9b::/96`) was already refused
+  as a whole, as one of the built-in blocked ranges, and still is.
+- 2026-10-16 a source host that is an IPv6 address in brackets with no port,
+  such as `[2001:db8::a]`, is fetched like one with a port, through `/v1/image/`
+  and through an encrypted URL (closes #295). The fetcher's check of the source
+  URL kept the brackets when no port followed them, could not look the host up,
+  and the request answered 500. It now checks the address without brackets, so a
+  private one is refused with 403, as with a port.
+- 2026-10-16 a `state_dir` whose name holds `%`, `?` or `#` keeps its database
+  at `state.sqlite3` in that directory (closes #290): the `db_url` derived from
+  it put the name into a `file:` URL as it was, so SQLite read `%41` as `A`, a
+  `?` or `#` ended the path early, and the journal mode parameter was lost. The
+  derived `db_url` is now built with Go's `net/url`, which writes those
+  characters as `%25`, `%3F` and `%23`. For a `state_dir` of `/` or one starting
+  with `//` it starts `file:////`, so SQLite no longer reads the first name in
+  the path as a host.
+- 2026-10-16 a size with one side `0` keeps the side computed from the source's
+  proportions at 1 or more (closes #283): it was rounded down, so for a thin
+  source it came out at 0, and libvips then made the size square. An 8192x1
+  source at `100x0` came out at 100x100, and at `1300x0` with `fit=cover` made
+  libvips ask for about 39 GB at once; an 8192x2 source at `100x0` answered 500.
+  `fit=contain` and `fit=inside` work both sides out again from the smaller of
+  the two scales and `fit=outside` from the larger, and each keeps both sides at
+  1 or more too, so a 1x8192 source at `0x100` with `fit=contain`, and a 49x8192
+  source at `0x100` or a 49x49 source at `1x1` with `fit=outside`, no longer
+  answer 500. An 8192x1 source at `1300x0` now comes out at 1300x1, and the
+  process running it alone peaked at about 34 MiB resident. With `fit=outside`
+  the image is scaled to cover the size, so that source at `100x0` comes out at
+  8192x1. `README.md` now says this under Signature Specification, and says how
+  a `0` side is worked out where it said `0` meant the original.
+- 2026-10-16 the generator page lower-cases the source host and writes an empty
+  source path as `/` before it makes the encrypted URL, as `/v1/image/` does
+  (closes #293). A host written in upper and in lower case, or a source URL with
+  no path and with the path `/`, made two cache keys and two upstream requests
+  for one image.
+- 2026-10-16 the source URL a request fetches is built with `net/url` from the
+  source host, path and query, not joined as text (closes #288). The source
+  path, decoded, is fetched percent-encoded again, so `100%25.png` fetches
+  `/100%25.png` where it answered 401, and `my%20cat.png` and `my%2520cat.png`
+  fetch different paths where both fetched `/my%20cat.png` under two cache keys.
+  The source query stays as the source URL writes it; the characters a browser
+  percent-encodes in a query, such as `'` or a space, which was sent raw and
+  answered 502, are percent-encoded when the image URL is read, so the query is
+  signed and cached as it is sent. The generator page answers 400, showing the
+  URL pixa would fetch, for a source URL its image URL would fetch written
+  another way, such as with `%2F` in the path, whatever else the path holds, or
+  with a user name and password. It also answers 400 for a source path holding a
+  `..` segment, as `/v1/image/` refuses one.
 - 2026-10-15 a thin source requested with `fit=cover` no longer makes libvips
-  build a huge image (closes #282): libvips scaled the whole source to cover the
-  requested size and copied that into memory before it cut out the centre, so an
-  8192x64 source at 8192x8192 made it allocate about 24 GiB, and an 8192x1
-  source answered 500. The image processor now cuts the centre of the source to
-  the requested size's proportions first and resizes that, so no image larger
-  than the source or the output is made; the crop is the same centre as before.
-  With the runtime image's libvips and JPEG output at 8192x8192, resident memory
-  peaked at about 44 MiB for the 8192x64 source, 40 MiB for the 8192x1 one, and
-  117 MiB for a 4000x3000 one, which took 373 MiB before.
+  build a huge image (closes #282): libvips' thumbnail scaled the whole source
+  to cover the requested size and copied that into memory before it cut out the
+  centre, so an 8192x64 source at 8192x8192 made it allocate about 24 GiB, and
+  an 8192x1 source answered 500. The image processor now first cuts the centre
+  of the source, widened to whole source pixels, and thumbnail scales and cuts
+  only that, by the same amount on both sides as before. What it copies into
+  memory is then larger than the output by less than one scaled source pixel on
+  each side. With the runtime image's libvips and JPEG output at 8192x8192,
+  resident memory peaked at about 242 MiB for the 8192x64 source and 431 MiB for
+  the 8192x1 one. The output can sit a fraction of an output pixel from where it
+  was.
+- 2026-10-15 a `/v1/image/` URL whose source path or source query holds a `#`,
+  written as `%23`, is refused with 400 (closes #286): the source URL built from
+  it ended at the `#` when fetched, so each text after it fetched the same
+  upstream image, without a signature for an allowlisted host, and cached it
+  under keys of its own. `README.md` says neither may hold a `#`.
+- 2026-10-15 the host of a `/v1/image/` URL must be a host name or an IPv4
+  address (letters, digits, hyphens, underscores and dots) or an IPv6 address in
+  brackets, either one optionally followed by `:` and a port, and any other host
+  is refused with 400 (closes #275): only `@` was refused, so a `?` written as
+  `%3F` gave the host `cdn.example.com?x=1`, which Go's URL parser reads as
+  `cdn.example.com` with a query. Such a URL passed the allowlist, and each text
+  after the `?` fetched the host's root path and cached the answer under keys of
+  its own. A `#`, `%`, `\` or space written percent-encoded is refused the same
+  way, and so is an IPv6 address without brackets, which needed a signature
+  before. Underscores are kept because `allowlist_hosts` accepts host names
+  holding them.
 - 2026-10-15 the README says how a source URL with a query is written into an
   image URL, and the image route accepts it (closes #255): the query follows the
   source path after `%3F`. pixa now reads the image URL's path decoded once, so

go.mod

@@ -14,7 +14,6 @@ require (
 	github.com/go-chi/httprate v0.16.0
 	github.com/gorilla/csrf v1.7.3
 	github.com/gorilla/securecookie v1.1.2
-	github.com/hashicorp/golang-lru/v2 v2.0.7
 	github.com/prometheus/client_golang v1.23.2
 	github.com/slok/go-http-metrics v0.13.0
 	github.com/spf13/cobra v1.10.2

go.sum

@@ -228,8 +228,6 @@ github.com/hashicorp/go-version v1.2.1/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.4 h1:YDjusn29QI/Das2iO9M0BHnIbxPeyuCHsjMW+lJfyTc=
 github.com/hashicorp/golang-lru v0.5.4/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
-github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs4luLUK2k=
-github.com/hashicorp/golang-lru/v2 v2.0.7/go.mod h1:QeFd9opnmA6QUJc5vARoKUSoFhyfM2/ZepoAG6RGpeM=
 github.com/hashicorp/hcl v1.0.1-vault-7 h1:ag5OxFVy3QYTFTJODRzTKVZ6xvdfLLCA1cy/Y6xGI0I=
 github.com/hashicorp/hcl v1.0.1-vault-7/go.mod h1:XYhtn6ijBSAj6n4YqAaf7RBPS4I06AItNorpy+MoQNM=
 github.com/hashicorp/logutils v1.0.0/go.mod h1:QIAnNjmIWmVIIkWDTG1z5v++HQmx9WQRO+LraFDTW64=

internal/allowlist/allowlist.go

@@ -72,13 +72,3 @@ func (w *HostAllowList) IsAllowed(u *url.URL) bool {
 
 	return false
 }
-
-// IsEmpty returns true if the allow list has no entries.
-func (w *HostAllowList) IsEmpty() bool {
-	return len(w.exactHosts) == 0 && len(w.suffixHosts) == 0
-}
-
-// Count returns the total number of allow list entries.
-func (w *HostAllowList) Count() int {
-	return len(w.exactHosts) + len(w.suffixHosts)
-}

internal/allowlist/allowlist_test.go

@@ -139,87 +139,3 @@ func TestHostAllowList_IsAllowed_SuffixMatch(t *testing.T) {
 		},
 	})
 }
-
-func TestHostAllowList_IsEmpty(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		name     string
-		patterns []string
-		want     bool
-	}{
-		{
-			name:     "empty",
-			patterns: []string{},
-			want:     true,
-		},
-		{
-			name:     "nil",
-			patterns: nil,
-			want:     true,
-		},
-		{
-			name:     "whitespace only",
-			patterns: []string{"  ", ""},
-			want:     true,
-		},
-		{
-			name:     "has entries",
-			patterns: []string{"example.com"},
-			want:     false,
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			w := allowlist.New(tt.patterns)
-			if got := w.IsEmpty(); got != tt.want {
-				t.Errorf("IsEmpty() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}
-
-func TestHostAllowList_Count(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		name     string
-		patterns []string
-		want     int
-	}{
-		{
-			name:     "empty",
-			patterns: []string{},
-			want:     0,
-		},
-		{
-			name:     "exact hosts only",
-			patterns: []string{"a.com", "b.com", "c.com"},
-			want:     3,
-		},
-		{
-			name:     "suffix hosts only",
-			patterns: []string{".a.com", ".b.com"},
-			want:     2,
-		},
-		{
-			name:     "mixed",
-			patterns: []string{"exact.com", ".suffix.com"},
-			want:     2,
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			w := allowlist.New(tt.patterns)
-			if got := w.Count(); got != tt.want {
-				t.Errorf("Count() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}

internal/app/app.go

@@ -7,6 +7,7 @@ import (
 	"os/signal"
 	"syscall"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/spf13/cobra"
 	"go.uber.org/fx"
 	"sneak.berlin/go/pixa/internal/config"
@@ -16,6 +17,7 @@ import (
 	"sneak.berlin/go/pixa/internal/healthcheck"
 	"sneak.berlin/go/pixa/internal/logger"
 	"sneak.berlin/go/pixa/internal/middleware"
+	"sneak.berlin/go/pixa/internal/providers"
 	"sneak.berlin/go/pixa/internal/server"
 )
 
@@ -61,7 +63,10 @@ func run(_ *cobra.Command, _ []string) {
 			server.New,
 			middleware.New,
 			healthcheck.New,
+			// The registry /metrics serves
+			func() prometheus.Registerer { return prometheus.DefaultRegisterer },
 		),
+		fx.Provide(providers.Constructors()...),
 		fx.Invoke(
 			func(log *logger.Logger) { log.Identify() },
 			func(*server.Server) {},

internal/config/blocked_networks_internal_test.go

@@ -88,3 +88,56 @@ func TestBlockedNetworksInvalidAbortsStartup(t *testing.T) {
 		},
 	})
 }
+
+// TestBlockedNetworksMappedEntryIsIPv4Range checks that an entry written in
+// the IPv4-mapped form (::ffff:a.b.c.d) is kept as the IPv4 range it covers,
+// since the fetcher matches an IPv4-mapped address as the IPv4 address it
+// holds. /96, the shortest such entry, covers every IPv4 address.
+func TestBlockedNetworksMappedEntryIsIPv4Range(t *testing.T) {
+	t.Parallel()
+
+	yamlContent := signingKeyLine + `blocked_networks:
+  - "::ffff:10.0.0.0/104"
+  - "::ffff:0:0/96"
+`
+
+	c, err := configFromYAML(t, yamlContent)
+	if err != nil {
+		t.Fatalf("IPv4-mapped blocked_networks entries should load, got error: %v", err)
+	}
+
+	want := []string{"10.0.0.0/8", "0.0.0.0/0"}
+	if len(c.BlockedNetworks) != len(want) {
+		t.Fatalf("BlockedNetworks = %v, want %d entries", c.BlockedNetworks, len(want))
+	}
+
+	for i, w := range want {
+		if got := c.BlockedNetworks[i].String(); got != w {
+			t.Errorf("BlockedNetworks[%d] = %q, want %q", i, got, w)
+		}
+	}
+}
+
+// TestBlockedNetworksMappedEntryShorterThan96AbortsStartup checks that an
+// entry in the IPv4-mapped form shorter than /96, which covers more than the
+// IPv4 addresses, aborts startup with an error naming the key and the value.
+func TestBlockedNetworksMappedEntryShorterThan96AbortsStartup(t *testing.T) {
+	t.Parallel()
+
+	runAbortCases(t, []abortCase{
+		{
+			name: "mapped-shorter-than-96",
+			yaml: signingKeyLine + `blocked_networks:
+  - "::ffff:0.0.0.0/80"
+`,
+			wantErrSubstrings: []string{keyBlockedNetworks, "::ffff:0.0.0.0/80"},
+		},
+		{
+			name: "mapped-95",
+			yaml: signingKeyLine + `blocked_networks:
+  - "::ffff:0:0/95"
+`,
+			wantErrSubstrings: []string{keyBlockedNetworks},
+		},
+	})
+}

internal/config/cache_max_bytes_internal_test.go

@@ -135,10 +135,38 @@ func TestCacheMaxBytesInvalidValuesAbortStartup(t *testing.T) {
 	}
 }
 
+// TestDefaultCacheMaxBytesAppliesFloor verifies that when 75% of the
+// free space plus what the cache holds is below 500 MiB, the default is
+// floored at DefaultCacheMaxBytesFloor.
+func TestDefaultCacheMaxBytesAppliesFloor(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name      string
+		freeBytes uint64
+	}{
+		{name: "100 MiB free", freeBytes: 104857600},
+		{name: "zero free", freeBytes: 0},
+		{name: "just below floor threshold", freeBytes: 699050665},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			got := DefaultCacheMaxBytes(tc.freeBytes, 0)
+			if got != DefaultCacheMaxBytesFloor {
+				t.Errorf("DefaultCacheMaxBytes = %d, want floor %d",
+					got, DefaultCacheMaxBytesFloor)
+			}
+		})
+	}
+}
+
 // TestCacheMaxBytesExplicitIsRecorded verifies that an omitted
-// cache_max_bytes is recorded as not explicit, so the cache works out
-// the default when it opens, and that an explicit zero is recorded as
-// explicit, so it disables the disk cache instead.
+// cache_max_bytes is recorded as not explicit, so pixad works out the
+// default when it builds the cache, and that an explicit zero is recorded
+// as explicit, so it disables the disk cache instead.
 func TestCacheMaxBytesExplicitIsRecorded(t *testing.T) {
 	t.Parallel()
 

internal/config/config.go

@@ -45,6 +45,37 @@ func DefaultMaxConcurrentProcessing() int {
 	return max(runtime.GOMAXPROCS(0)/2, 1) //nolint:mnd // half the CPUs
 }
 
+// DefaultCacheMaxBytesFloor is the least DefaultCacheMaxBytes returns:
+// 500 MiB. It applies only to the default, never to an explicit
+// cache_max_bytes.
+const DefaultCacheMaxBytesFloor int64 = 500 << 20
+
+// freeSpaceFractionNumerator and freeSpaceFractionDenominator express
+// the 75% share of DefaultCacheMaxBytes as integer arithmetic (dividing
+// before multiplying avoids overflow).
+const (
+	freeSpaceFractionNumerator   uint64 = 3
+	freeSpaceFractionDenominator uint64 = 4
+)
+
+// DefaultCacheMaxBytes returns the disk cache limit when cache_max_bytes
+// is omitted: 75% of the sum of freeBytes, the space free on the
+// filesystem holding the cache, and heldBytes, the bytes the cache
+// already holds, and at least DefaultCacheMaxBytesFloor. Counting what
+// the cache holds keeps the limit from shrinking as the cache fills.
+// pixad works it out when it builds the cache, as both numbers are known
+// only then.
+func DefaultCacheMaxBytes(freeBytes uint64, heldBytes int64) int64 {
+	// Both terms are at most math.MaxInt64, so the sum cannot overflow.
+	//nolint:gosec // G115: heldBytes is the cache's total, never negative
+	spaceBytes := min(freeBytes, math.MaxInt64) + uint64(heldBytes)
+
+	computed := spaceBytes / freeSpaceFractionDenominator * freeSpaceFractionNumerator
+	computed = min(computed, math.MaxInt64)
+
+	return max(int64(computed), DefaultCacheMaxBytesFloor)
+}
+
 // Configuration key names.
 const (
 	keyDebug                      = "debug"
@@ -91,6 +122,7 @@ var (
 	errNotABoolean       = errors.New("not a boolean")
 	errNotAStringList    = errors.New("not a list of strings")
 	errNotAValidCIDR     = errors.New("not a valid CIDR network")
+	errMappedTooShort    = errors.New("in the IPv4-mapped form but shorter than /96")
 	errNotAMetricsMap    = errors.New("not a map of metrics settings")
 	errEmptyListEntry    = errors.New("list contains an empty entry")
 	errEmptyEntry        = errors.New("contains an empty entry")
@@ -189,18 +221,14 @@ type Config struct {
 	// address, and an explicit list replaces the default.
 	TrustedProxies []netip.Prefix
 
-	// CacheMaxBytes is the disk cache size limit in bytes. Only an
-	// explicit zero (CacheMaxBytesExplicit true) disables the disk
-	// cache. Zero with CacheMaxBytesExplicit false means
-	// cache_max_bytes was omitted, and the cache works out the default
-	// limit when it opens.
+	// CacheMaxBytes is the disk cache size limit in bytes, as set; 0
+	// turns the disk cache off.
 	CacheMaxBytes int64
 
 	// CacheMaxBytesExplicit records whether cache_max_bytes was
 	// explicitly set, in the environment or the configuration file.
-	// Explicit values are used exactly as given; for an omitted key the
-	// cache works out the default limit when it opens (see
-	// imgcache.CacheConfig.UseDefaultMaxBytes).
+	// Explicit values are used exactly as given. For an omitted key
+	// pixad works out DefaultCacheMaxBytes when it builds the cache.
 	CacheMaxBytesExplicit bool
 }
 
@@ -238,8 +266,8 @@ func New(_ fx.Lifecycle, params Params) (*Config, error) {
 		return nil, err
 	}
 
-	// An omitted cache_max_bytes is worked out and logged when the
-	// cache opens.
+	// An omitted cache_max_bytes is worked out and logged when pixad
+	// builds the cache.
 	if c.CacheMaxBytesExplicit {
 		log.Info("effective cache size limit",
 			"cache_max_bytes", c.CacheMaxBytes,
@@ -324,8 +352,8 @@ func newFromSmartConfig(sc *smartconfig.Config) (*Config, error) {
 	}
 
 	// The default for an omitted cache_max_bytes is worked out when
-	// the cache opens; here we only record whether the operator set
-	// the key explicitly.
+	// pixad builds the cache; here we only record whether the operator
+	// set the key explicitly.
 	_, c.CacheMaxBytesExplicit = lookupValue(sc, keyCacheMaxBytes)
 
 	// Build DBURL from StateDir if not explicitly set. The derived URL
@@ -338,8 +366,7 @@ func newFromSmartConfig(sc *smartconfig.Config) (*Config, error) {
 				settingName(keyDBURL), errValueEmpty)
 		}
 
-		// The driver sets the journal mode only through a _pragma parameter.
-		c.DBURL = fmt.Sprintf("file:%s/state.sqlite3?_pragma=journal_mode(WAL)", c.StateDir)
+		c.DBURL = defaultDBURL(c.StateDir)
 	}
 
 	if loader.err != nil {
@@ -354,6 +381,30 @@ func newFromSmartConfig(sc *smartconfig.Config) (*Config, error) {
 	return c, nil
 }
 
+// defaultDBURL returns the db_url used when db_url is omitted: the file
+// state.sqlite3 in stateDir, in WAL mode, which the driver sets only
+// through a _pragma parameter. String() percent-encodes any %, ? or # in
+// the directory name, which SQLite decodes back, so the URL names exactly
+// this file. OmitHost writes file:/var/lib/pixa/... instead of
+// file:///var/lib/pixa/..., and keeps a relative stateDir from being read
+// as a host name. The path written into the URL is stateDir followed by
+// /state.sqlite3; when it starts with //, as it does for a stateDir of /
+// or one starting with //, the empty host is kept, so the URL starts
+// file://// and SQLite does not read the first name in the path as a
+// host.
+func defaultDBURL(stateDir string) string {
+	dbPath := stateDir + "/state.sqlite3"
+
+	dbURL := url.URL{
+		Scheme:   "file",
+		OmitHost: !strings.HasPrefix(dbPath, "//"),
+		Path:     dbPath,
+		RawQuery: "_pragma=journal_mode(WAL)",
+	}
+
+	return dbURL.String()
+}
+
 // validateKnownKeys rejects configuration files containing keys the
 // application does not understand, so typos fail at startup instead of
 // being silently ignored, and rejects keys that are explicitly set to
@@ -1225,6 +1276,13 @@ func defaultTrustedProxies() []netip.Prefix {
 // wrong type, an empty entry, a non-string entry, or an unparseable CIDR
 // aborts startup naming the key and the offending value; the default
 // (an empty list) applies only to an omitted key.
+//
+// An entry written in the IPv4-mapped form (::ffff:a.b.c.d) is kept as the
+// IPv4 range it covers: ::ffff:10.0.0.0/104 is kept as 10.0.0.0/8. Both
+// blocked_networks and trusted_proxies are matched against an IPv4-mapped
+// address as the IPv4 address it holds, so the entry as written would match
+// nothing. Such an entry shorter than /96 covers more than the IPv4
+// addresses and aborts startup.
 func parseCIDRList(sc *smartconfig.Config, key string) ([]netip.Prefix, error) {
 	raw, ok := lookupValue(sc, key)
 	if !ok {
@@ -1240,6 +1298,10 @@ func parseCIDRList(sc *smartconfig.Config, key string) ([]netip.Prefix, error) {
 		return nil, err
 	}
 
+	// An IPv4-mapped address is the 96 bits of ::ffff:0:0/96 followed by
+	// the 32 bits of the IPv4 address it holds.
+	const mappedPrefixBits = 96
+
 	prefixes := make([]netip.Prefix, 0, len(entries))
 
 	for _, entry := range entries {
@@ -1249,6 +1311,16 @@ func parseCIDRList(sc *smartconfig.Config, key string) ([]netip.Prefix, error) {
 				settingName(key), entry, errNotAValidCIDR)
 		}
 
+		if prefix.Addr().Is4In6() && prefix.Bits() < mappedPrefixBits {
+			return nil, fmt.Errorf("%s: value %q is %w",
+				settingName(key), entry, errMappedTooShort)
+		}
+
+		if prefix.Addr().Is4In6() {
+			prefix = netip.PrefixFrom(prefix.Addr().Unmap(),
+				prefix.Bits()-mappedPrefixBits)
+		}
+
 		prefixes = append(prefixes, prefix)
 	}
 

internal/config/config_validation_internal_test.go

@@ -135,6 +135,104 @@ func TestDefaultDBURLOpensTheDatabaseInWALMode(t *testing.T) {
 	}
 }
 
+// TestDerivedDBURLOpensStateDirHoldingURLCharacters opens the db_url
+// derived from a state_dir whose name holds %41, ? and #, and checks that
+// the database is state.sqlite3 in that directory, in WAL mode. Put into
+// a file: URL as it is, the name would lose its meaning: %41 is read as
+// A, and the path ends at the ?, which also loses the journal mode.
+func TestDerivedDBURLOpensStateDirHoldingURLCharacters(t *testing.T) {
+	t.Parallel()
+
+	stateDir := filepath.Join(t.TempDir(), "a%41b?c#d")
+
+	err := os.Mkdir(stateDir, 0o750)
+	if err != nil {
+		t.Fatalf("failed to create %q: %v", stateDir, err)
+	}
+
+	// Quoted so YAML takes the whole name as it is.
+	c, err := configFromYAML(t, signingKeyLine+"state_dir: '"+stateDir+"'\n")
+	if err != nil {
+		t.Fatalf("config with state_dir %q should be valid, got: %v", stateDir, err)
+	}
+
+	t.Logf("state_dir %q gives db_url %q", stateDir, c.DBURL)
+
+	checkDBURLOpensFileInWALMode(t, c.DBURL, filepath.Join(stateDir, "state.sqlite3"))
+}
+
+// TestDerivedDBURLOpensStateDirStartingWithTwoSlashes opens the db_url
+// derived from a state_dir that starts with //, and checks that the
+// database is state.sqlite3 in that directory, in WAL mode. Written right
+// after file:, such a name gives a URL starting file://, and SQLite reads
+// the first directory name as a host and refuses to open it.
+func TestDerivedDBURLOpensStateDirStartingWithTwoSlashes(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	stateDir := "/" + dir
+
+	c, err := configFromYAML(t, signingKeyLine+"state_dir: "+stateDir+"\n")
+	if err != nil {
+		t.Fatalf("config with state_dir %q should be valid, got: %v", stateDir, err)
+	}
+
+	t.Logf("state_dir %q gives db_url %q", stateDir, c.DBURL)
+
+	checkDBURLOpensFileInWALMode(t, c.DBURL, filepath.Join(dir, "state.sqlite3"))
+}
+
+// TestDerivedDBURLForRootStateDir checks the db_url derived from a
+// state_dir of /. The path written into the URL is then
+// //state.sqlite3, and written right after file: it gives a URL starting
+// file://, where SQLite reads state.sqlite3 as a host and refuses to open
+// it. The test only checks the URL, since it cannot write to /.
+func TestDerivedDBURLForRootStateDir(t *testing.T) {
+	t.Parallel()
+
+	c, err := configFromYAML(t, signingKeyLine+"state_dir: /\n")
+	if err != nil {
+		t.Fatalf("config with state_dir / should be valid, got: %v", err)
+	}
+
+	t.Logf("state_dir / gives db_url %q", c.DBURL)
+
+	wantDBURL := "file:////state.sqlite3?_pragma=journal_mode(WAL)"
+	if c.DBURL != wantDBURL {
+		t.Errorf("DBURL = %q, want %q", c.DBURL, wantDBURL)
+	}
+}
+
+// checkDBURLOpensFileInWALMode opens dbURL with the SQLite driver pixad
+// uses, and checks that the database is in WAL mode and is the file
+// dbFile.
+func checkDBURLOpensFileInWALMode(t *testing.T, dbURL, dbFile string) {
+	t.Helper()
+
+	db, err := sql.Open("sqlite", dbURL)
+	if err != nil {
+		t.Fatalf("failed to open %q: %v", dbURL, err)
+	}
+
+	t.Cleanup(func() { _ = db.Close() })
+
+	var journalMode string
+
+	err = db.QueryRowContext(t.Context(), "PRAGMA journal_mode").Scan(&journalMode)
+	if err != nil {
+		t.Fatalf("failed to read the journal mode of %q: %v", dbURL, err)
+	}
+
+	if journalMode != "wal" {
+		t.Errorf("journal mode of %q = %q, want wal", dbURL, journalMode)
+	}
+
+	_, err = os.Stat(dbFile)
+	if err != nil {
+		t.Errorf("opening %q did not create %q: %v", dbURL, dbFile, err)
+	}
+}
+
 func TestExplicitValidValuesAreUsed(t *testing.T) {
 	t.Parallel()
 

internal/config/trusted_proxies_internal_test.go

@@ -83,3 +83,41 @@ func TestTrustedProxiesInvalidAbortsStartup(t *testing.T) {
 		},
 	})
 }
+
+// TestTrustedProxiesMappedEntryIsIPv4Range checks that an entry written in
+// the IPv4-mapped form (::ffff:a.b.c.d) is kept as the IPv4 range it covers,
+// since the client address is matched as the IPv4 address it holds. /96, the
+// shortest such entry, covers every IPv4 address.
+func TestTrustedProxiesMappedEntryIsIPv4Range(t *testing.T) {
+	t.Parallel()
+
+	c, err := configFromYAML(t, signingKeyLine+
+		`trusted_proxies: ["::ffff:10.0.0.0/104", "::ffff:0:0/96"]`+"\n")
+	if err != nil {
+		t.Fatalf("IPv4-mapped trusted_proxies entries should load: %v", err)
+	}
+
+	got := make([]string, len(c.TrustedProxies))
+	for i, p := range c.TrustedProxies {
+		got[i] = p.String()
+	}
+
+	if joined := strings.Join(got, ","); joined != "10.0.0.0/8,0.0.0.0/0" {
+		t.Errorf("TrustedProxies = %v, want 10.0.0.0/8 and 0.0.0.0/0", got)
+	}
+}
+
+// TestTrustedProxiesMappedEntryShorterThan96AbortsStartup checks that an
+// entry in the IPv4-mapped form shorter than /96, which covers more than the
+// IPv4 addresses, aborts startup with an error naming the key and the value.
+func TestTrustedProxiesMappedEntryShorterThan96AbortsStartup(t *testing.T) {
+	t.Parallel()
+
+	runAbortCases(t, []abortCase{
+		{
+			name:              "mapped-95",
+			yaml:              signingKeyLine + `trusted_proxies: ["::ffff:0:0/95"]` + "\n",
+			wantErrSubstrings: []string{keyTrustedProxies, "::ffff:0:0/95"},
+		},
+	})
+}

internal/database/concurrent_writes_internal_test.go

@@ -104,40 +104,31 @@ func writeConcurrently(t *testing.T, db *sql.DB) {
 
 	wg.Wait()
 
-	var hits, sources int
+	var sources int
 
-	err := db.QueryRowContext(ctx, `
-		SELECT hit_count, (SELECT COUNT(*) FROM source_content)
-		FROM cache_stats WHERE id = 1
-	`).Scan(&hits, &sources)
+	err := db.QueryRowContext(ctx, `SELECT COUNT(*) FROM source_content`).
+		Scan(&sources)
 	if err != nil {
 		t.Fatalf("failed to count the writes: %v", err)
 	}
 
-	if hits != totalRequests || sources != totalRequests {
-		t.Errorf("hit_count = %d and %d source_content rows, want %d of each",
-			hits, sources, totalRequests)
+	if sources != totalRequests {
+		t.Errorf("%d source_content rows, want %d", sources, totalRequests)
 	}
 }
 
 // writeLikeOneRequest makes the writes one request and the eviction pass
-// make: it counts a cache hit, stores a source, records a transformed image
-// and deletes that record again.
+// make: it stores a source, records a transformed image and deletes that
+// record again.
 func writeLikeOneRequest(ctx context.Context, db *sql.DB, key string) error {
-	_, err := db.ExecContext(ctx,
-		`UPDATE cache_stats SET hit_count = hit_count + 1 WHERE id = 1`)
-	if err != nil {
-		return fmt.Errorf("counting a cache hit: %w", err)
-	}
-
-	_, err = db.ExecContext(ctx, `INSERT INTO source_content
-		(content_hash, content_type, size_bytes) VALUES (?, 'image/png', 1)`, key)
+	_, err := db.ExecContext(ctx, `INSERT INTO source_content
+		(source_key, size_bytes) VALUES (?, 1)`, key)
 	if err != nil {
 		return fmt.Errorf("storing a source: %w", err)
 	}
 
 	_, err = db.ExecContext(ctx, `INSERT INTO variant_content
-		(cache_key, size_bytes, content_type) VALUES (?, 1, 'image/png')`, key)
+		(cache_key, size_bytes) VALUES (?, 1)`, key)
 	if err != nil {
 		return fmt.Errorf("recording a transformed image: %w", err)
 	}

internal/database/database.go

@@ -82,7 +82,11 @@ func ParseMigrationVersion(filename string) (int, error) {
 	return version, nil
 }
 
-// New creates a new Database instance.
+// New opens the database and applies the migrations, so that the parts
+// fx builds after it can read the database while they are built. Its
+// stop hook closes the database. fx runs stop hooks in the reverse of the
+// order it built their parts in, so the stop hooks of those parts run
+// before this one.
 func New(lc fx.Lifecycle, params Params) (*Database, error) {
 	s := &Database{
 		log:    params.Logger.Get(),
@@ -91,20 +95,16 @@ func New(lc fx.Lifecycle, params Params) (*Database, error) {
 
 	s.log.Info("Database instantiated")
 
-	lc.Append(fx.Hook{
-		OnStart: func(ctx context.Context) error {
-			s.log.Info("Database OnStart Hook")
+	err := s.connect(context.Background())
+	if err != nil {
+		return nil, err
+	}
 
-			return s.connect(ctx)
-		},
+	lc.Append(fx.Hook{
 		OnStop: func(_ context.Context) error {
 			s.log.Info("Database OnStop Hook")
 
-			if s.db != nil {
-				return s.db.Close()
-			}
-
-			return nil
+			return s.db.Close()
 		},
 	})
 

internal/database/database_internal_test.go

@@ -159,10 +159,7 @@ func TestApplyMigrations_CreatesSchemaAndTables(t *testing.T) {
 	}
 
 	// Verify that the application tables created by 001.sql exist.
-	tables := []string{
-		"source_content", "source_metadata", "output_content",
-		"request_cache", "negative_cache", "cache_stats",
-	}
+	tables := []string{"source_content", "negative_cache"}
 	for _, table := range tables {
 		var count int
 

internal/db/migrations/001_schema.sql

@@ -1,52 +1,27 @@
 -- Migration 001: Initial schema
 -- Creates all tables for the pixa caching image proxy
 
--- Source content blobs
--- Files stored at: cache/sources/<ab>/<cd>/<sha256>
+-- Source images, one row per source URL
+-- Files stored at: cache/sources/<ab>/<cd>/<source_key>, where source_key
+-- is the SHA-256 of the source's host, path and query
 CREATE TABLE IF NOT EXISTS source_content (
-    content_hash TEXT PRIMARY KEY,
-    content_type TEXT NOT NULL,
+    source_key TEXT PRIMARY KEY,
     size_bytes INTEGER NOT NULL,
-    fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     last_accessed_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
 );
 CREATE INDEX IF NOT EXISTS idx_source_content_last_accessed
     ON source_content(last_accessed_at);
 
--- Source URL metadata - maps URLs to content hashes
--- JSON stored at: cache/metadata/<hostname>/<path_hash>.json
-CREATE TABLE IF NOT EXISTS source_metadata (
-    id INTEGER PRIMARY KEY AUTOINCREMENT,
-    source_host TEXT NOT NULL,
-    source_path TEXT NOT NULL,
-    source_query TEXT NOT NULL DEFAULT '',
-    path_hash TEXT NOT NULL,
-    content_hash TEXT,
-    status_code INTEGER NOT NULL,
-    content_type TEXT,
-    response_headers TEXT,
-    fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
-    expires_at DATETIME,
-    etag TEXT,
-    last_modified TEXT,
-    UNIQUE(source_host, source_path, source_query),
-    FOREIGN KEY (content_hash) REFERENCES source_content(content_hash)
-);
-CREATE INDEX IF NOT EXISTS idx_source_meta_host ON source_metadata(source_host);
-CREATE INDEX IF NOT EXISTS idx_source_meta_path_hash ON source_metadata(path_hash);
-CREATE INDEX IF NOT EXISTS idx_source_meta_expires ON source_metadata(expires_at);
-CREATE INDEX IF NOT EXISTS idx_source_meta_content_hash ON source_metadata(content_hash);
-
 -- Processed variant blobs
--- Files stored at: cache/variants/<ab>/<cd>/<cache_key> (plus a .meta
--- sidecar with the content type). Tracked here (like source content
--- blobs above) so total cache usage is known without a directory scan,
--- and so LRU eviction has a timestamp to order on.
+-- Files stored at: cache/variants/<ab>/<cd>/<cache_key>. Tracked here
+-- (like source content blobs above) so total cache usage is known
+-- without a directory scan, and so LRU eviction has a timestamp to order
+-- on. A cache hit does not read this table: it takes the content type
+-- from the file's first bytes, and its last_accessed_at is written
+-- later, in a batch.
 CREATE TABLE IF NOT EXISTS variant_content (
     cache_key TEXT PRIMARY KEY,
     size_bytes INTEGER NOT NULL,
-    content_type TEXT NOT NULL,
-    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
     last_accessed_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
 );
 CREATE INDEX IF NOT EXISTS idx_variant_content_last_accessed
@@ -120,63 +95,19 @@ BEGIN
     WHERE id = 1;
 END;
 
--- Output/transformed content blobs
--- Not written: transformed images are stored in cache/variants and
--- tracked in variant_content above.
-CREATE TABLE IF NOT EXISTS output_content (
-    content_hash TEXT PRIMARY KEY,
-    content_type TEXT NOT NULL,
-    size_bytes INTEGER NOT NULL,
-    fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP
-);
-
--- Request cache - maps full request params to output content
-CREATE TABLE IF NOT EXISTS request_cache (
-    id INTEGER PRIMARY KEY AUTOINCREMENT,
-    cache_key TEXT NOT NULL UNIQUE,
-    source_metadata_id INTEGER NOT NULL,
-    output_hash TEXT NOT NULL,
-    width INTEGER NOT NULL,
-    height INTEGER NOT NULL,
-    format TEXT NOT NULL,
-    quality INTEGER NOT NULL DEFAULT 85,
-    fit_mode TEXT NOT NULL DEFAULT 'cover',
-    fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
-    access_count INTEGER NOT NULL DEFAULT 1,
-    FOREIGN KEY (source_metadata_id) REFERENCES source_metadata(id),
-    FOREIGN KEY (output_hash) REFERENCES output_content(content_hash)
-);
-CREATE INDEX IF NOT EXISTS idx_request_cache_key ON request_cache(cache_key);
-CREATE INDEX IF NOT EXISTS idx_request_cache_source ON request_cache(source_metadata_id);
-CREATE INDEX IF NOT EXISTS idx_request_cache_output ON request_cache(output_hash);
-CREATE INDEX IF NOT EXISTS idx_request_cache_fetched ON request_cache(fetched_at);
-
--- Negative cache for failed fetches (404s, timeouts, etc.)
+-- Negative cache: source URLs whose fetch failed with an upstream error
+-- status, or whose first bytes did not match their Content-Type. pixa does
+-- not fetch such a URL again until its row expires.
 CREATE TABLE IF NOT EXISTS negative_cache (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
     source_host TEXT NOT NULL,
     source_path TEXT NOT NULL,
     source_query TEXT NOT NULL DEFAULT '',
-    status_code INTEGER NOT NULL,
-    error_message TEXT,
-    fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     expires_at DATETIME NOT NULL,
     UNIQUE(source_host, source_path, source_query)
 );
 CREATE INDEX IF NOT EXISTS idx_negative_cache_expires ON negative_cache(expires_at);
 
--- Cache statistics for monitoring
-CREATE TABLE IF NOT EXISTS cache_stats (
-    id INTEGER PRIMARY KEY CHECK (id = 1),
-    hit_count INTEGER NOT NULL DEFAULT 0,
-    miss_count INTEGER NOT NULL DEFAULT 0,
-    upstream_fetch_count INTEGER NOT NULL DEFAULT 0,
-    upstream_fetch_bytes INTEGER NOT NULL DEFAULT 0,
-    transform_count INTEGER NOT NULL DEFAULT 0,
-    last_updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
-);
-INSERT OR IGNORE INTO cache_stats (id) VALUES (1);
-
 -- A random value that a login session carries from its login. pixa makes it
 -- when the table has no row, and each logout replaces it; a login session
 -- carrying another value is refused, so logging out ends every login session.

internal/encurl/encurl.go

@@ -7,18 +7,15 @@ import (
 
 	"github.com/fxamacker/cbor/v2"
 
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/seal"
 )
 
 // Default values for optional fields.
 const (
 	DefaultQuality = 85
-	DefaultFormat  = imgcache.FormatJXL
-	DefaultFitMode = imgcache.FitCover
-
-	// HKDF salt for URL encryption key derivation
-	urlKeySalt = "pixa-urlenc-v1"
+	DefaultFormat  = imagerequest.FormatJXL
+	DefaultFitMode = imagerequest.FitCover
 )
 
 // Errors returned by encurl operations.
@@ -28,19 +25,19 @@ var (
 	ErrDecryptFailed = errors.New("failed to decrypt URL")
 )
 
-// Payload contains all image request parameters in a compact format.
+// payload contains all image request parameters in a compact format.
 // Field names are short to minimize encoded size.
 // Fields with omitempty use sane defaults when absent.
-type Payload struct {
-	SourceHost  string               `cbor:"h"`            // required
-	SourcePath  string               `cbor:"p"`            // required
-	SourceQuery string               `cbor:"q,omitempty"`  // optional
-	Width       int                  `cbor:"w,omitempty"`  // 0 = original
-	Height      int                  `cbor:"ht,omitempty"` // 0 = original
-	Format      imgcache.ImageFormat `cbor:"f,omitempty"`  // default: jxl
-	Quality     int                  `cbor:"ql,omitempty"` // default: 85
-	FitMode     imgcache.FitMode     `cbor:"fm,omitempty"` // default: cover
-	ExpiresAt   int64                `cbor:"e,omitempty"`  // 0 = never expires
+type payload struct {
+	SourceHost  string              `cbor:"h"`            // required
+	SourcePath  string              `cbor:"p"`            // required
+	SourceQuery string              `cbor:"q,omitempty"`  // optional
+	Width       int                 `cbor:"w,omitempty"`  // 0 = original
+	Height      int                 `cbor:"ht,omitempty"` // 0 = original
+	Format      imagerequest.Format `cbor:"f,omitempty"`  // default: jxl
+	Quality     int                 `cbor:"ql,omitempty"` // default: 85
+	FitMode     imagerequest.Fit    `cbor:"fm,omitempty"` // default: cover
+	ExpiresAt   int64               `cbor:"e,omitempty"`  // 0 = never expires
 }
 
 // Generator creates and parses encrypted URL tokens.
@@ -48,20 +45,35 @@ type Generator struct {
 	key [seal.KeySize]byte
 }
 
-// NewGenerator creates an encrypted URL generator with a key derived
-// from the signing key.
-func NewGenerator(signingKey string) (*Generator, error) {
-	key, err := seal.DeriveKey([]byte(signingKey), urlKeySalt)
-	if err != nil {
-		return nil, err
-	}
-
-	return &Generator{key: key}, nil
+// NewGenerator creates an encrypted URL generator that encrypts its tokens
+// with key.
+func NewGenerator(key [seal.KeySize]byte) *Generator {
+	return &Generator{key: key}
 }
 
-// Generate creates an encrypted URL token from the payload.
-// The token is CBOR-encoded, encrypted with NaCl secretbox, and base64url-encoded.
-func (g *Generator) Generate(p *Payload) (string, error) {
+// Generate creates an encrypted URL token from the request's source and
+// transform, each as the request holds it, and from expires; an empty format,
+// a quality of 0 or an empty fit mode is left out of the token, and a zero
+// expires makes a token that never expires. The token is CBOR-encoded,
+// encrypted with NaCl secretbox, and base64url-encoded.
+func (g *Generator) Generate(
+	req *imagerequest.Request, expires time.Time,
+) (string, error) {
+	p := &payload{
+		SourceHost:  req.Source.Host,
+		SourcePath:  req.Source.Path,
+		SourceQuery: req.Source.Query,
+		Width:       req.Transform.Size.Width,
+		Height:      req.Transform.Size.Height,
+		Format:      req.Transform.Format,
+		Quality:     req.Transform.Quality,
+		FitMode:     req.Transform.FitMode,
+	}
+
+	if !expires.IsZero() {
+		p.ExpiresAt = expires.Unix()
+	}
+
 	// CBOR encode the payload
 	data, err := cbor.Marshal(p)
 	if err != nil {
@@ -72,40 +84,35 @@ func (g *Generator) Generate(p *Payload) (string, error) {
 	return seal.Encrypt(g.key, data)
 }
 
-// Parse decrypts and validates an encrypted URL token.
+// Parse decrypts and validates an encrypted URL token and returns the
+// request it holds, with default values for omitted optional fields, and its
+// expiry. A token that never expires gives the zero time.
 // Returns ErrExpired if the token has expired, or other errors for invalid tokens.
-func (g *Generator) Parse(token string) (*Payload, error) {
+func (g *Generator) Parse(token string) (*imagerequest.Request, time.Time, error) {
 	// Decrypt
 	data, err := seal.Decrypt(g.key, token)
 	if err != nil {
 		if errors.Is(err, seal.ErrDecryptionFailed) ||
 			errors.Is(err, seal.ErrInvalidPayload) {
-			return nil, ErrDecryptFailed
+			return nil, time.Time{}, ErrDecryptFailed
 		}
 
-		return nil, err
+		return nil, time.Time{}, err
 	}
 
 	// CBOR decode
-	var p Payload
+	var p payload
 
 	err = cbor.Unmarshal(data, &p)
 	if err != nil {
-		return nil, ErrInvalidFormat
+		return nil, time.Time{}, ErrInvalidFormat
 	}
 
 	// Check expiration (0 = never expires)
 	if p.ExpiresAt != 0 && time.Now().Unix() > p.ExpiresAt {
-		return nil, ErrExpired
+		return nil, time.Time{}, ErrExpired
 	}
 
-	return &p, nil
-}
-
-// ToImageRequest converts the payload to an ImageRequest.
-// Applies default values for omitted optional fields. An ExpiresAt of 0, a URL
-// that never expires, gives the zero Expires.
-func (p *Payload) ToImageRequest() *imgcache.ImageRequest {
 	format := p.Format
 	if format == "" {
 		format = DefaultFormat
@@ -126,44 +133,17 @@ func (p *Payload) ToImageRequest() *imgcache.ImageRequest {
 		expires = time.Unix(p.ExpiresAt, 0)
 	}
 
-	return &imgcache.ImageRequest{
-		SourceHost:  p.SourceHost,
-		SourcePath:  p.SourcePath,
-		SourceQuery: p.SourceQuery,
-		Size: imgcache.Size{
-			Width:  p.Width,
-			Height: p.Height,
+	return &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host:  p.SourceHost,
+			Path:  p.SourcePath,
+			Query: p.SourceQuery,
 		},
-		Format:  format,
-		Quality: quality,
-		FitMode: fitMode,
-		Expires: expires,
-	}
-}
-
-// FromImageRequest creates a Payload from an ImageRequest with the given expiration.
-func FromImageRequest(req *imgcache.ImageRequest, expiresAt time.Time) *Payload {
-	p := &Payload{
-		SourceHost:  req.SourceHost,
-		SourcePath:  req.SourcePath,
-		SourceQuery: req.SourceQuery,
-		Width:       req.Size.Width,
-		Height:      req.Size.Height,
-		ExpiresAt:   expiresAt.Unix(),
-	}
-
-	// Only set non-default values to benefit from omitempty
-	if req.Format != "" && req.Format != DefaultFormat {
-		p.Format = req.Format
-	}
-
-	if req.Quality != 0 && req.Quality != DefaultQuality {
-		p.Quality = req.Quality
-	}
-
-	if req.FitMode != "" && req.FitMode != DefaultFitMode {
-		p.FitMode = req.FitMode
-	}
-
-	return p
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: p.Width, Height: p.Height},
+			Format:  format,
+			Quality: quality,
+			FitMode: fitMode,
+		},
+	}, expires, nil
 }

internal/encurl/encurl_test.go

@@ -6,7 +6,8 @@ import (
 	"time"
 
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/seal"
 )
 
 // Shared test fixture strings.
@@ -19,24 +20,29 @@ const (
 func TestGenerator_GenerateAndParse(t *testing.T) {
 	t.Parallel()
 
-	gen, err := encurl.NewGenerator("test-signing-key-12345")
+	keys, err := seal.DeriveKeys("test-signing-key-12345")
 	if err != nil {
-		t.Fatalf("NewGenerator() error = %v", err)
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
 	}
 
-	payload := &encurl.Payload{
-		SourceHost:  testSourceHost,
-		SourcePath:  testSourcePath,
-		SourceQuery: testSourceQuery,
-		Width:       800,
-		Height:      600,
-		Format:      imgcache.FormatWebP,
-		Quality:     90,
-		FitMode:     imgcache.FitContain,
-		ExpiresAt:   time.Now().Add(time.Hour).Unix(),
-	}
+	gen := encurl.NewGenerator(keys.EncryptedURLKey)
 
-	token, err := gen.Generate(payload)
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host:  testSourceHost,
+			Path:  testSourcePath,
+			Query: testSourceQuery,
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 800, Height: 600},
+			Format:  imagerequest.FormatWebP,
+			Quality: 90,
+			FitMode: imagerequest.FitContain,
+		},
+	}
+	expires := time.Now().Add(time.Hour)
+
+	token, err := gen.Generate(req, expires)
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
@@ -45,66 +51,73 @@ func TestGenerator_GenerateAndParse(t *testing.T) {
 		t.Fatal("Generate() returned empty token")
 	}
 
-	parsed, err := gen.Parse(token)
+	parsed, parsedExpires, err := gen.Parse(token)
 	if err != nil {
 		t.Fatalf("Parse() error = %v", err)
 	}
 
 	// Verify all fields
-	if parsed.SourceHost != payload.SourceHost {
-		t.Errorf("SourceHost = %q, want %q", parsed.SourceHost, payload.SourceHost)
+	if parsed.Source.Host != req.Source.Host {
+		t.Errorf("SourceHost = %q, want %q", parsed.Source.Host, req.Source.Host)
 	}
 
-	if parsed.SourcePath != payload.SourcePath {
-		t.Errorf("SourcePath = %q, want %q", parsed.SourcePath, payload.SourcePath)
+	if parsed.Source.Path != req.Source.Path {
+		t.Errorf("SourcePath = %q, want %q", parsed.Source.Path, req.Source.Path)
 	}
 
-	if parsed.SourceQuery != payload.SourceQuery {
-		t.Errorf("SourceQuery = %q, want %q", parsed.SourceQuery, payload.SourceQuery)
+	if parsed.Source.Query != req.Source.Query {
+		t.Errorf("SourceQuery = %q, want %q", parsed.Source.Query, req.Source.Query)
 	}
 
-	if parsed.Width != payload.Width {
-		t.Errorf("Width = %d, want %d", parsed.Width, payload.Width)
+	if parsed.Transform.Size.Width != req.Transform.Size.Width {
+		t.Errorf("Width = %d, want %d",
+			parsed.Transform.Size.Width, req.Transform.Size.Width)
 	}
 
-	if parsed.Height != payload.Height {
-		t.Errorf("Height = %d, want %d", parsed.Height, payload.Height)
+	if parsed.Transform.Size.Height != req.Transform.Size.Height {
+		t.Errorf("Height = %d, want %d",
+			parsed.Transform.Size.Height, req.Transform.Size.Height)
 	}
 
-	if parsed.Format != payload.Format {
-		t.Errorf("Format = %q, want %q", parsed.Format, payload.Format)
+	if parsed.Transform.Format != req.Transform.Format {
+		t.Errorf("Format = %q, want %q",
+			parsed.Transform.Format, req.Transform.Format)
 	}
 
-	if parsed.Quality != payload.Quality {
-		t.Errorf("Quality = %d, want %d", parsed.Quality, payload.Quality)
+	if parsed.Transform.Quality != req.Transform.Quality {
+		t.Errorf("Quality = %d, want %d",
+			parsed.Transform.Quality, req.Transform.Quality)
 	}
 
-	if parsed.FitMode != payload.FitMode {
-		t.Errorf("FitMode = %q, want %q", parsed.FitMode, payload.FitMode)
+	if parsed.Transform.FitMode != req.Transform.FitMode {
+		t.Errorf("FitMode = %q, want %q",
+			parsed.Transform.FitMode, req.Transform.FitMode)
 	}
 
-	if parsed.ExpiresAt != payload.ExpiresAt {
-		t.Errorf("ExpiresAt = %d, want %d", parsed.ExpiresAt, payload.ExpiresAt)
+	if parsedExpires.Unix() != expires.Unix() {
+		t.Errorf("ExpiresAt = %d, want %d", parsedExpires.Unix(), expires.Unix())
 	}
 }
 
 func TestGenerator_Parse_Expired(t *testing.T) {
 	t.Parallel()
 
-	gen, _ := encurl.NewGenerator("test-signing-key-12345")
+	keys, _ := seal.DeriveKeys("test-signing-key-12345")
+	gen := encurl.NewGenerator(keys.EncryptedURLKey)
 
-	payload := &encurl.Payload{
-		SourceHost: testSourceHost,
-		SourcePath: testSourcePath,
-		ExpiresAt:  time.Now().Add(-time.Hour).Unix(), // Already expired
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testSourceHost,
+			Path: testSourcePath,
+		},
 	}
 
-	token, err := gen.Generate(payload)
+	token, err := gen.Generate(req, time.Now().Add(-time.Hour)) // Already expired
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
 
-	_, err = gen.Parse(token)
+	_, _, err = gen.Parse(token)
 	if err == nil {
 		t.Error("Parse() should fail for expired token")
 	}
@@ -117,9 +130,10 @@ func TestGenerator_Parse_Expired(t *testing.T) {
 func TestGenerator_Parse_InvalidToken(t *testing.T) {
 	t.Parallel()
 
-	gen, _ := encurl.NewGenerator("test-signing-key-12345")
+	keys, _ := seal.DeriveKeys("test-signing-key-12345")
+	gen := encurl.NewGenerator(keys.EncryptedURLKey)
 
-	_, err := gen.Parse("not-a-valid-token")
+	_, _, err := gen.Parse("not-a-valid-token")
 	if err == nil {
 		t.Error("Parse() should fail for invalid token")
 	}
@@ -128,15 +142,17 @@ func TestGenerator_Parse_InvalidToken(t *testing.T) {
 func TestGenerator_Parse_TamperedToken(t *testing.T) {
 	t.Parallel()
 
-	gen, _ := encurl.NewGenerator("test-signing-key-12345")
+	keys, _ := seal.DeriveKeys("test-signing-key-12345")
+	gen := encurl.NewGenerator(keys.EncryptedURLKey)
 
-	payload := &encurl.Payload{
-		SourceHost: testSourceHost,
-		SourcePath: testSourcePath,
-		ExpiresAt:  time.Now().Add(time.Hour).Unix(),
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testSourceHost,
+			Path: testSourcePath,
+		},
 	}
 
-	token, _ := gen.Generate(payload)
+	token, _ := gen.Generate(req, time.Now().Add(time.Hour))
 
 	// Tamper with the token
 	tampered := []byte(token)
@@ -144,7 +160,7 @@ func TestGenerator_Parse_TamperedToken(t *testing.T) {
 		tampered[10] ^= 0x01
 	}
 
-	_, err := gen.Parse(string(tampered))
+	_, _, err := gen.Parse(string(tampered))
 	if err == nil {
 		t.Error("Parse() should fail for tampered token")
 	}
@@ -153,172 +169,78 @@ func TestGenerator_Parse_TamperedToken(t *testing.T) {
 func TestGenerator_Parse_WrongKey(t *testing.T) {
 	t.Parallel()
 
-	gen1, _ := encurl.NewGenerator("signing-key-1")
-	gen2, _ := encurl.NewGenerator("signing-key-2")
+	keys1, _ := seal.DeriveKeys("signing-key-1")
+	keys2, _ := seal.DeriveKeys("signing-key-2")
+	gen1 := encurl.NewGenerator(keys1.EncryptedURLKey)
+	gen2 := encurl.NewGenerator(keys2.EncryptedURLKey)
 
-	payload := &encurl.Payload{
-		SourceHost: testSourceHost,
-		SourcePath: testSourcePath,
-		ExpiresAt:  time.Now().Add(time.Hour).Unix(),
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testSourceHost,
+			Path: testSourcePath,
+		},
 	}
 
-	token, _ := gen1.Generate(payload)
+	token, _ := gen1.Generate(req, time.Now().Add(time.Hour))
 
-	_, err := gen2.Parse(token)
+	_, _, err := gen2.Parse(token)
 	if err == nil {
 		t.Error("Parse() should fail with different signing key")
 	}
 }
 
-func TestPayload_ToImageRequest(t *testing.T) {
+func TestGenerator_Parse_Defaults(t *testing.T) {
 	t.Parallel()
 
-	payload := &encurl.Payload{
-		SourceHost:  testSourceHost,
-		SourcePath:  testSourcePath,
-		SourceQuery: testSourceQuery,
-		Width:       800,
-		Height:      600,
-		Format:      imgcache.FormatWebP,
-		Quality:     90,
-		FitMode:     imgcache.FitContain,
-		ExpiresAt:   time.Now().Add(time.Hour).Unix(),
+	keys, _ := seal.DeriveKeys("test-signing-key-12345")
+	gen := encurl.NewGenerator(keys.EncryptedURLKey)
+
+	// Request with only required fields - should get defaults
+	token, err := gen.Generate(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testSourceHost,
+			Path: testSourcePath,
+		},
+	}, time.Now().Add(time.Hour))
+	if err != nil {
+		t.Fatalf("Generate() error = %v", err)
 	}
 
-	req := payload.ToImageRequest()
-
-	if req.SourceHost != payload.SourceHost {
-		t.Errorf("SourceHost = %q, want %q", req.SourceHost, payload.SourceHost)
+	req, _, err := gen.Parse(token)
+	if err != nil {
+		t.Fatalf("Parse() error = %v", err)
 	}
 
-	if req.SourcePath != payload.SourcePath {
-		t.Errorf("SourcePath = %q, want %q", req.SourcePath, payload.SourcePath)
+	if req.Transform.Format != encurl.DefaultFormat {
+		t.Errorf("Format = %q, want default %q",
+			req.Transform.Format, encurl.DefaultFormat)
 	}
 
-	if req.SourceQuery != payload.SourceQuery {
-		t.Errorf("SourceQuery = %q, want %q", req.SourceQuery, payload.SourceQuery)
+	if req.Transform.Quality != encurl.DefaultQuality {
+		t.Errorf("Quality = %d, want default %d",
+			req.Transform.Quality, encurl.DefaultQuality)
 	}
 
-	if req.Size.Width != payload.Width {
-		t.Errorf("Width = %d, want %d", req.Size.Width, payload.Width)
-	}
-
-	if req.Size.Height != payload.Height {
-		t.Errorf("Height = %d, want %d", req.Size.Height, payload.Height)
-	}
-
-	if req.Format != payload.Format {
-		t.Errorf("Format = %q, want %q", req.Format, payload.Format)
-	}
-
-	if req.Quality != payload.Quality {
-		t.Errorf("Quality = %d, want %d", req.Quality, payload.Quality)
-	}
-
-	if req.FitMode != payload.FitMode {
-		t.Errorf("FitMode = %q, want %q", req.FitMode, payload.FitMode)
-	}
-}
-
-func TestPayload_ToImageRequest_Defaults(t *testing.T) {
-	t.Parallel()
-
-	// Payload with only required fields - should get defaults
-	payload := &encurl.Payload{
-		SourceHost: testSourceHost,
-		SourcePath: testSourcePath,
-		ExpiresAt:  time.Now().Add(time.Hour).Unix(),
-	}
-
-	req := payload.ToImageRequest()
-
-	if req.Format != encurl.DefaultFormat {
-		t.Errorf("Format = %q, want default %q", req.Format, encurl.DefaultFormat)
-	}
-
-	if req.Quality != encurl.DefaultQuality {
-		t.Errorf("Quality = %d, want default %d", req.Quality, encurl.DefaultQuality)
-	}
-
-	if req.FitMode != encurl.DefaultFitMode {
-		t.Errorf("FitMode = %q, want default %q", req.FitMode, encurl.DefaultFitMode)
-	}
-}
-
-func TestFromImageRequest(t *testing.T) {
-	t.Parallel()
-
-	req := &imgcache.ImageRequest{
-		SourceHost:  testSourceHost,
-		SourcePath:  testSourcePath,
-		SourceQuery: testSourceQuery,
-		Size:        imgcache.Size{Width: 800, Height: 600},
-		Format:      imgcache.FormatWebP,
-		Quality:     90,
-		FitMode:     imgcache.FitContain,
-	}
-
-	expiresAt := time.Now().Add(time.Hour)
-	payload := encurl.FromImageRequest(req, expiresAt)
-
-	if payload.SourceHost != req.SourceHost {
-		t.Errorf("SourceHost = %q, want %q", payload.SourceHost, req.SourceHost)
-	}
-
-	if payload.SourcePath != req.SourcePath {
-		t.Errorf("SourcePath = %q, want %q", payload.SourcePath, req.SourcePath)
-	}
-
-	if payload.Width != req.Size.Width {
-		t.Errorf("Width = %d, want %d", payload.Width, req.Size.Width)
-	}
-
-	if payload.ExpiresAt != expiresAt.Unix() {
-		t.Errorf("ExpiresAt = %d, want %d", payload.ExpiresAt, expiresAt.Unix())
-	}
-}
-
-func TestFromImageRequest_OmitsDefaults(t *testing.T) {
-	t.Parallel()
-
-	// Request with default values - payload should omit them for
-	// smaller encoding
-	req := &imgcache.ImageRequest{
-		SourceHost: testSourceHost,
-		SourcePath: testSourcePath,
-		Format:     encurl.DefaultFormat,
-		Quality:    encurl.DefaultQuality,
-		FitMode:    encurl.DefaultFitMode,
-	}
-
-	payload := encurl.FromImageRequest(req, time.Now().Add(time.Hour))
-
-	// These should be zero/empty because they match defaults
-	if payload.Format != "" {
-		t.Errorf("Format should be empty for default, got %q", payload.Format)
-	}
-
-	if payload.Quality != 0 {
-		t.Errorf("Quality should be 0 for default, got %d", payload.Quality)
-	}
-
-	if payload.FitMode != "" {
-		t.Errorf("FitMode should be empty for default, got %q", payload.FitMode)
+	if req.Transform.FitMode != encurl.DefaultFitMode {
+		t.Errorf("FitMode = %q, want default %q",
+			req.Transform.FitMode, encurl.DefaultFitMode)
 	}
 }
 
 func TestGenerator_TokenIsURLSafe(t *testing.T) {
 	t.Parallel()
 
-	gen, _ := encurl.NewGenerator("test-signing-key-12345")
+	keys, _ := seal.DeriveKeys("test-signing-key-12345")
+	gen := encurl.NewGenerator(keys.EncryptedURLKey)
 
-	payload := &encurl.Payload{
-		SourceHost: testSourceHost,
-		SourcePath: testSourcePath,
-		ExpiresAt:  time.Now().Add(time.Hour).Unix(),
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testSourceHost,
+			Path: testSourcePath,
+		},
 	}
 
-	token, _ := gen.Generate(payload)
+	token, _ := gen.Generate(req, time.Now().Add(time.Hour))
 
 	// Check that token only contains URL-safe characters
 	for _, c := range token {

internal/handlers/auth.go

@@ -9,12 +9,14 @@ import (
 	"math"
 	"net/http"
 	"net/url"
+	"slices"
 	"strconv"
+	"strings"
 	"time"
 
 	"sneak.berlin/go/pixa/internal/clientip"
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/templates"
 )
 
@@ -125,7 +127,7 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 		sourceURL := r.FormValue("url")
 
 		// Validate source URL
-		parsed, err := url.Parse(sourceURL)
+		parsed, err := parseSourceURL(sourceURL)
 		if err != nil || parsed.Host == "" {
 			s.renderGeneratorWithForm(w, r, "Invalid source URL", r.Form,
 				http.StatusBadRequest)
@@ -133,7 +135,17 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 			return
 		}
 
-		payload, expiresAt, ttl, err := buildGeneratePayload(parsed, r.Form)
+		// /v1/image/ refuses a ".." segment in the source path, and so does
+		// the generator. The path is decoded, so %2e%2e counts too
+		if slices.Contains(strings.Split(parsed.Path, "/"), "..") {
+			s.renderGeneratorWithForm(w, r,
+				"Source URL path cannot hold a .. segment", r.Form,
+				http.StatusBadRequest)
+
+			return
+		}
+
+		req, expiresAt, ttl, err := buildGenerateRequest(parsed, r.Form)
 		if err != nil {
 			s.renderGeneratorWithForm(w, r, err.Error(), r.Form,
 				http.StatusBadRequest)
@@ -141,8 +153,20 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 			return
 		}
 
+		// The image URL must fetch the source URL as it was written. The
+		// fetcher fetches over http only when allow_http is set.
+		fetchURL := req.Source.URL(s.config.AllowHTTP)
+
+		if !fetchedAsWritten(parsed, fetchURL) {
+			s.renderGeneratorWithForm(w, r, "Source URL cannot be fetched as "+
+				"written: pixa would fetch "+fetchURL.String(),
+				r.Form, http.StatusBadRequest)
+
+			return
+		}
+
 		// Generate encrypted token
-		token, err := s.encGen.Generate(payload)
+		token, err := s.encGen.Generate(req, expiresAt)
 		if err != nil {
 			s.log.Error("failed to generate encrypted URL", "error", err)
 			s.renderGeneratorWithForm(w, r, "Failed to generate URL", r.Form,
@@ -173,14 +197,55 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 	}
 }
 
-// buildGeneratePayload parses the numeric form fields and assembles the
-// encrypted URL payload. ttl=0 means never expires (ExpiresAt stays 0). A
-// non-numeric or out-of-range width, height, quality or ttl, or an
-// unrecognized fit mode, is a client error naming the offending field. The
-// format field is passed through unchecked.
-func buildGeneratePayload(
+// parseSourceURL parses the source URL entered on the generator page with its
+// host lower-cased and an empty path written as "/", as /v1/image/ reads a
+// source URL, so that each spelling of one source URL makes one cache key and
+// one upstream request.
+func parseSourceURL(sourceURL string) (*url.URL, error) {
+	parsed, err := url.Parse(sourceURL)
+	if err != nil {
+		return nil, err
+	}
+
+	parsed.Host = strings.ToLower(parsed.Host)
+
+	if parsed.Path == "" {
+		parsed.Path = "/"
+	}
+
+	return parsed, nil
+}
+
+// fetchedAsWritten reports whether fetchURL, the URL pixa fetches for an
+// image URL made from the source URL source, is source as it was written,
+// apart from the scheme, which the token does not keep. It is not when source
+// holds a user name and password, which the token does not keep either, or a
+// "?" with no query after it. The token keeps the source path decoded and
+// pixa fetches it percent-encoded again, so a path written another way, such
+// as with %2F, is fetched as another path. url.URL keeps the path as written
+// in RawPath when it is not the decoded path percent-encoded again.
+// EscapedPath ignores RawPath when it also holds a character net/url encodes,
+// such as a space, so RawPath is compared itself.
+func fetchedAsWritten(source, fetchURL *url.URL) bool {
+	writtenPath := source.RawPath
+	if writtenPath == "" {
+		writtenPath = source.EscapedPath()
+	}
+
+	return source.User == nil && !source.ForceQuery &&
+		fetchURL.EscapedPath() == writtenPath &&
+		fetchURL.RawQuery == source.RawQuery
+}
+
+// buildGenerateRequest parses the numeric form fields and assembles the
+// image request the encrypted URL's token is made from, and its expiry.
+// ttl=0 means never expires (the expiry is the zero time). A non-numeric or
+// out-of-range width, height, quality or ttl, or an unrecognized fit mode, is
+// a client error naming the offending field. The format field is passed
+// through unchecked.
+func buildGenerateRequest(
 	parsed *url.URL, form url.Values,
-) (*encurl.Payload, time.Time, int, error) {
+) (*imagerequest.Request, time.Time, int, error) {
 	width, err := parseFormDimension(form, "width")
 	if err != nil {
 		return nil, time.Time{}, 0, err
@@ -202,42 +267,39 @@ func buildGeneratePayload(
 		return nil, time.Time{}, 0, err
 	}
 
-	fitMode := imgcache.FitMode(form.Get("fit"))
+	fitMode := imagerequest.Fit(form.Get("fit"))
 
-	err = imgcache.ValidateFitMode(fitMode)
+	err = imagerequest.ValidateFitMode(fitMode)
 	if err != nil {
 		return nil, time.Time{}, 0,
-			fmt.Errorf("%w: %s", imgcache.ErrInvalidFitMode, form.Get("fit"))
+			fmt.Errorf("%w: %s", imagerequest.ErrInvalidFitMode, form.Get("fit"))
 	}
 
-	var (
-		expiresAt     time.Time
-		expiresAtUnix int64
-	)
-
+	var expiresAt time.Time
 	if ttl > 0 {
 		expiresAt = time.Now().Add(time.Duration(ttl) * time.Second)
-		expiresAtUnix = expiresAt.Unix()
 	}
 
-	payload := &encurl.Payload{
-		SourceHost:  parsed.Host,
-		SourcePath:  parsed.Path,
-		SourceQuery: parsed.RawQuery,
-		Width:       width,
-		Height:      height,
-		Format:      imgcache.ImageFormat(form.Get("format")),
-		Quality:     quality,
-		FitMode:     fitMode,
-		ExpiresAt:   expiresAtUnix,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host:  parsed.Host,
+			Path:  parsed.Path,
+			Query: parsed.RawQuery,
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: width, Height: height},
+			Format:  imagerequest.Format(form.Get("format")),
+			Quality: quality,
+			FitMode: fitMode,
+		},
 	}
 
-	return payload, expiresAt, ttl, nil
+	return req, expiresAt, ttl, nil
 }
 
 // parseFormDimension reads an optional width or height form field. An empty
 // value means "original size" (0). A non-numeric value, or one
-// imgcache.ValidateDimension rejects, is an error naming the field.
+// imagerequest.ValidateDimension rejects, is an error naming the field.
 func parseFormDimension(form url.Values, field string) (int, error) {
 	raw := form.Get(field)
 	if raw == "" {
@@ -249,7 +311,7 @@ func parseFormDimension(form url.Values, field string) (int, error) {
 		return 0, fmt.Errorf("%w %s: not a number", errInvalidFormField, field)
 	}
 
-	err = imgcache.ValidateDimension(field, value)
+	err = imagerequest.ValidateDimension(field, value)
 	if err != nil {
 		return 0, err
 	}

internal/handlers/auth_csrf_internal_test.go

@@ -14,6 +14,7 @@ import (
 
 	"sneak.berlin/go/pixa/internal/config"
 	"sneak.berlin/go/pixa/internal/encurl"
+	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
 )
 
@@ -44,27 +45,17 @@ func newCSRFTestRouter(t *testing.T) (*Handlers, http.Handler) {
 
 	cfg := &config.Config{SigningKey: testSigningKey, Debug: true}
 
-	sessMgr, err := session.NewManager(testSigningKey)
+	keys, err := seal.DeriveKeys(testSigningKey)
 	if err != nil {
-		t.Fatalf("session.NewManager() error = %v", err)
-	}
-
-	encGen, err := encurl.NewGenerator(testSigningKey)
-	if err != nil {
-		t.Fatalf("encurl.NewGenerator() error = %v", err)
-	}
-
-	protect, err := newCSRFProtect(testSigningKey, cfg.Debug)
-	if err != nil {
-		t.Fatalf("newCSRFProtect() error = %v", err)
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
 	}
 
 	h := &Handlers{
 		log:         slog.New(slog.DiscardHandler),
 		config:      cfg,
-		sessMgr:     sessMgr,
-		encGen:      encGen,
-		csrfProtect: protect,
+		sessMgr:     session.NewManager(keys.SessionHashKey, keys.SessionBlockKey),
+		encGen:      encurl.NewGenerator(keys.EncryptedURLKey),
+		csrfProtect: newCSRFProtect(keys.CSRFKey, cfg.Debug),
 	}
 
 	r := chi.NewRouter()

internal/handlers/auth_generate_internal_test.go

@@ -11,7 +11,7 @@ import (
 	"time"
 
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // Generator form field names, and a value that is not a number.
@@ -125,10 +125,10 @@ func TestGeneratePostRejectsBadField(t *testing.T) {
 	}
 }
 
-// TestBuildGeneratePayloadDefaultAndLimits verifies that an empty quality
+// TestBuildGenerateRequestDefaultAndLimits verifies that an empty quality
 // takes the default, and that the largest accepted width, height, quality and
 // ttl are accepted with an expiry still in the future.
-func TestBuildGeneratePayloadDefaultAndLimits(t *testing.T) {
+func TestBuildGenerateRequestDefaultAndLimits(t *testing.T) {
 	t.Parallel()
 
 	parsed, err := url.Parse(testSourceURL)
@@ -136,19 +136,19 @@ func TestBuildGeneratePayloadDefaultAndLimits(t *testing.T) {
 		t.Fatalf("url.Parse() error = %v", err)
 	}
 
-	payload, _, _, err := buildGeneratePayload(parsed, url.Values{})
+	req, _, _, err := buildGenerateRequest(parsed, url.Values{})
 	if err != nil {
 		t.Fatalf("empty form: error = %v", err)
 	}
 
-	if payload.Quality != encurl.DefaultQuality {
+	if req.Transform.Quality != encurl.DefaultQuality {
 		t.Errorf("empty quality gave %d, want %d",
-			payload.Quality, encurl.DefaultQuality)
+			req.Transform.Quality, encurl.DefaultQuality)
 	}
 
-	_, expiresAt, _, err := buildGeneratePayload(parsed, url.Values{
-		widthField:   {strconv.Itoa(imgcache.MaxDimension)},
-		heightField:  {strconv.Itoa(imgcache.MaxDimension)},
+	_, expiresAt, _, err := buildGenerateRequest(parsed, url.Values{
+		widthField:   {strconv.Itoa(imagerequest.MaxDimension)},
+		heightField:  {strconv.Itoa(imagerequest.MaxDimension)},
 		qualityField: {strconv.Itoa(maxQuality)},
 		ttlField:     {strconv.Itoa(maxTTL)},
 	})

internal/handlers/auth_login_log_internal_test.go

@@ -10,6 +10,7 @@ import (
 	"testing"
 
 	"sneak.berlin/go/pixa/internal/config"
+	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
 )
 
@@ -22,15 +23,15 @@ func TestLoginLogLeavesOutSubmittedKey(t *testing.T) {
 
 	var buf bytes.Buffer
 
-	sessMgr, err := session.NewManager(testSigningKey)
+	keys, err := seal.DeriveKeys(testSigningKey)
 	if err != nil {
-		t.Fatalf("session.NewManager() error = %v", err)
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
 	}
 
 	h := &Handlers{
 		log:     slog.New(slog.NewJSONHandler(&buf, nil)),
 		config:  &config.Config{SigningKey: testSigningKey},
-		sessMgr: sessMgr,
+		sessMgr: session.NewManager(keys.SessionHashKey, keys.SessionBlockKey),
 	}
 
 	submittedKeys := []string{wrongKey, testSigningKey}

internal/handlers/auth_session_internal_test.go

@@ -10,7 +10,8 @@ import (
 	"testing"
 	"time"
 
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
 )
 
@@ -232,8 +233,13 @@ func TestHandleLogout_SaveFails_Answers500(t *testing.T) {
 
 	db := setupTestDB(t)
 
+	keys, err := seal.DeriveKeys(testSigningKey)
+	if err != nil {
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
+	}
+
 	sessMgr, err := session.NewManagerWithDatabase(
-		t.Context(), testSigningKey, db)
+		t.Context(), keys.SessionHashKey, keys.SessionBlockKey, db)
 	if err != nil {
 		t.Fatalf("session.NewManagerWithDatabase() error = %v", err)
 	}
@@ -314,7 +320,7 @@ func TestGeneratePost_URLServesImage(t *testing.T) {
 		sourceURLField: {"https://" + signedHost + photoPath},
 		widthField:     {"50"},
 		heightField:    {"50"},
-		formatField:    {string(imgcache.FormatJPEG)},
+		formatField:    {string(imagerequest.FormatJPEG)},
 	})
 
 	if rec.Code != http.StatusOK {
@@ -347,7 +353,7 @@ func TestGeneratePost_URLWithTTLExpires(t *testing.T) {
 		sourceURLField: {"https://" + signedHost + photoPath},
 		widthField:     {"50"},
 		heightField:    {"50"},
-		formatField:    {string(imgcache.FormatJPEG)},
+		formatField:    {string(imagerequest.FormatJPEG)},
 		ttlField:       {"1"},
 	})
 

internal/handlers/avif_too_large_internal_test.go

@@ -0,0 +1,39 @@
+package handlers
+
+import (
+	"fmt"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
+)
+
+// TestAVIFOutputTooLargeAnswers400 checks that respondImageError, which
+// answers the errors of both image routes, answers 400 naming the AVIF pixel
+// limit when the image processor refuses an AVIF output above it, wrapped as
+// the service wraps it. The request's source only goes into a log line, so it
+// is left empty.
+func TestAVIFOutputTooLargeAnswers400(t *testing.T) {
+	t.Parallel()
+
+	h := &Handlers{log: slog.New(slog.DiscardHandler)}
+	err := fmt.Errorf("image processing failed: %w: 4097x4096",
+		imageprocessor.ErrAVIFOutputTooLarge)
+	wantBody := fmt.Sprintf("above %d pixels", imageprocessor.MaxAVIFOutputPixels)
+
+	rec := httptest.NewRecorder()
+	h.respondImageError(rec, &imagerequest.Request{}, err)
+	t.Logf("status = %d, body = %q", rec.Code, rec.Body.String())
+
+	if rec.Code != http.StatusBadRequest {
+		t.Errorf("status = %d, want %d", rec.Code, http.StatusBadRequest)
+	}
+
+	if !strings.Contains(rec.Body.String(), wantBody) {
+		t.Errorf("body = %q, want it to say %q", rec.Body.String(), wantBody)
+	}
+}

internal/handlers/bodylimit_internal_test.go

@@ -11,6 +11,7 @@ import (
 
 	"sneak.berlin/go/pixa/internal/config"
 	"sneak.berlin/go/pixa/internal/encurl"
+	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
 )
 
@@ -32,27 +33,17 @@ func newBodyLimitTestRouter(
 
 	cfg := &config.Config{SigningKey: testSigningKey, Debug: true}
 
-	sessMgr, err := session.NewManager(testSigningKey)
+	keys, err := seal.DeriveKeys(testSigningKey)
 	if err != nil {
-		t.Fatalf("session.NewManager() error = %v", err)
-	}
-
-	encGen, err := encurl.NewGenerator(testSigningKey)
-	if err != nil {
-		t.Fatalf("encurl.NewGenerator() error = %v", err)
-	}
-
-	protect, err := newCSRFProtect(testSigningKey, cfg.Debug)
-	if err != nil {
-		t.Fatalf("newCSRFProtect() error = %v", err)
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
 	}
 
 	h := &Handlers{
 		log:         slog.New(slog.DiscardHandler),
 		config:      cfg,
-		sessMgr:     sessMgr,
-		encGen:      encGen,
-		csrfProtect: protect,
+		sessMgr:     session.NewManager(keys.SessionHashKey, keys.SessionBlockKey),
+		encGen:      encurl.NewGenerator(keys.EncryptedURLKey),
+		csrfProtect: newCSRFProtect(keys.CSRFKey, cfg.Debug),
 	}
 
 	r := chi.NewRouter()

internal/handlers/cache_hit_internal_test.go

@@ -0,0 +1,277 @@
+package handlers
+
+import (
+	"bytes"
+	"context"
+	"database/sql"
+	"database/sql/driver"
+	"image"
+	"image/jpeg"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"sync/atomic"
+	"testing"
+	"testing/fstest"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/prometheus/client_golang/prometheus"
+
+	"sneak.berlin/go/pixa/internal/allowlist"
+	"sneak.berlin/go/pixa/internal/database"
+	"sneak.berlin/go/pixa/internal/encurl"
+	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/seal"
+	"sneak.berlin/go/pixa/internal/signature"
+)
+
+// countingHost is the allowlisted host whose photoPath the server of
+// newCountingDatabaseServer serves.
+const countingHost = "counting.example.com"
+
+// countingConnector opens connections to the SQLite database file name with
+// sqliteDriver, each one counting in statements the statements run on it.
+type countingConnector struct {
+	sqliteDriver driver.Driver
+	name         string
+	statements   *atomic.Int64
+}
+
+func (c countingConnector) Connect(context.Context) (driver.Conn, error) {
+	conn, err := c.sqliteDriver.Open(c.name)
+	if err != nil {
+		return nil, err
+	}
+
+	return countingConn{Conn: conn, statements: c.statements}, nil
+}
+
+func (c countingConnector) Driver() driver.Driver {
+	return c.sqliteDriver
+}
+
+// countingConn counts the statements run on its connection. It has only the
+// methods of driver.Conn, so database/sql prepares every query and every
+// other statement with Prepare, which counts it.
+type countingConn struct {
+	driver.Conn
+
+	statements *atomic.Int64
+}
+
+func (c countingConn) Prepare(query string) (driver.Stmt, error) {
+	c.statements.Add(1)
+
+	return c.Conn.Prepare(query)
+}
+
+// newCountingDatabase returns a database with pixa's schema, in a file of
+// its own and with one connection, and the count of the statements run on
+// it once the schema is in place.
+func newCountingDatabase(tb testing.TB) (*sql.DB, *atomic.Int64) {
+	tb.Helper()
+
+	path := filepath.Join(tb.TempDir(), "state.sqlite3")
+
+	schemaDB, err := sql.Open("sqlite", path)
+	if err != nil {
+		tb.Fatalf("opening the database: %v", err)
+	}
+
+	defer func() { _ = schemaDB.Close() }()
+
+	err = database.ApplyMigrations(tb.Context(), schemaDB, nil)
+	if err != nil {
+		tb.Fatalf("applying the migrations: %v", err)
+	}
+
+	statements := new(atomic.Int64)
+
+	db := sql.OpenDB(countingConnector{
+		sqliteDriver: schemaDB.Driver(),
+		name:         path,
+		statements:   statements,
+	})
+	db.SetMaxOpenConns(1)
+
+	tb.Cleanup(func() { _ = db.Close() })
+
+	return db, statements
+}
+
+// newCountingDatabaseServer returns a router for both image routes whose
+// image cache uses newCountingDatabase, the count of the statements run on
+// that database, and a URL on each route for a different image of
+// photoPath on countingHost. Nothing writes the cache's access times in the
+// background, so every statement counted comes from a request.
+func newCountingDatabaseServer(
+	tb testing.TB,
+) (http.Handler, *atomic.Int64, []string) {
+	tb.Helper()
+
+	db, statements := newCountingDatabase(tb)
+
+	var photo bytes.Buffer
+
+	err := jpeg.Encode(&photo, image.NewRGBA(image.Rect(0, 0, 100, 100)), nil)
+	if err != nil {
+		tb.Fatalf("encoding the photo: %v", err)
+	}
+
+	cache, err := imgcache.NewCache(db, imgcache.CacheConfig{
+		StateDir:    tb.TempDir(),
+		NegativeTTL: 5 * time.Minute,
+		MaxBytes:    1 << 30,
+	}, prometheus.NewRegistry())
+	if err != nil {
+		tb.Fatalf("imgcache.NewCache() error = %v", err)
+	}
+
+	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
+		Cache: cache,
+		Fetcher: newMockFetcher(fstest.MapFS{
+			countingHost + photoPath: &fstest.MapFile{Data: photo.Bytes()},
+		}),
+		Processor: imageprocessor.New(imageprocessor.Params{
+			MaxInputBytes:           50 << 20,
+			MaxConcurrentProcessing: 2,
+		}),
+		MaxResponseSize: 50 << 20,
+		Logger:          slog.New(slog.DiscardHandler),
+	})
+	if err != nil {
+		tb.Fatalf("imgcache.NewService() error = %v", err)
+	}
+
+	keys, err := seal.DeriveKeys(testSigningKey)
+	if err != nil {
+		tb.Fatalf("seal.DeriveKeys() error = %v", err)
+	}
+
+	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
+
+	token, err := encGen.Generate(&imagerequest.Request{
+		Source: imagerequest.Source{Host: countingHost, Path: photoPath},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 40, Height: 40},
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
+	}, time.Time{})
+	if err != nil {
+		tb.Fatalf("encGen.Generate() error = %v", err)
+	}
+
+	h := &Handlers{
+		log:       slog.New(slog.DiscardHandler),
+		imgSvc:    svc,
+		encGen:    encGen,
+		signer:    signature.New(testSigningKey),
+		allowlist: allowlist.New([]string{countingHost}),
+	}
+
+	r := chi.NewRouter()
+	r.Get("/v1/image/*", h.HandleImage())
+	r.Get("/v1/e/{token}/*", h.HandleImageEnc())
+
+	return r, statements, []string{
+		"/v1/image/" + countingHost + photoPath + "/50x50.jpeg",
+		"/v1/e/" + token + "/img.jpg",
+	}
+}
+
+// serveImage sends srv a GET for target and returns the response, failing
+// the test unless it is a 200 with an image.
+func serveImage(
+	tb testing.TB, srv http.Handler, target string,
+) *httptest.ResponseRecorder {
+	tb.Helper()
+
+	rec := httptest.NewRecorder()
+	srv.ServeHTTP(rec,
+		httptest.NewRequestWithContext(tb.Context(), http.MethodGet, target, nil))
+
+	if rec.Code != http.StatusOK || rec.Body.Len() == 0 {
+		tb.Errorf("GET %s: %d with %d bytes, want 200 with an image",
+			target, rec.Code, rec.Body.Len())
+	}
+
+	return rec
+}
+
+// TestImageRoutes_CacheHitsMakeNoDatabaseCall serves an image on each image
+// route once, which makes and caches it, then serves it again from the cache.
+// Serving those cache hits must run no statement on the database.
+func TestImageRoutes_CacheHitsMakeNoDatabaseCall(t *testing.T) {
+	t.Parallel()
+
+	srv, statements, targets := newCountingDatabaseServer(t)
+
+	for _, target := range targets {
+		before := statements.Load()
+
+		serveImage(t, srv, target)
+
+		afterMiss := statements.Load()
+		t.Logf("GET %s, a miss: %d statements", target, afterMiss-before)
+
+		if afterMiss == before {
+			t.Fatalf("GET %s, a miss: no statement counted, want some", target)
+		}
+
+		for range 3 {
+			rec := serveImage(t, srv, target)
+
+			cacheStatus := rec.Header().Get("X-Pixa-Cache")
+			if cacheStatus != string(imgcache.CacheHit) {
+				t.Errorf("GET %s: X-Pixa-Cache = %q, want %s",
+					target, cacheStatus, imgcache.CacheHit)
+			}
+		}
+
+		if hitStatements := statements.Load() - afterMiss; hitStatements != 0 {
+			t.Errorf("GET %s: 3 cache hits ran %d statements, want 0",
+				target, hitStatements)
+		}
+	}
+}
+
+// BenchmarkHandleImage_CacheHits serves one cached image through the
+// /v1/image/ route from b.RunParallel's goroutines, and reports the cache
+// hits served per second. It fails if serving them ran any statement on the
+// database. script/bench runs it.
+func BenchmarkHandleImage_CacheHits(b *testing.B) {
+	srv, statements, targets := newCountingDatabaseServer(b)
+	target := targets[0]
+
+	serveImage(b, srv, target)
+
+	before := statements.Load()
+
+	b.ResetTimer()
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			rec := serveImage(b, srv, target)
+
+			cacheStatus := rec.Header().Get("X-Pixa-Cache")
+			if cacheStatus != string(imgcache.CacheHit) {
+				b.Errorf("GET %s: X-Pixa-Cache = %q, want %s",
+					target, cacheStatus, imgcache.CacheHit)
+
+				return
+			}
+		}
+	})
+
+	b.ReportMetric(float64(b.N)/b.Elapsed().Seconds(), "hits/s")
+
+	if hitStatements := statements.Load() - before; hitStatements != 0 {
+		b.Fatalf("%d cache hits ran %d statements, want 0", b.N, hitStatements)
+	}
+}

internal/handlers/cache_max_bytes_internal_test.go

@@ -1,147 +0,0 @@
-package handlers
-
-import (
-	"os"
-	"path/filepath"
-	"testing"
-
-	"go.uber.org/fx/fxtest"
-
-	"sneak.berlin/go/pixa/internal/config"
-	"sneak.berlin/go/pixa/internal/database"
-	"sneak.berlin/go/pixa/internal/globals"
-	"sneak.berlin/go/pixa/internal/logger"
-)
-
-// TestNewCacheConfigFromCacheMaxBytes checks the cache configuration
-// built from cache_max_bytes: omitted, the cache works out the default
-// limit; 0 turns the disk cache off; a positive value is the limit,
-// unchanged.
-func TestNewCacheConfigFromCacheMaxBytes(t *testing.T) {
-	t.Parallel()
-
-	const oneGiB = 1 << 30
-
-	cases := []struct {
-		name                   string
-		cacheMaxBytes          int64
-		cacheMaxBytesExplicit  bool
-		wantMaxBytes           int64
-		wantUseDefaultMaxBytes bool
-		wantDisableDiskCache   bool
-	}{
-		{
-			name:                   "cache_max_bytes omitted",
-			cacheMaxBytes:          0,
-			cacheMaxBytesExplicit:  false,
-			wantMaxBytes:           0,
-			wantUseDefaultMaxBytes: true,
-			wantDisableDiskCache:   false,
-		},
-		{
-			name:                   "cache_max_bytes: 0",
-			cacheMaxBytes:          0,
-			cacheMaxBytesExplicit:  true,
-			wantMaxBytes:           0,
-			wantUseDefaultMaxBytes: false,
-			wantDisableDiskCache:   true,
-		},
-		{
-			name:                   "cache_max_bytes: 1 GiB",
-			cacheMaxBytes:          oneGiB,
-			cacheMaxBytesExplicit:  true,
-			wantMaxBytes:           oneGiB,
-			wantUseDefaultMaxBytes: false,
-			wantDisableDiskCache:   false,
-		},
-	}
-
-	for _, tc := range cases {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			cfg := &config.Config{
-				CacheMaxBytes:         tc.cacheMaxBytes,
-				CacheMaxBytesExplicit: tc.cacheMaxBytesExplicit,
-			}
-
-			got := newCacheConfig(cfg, nil)
-			t.Logf("MaxBytes = %d, UseDefaultMaxBytes = %v, DisableDiskCache = %v",
-				got.MaxBytes, got.UseDefaultMaxBytes, got.DisableDiskCache)
-
-			if got.MaxBytes != tc.wantMaxBytes {
-				t.Errorf("MaxBytes = %d, want %d", got.MaxBytes, tc.wantMaxBytes)
-			}
-
-			if got.UseDefaultMaxBytes != tc.wantUseDefaultMaxBytes {
-				t.Errorf("UseDefaultMaxBytes = %v, want %v",
-					got.UseDefaultMaxBytes, tc.wantUseDefaultMaxBytes)
-			}
-
-			if got.DisableDiskCache != tc.wantDisableDiskCache {
-				t.Errorf("DisableDiskCache = %v, want %v",
-					got.DisableDiskCache, tc.wantDisableDiskCache)
-			}
-		})
-	}
-}
-
-// TestDiskCacheOffOnlyForExplicitZeroCacheMaxBytes starts the handlers
-// once with cache_max_bytes omitted and once with cache_max_bytes: 0,
-// and checks by whether the cache directories were created that the
-// disk cache is on in the first case and off in the second.
-func TestDiskCacheOffOnlyForExplicitZeroCacheMaxBytes(t *testing.T) {
-	t.Parallel()
-
-	cases := []struct {
-		name                  string
-		cacheMaxBytesExplicit bool
-		wantDiskCache         bool
-	}{
-		{name: "cache_max_bytes omitted", cacheMaxBytesExplicit: false, wantDiskCache: true},
-		{name: "cache_max_bytes: 0", cacheMaxBytesExplicit: true, wantDiskCache: false},
-	}
-
-	for _, tc := range cases {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			stateDir := t.TempDir()
-			cfg := &config.Config{
-				SigningKey:            testSigningKey,
-				StateDir:              stateDir,
-				DBURL:                 "file:" + filepath.Join(stateDir, "state.sqlite3"),
-				CacheMaxBytes:         0,
-				CacheMaxBytesExplicit: tc.cacheMaxBytesExplicit,
-			}
-
-			lc := fxtest.NewLifecycle(t)
-
-			log, err := logger.New(lc, logger.Params{Globals: &globals.Globals{}})
-			if err != nil {
-				t.Fatalf("logger.New() error = %v", err)
-			}
-
-			db, err := database.New(lc, database.Params{Logger: log, Config: cfg})
-			if err != nil {
-				t.Fatalf("database.New() error = %v", err)
-			}
-
-			_, err = New(lc, Params{Logger: log, Database: db, Config: cfg})
-			if err != nil {
-				t.Fatalf("New() error = %v", err)
-			}
-
-			lc.RequireStart()
-			t.Cleanup(lc.RequireStop)
-
-			_, err = os.Stat(filepath.Join(stateDir, "cache", "variants"))
-			gotDiskCache := err == nil
-
-			if gotDiskCache != tc.wantDiskCache {
-				t.Errorf("cache directories created = %v, want %v",
-					gotDiskCache, tc.wantDiskCache)
-			}
-		})
-	}
-}

internal/handlers/csrf.go

@@ -9,15 +9,10 @@ import (
 	"sneak.berlin/go/pixa/internal/seal"
 )
 
-// csrfKeySalt provides domain separation for the CSRF authentication key,
-// derived from the signing key so tokens survive restarts without extra
-// configuration and never reuse the session or encrypted-URL key material.
-const csrfKeySalt = "pixa-csrf-v1"
-
 // newCSRFProtect builds the CSRF-protection middleware for the
 // state-mutating HTML form routes. The token lives in its own cookie,
 // independent of the session cookie, so it also protects the login POST
-// where no session exists yet (login CSRF).
+// where no session exists yet (login CSRF). key signs that cookie.
 //
 // When plaintext is true (local HTTP development), requests are marked
 // plaintext so the library neither demands an https Referer nor sets a
@@ -25,13 +20,8 @@ const csrfKeySalt = "pixa-csrf-v1"
 // service runs behind a TLS-terminating proxy, so plaintext is false and
 // the library enforces its https Referer origin check.
 func newCSRFProtect(
-	signingKey string, plaintext bool,
-) (func(http.Handler) http.Handler, error) {
-	key, err := seal.DeriveKey([]byte(signingKey), csrfKeySalt)
-	if err != nil {
-		return nil, err
-	}
-
+	key [seal.KeySize]byte, plaintext bool,
+) func(http.Handler) http.Handler {
 	protect := csrf.Protect(
 		key[:],
 		csrf.Path("/"),
@@ -40,7 +30,7 @@ func newCSRFProtect(
 	)
 
 	if !plaintext {
-		return protect, nil
+		return protect
 	}
 
 	return func(next http.Handler) http.Handler {
@@ -49,7 +39,7 @@ func newCSRFProtect(
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			protected.ServeHTTP(w, csrf.PlaintextHTTPRequest(r))
 		})
-	}, nil
+	}
 }
 
 // CSRF returns the CSRF-protection middleware for the login and generator

internal/handlers/fetcher_internal_test.go

@@ -1,61 +0,0 @@
-package handlers
-
-import (
-	"net/http"
-	"net/netip"
-	"path/filepath"
-	"testing"
-	"time"
-
-	"github.com/go-chi/chi/v5"
-	"go.uber.org/fx"
-	"go.uber.org/fx/fxtest"
-
-	"sneak.berlin/go/pixa/internal/config"
-	"sneak.berlin/go/pixa/internal/database"
-	"sneak.berlin/go/pixa/internal/globals"
-	"sneak.berlin/go/pixa/internal/healthcheck"
-	"sneak.berlin/go/pixa/internal/logger"
-)
-
-// TestHandlersBuildTheirOwnFetcherWhenNoneIsProvided builds the handlers as
-// pixad does, in an fx app that provides no fetcher, and requests an image
-// from 192.0.2.10, which is on the allowlist and in blocked_networks. The URL
-// check accepts that address; only the dialer that refuses internal
-// addresses checks blocked_networks, so the answer is 403 only if the
-// fetcher the handlers build from the config connects with that dialer. Any
-// other dialer would try to connect until the upstream fetch timeout, which
-// is short so that the test then fails quickly.
-func TestHandlersBuildTheirOwnFetcherWhenNoneIsProvided(t *testing.T) {
-	t.Parallel()
-
-	const host = "192.0.2.10"
-
-	stateDir := t.TempDir()
-	cfg := &config.Config{
-		SigningKey:           testSigningKey,
-		StateDir:             stateDir,
-		DBURL:                "file:" + filepath.Join(stateDir, "state.sqlite3"),
-		AllowlistHosts:       []string{host},
-		BlockedNetworks:      []netip.Prefix{netip.MustParsePrefix("192.0.2.0/24")},
-		UpstreamFetchTimeout: 2 * time.Second,
-		// With no connection slots, the fetch would fail before dialing.
-		UpstreamConnections: config.DefaultUpstreamConnections,
-	}
-
-	var h *Handlers
-
-	app := fxtest.New(t,
-		fx.Supply(cfg),
-		fx.Provide(globals.New, logger.New, database.New, healthcheck.New, New),
-		fx.Populate(&h),
-	)
-	app.RequireStart()
-	t.Cleanup(app.RequireStop)
-
-	r := chi.NewRouter()
-	r.Get("/v1/image/*", h.HandleImage())
-
-	rec := sendGet(t, r, photoURL(host))
-	checkErrorBody(t, rec, http.StatusForbidden, "forbidden")
-}

internal/handlers/first_bytes_internal_test.go

@@ -0,0 +1,202 @@
+package handlers
+
+import (
+	"bytes"
+	"encoding/json"
+	"image/color"
+	"log/slog"
+	"net/http"
+	"slices"
+	"testing"
+	"testing/fstest"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/prometheus/client_golang/prometheus"
+	"sneak.berlin/go/pixa/internal/allowlist"
+	"sneak.berlin/go/pixa/internal/encurl"
+	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/seal"
+	"sneak.berlin/go/pixa/internal/signature"
+)
+
+// mismatchedSourcePath is the path of the source that
+// TestFirstBytesNotMatchingContentType serves on allowlistedHost. The mock
+// fetcher names a file's Content-Type from its extension, so the source is
+// sent as image/png.
+const mismatchedSourcePath = "/images/source.png"
+
+// newRoutesFetchingThrough returns both image routes, and the Handlers behind
+// them, whose image service fetches through fetcher, and which have
+// allowlistedHost on their allowlist. The handlers and the image service log
+// to log.
+func newRoutesFetchingThrough(
+	t *testing.T, fetcher httpfetcher.Fetcher, log *slog.Logger,
+) (*Handlers, http.Handler) {
+	t.Helper()
+
+	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.CacheConfig{
+		StateDir:    t.TempDir(),
+		NegativeTTL: 5 * time.Minute,
+		MaxBytes:    1 << 30,
+	}, prometheus.NewRegistry())
+	if err != nil {
+		t.Fatalf("imgcache.NewCache() error = %v", err)
+	}
+
+	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
+		Cache:   cache,
+		Fetcher: fetcher,
+		Processor: imageprocessor.New(imageprocessor.Params{
+			MaxInputBytes:           50 << 20,
+			MaxConcurrentProcessing: 2,
+		}),
+		MaxResponseSize: 50 << 20,
+		Logger:          log,
+	})
+	if err != nil {
+		t.Fatalf("imgcache.NewService() error = %v", err)
+	}
+
+	keys, err := seal.DeriveKeys(testSigningKey)
+	if err != nil {
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
+	}
+
+	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
+
+	h := &Handlers{
+		log:       log,
+		imgSvc:    svc,
+		encGen:    encGen,
+		signer:    signature.New(testSigningKey),
+		allowlist: allowlist.New([]string{allowlistedHost}),
+	}
+
+	r := chi.NewRouter()
+	r.Get("/v1/image/*", h.HandleImage())
+	r.Get("/v1/e/{token}/*", h.HandleImageEnc())
+
+	return h, r
+}
+
+// mismatchedSourcePlainURL returns the /v1/image/ URL of mismatchedSourcePath
+// on allowlistedHost at 50x50 as a JPEG.
+func mismatchedSourcePlainURL(*testing.T, *Handlers) string {
+	return "/v1/image/" + allowlistedHost + mismatchedSourcePath + "/50x50.jpeg"
+}
+
+// mismatchedSourceEncURL returns an encrypted /v1/e/ URL, made with h's
+// generator, of mismatchedSourcePath on allowlistedHost at 50x50 as a JPEG.
+func mismatchedSourceEncURL(t *testing.T, h *Handlers) string {
+	t.Helper()
+
+	token, err := h.encGen.Generate(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: allowlistedHost,
+			Path: mismatchedSourcePath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatJPEG,
+		},
+	}, time.Time{})
+	if err != nil {
+		t.Fatalf("Generate() error = %v", err)
+	}
+
+	return "/v1/e/" + token + "/img.jpg"
+}
+
+// loggedLevels reads the JSON log lines in logs and returns the messages
+// logged at each level.
+func loggedLevels(t *testing.T, logs *bytes.Buffer) map[string][]string {
+	t.Helper()
+
+	t.Logf("logged:\n%s", logs.String())
+
+	messages := make(map[string][]string)
+
+	dec := json.NewDecoder(logs)
+	for dec.More() {
+		var line struct {
+			Level string `json:"level"`
+			Msg   string `json:"msg"`
+		}
+
+		err := dec.Decode(&line)
+		if err != nil {
+			t.Fatalf("decoding log line: %v", err)
+		}
+
+		messages[line.Level] = append(messages[line.Level], line.Msg)
+	}
+
+	return messages
+}
+
+// TestFirstBytesNotMatchingContentType checks that both image routes answer
+// 415 for an upstream body whose first bytes are not those of the format its
+// Content-Type names, and log it as a refused source, not as an error of
+// pixa's. The next request for that source must answer 502 without fetching
+// it again, as after an upstream error status.
+func TestFirstBytesNotMatchingContentType(t *testing.T) {
+	t.Parallel()
+
+	bodies := map[string][]byte{
+		"JPEG sent as image/png":          generateTestJPEG(t, 10, 10, color.Black),
+		"text sent as image/png":          []byte("This is just text, not a PNG"),
+		"body too short to name a format": []byte("short"),
+	}
+
+	// The source's URL on each image route.
+	sourceURLs := map[string]func(*testing.T, *Handlers) string{
+		"plain URL":     mismatchedSourcePlainURL,
+		"encrypted URL": mismatchedSourceEncURL,
+	}
+
+	for bodyName, body := range bodies {
+		for urlName, sourceURL := range sourceURLs {
+			t.Run(urlName+", "+bodyName, func(t *testing.T) {
+				t.Parallel()
+
+				fetcher := &countingFetcher{
+					Fetcher: httpfetcher.NewMock(fstest.MapFS{
+						allowlistedHost + mismatchedSourcePath: &fstest.MapFile{
+							Data: body,
+						},
+					}),
+				}
+
+				var logs bytes.Buffer
+
+				h, routes := newRoutesFetchingThrough(t, fetcher,
+					slog.New(slog.NewJSONHandler(&logs, nil)))
+				target := sourceURL(t, h)
+
+				checkErrorBody(t, sendGet(t, routes, target),
+					http.StatusUnsupportedMediaType, "unsupported source format")
+
+				levels := loggedLevels(t, &logs)
+				if len(levels[slog.LevelError.String()]) != 0 {
+					t.Errorf("logged at error level: %q",
+						levels[slog.LevelError.String()])
+				}
+
+				if !slices.Contains(levels[slog.LevelWarn.String()], "source refused") {
+					t.Error(`no "source refused" line logged at warning level`)
+				}
+
+				checkErrorBody(t, sendGet(t, routes, target),
+					http.StatusBadGateway, "upstream error")
+
+				if n := fetcher.fetches.Load(); n != 1 {
+					t.Errorf("upstream fetched %d times, want 1", n)
+				}
+			})
+		}
+	}
+}

internal/handlers/format_auto.go

@@ -8,7 +8,7 @@ import (
 	"strconv"
 	"strings"
 
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // Errors for an Accept header that an auto URL cannot be served for.
@@ -18,16 +18,17 @@ var (
 		"image/jxl, image/avif, image/webp or image/jpeg")
 )
 
-// chooseAutoFormat replaces the format auto in req with the format
-// formatForAccept chooses from r's Accept header, and adds Vary: Accept to the
+// chooseAutoFormat returns the format to serve for the requested format: for
+// the format auto, the format formatForAccept chooses from r's Accept header,
+// and any other format as it is. For auto it adds Vary: Accept to the
 // response, which then depends on that header. It answers 400 for an Accept
 // header that is not valid and 406 for one that allows none of the formats,
-// and reports whether req can be served. Any other format is left as it is.
+// and reports whether the image can be served.
 func (s *Handlers) chooseAutoFormat(
-	w http.ResponseWriter, r *http.Request, req *imgcache.ImageRequest,
-) bool {
-	if req.Format != imgcache.FormatAuto {
-		return true
+	w http.ResponseWriter, r *http.Request, requested imagerequest.Format,
+) (imagerequest.Format, bool) {
+	if requested != imagerequest.FormatAuto {
+		return requested, true
 	}
 
 	w.Header().Add("Vary", "Accept")
@@ -36,18 +37,16 @@ func (s *Handlers) chooseAutoFormat(
 	if errors.Is(err, errNotAcceptable) {
 		s.respondError(w, err.Error(), http.StatusNotAcceptable)
 
-		return false
+		return "", false
 	}
 
 	if err != nil {
 		s.respondError(w, err.Error(), http.StatusBadRequest)
 
-		return false
+		return "", false
 	}
 
-	req.Format = format
-
-	return true
+	return format, true
 }
 
 // formatForAccept returns the format an auto URL is served in for the Accept
@@ -56,26 +55,26 @@ func (s *Handlers) chooseAutoFormat(
 // specific entry of image/jpeg, image/* and */* allows it, or when it names
 // nothing. A q of 0 refuses a format. JPEG XL, AVIF and WebP must be named, as
 // clients that cannot show them send image/* and */* too.
-func formatForAccept(accept string) (imgcache.ImageFormat, error) {
+func formatForAccept(accept string) (imagerequest.Format, error) {
 	qualities, err := parseAccept(accept)
 	if err != nil {
 		return "", err
 	}
 
 	if len(qualities) == 0 {
-		return imgcache.FormatJPEG, nil
+		return imagerequest.FormatJPEG, nil
 	}
 
 	if qualities["image/jxl"] > 0 {
-		return imgcache.FormatJXL, nil
+		return imagerequest.FormatJXL, nil
 	}
 
 	if qualities["image/avif"] > 0 {
-		return imgcache.FormatAVIF, nil
+		return imagerequest.FormatAVIF, nil
 	}
 
 	if qualities["image/webp"] > 0 {
-		return imgcache.FormatWebP, nil
+		return imagerequest.FormatWebP, nil
 	}
 
 	// For JPEG, the most specific entry the header has decides
@@ -89,7 +88,7 @@ func formatForAccept(accept string) (imgcache.ImageFormat, error) {
 	}
 
 	if quality > 0 {
-		return imgcache.FormatJPEG, nil
+		return imagerequest.FormatJPEG, nil
 	}
 
 	return "", errNotAcceptable

internal/handlers/format_auto_internal_test.go

@@ -12,8 +12,7 @@ import (
 
 	"github.com/go-chi/chi/v5"
 
-	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // The content types the tests below expect.
@@ -33,24 +32,24 @@ func TestFormatForAccept(t *testing.T) {
 	tests := []struct {
 		name    string
 		accept  string
-		want    imgcache.ImageFormat
+		want    imagerequest.Format
 		wantErr error
 	}{
 		{"AVIF-capable browser",
 			"image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8",
-			imgcache.FormatAVIF, nil},
+			imagerequest.FormatAVIF, nil},
 		{"WebP-capable browser",
 			"image/webp,image/png,image/svg+xml,image/*;q=0.8,*/*;q=0.5",
-			imgcache.FormatWebP, nil},
-		{"WebP only", webpType, imgcache.FormatWebP, nil},
-		{"neither", "image/png,image/*;q=0.8,*/*;q=0.5", imgcache.FormatJPEG, nil},
-		{"wildcard only", "*/*", imgcache.FormatJPEG, nil},
-		{"image wildcard only", "image/*", imgcache.FormatJPEG, nil},
-		{"absent", "", imgcache.FormatJPEG, nil},
-		{"q=0 on AVIF", "image/avif;q=0,image/webp,*/*", imgcache.FormatWebP, nil},
+			imagerequest.FormatWebP, nil},
+		{"WebP only", webpType, imagerequest.FormatWebP, nil},
+		{"neither", "image/png,image/*;q=0.8,*/*;q=0.5", imagerequest.FormatJPEG, nil},
+		{"wildcard only", "*/*", imagerequest.FormatJPEG, nil},
+		{"image wildcard only", "image/*", imagerequest.FormatJPEG, nil},
+		{"absent", "", imagerequest.FormatJPEG, nil},
+		{"q=0 on AVIF", "image/avif;q=0,image/webp,*/*", imagerequest.FormatWebP, nil},
 		{"AVIF named twice, once with q=0", "image/avif,image/avif;q=0.0,*/*",
-			imgcache.FormatJPEG, nil},
-		{"upper case and spaces", " Image/AVIF ; Q=0.5 ", imgcache.FormatAVIF, nil},
+			imagerequest.FormatJPEG, nil},
+		{"upper case and spaces", " Image/AVIF ; Q=0.5 ", imagerequest.FormatAVIF, nil},
 		{"q=0 on JPEG", "image/jpeg;q=0,image/*", "", errNotAcceptable},
 		{"q=0 on everything", "*/*;q=0", "", errNotAcceptable},
 		{"PNG only", "image/png", "", errNotAcceptable},
@@ -76,28 +75,33 @@ func TestFormatForAccept(t *testing.T) {
 
 // autoPhotoURLs returns a signed /v1/image/ URL and an encrypted /v1/e/ URL,
 // both valid for a minute, for the JPEG at photoPath on signedHost at 50x50 in
-// the format auto, made with h's image service and generator.
+// the format auto. The first is signed with testSigningKey, the key the
+// handlers that newSignedHostServer builds check signatures with. The second
+// is made with h's generator.
 func autoPhotoURLs(t *testing.T, h *Handlers) (string, string) {
 	t.Helper()
 
-	signedURL, err := h.imgSvc.GenerateSignedURL("", &imgcache.ImageRequest{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Size:       imgcache.Size{Width: 50, Height: 50},
-		Format:     imgcache.FormatAuto,
+	signedURL := generateSignedURL(testSigningKey, &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatAuto,
+		},
 	}, time.Minute)
-	if err != nil {
-		t.Fatalf("GenerateSignedURL() error = %v", err)
-	}
 
-	token, err := h.encGen.Generate(&encurl.Payload{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Width:      50,
-		Height:     50,
-		Format:     imgcache.FormatAuto,
-		ExpiresAt:  time.Now().Add(time.Minute).Unix(),
-	})
+	token, err := h.encGen.Generate(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatAuto,
+		},
+	}, time.Now().Add(time.Minute))
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
@@ -182,17 +186,18 @@ func TestFormatAuto_ChosenFromAccept(t *testing.T) {
 func TestFormatAuto_SignatureCoversAuto(t *testing.T) {
 	t.Parallel()
 
-	h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
+	_, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
 
-	signedForAVIF, err := h.imgSvc.GenerateSignedURL("", &imgcache.ImageRequest{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Size:       imgcache.Size{Width: 50, Height: 50},
-		Format:     imgcache.FormatAVIF,
+	signedForAVIF := generateSignedURL(testSigningKey, &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatAVIF,
+		},
 	}, time.Minute)
-	if err != nil {
-		t.Fatalf("GenerateSignedURL() error = %v", err)
-	}
 
 	target := strings.Replace(signedForAVIF, "/50x50.avif?", "/50x50.auto?", 1)
 	if target == signedForAVIF {

internal/handlers/handlers.go

@@ -4,7 +4,6 @@ package handlers
 import (
 	"context"
 	"encoding/json"
-	"errors"
 	"log/slog"
 	"net/http"
 	"time"
@@ -12,13 +11,13 @@ import (
 	"go.uber.org/fx"
 	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/config"
-	"sneak.berlin/go/pixa/internal/database"
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/healthcheck"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imgcache"
 	"sneak.berlin/go/pixa/internal/logger"
+	"sneak.berlin/go/pixa/internal/seal"
 	"sneak.berlin/go/pixa/internal/session"
+	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // Params defines dependencies for Handlers.
@@ -27,70 +26,48 @@ type Params struct {
 
 	Logger      *logger.Logger
 	Healthcheck *healthcheck.Healthcheck
-	Database    *database.Database
 	Config      *config.Config
+	Keys        seal.Keys
 
-	// Fetcher, when provided, fetches upstream images in place of the
-	// fetcher the handlers build from the config. Only tests provide one;
-	// pixad does not.
-	Fetcher httpfetcher.Fetcher `optional:"true"`
+	ImageService          *imgcache.Service
+	SessionManager        *session.Manager
+	EncryptedURLGenerator *encurl.Generator
 }
 
 // Handlers provides HTTP request handlers.
 type Handlers struct {
 	log         *slog.Logger
 	hc          *healthcheck.Healthcheck
-	db          *database.Database
 	config      *config.Config
-	fetcher     httpfetcher.Fetcher
 	imgSvc      *imgcache.Service
-	imgCache    *imgcache.Cache
 	sessMgr     *session.Manager
 	encGen      *encurl.Generator
 	csrfProtect func(http.Handler) http.Handler
 
+	// signer checks the signature of a /v1/image/ URL with signing_key.
+	signer *signature.Signer
+	// allowlist matches the hosts of allowlist_hosts, which a /v1/image/
+	// URL may name without a signature.
+	allowlist *allowlist.HostAllowList
 	// refererBlocklist matches the hosts of referer_blocklist; its IsAllowed
 	// reports whether a URL's host is on that list.
 	refererBlocklist *allowlist.HostAllowList
 }
 
 // New creates a new Handlers instance.
-func New(lc fx.Lifecycle, params Params) (*Handlers, error) {
-	csrfProtect, err := newCSRFProtect(params.Config.SigningKey, params.Config.Debug)
-	if err != nil {
-		return nil, err
-	}
-
-	s := &Handlers{
+func New(_ fx.Lifecycle, params Params) *Handlers {
+	return &Handlers{
 		log:              params.Logger.Get(),
 		hc:               params.Healthcheck,
-		db:               params.Database,
 		config:           params.Config,
-		fetcher:          params.Fetcher,
-		csrfProtect:      csrfProtect,
+		imgSvc:           params.ImageService,
+		sessMgr:          params.SessionManager,
+		encGen:           params.EncryptedURLGenerator,
+		csrfProtect:      newCSRFProtect(params.Keys.CSRFKey, params.Config.Debug),
+		signer:           signature.New(params.Config.SigningKey),
+		allowlist:        allowlist.New(params.Config.AllowlistHosts),
 		refererBlocklist: allowlist.New(params.Config.RefererBlocklist),
 	}
-
-	lc.Append(fx.Hook{
-		//nolint:contextcheck // the cache's goroutines outlive OnStart; OnStop stops them
-		OnStart: func(_ context.Context) error {
-			return s.initImageService()
-		},
-		// The pending counts are written here, before the database's stop
-		// hook closes it.
-		OnStop: func(ctx context.Context) error {
-			if s.imgCache == nil {
-				return nil
-			}
-
-			return errors.Join(
-				s.imgCache.StopEviction(ctx),
-				s.imgCache.StopPendingCountWrites(ctx),
-			)
-		},
-	})
-
-	return s, nil
 }
 
 // WaitForProcessing waits until no image is being processed, or until ctx
@@ -99,94 +76,6 @@ func (s *Handlers) WaitForProcessing(ctx context.Context) int {
 	return s.imgSvc.WaitForProcessing(ctx)
 }
 
-// newCacheConfig builds the image cache's configuration from cfg.
-// cache_max_bytes: 0 disables the disk cache entirely; any other value
-// is the eviction limit in bytes; when it is omitted, the cache works
-// out the default limit itself.
-func newCacheConfig(cfg *config.Config, log *slog.Logger) imgcache.CacheConfig {
-	return imgcache.CacheConfig{
-		StateDir:           cfg.StateDir,
-		NegativeTTL:        imgcache.DefaultNegativeTTL,
-		MaxBytes:           cfg.CacheMaxBytes,
-		UseDefaultMaxBytes: !cfg.CacheMaxBytesExplicit,
-		DisableDiskCache:   cfg.CacheMaxBytesExplicit && cfg.CacheMaxBytes == 0,
-		Logger:             log,
-	}
-}
-
-// initImageService initializes the image cache and service.
-func (s *Handlers) initImageService() error {
-	cache, err := imgcache.NewCache(s.db.DB(), newCacheConfig(s.config, s.log))
-	if err != nil {
-		return err
-	}
-
-	s.imgCache = cache
-
-	// Background eviction: startup reconciliation, then periodic and
-	// write-pressure passes, and the removal of expired negative cache
-	// rows, which is all it does when the disk cache is disabled.
-	cache.StartEviction(imgcache.DefaultEvictionInterval)
-
-	// Writes the counts requests could not write by their deadline
-	cache.StartPendingCountWrites()
-
-	// Create the fetcher config
-	fetcherCfg := httpfetcher.DefaultConfig()
-	fetcherCfg.AllowHTTP = s.config.AllowHTTP
-	fetcherCfg.Timeout = s.config.UpstreamFetchTimeout
-	fetcherCfg.MaxResponseSize = s.config.UpstreamMaxResponseSize
-
-	if s.config.UpstreamConnectionsPerHost > 0 {
-		fetcherCfg.MaxConnectionsPerHost = s.config.UpstreamConnectionsPerHost
-	}
-
-	fetcherCfg.MaxConnections = s.config.UpstreamConnections
-	fetcherCfg.BlockedNetworks = s.config.BlockedNetworks
-
-	// Create the service. With no fetcher provided, it builds its own from
-	// fetcherCfg.
-	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
-		Cache:                   cache,
-		FetcherConfig:           fetcherCfg,
-		Fetcher:                 s.fetcher,
-		SigningKey:              s.config.SigningKey,
-		Allowlist:               s.config.AllowlistHosts,
-		MaxConcurrentProcessing: s.config.MaxConcurrentProcessing,
-		Logger:                  s.log,
-	})
-	if err != nil {
-		return err
-	}
-
-	s.imgSvc = svc
-	s.log.Info("image service initialized")
-
-	// Initialize session manager (signing key is validated at config load
-	// time). Session cookies are always Secure/HttpOnly/SameSite=Strict.
-	// The random value that each logout replaces is saved in the database,
-	// so it outlasts a restart.
-	sessMgr, err := session.NewManagerWithDatabase(
-		context.Background(), s.config.SigningKey, s.db.DB())
-	if err != nil {
-		return err
-	}
-
-	s.sessMgr = sessMgr
-
-	// Initialize encrypted URL generator
-	encGen, err := encurl.NewGenerator(s.config.SigningKey)
-	if err != nil {
-		return err
-	}
-
-	s.encGen = encGen
-
-	s.log.Info("session manager and URL generator initialized")
-
-	return nil
-}
-
 func (s *Handlers) respondJSON(w http.ResponseWriter, data any, status int) {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(status)

internal/handlers/handlers_internal_test.go

@@ -18,15 +18,19 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
+	"github.com/prometheus/client_golang/prometheus"
+	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/database"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // testFixtures contains test data.
 type testFixtures struct {
 	handler  *Handlers
-	service  *imgcache.Service
 	goodHost string
 }
 
@@ -48,29 +52,34 @@ func setupTestHandler(t *testing.T) *testFixtures {
 	cache, err := imgcache.NewCache(db, imgcache.CacheConfig{
 		StateDir:    tmpDir,
 		NegativeTTL: 5 * time.Minute,
-	})
+		MaxBytes:    1 << 30,
+	}, prometheus.NewRegistry())
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
 	}
 
 	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
-		Cache:      cache,
-		Fetcher:    newMockFetcher(mockFS),
-		SigningKey: "test-signing-key-must-be-32-chars",
-		Allowlist:  []string{goodHost},
+		Cache:   cache,
+		Fetcher: newMockFetcher(mockFS),
+		Processor: imageprocessor.New(imageprocessor.Params{
+			MaxInputBytes:           50 << 20,
+			MaxConcurrentProcessing: 2,
+		}),
+		MaxResponseSize: 50 << 20,
 	})
 	if err != nil {
 		t.Fatalf("failed to create service: %v", err)
 	}
 
 	h := &Handlers{
-		imgSvc: svc,
-		log:    slog.Default(),
+		imgSvc:    svc,
+		log:       slog.Default(),
+		signer:    signature.New("test-signing-key-must-be-32-chars"),
+		allowlist: allowlist.New([]string{goodHost}),
 	}
 
 	return &testFixtures{
 		handler:  h,
-		service:  svc,
 		goodHost: goodHost,
 	}
 }
@@ -121,10 +130,9 @@ func newMockFetcher(fs fs.FS) *mockFetcher {
 }
 
 func (f *mockFetcher) Fetch(
-	_ context.Context, url string,
+	_ context.Context, source imagerequest.Source,
 ) (*httpfetcher.FetchResult, error) {
-	// Remove https:// prefix
-	path := url[8:] // Remove "https://"
+	path := source.Host + source.Path
 
 	data, err := fs.ReadFile(f.fs, path)
 	if err != nil {

internal/handlers/image.go

@@ -7,13 +7,16 @@ import (
 	"net/http"
 	"net/url"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/go-chi/chi/v5/middleware"
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/magic"
 )
 
 // HandleImage handles the main image proxy route:
@@ -25,17 +28,17 @@ func (s *Handlers) HandleImage() http.HandlerFunc {
 			return
 		}
 
-		req, ok := s.parseImageRequest(w, r)
+		req, sig, expires, ok := s.parseImageRequest(w, r)
 		if !ok {
 			return
 		}
 
 		// Validate signature if required
-		err := s.imgSvc.ValidateRequest(req)
+		err := s.validateSignature(req, sig, expires)
 		if err != nil {
 			s.log.Warn("signature validation failed",
-				"host", req.SourceHost,
-				"path", req.SourcePath,
+				"host", req.Source.Host,
+				"path", req.Source.Path,
 				"error", err,
 			)
 			s.respondError(w, "unauthorized", http.StatusUnauthorized)
@@ -43,27 +46,7 @@ func (s *Handlers) HandleImage() http.HandlerFunc {
 			return
 		}
 
-		// The signature covers the format auto, not the format chosen
-		if !s.chooseAutoFormat(w, r, req) {
-			return
-		}
-
-		// Get cache key for logging
-		cacheKey := imgcache.CacheKey(req)
-
-		// Get the image (from cache or fetch/process)
-		startTime := time.Now()
-
-		resp, err := s.imgSvc.Get(r.Context(), req)
-		if err != nil {
-			s.respondImageError(w, req, err)
-
-			return
-		}
-
-		defer func() { _ = resp.Content.Close() }()
-
-		s.writeImageResponse(w, r, req, resp, cacheKey, startTime)
+		s.serveImage(w, r, req, expires)
 	}
 }
 
@@ -80,17 +63,17 @@ func (s *Handlers) HandleRobotsTxt() http.HandlerFunc {
 }
 
 // parseImageRequest parses the image URL's path and query parameters into
-// an ImageRequest. On invalid input it writes an error response and
-// returns false.
+// an image request, and returns it with the URL's signature and expiry. On
+// invalid input it writes an error response and returns false.
 func (s *Handlers) parseImageRequest(
 	w http.ResponseWriter, r *http.Request,
-) (*imgcache.ImageRequest, bool) {
+) (*imagerequest.Request, string, time.Time, bool) {
 	// The path is parsed decoded once, as r.URL.Path holds it, and not from
 	// chi's wildcard: chi routes on the path as the client wrote it whenever
 	// that is not Go's own encoding of it, so its wildcard would still hold
 	// the %3F before a source query when, say, a "/" in the query is written
 	// as %2F
-	parsed, err := imgcache.ParseImageURL(r.URL.Path)
+	req, err := imagerequest.ParseImageURL(r.URL.Path)
 	if err != nil {
 		s.log.Warn("failed to parse image URL",
 			"path", r.URL.Path,
@@ -98,12 +81,9 @@ func (s *Handlers) parseImageRequest(
 		)
 		s.respondError(w, "invalid image URL: "+err.Error(), http.StatusBadRequest)
 
-		return nil, false
+		return nil, "", time.Time{}, false
 	}
 
-	// Convert to ImageRequest
-	req := parsed.ToImageRequest()
-
 	// Parse signature params from query string. r.URL.Query() would silently
 	// drop a pair it cannot decode, such as q=80%, so that q would be served
 	// at 85; a query string that cannot be decoded is refused instead. A
@@ -114,7 +94,7 @@ func (s *Handlers) parseImageRequest(
 		s.respondError(w, fmt.Sprintf("invalid query string %q: %v",
 			r.URL.RawQuery, err), http.StatusBadRequest)
 
-		return nil, false
+		return nil, "", time.Time{}, false
 	}
 
 	for name, values := range query {
@@ -122,17 +102,15 @@ func (s *Handlers) parseImageRequest(
 			s.respondError(w, fmt.Sprintf("invalid %s: given more than once",
 				name), http.StatusBadRequest)
 
-			return nil, false
+			return nil, "", time.Time{}, false
 		}
 	}
 
-	req.Signature = query.Get("sig")
-
-	req.Expires, err = parseExpires(query)
+	expires, err := parseExpires(query)
 	if err != nil {
 		s.respondError(w, err.Error(), http.StatusBadRequest)
 
-		return nil, false
+		return nil, "", time.Time{}, false
 	}
 
 	// Parse optional quality and fit params. Only a q missing from the URL is
@@ -144,51 +122,76 @@ func (s *Handlers) parseImageRequest(
 		s.respondError(w, `invalid q: not a number, got ""`,
 			http.StatusBadRequest)
 
-		return nil, false
+		return nil, "", time.Time{}, false
 	}
 
-	req.Quality, err = parseFormInt(query, "q",
+	req.Transform.Quality, err = parseFormInt(query, "q",
 		encurl.DefaultQuality, minQuality, maxQuality)
 	if err != nil {
 		s.respondError(w, fmt.Sprintf("%v, got %q", err, qStr),
 			http.StatusBadRequest)
 
-		return nil, false
+		return nil, "", time.Time{}, false
 	}
 
 	// Only a fit missing from the URL is cover. A fit in the URL that is not a
 	// fit mode is refused by the fit-mode check below; that check would take an
 	// empty fit as missing, so an empty one is refused here.
-	req.FitMode = imgcache.FitMode(query.Get("fit"))
-	if query.Has("fit") && req.FitMode == "" {
+	req.Transform.FitMode = imagerequest.Fit(query.Get("fit"))
+	if query.Has("fit") && req.Transform.FitMode == "" {
 		s.respondError(w, `invalid fit: not a fit mode, got ""`, http.StatusBadRequest)
 
-		return nil, false
+		return nil, "", time.Time{}, false
 	}
 
 	// Default fit mode if not set
-	if req.FitMode == "" {
-		req.FitMode = imgcache.FitCover
+	if req.Transform.FitMode == "" {
+		req.Transform.FitMode = imagerequest.FitCover
 	}
 
 	// Enforce dimension and fit-mode bounds, shared with the encrypted-URL
 	// route. Dimensions are already bounded by the path parser above; this
 	// also rejects an unrecognized fit mode with 400 instead of letting it
 	// reach the processor as a 500.
-	err = imgcache.ValidateImageRequest(req)
+	err = imagerequest.ValidateImageRequest(req)
 	if err != nil {
 		s.respondError(w, "invalid image request: "+err.Error(),
 			http.StatusBadRequest)
 
-		return nil, false
+		return nil, "", time.Time{}, false
 	}
 
-	return req, true
+	return req, query.Get("sig"), expires, true
+}
+
+// validateSignature returns nil when the source host of req is on
+// allowlist_hosts and names no port. Otherwise it verifies sig, the URL's
+// signature of req, and expires, the URL's expiry.
+func (s *Handlers) validateSignature(
+	req *imagerequest.Request, sig string, expires time.Time,
+) error {
+	// An allowlist entry names no port, so a host followed by ":", with or
+	// without a port, needs a signature. Go's URL type reads the port as the
+	// fetcher does: in an IPv6 address written without brackets, such as
+	// 2001:db8::1:8443, it is what follows the last ":". This is checked here
+	// and not in allowlist.IsAllowed, which also matches referer_blocklist,
+	// where a Referer must be blocked whatever its port. Port and IsAllowed
+	// read only the host of a URL.
+	sourceURL := &url.URL{Host: req.Source.Host}
+	hostHasPort := sourceURL.Port() != "" ||
+		strings.HasSuffix(sourceURL.Host, ":")
+
+	if !hostHasPort && s.allowlist.IsAllowed(sourceURL) {
+		return nil
+	}
+
+	// Signature required for non-allowed hosts
+	return s.signer.Verify(req, sig, expires)
 }
 
 // parseExpires reads the exp query parameter, a Unix time in seconds. An exp
-// missing from the URL gives the zero time, which the signature check takes
-// as no expiration. An exp in the URL that is not a whole number, an empty
+// missing from the URL gives the zero time, which the signature check refuses
+// as a missing exp. An exp in the URL that is not a whole number, an empty
 // one included, is an error naming exp and the value.
 func parseExpires(query url.Values) (time.Time, error) {
 	if !query.Has("exp") {
@@ -216,55 +219,73 @@ func (s *Handlers) HandleTooManyRequests() http.HandlerFunc {
 	}
 }
 
-// respondImageError maps image retrieval errors to HTTP responses.
+// respondImageError answers err, the image service's error for req, on both
+// image routes. It logs a 500 at error level, as pixa's own failure. It logs
+// the other answers at warn level, since the client, the upstream or a full
+// limit caused them. The 415 for a source refused for its first bytes is not
+// logged here, because the image service logs it.
 func (s *Handlers) respondImageError(
-	w http.ResponseWriter, req *imgcache.ImageRequest, err error,
+	w http.ResponseWriter, req *imagerequest.Request, err error,
 ) {
-	s.log.Error("failed to get image",
-		"host", req.SourceHost,
-		"path", req.SourcePath,
-		"error", err,
-	)
-
-	// Check for specific error types
-	if errors.Is(err, httpfetcher.ErrSSRFBlocked) {
-		s.respondError(w, "forbidden", http.StatusForbidden)
-
-		return
-	}
-
-	if errors.Is(err, httpfetcher.ErrUpstreamError) {
-		s.respondError(w, "upstream error", http.StatusBadGateway)
-
-		return
-	}
-
-	if errors.Is(err, httpfetcher.ErrTooManyConnections) ||
-		errors.Is(err, imageprocessor.ErrTooManyImages) ||
-		errors.Is(err, imgcache.ErrProcessingTimedOut) {
-		s.respondError(w, "server busy, try again later",
-			http.StatusServiceUnavailable)
-
-		return
-	}
-
-	if errors.Is(err, httpfetcher.ErrInvalidContentType) ||
-		errors.Is(err, imageprocessor.ErrUnsupportedInputFormat) {
+	// An upstream body whose first bytes are not those of the format its
+	// Content-Type names is the upstream's error, not pixa's: the image
+	// service has logged it as a refused source.
+	if errors.Is(err, magic.ErrMagicByteMismatch) ||
+		errors.Is(err, magic.ErrUnknownFormat) ||
+		errors.Is(err, magic.ErrNotEnoughData) {
 		s.respondError(w, "unsupported source format",
 			http.StatusUnsupportedMediaType)
 
 		return
 	}
 
-	if errors.Is(err, imageprocessor.ErrOutputTooLarge) {
-		s.respondError(w, fmt.Sprintf("size too large for the source: the side "+
+	var (
+		status  int
+		message string
+	)
+
+	switch {
+	case errors.Is(err, httpfetcher.ErrSSRFBlocked):
+		status, message = http.StatusForbidden, "forbidden"
+	case errors.Is(err, httpfetcher.ErrUpstreamError):
+		status, message = http.StatusBadGateway, "upstream error"
+	case errors.Is(err, httpfetcher.ErrUpstreamTimeout):
+		status, message = http.StatusGatewayTimeout, "upstream timeout"
+	case errors.Is(err, httpfetcher.ErrTooManyConnections),
+		errors.Is(err, imageprocessor.ErrTooManyImages),
+		errors.Is(err, imgcache.ErrProcessingTimedOut):
+		status = http.StatusServiceUnavailable
+		message = "server busy, try again later"
+	case errors.Is(err, httpfetcher.ErrInvalidContentType),
+		errors.Is(err, imageprocessor.ErrUnsupportedInputFormat):
+		status = http.StatusUnsupportedMediaType
+		message = "unsupported source format"
+	case errors.Is(err, imageprocessor.ErrOutputTooLarge):
+		status = http.StatusBadRequest
+		message = fmt.Sprintf("size too large for the source: the side "+
 			"computed from its proportions is above %d",
-			imageprocessor.MaxOutputDimension), http.StatusBadRequest)
+			imageprocessor.MaxOutputDimension)
+	case errors.Is(err, imageprocessor.ErrAVIFOutputTooLarge):
+		status = http.StatusBadRequest
+		message = fmt.Sprintf("size too large for AVIF: the output "+
+			"would be above %d pixels", imageprocessor.MaxAVIFOutputPixels)
+	default:
+		s.log.Error("failed to get image",
+			"host", req.Source.Host,
+			"path", req.Source.Path,
+			"error", err,
+		)
+		s.respondError(w, "internal error", http.StatusInternalServerError)
 
 		return
 	}
 
-	s.respondError(w, "internal error", http.StatusInternalServerError)
+	s.log.Warn("failed to get image",
+		"host", req.Source.Host,
+		"path", req.Source.Path,
+		"error", err,
+	)
+	s.respondError(w, message, status)
 }
 
 // cacheControl returns the Cache-Control header for an image served through a
@@ -321,13 +342,34 @@ func notModified(w http.ResponseWriter, r *http.Request, etag string) bool {
 	return true
 }
 
-// writeImageResponse writes headers and streams the image content,
-// handling conditional and HEAD requests.
-func (s *Handlers) writeImageResponse(
+// serveImage serves the image that req asks for. Both image routes call it
+// once they have the request and its URL's expiry, which ends the
+// Cache-Control max-age. It chooses the format for the format auto, answers
+// If-None-Match with 304 and HEAD with the headers only, and answers an error
+// of the image service with respondImageError.
+func (s *Handlers) serveImage(
 	w http.ResponseWriter, r *http.Request,
-	req *imgcache.ImageRequest, resp *imgcache.ImageResponse,
-	cacheKey imgcache.VariantKey, startTime time.Time,
+	req *imagerequest.Request, expires time.Time,
 ) {
+	// The signature or the token covers the format auto, not the format chosen
+	format, ok := s.chooseAutoFormat(w, r, req.Transform.Format)
+	if !ok {
+		return
+	}
+
+	req.Transform.Format = format
+
+	startTime := time.Now()
+
+	resp, err := s.imgSvc.Get(r.Context(), req)
+	if err != nil {
+		s.respondImageError(w, req, err)
+
+		return
+	}
+
+	defer func() { _ = resp.Content.Close() }()
+
 	// Set response headers
 	w.Header().Set("Content-Type", resp.ContentType)
 
@@ -336,7 +378,7 @@ func (s *Handlers) writeImageResponse(
 	}
 
 	// Cache control headers
-	w.Header().Set("Cache-Control", cacheControl(req.Expires))
+	w.Header().Set("Cache-Control", cacheControl(expires))
 	w.Header().Set("X-Pixa-Cache", string(resp.CacheStatus))
 
 	if notModified(w, r, resp.ETag) {
@@ -353,21 +395,31 @@ func (s *Handlers) writeImageResponse(
 	// Stream the response
 	w.WriteHeader(http.StatusOK)
 
+	// A failed write is most often a client that has gone away, not pixa's
+	// failure, so it is logged at warn level
 	servedBytes, err := io.Copy(w, resp.Content)
 	if err != nil {
-		s.log.Error("failed to write response",
+		s.log.Warn("failed to write response",
+			"request_id", middleware.GetReqID(r.Context()),
+			"host", req.Source.Host,
+			"path", req.Source.Path,
+			"served_bytes", servedBytes,
 			"error", err,
 		)
+
+		return
 	}
 
 	// Log cache status and timing after serving
 	duration := time.Since(startTime)
 	s.log.Info("image served",
 		"request_id", middleware.GetReqID(r.Context()),
-		"cache_key", cacheKey,
+		"cache_key", imagerequest.CacheKey(req),
+		"host", req.Source.Host,
+		"path", req.Source.Path,
 		"cache_status", resp.CacheStatus,
 		"duration_ms", duration.Milliseconds(),
-		"format", req.Format,
+		"format", req.Transform.Format,
 		"served_bytes", servedBytes,
 		"fetched_bytes", resp.FetchedBytes,
 	)

internal/handlers/image_cache_control_internal_test.go

@@ -12,9 +12,15 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
+	"github.com/prometheus/client_golang/prometheus"
 
+	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/encurl"
+	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/seal"
+	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // photoPath is the path of the JPEG that newSignedHostServer serves.
@@ -32,7 +38,8 @@ func newSignedHostServer(
 	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.CacheConfig{
 		StateDir:    t.TempDir(),
 		NegativeTTL: 5 * time.Minute,
-	})
+		MaxBytes:    1 << 30,
+	}, prometheus.NewRegistry())
 	if err != nil {
 		t.Fatalf("imgcache.NewCache() error = %v", err)
 	}
@@ -44,22 +51,30 @@ func newSignedHostServer(
 		Fetcher: newMockFetcher(fstest.MapFS{
 			signedHost + photoPath: &fstest.MapFile{Data: jpegData},
 		}),
-		SigningKey: testSigningKey,
-		Logger:     log,
+		Processor: imageprocessor.New(imageprocessor.Params{
+			MaxInputBytes:           50 << 20,
+			MaxConcurrentProcessing: 2,
+		}),
+		MaxResponseSize: 50 << 20,
+		Logger:          log,
 	})
 	if err != nil {
 		t.Fatalf("imgcache.NewService() error = %v", err)
 	}
 
-	encGen, err := encurl.NewGenerator(testSigningKey)
+	keys, err := seal.DeriveKeys(testSigningKey)
 	if err != nil {
-		t.Fatalf("encurl.NewGenerator() error = %v", err)
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
 	}
 
+	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
+
 	h := &Handlers{
-		log:    log,
-		imgSvc: svc,
-		encGen: encGen,
+		log:       log,
+		imgSvc:    svc,
+		encGen:    encGen,
+		signer:    signature.New(testSigningKey),
+		allowlist: allowlist.New(nil),
 	}
 
 	r := chi.NewRouter()
@@ -105,17 +120,18 @@ func getMaxAge(t *testing.T, srv http.Handler, target string) int {
 func TestHandleImage_SignedURL_MaxAgeEndsAtExp(t *testing.T) {
 	t.Parallel()
 
-	h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
+	_, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
 
-	signedURL, err := h.imgSvc.GenerateSignedURL("", &imgcache.ImageRequest{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Size:       imgcache.Size{Width: 50, Height: 50},
-		Format:     imgcache.FormatJPEG,
+	signedURL := generateSignedURL(testSigningKey, &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatJPEG,
+		},
 	}, time.Minute)
-	if err != nil {
-		t.Fatalf("GenerateSignedURL() error = %v", err)
-	}
 
 	maxAge := getMaxAge(t, srv, signedURL)
 	if maxAge < 50 || maxAge > 60 {
@@ -168,13 +184,13 @@ func TestHandleImageEnc_MaxAge(t *testing.T) {
 
 	tests := []struct {
 		name        string
-		expiresAt   int64
+		expires     time.Time
 		wantAtLeast int
 		wantAtMost  int
 	}{
-		{"60 second TTL", time.Now().Add(time.Minute).Unix(), 50, 60},
-		{"two-year TTL", time.Now().Add(2 * 365 * 24 * time.Hour).Unix(), 31536000, 31536000},
-		{"no TTL", 0, 31536000, 31536000},
+		{"60 second TTL", time.Now().Add(time.Minute), 50, 60},
+		{"two-year TTL", time.Now().Add(2 * 365 * 24 * time.Hour), 31536000, 31536000},
+		{"no TTL", time.Time{}, 31536000, 31536000},
 	}
 
 	for _, tt := range tests {
@@ -183,14 +199,16 @@ func TestHandleImageEnc_MaxAge(t *testing.T) {
 
 			h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
 
-			token, err := h.encGen.Generate(&encurl.Payload{
-				SourceHost: signedHost,
-				SourcePath: photoPath,
-				Width:      50,
-				Height:     50,
-				Format:     imgcache.FormatJPEG,
-				ExpiresAt:  tt.expiresAt,
-			})
+			token, err := h.encGen.Generate(&imagerequest.Request{
+				Source: imagerequest.Source{
+					Host: signedHost,
+					Path: photoPath,
+				},
+				Transform: imagerequest.Transform{
+					Size:   imagerequest.Size{Width: 50, Height: 50},
+					Format: imagerequest.FormatJPEG,
+				},
+			}, tt.expires)
 			if err != nil {
 				t.Fatalf("Generate() error = %v", err)
 			}

internal/handlers/image_errors_internal_test.go

@@ -1,19 +1,28 @@
 package handlers
 
 import (
+	"bytes"
+	"context"
 	"encoding/json"
 	"fmt"
 	"image/color"
+	"io"
 	"log/slog"
 	"net/http"
 	"net/http/httptest"
+	"slices"
 	"strings"
 	"testing"
 	"testing/fstest"
 	"time"
 
 	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+	"github.com/prometheus/client_golang/prometheus"
+	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
 	"sneak.berlin/go/pixa/internal/signature"
 )
@@ -23,29 +32,38 @@ import (
 const allowlistedHost = "allowed.example.com"
 
 // newImageRoute returns the image route of a Handlers whose service fetches
-// with fetcher and checks signatures with testSigningKey.
+// with fetcher, and which checks signatures with testSigningKey.
 func newImageRoute(t *testing.T, fetcher httpfetcher.Fetcher) http.Handler {
 	t.Helper()
 
 	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.CacheConfig{
 		StateDir:    t.TempDir(),
 		NegativeTTL: 5 * time.Minute,
-	})
+		MaxBytes:    1 << 30,
+	}, prometheus.NewRegistry())
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
 	}
 
 	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
-		Cache:      cache,
-		Fetcher:    fetcher,
-		SigningKey: testSigningKey,
-		Allowlist:  []string{allowlistedHost},
+		Cache:   cache,
+		Fetcher: fetcher,
+		Processor: imageprocessor.New(imageprocessor.Params{
+			MaxInputBytes:           50 << 20,
+			MaxConcurrentProcessing: 2,
+		}),
+		MaxResponseSize: 50 << 20,
 	})
 	if err != nil {
 		t.Fatalf("failed to create service: %v", err)
 	}
 
-	h := &Handlers{imgSvc: svc, log: slog.New(slog.DiscardHandler)}
+	h := &Handlers{
+		imgSvc:    svc,
+		log:       slog.New(slog.DiscardHandler),
+		signer:    signature.New(testSigningKey),
+		allowlist: allowlist.New([]string{allowlistedHost}),
+	}
 
 	r := chi.NewRouter()
 	r.Get("/v1/image/*", h.HandleImage())
@@ -54,7 +72,7 @@ func newImageRoute(t *testing.T, fetcher httpfetcher.Fetcher) http.Handler {
 }
 
 // newPhotoFetcher returns a mock fetcher that serves a JPEG at photoPath on
-// each of hosts, and answers any other URL with an upstream error.
+// each of hosts, and answers any other source with an upstream error.
 func newPhotoFetcher(t *testing.T, hosts ...string) *httpfetcher.MockFetcher {
 	t.Helper()
 
@@ -81,19 +99,27 @@ func photoURLWithSig(host, sig string, expires time.Time) string {
 	return fmt.Sprintf("%s?sig=%s&exp=%d", photoURL(host), sig, expires.Unix())
 }
 
+// photoRequest returns the image request of photoURL(host) at the default
+// quality and fit.
+func photoRequest(host string) *imagerequest.Request {
+	return &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: host,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 50, Height: 50},
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
+	}
+}
+
 // photoSignature returns the signature of photoURL(host) at the default
 // quality and fit, made with key and expiring at expires.
 func photoSignature(key, host string, expires time.Time) string {
-	return signature.New(key).Sign(&signature.Request{
-		SourceHost: host,
-		SourcePath: photoPath,
-		Width:      50,
-		Height:     50,
-		Format:     string(imgcache.FormatJPEG),
-		Quality:    85,
-		FitMode:    string(imgcache.FitCover),
-		Expires:    expires,
-	})
+	return signature.New(key).Sign(photoRequest(host), expires)
 }
 
 // sendGet sends a GET for target to route and returns the response.
@@ -164,7 +190,12 @@ func TestHandleImage_ErrorAnswers(t *testing.T) {
 	photos := newPhotoFetcher(t,
 		signedHost, parentHost, siblingHost, subdomainHost, appendedHost)
 	// The real fetcher refuses localhost before any lookup or connection.
-	realFetcher := httpfetcher.New(httpfetcher.DefaultConfig())
+	realFetcher := httpfetcher.New(&httpfetcher.Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        64,
+	})
 
 	exp := time.Now().Add(time.Hour)
 	expired := time.Now().Add(-time.Hour)
@@ -264,3 +295,292 @@ func TestHandleImage_AllowlistOrSignature(t *testing.T) {
 		})
 	}
 }
+
+// TestHandleImage_InvalidHost_Returns400 sends image URLs whose host no URL
+// host can be, and checks that each is refused with 400 naming the host as
+// decoded: allowlistedHost with a character after it that a URL host cannot
+// hold, percent-encoded, an IPv6 address without brackets, and brackets
+// around something that is not an IPv6 address. Later steps put the host
+// unparsed into the allowlist check, the cache key and the upstream URL, so
+// such a host is refused first.
+func TestHandleImage_InvalidHost_Returns400(t *testing.T) {
+	t.Parallel()
+
+	photos := newPhotoFetcher(t, allowlistedHost)
+
+	tests := []struct {
+		name        string
+		writtenHost string
+		decodedHost string
+	}{
+		{"? written as %3F", allowlistedHost + "%3Fx=1", allowlistedHost + "?x=1"},
+		{"# written as %23", allowlistedHost + "%23x", allowlistedHost + "#x"},
+		{"% written as %25", allowlistedHost + "%253F", allowlistedHost + "%3F"},
+		{`\ written as %5C`, allowlistedHost + "%5Cx", allowlistedHost + `\x`},
+		{"space written as %20", allowlistedHost + "%20", allowlistedHost + " "},
+		{"IPv6 address without brackets", "2001:db8::1", "2001:db8::1"},
+		{"IPv4 address in brackets", "[203.0.113.5]", "[203.0.113.5]"},
+		{"no address in brackets", "[abc]", "[abc]"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			rec := sendGet(t, newImageRoute(t, photos), photoURL(tt.writtenHost))
+			checkErrorBody(t, rec, http.StatusBadRequest,
+				fmt.Sprintf("invalid image URL: invalid source host: %q",
+					tt.decodedHost))
+		})
+	}
+}
+
+// TestHandleImage_HostForms_Served checks that the image route serves, with
+// a valid signature, the image at photoPath on a host name, an IPv4 address,
+// an IPv6 address in brackets, and a host followed by ":" with or without a
+// port.
+func TestHandleImage_HostForms_Served(t *testing.T) {
+	t.Parallel()
+
+	hosts := []string{
+		allowlistedHost,
+		"img_1.example.com",
+		"203.0.113.5",
+		"[2001:db8::1]",
+		allowlistedHost + ":8443",
+		"[2001:db8::1]:8443",
+		allowlistedHost + ":",
+	}
+
+	photos := newPhotoFetcher(t, hosts...)
+	exp := time.Now().Add(time.Hour)
+
+	for _, host := range hosts {
+		t.Run(host, func(t *testing.T) {
+			t.Parallel()
+
+			sig := photoSignature(testSigningKey, host, exp)
+
+			rec := sendGet(t, newImageRoute(t, photos),
+				photoURLWithSig(host, sig, exp))
+			if rec.Code != http.StatusOK {
+				t.Errorf("status = %d, want %d: %s",
+					rec.Code, http.StatusOK, rec.Body)
+			}
+		})
+	}
+}
+
+// TestHandleImage_HashInSourcePathOrQuery_Returns400 sends image URLs whose
+// source path or source query holds a "#", written as %23, and checks that
+// each is refused with 400, the one signed for that source path included.
+// A "#" starts a URL's fragment, so neither the source path nor the source
+// query may hold one.
+func TestHandleImage_HashInSourcePathOrQuery_Returns400(t *testing.T) {
+	t.Parallel()
+
+	photos := newPhotoFetcher(t, allowlistedHost, signedHost)
+	exp := time.Now().Add(time.Hour)
+
+	sig := signature.New(testSigningKey).Sign(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath + "#x",
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 50, Height: 50},
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
+	}, exp)
+
+	tests := []struct {
+		name   string
+		target string
+	}{
+		{"# in the source path",
+			"/v1/image/" + allowlistedHost + photoPath + "%23x/50x50.jpeg"},
+		{"# in the source query",
+			"/v1/image/" + allowlistedHost + photoPath + "%3Fv=1%23x/50x50.jpeg"},
+		{"# in the source path, signed",
+			fmt.Sprintf("/v1/image/%s%s%%23x/50x50.jpeg?sig=%s&exp=%d",
+				signedHost, photoPath, sig, exp.Unix())},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			rec := sendGet(t, newImageRoute(t, photos), tt.target)
+			checkErrorBody(t, rec, http.StatusBadRequest,
+				`invalid image URL: invalid image path: `+
+					`the source path or query holds a "#"`)
+		})
+	}
+}
+
+// failingFetcher answers every fetch with its error.
+type failingFetcher struct {
+	err error
+}
+
+// Fetch returns f's error.
+func (f failingFetcher) Fetch(
+	context.Context, imagerequest.Source,
+) (*httpfetcher.FetchResult, error) {
+	return nil, f.err
+}
+
+// photoURLsByRoute returns, for each image route, the function that makes the
+// URL of the JPEG at photoPath on signedHost on that route.
+func photoURLsByRoute() map[string]func(*testing.T, *Handlers) string {
+	return map[string]func(*testing.T, *Handlers) string{
+		"/v1/image/": signedPhotoURL,
+		"/v1/e/":     encPhotoURL,
+	}
+}
+
+// TestImageRoutes_SameErrorAnswers checks that both image routes answer each
+// upstream fetch error below with the same status. They log it as "failed to
+// get image" at the same level: error for the 500 and warn for the others.
+// Each request gets routes of its own, so no request finds another's failed
+// fetch in the negative cache.
+func TestImageRoutes_SameErrorAnswers(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name       string
+		err        error
+		wantStatus int
+		wantLevel  slog.Level
+	}{
+		{"blocked upstream address", httpfetcher.ErrSSRFBlocked,
+			http.StatusForbidden, slog.LevelWarn},
+		{"upstream error status",
+			fmt.Errorf("%w: status 404", httpfetcher.ErrUpstreamError),
+			http.StatusBadGateway, slog.LevelWarn},
+		{"no response headers within the fetch timeout",
+			httpfetcher.ErrUpstreamTimeout, http.StatusGatewayTimeout,
+			slog.LevelWarn},
+		{"no free upstream connection", httpfetcher.ErrTooManyConnections,
+			http.StatusServiceUnavailable, slog.LevelWarn},
+		{"Content-Type not a source format",
+			fmt.Errorf("%w: image/svg+xml", httpfetcher.ErrInvalidContentType),
+			http.StatusUnsupportedMediaType, slog.LevelWarn},
+		{"any other failure", io.ErrUnexpectedEOF,
+			http.StatusInternalServerError, slog.LevelError},
+	}
+
+	for _, tt := range tests {
+		for route, imageURL := range photoURLsByRoute() {
+			t.Run(route+" "+tt.name, func(t *testing.T) {
+				t.Parallel()
+
+				var logs bytes.Buffer
+
+				h, routes := newRoutesFetchingThrough(t,
+					failingFetcher{err: tt.err},
+					slog.New(slog.NewJSONHandler(&logs, nil)))
+
+				rec := sendGet(t, routes, imageURL(t, h))
+				if rec.Code != tt.wantStatus {
+					t.Errorf("status = %d, want %d: %s",
+						rec.Code, tt.wantStatus, rec.Body)
+				}
+
+				levels := loggedLevels(t, &logs)
+				if !slices.Contains(levels[tt.wantLevel.String()],
+					"failed to get image") {
+					t.Errorf(`no "failed to get image" line logged at level %s`,
+						tt.wantLevel)
+				}
+
+				if tt.wantLevel != slog.LevelError &&
+					len(levels[slog.LevelError.String()]) != 0 {
+					t.Errorf("logged at error level: %q",
+						levels[slog.LevelError.String()])
+				}
+			})
+		}
+	}
+}
+
+// failingResponseWriter is a response writer whose Write always fails, as when
+// the client has gone away.
+type failingResponseWriter struct {
+	*httptest.ResponseRecorder
+}
+
+// Write writes nothing and returns io.ErrClosedPipe.
+func (failingResponseWriter) Write([]byte) (int, error) {
+	return 0, io.ErrClosedPipe
+}
+
+// TestImageRoutes_FailedWriteLoggedOnce checks that both image routes log a
+// failed write of the image once, at warn level, with the request's ID, the
+// source host and path, the bytes served and the error. Neither may also log
+// the image as served.
+func TestImageRoutes_FailedWriteLoggedOnce(t *testing.T) {
+	t.Parallel()
+
+	const requestID = "test-request-id"
+
+	for route, imageURL := range photoURLsByRoute() {
+		t.Run(route, func(t *testing.T) {
+			t.Parallel()
+
+			var logs bytes.Buffer
+
+			h, srv := newSignedHostServer(t,
+				slog.New(slog.NewJSONHandler(&logs, nil)))
+
+			ctx := context.WithValue(t.Context(),
+				middleware.RequestIDKey, requestID)
+			srv.ServeHTTP(failingResponseWriter{httptest.NewRecorder()},
+				httptest.NewRequestWithContext(
+					ctx, http.MethodGet, imageURL(t, h), nil))
+
+			t.Logf("logged:\n%s", logs.String())
+
+			var failedWrites []map[string]any
+
+			dec := json.NewDecoder(&logs)
+			for dec.More() {
+				var line map[string]any
+
+				err := dec.Decode(&line)
+				if err != nil {
+					t.Fatalf("decoding log line: %v", err)
+				}
+
+				switch line["msg"] {
+				case "image served":
+					t.Error(`"image served" logged after a failed write`)
+				case "failed to write response":
+					failedWrites = append(failedWrites, line)
+				}
+			}
+
+			if len(failedWrites) != 1 {
+				t.Fatalf(`"failed to write response" logged %d times, want 1`,
+					len(failedWrites))
+			}
+
+			want := map[string]any{
+				"level":        slog.LevelWarn.String(),
+				"request_id":   requestID,
+				"host":         signedHost,
+				"path":         photoPath,
+				"served_bytes": float64(0),
+				"error":        io.ErrClosedPipe.Error(),
+			}
+
+			for key, wantValue := range want {
+				if got := failedWrites[0][key]; got != wantValue {
+					t.Errorf("%s = %v, want %v", key, got, wantValue)
+				}
+			}
+		})
+	}
+}

internal/handlers/image_signature_internal_test.go

@@ -5,11 +5,12 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"testing"
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/signature"
 )
 
@@ -36,6 +37,47 @@ func getImage(t *testing.T, fix *testFixtures, target string) int {
 	return rec.Code
 }
 
+// generateSignedURL returns the /v1/image/ URL of req, signed with key and
+// expiring after ttl. It signs a copy of req, so req itself is not changed.
+// An unset quality or fit in the copy is set to 85 or cover, the values the
+// route uses when a URL has no q or fit. The URL carries q and fit next to sig
+// and exp, so the route verifies it for the quality and fit it was signed
+// with.
+func generateSignedURL(
+	key string, req *imagerequest.Request, ttl time.Duration,
+) string {
+	signed := *req
+
+	if signed.Transform.Quality == 0 {
+		signed.Transform.Quality = 85
+	}
+
+	if signed.Transform.FitMode == "" {
+		signed.Transform.FitMode = imagerequest.FitCover
+	}
+
+	expires := time.Now().Add(ttl)
+	sig := signature.New(key).Sign(&signed, expires)
+
+	// A source query follows the source path after a "?". The image route
+	// reads the path decoded once, so the whole path is written in Go's own
+	// percent-encoding of a URL path, which writes "?" as %3F and "%" as %25,
+	// and leaves "/", ";", ",", "=" and "&" as they are.
+	sourcePathAndQuery := signed.Source.Path
+	if signed.Source.Query != "" {
+		sourcePathAndQuery += "?" + signed.Source.Query
+	}
+
+	unescapedPath := fmt.Sprintf("/v1/image/%s%s/%dx%d.%s",
+		signed.Source.Host, sourcePathAndQuery,
+		signed.Transform.Size.Width, signed.Transform.Size.Height,
+		signed.Transform.Format)
+
+	return fmt.Sprintf("%s?sig=%s&exp=%d&q=%d&fit=%s",
+		(&url.URL{Path: unescapedPath}).EscapedPath(), sig, expires.Unix(),
+		signed.Transform.Quality, signed.Transform.FitMode)
+}
+
 // TestHandleImage_SignatureCoversQualityAndFit signs a URL for quality 85
 // and fit cover, the values the route uses when a URL has no q or fit, and
 // sends that signature with each q and fit below.
@@ -44,16 +86,18 @@ func TestHandleImage_SignatureCoversQualityAndFit(t *testing.T) {
 
 	expires := time.Now().Add(time.Hour)
 	signer := signature.New("test-signing-key-must-be-32-chars")
-	sig := signer.Sign(&signature.Request{
-		SourceHost: signedHost,
-		SourcePath: "/images/photo.jpg",
-		Width:      50,
-		Height:     50,
-		Format:     string(imgcache.FormatJPEG),
-		Quality:    85,
-		FitMode:    string(imgcache.FitCover),
-		Expires:    expires,
-	})
+	sig := signer.Sign(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: "/images/photo.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 50, Height: 50},
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
+	}, expires)
 	signedURL := fmt.Sprintf("/v1/image/%s/images/photo.jpg/50x50.jpeg?sig=%s&exp=%d",
 		signedHost, sig, expires.Unix())
 
@@ -80,17 +124,17 @@ func TestHandleImage_SignatureCoversQualityAndFit(t *testing.T) {
 	}
 }
 
-// TestHandleImage_GeneratedSignedURLVerifies sends URLs built by the
-// service's signed-URL generator to the route.
+// TestHandleImage_GeneratedSignedURLVerifies sends URLs built by
+// generateSignedURL to the route.
 func TestHandleImage_GeneratedSignedURLVerifies(t *testing.T) {
 	t.Parallel()
 
 	tests := []struct {
 		name    string
 		quality int
-		fitMode imgcache.FitMode
+		fitMode imagerequest.Fit
 	}{
-		{"quality 40 and fit contain", 40, imgcache.FitContain},
+		{"quality 40 and fit contain", 40, imagerequest.FitContain},
 		{"quality and fit unset", 0, ""},
 	}
 
@@ -98,21 +142,21 @@ func TestHandleImage_GeneratedSignedURLVerifies(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			fix := setupTestHandler(t)
+			signedURL := generateSignedURL("test-signing-key-must-be-32-chars",
+				&imagerequest.Request{
+					Source: imagerequest.Source{
+						Host: signedHost,
+						Path: "/images/photo.jpg",
+					},
+					Transform: imagerequest.Transform{
+						Size:    imagerequest.Size{Width: 50, Height: 50},
+						Format:  imagerequest.FormatJPEG,
+						Quality: tt.quality,
+						FitMode: tt.fitMode,
+					},
+				}, time.Hour)
 
-			signedURL, err := fix.service.GenerateSignedURL("", &imgcache.ImageRequest{
-				SourceHost: signedHost,
-				SourcePath: "/images/photo.jpg",
-				Size:       imgcache.Size{Width: 50, Height: 50},
-				Format:     imgcache.FormatJPEG,
-				Quality:    tt.quality,
-				FitMode:    tt.fitMode,
-			}, time.Hour)
-			if err != nil {
-				t.Fatalf("GenerateSignedURL() error = %v", err)
-			}
-
-			status := getImage(t, fix, signedURL)
+			status := getImage(t, setupTestHandler(t), signedURL)
 			if status != http.StatusBadGateway {
 				t.Errorf("status = %d, want %d", status, http.StatusBadGateway)
 			}
@@ -171,10 +215,10 @@ func TestHandleImage_InvalidExp_Returns400(t *testing.T) {
 }
 
 // TestHandleImage_GeneratedSignedURLWithSourceQueryVerifies sends URLs built
-// by the service's signed-URL generator for source URLs with a query to the
-// route, through a chi router: chi routes on the path as the client wrote it
-// whenever that is not Go's own encoding of it. A 502 means the signature
-// passed, so the route read the source path and query that were signed.
+// by generateSignedURL for source URLs with a query to the route, through a
+// chi router: chi routes on the path as the client wrote it whenever that is
+// not Go's own encoding of it. A 502 means the signature passed, so the route
+// read the source path and query that were signed.
 func TestHandleImage_GeneratedSignedURLWithSourceQueryVerifies(t *testing.T) {
 	t.Parallel()
 
@@ -194,20 +238,20 @@ func TestHandleImage_GeneratedSignedURLWithSourceQueryVerifies(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			fix := setupTestHandler(t)
+			signedURL := generateSignedURL("test-signing-key-must-be-32-chars",
+				&imagerequest.Request{
+					Source: imagerequest.Source{
+						Host:  signedHost,
+						Path:  photoPath,
+						Query: tt.query,
+					},
+					Transform: imagerequest.Transform{
+						Size:   imagerequest.Size{Width: 50, Height: 50},
+						Format: imagerequest.FormatJPEG,
+					},
+				}, time.Hour)
 
-			signedURL, err := fix.service.GenerateSignedURL("", &imgcache.ImageRequest{
-				SourceHost:  signedHost,
-				SourcePath:  photoPath,
-				SourceQuery: tt.query,
-				Size:        imgcache.Size{Width: 50, Height: 50},
-				Format:      imgcache.FormatJPEG,
-			}, time.Hour)
-			if err != nil {
-				t.Fatalf("GenerateSignedURL() error = %v", err)
-			}
-
-			status := getImage(t, fix, signedURL)
+			status := getImage(t, setupTestHandler(t), signedURL)
 			if status != http.StatusBadGateway {
 				t.Errorf("status = %d, want %d", status, http.StatusBadGateway)
 			}
@@ -224,17 +268,19 @@ func TestHandleImage_SourceQueryEncodedAnyWay(t *testing.T) {
 
 	expires := time.Now().Add(time.Hour)
 	signer := signature.New("test-signing-key-must-be-32-chars")
-	sig := signer.Sign(&signature.Request{
-		SourceHost:  signedHost,
-		SourcePath:  photoPath,
-		SourceQuery: "url=https://origin.example.com/my%20cat.jpg",
-		Width:       50,
-		Height:      50,
-		Format:      string(imgcache.FormatJPEG),
-		Quality:     85,
-		FitMode:     string(imgcache.FitCover),
-		Expires:     expires,
-	})
+	sig := signer.Sign(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host:  signedHost,
+			Path:  photoPath,
+			Query: "url=https://origin.example.com/my%20cat.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 50, Height: 50},
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
+	}, expires)
 
 	tests := []struct {
 		name         string
@@ -266,7 +312,7 @@ func TestHandleImage_SourceQueryEncodedAnyWay(t *testing.T) {
 // TestHandleImage_SourceURLHoldingPercent25Verifies signs a source path and a
 // source query that each hold %25, the percent-escape of a literal "%", and
 // sends each to the route written as the README says, with that "%" written as
-// %25, and as GenerateSignedURL writes it. A 502 means the signature passed.
+// %25, and as generateSignedURL writes it. A 502 means the signature passed.
 func TestHandleImage_SourceURLHoldingPercent25Verifies(t *testing.T) {
 	t.Parallel()
 
@@ -288,17 +334,19 @@ func TestHandleImage_SourceURLHoldingPercent25Verifies(t *testing.T) {
 
 			expires := time.Now().Add(time.Hour)
 			signer := signature.New("test-signing-key-must-be-32-chars")
-			sig := signer.Sign(&signature.Request{
-				SourceHost:  signedHost,
-				SourcePath:  tt.sourcePath,
-				SourceQuery: tt.sourceQuery,
-				Width:       50,
-				Height:      50,
-				Format:      string(imgcache.FormatJPEG),
-				Quality:     85,
-				FitMode:     string(imgcache.FitCover),
-				Expires:     expires,
-			})
+			sig := signer.Sign(&imagerequest.Request{
+				Source: imagerequest.Source{
+					Host:  signedHost,
+					Path:  tt.sourcePath,
+					Query: tt.sourceQuery,
+				},
+				Transform: imagerequest.Transform{
+					Size:    imagerequest.Size{Width: 50, Height: 50},
+					Format:  imagerequest.FormatJPEG,
+					Quality: 85,
+					FitMode: imagerequest.FitCover,
+				},
+			}, expires)
 
 			target := fmt.Sprintf("/v1/image/%s%s/50x50.jpeg?sig=%s&exp=%d",
 				signedHost, tt.writtenPathAndQuery, sig, expires.Unix())
@@ -309,23 +357,23 @@ func TestHandleImage_SourceURLHoldingPercent25Verifies(t *testing.T) {
 			}
 		})
 
-		t.Run(tt.name+" written by GenerateSignedURL", func(t *testing.T) {
+		t.Run(tt.name+" written by generateSignedURL", func(t *testing.T) {
 			t.Parallel()
 
-			fix := setupTestHandler(t)
+			signedURL := generateSignedURL("test-signing-key-must-be-32-chars",
+				&imagerequest.Request{
+					Source: imagerequest.Source{
+						Host:  signedHost,
+						Path:  tt.sourcePath,
+						Query: tt.sourceQuery,
+					},
+					Transform: imagerequest.Transform{
+						Size:   imagerequest.Size{Width: 50, Height: 50},
+						Format: imagerequest.FormatJPEG,
+					},
+				}, time.Hour)
 
-			signedURL, err := fix.service.GenerateSignedURL("", &imgcache.ImageRequest{
-				SourceHost:  signedHost,
-				SourcePath:  tt.sourcePath,
-				SourceQuery: tt.sourceQuery,
-				Size:        imgcache.Size{Width: 50, Height: 50},
-				Format:      imgcache.FormatJPEG,
-			}, time.Hour)
-			if err != nil {
-				t.Fatalf("GenerateSignedURL() error = %v", err)
-			}
-
-			status := getImage(t, fix, signedURL)
+			status := getImage(t, setupTestHandler(t), signedURL)
 			if status != http.StatusBadGateway {
 				t.Errorf("status = %d, want %d", status, http.StatusBadGateway)
 			}

internal/handlers/imageenc.go

@@ -2,19 +2,13 @@ package handlers
 
 import (
 	"errors"
-	"fmt"
-	"io"
 	"net/http"
-	"strconv"
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"github.com/go-chi/chi/v5/middleware"
 
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
-	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // HandleImageEnc handles requests to /v1/e/{token}/* for encrypted
@@ -26,152 +20,59 @@ func (s *Handlers) HandleImageEnc() http.HandlerFunc {
 			return
 		}
 
-		ctx := r.Context()
-		start := time.Now()
-
-		req, ok := s.parseImageEncRequest(w, r)
-		if !ok || !s.chooseAutoFormat(w, r, req) {
+		req, expires, ok := s.parseImageEncRequest(w, r)
+		if !ok {
 			return
 		}
 
-		// Log the request
-		s.log.Debug("encrypted image request",
-			"host", req.SourceHost,
-			"path", req.SourcePath,
-			"dimensions", fmt.Sprintf("%dx%d", req.Size.Width, req.Size.Height),
-			"format", req.Format,
-		)
-
-		// Fetch and process the image (no signature validation
-		// needed - encrypted URL is trusted)
-		resp, err := s.imgSvc.Get(ctx, req)
-		if err != nil {
-			s.handleImageError(w, err)
-
-			return
-		}
-
-		defer func() { _ = resp.Content.Close() }()
-
-		// Set response headers
-		w.Header().Set("Content-Type", resp.ContentType)
-
-		if resp.ContentLength > 0 {
-			w.Header().Set("Content-Length", strconv.FormatInt(resp.ContentLength, 10))
-		}
-
-		// Cache headers: max-age ends at the URL's expiry
-		w.Header().Set("Cache-Control", cacheControl(req.Expires))
-		w.Header().Set("X-Pixa-Cache", string(resp.CacheStatus))
-
-		if notModified(w, r, resp.ETag) {
-			return
-		}
-
-		// A HEAD request gets the headers only
-		if r.Method == http.MethodHead {
-			w.WriteHeader(http.StatusOK)
-
-			return
-		}
-
-		// Stream the response
-		written, err := io.Copy(w, resp.Content)
-		if err != nil {
-			s.log.Error("failed to write response", "error", err)
-
-			return
-		}
-
-		// Log completion
-		duration := time.Since(start)
-		s.log.Info("image served",
-			"request_id", middleware.GetReqID(ctx),
-			"cache_key", imgcache.CacheKey(req),
-			"host", req.SourceHost,
-			"path", req.SourcePath,
-			"format", req.Format,
-			"cache_status", resp.CacheStatus,
-			"served_bytes", written,
-			"duration_ms", duration.Milliseconds(),
-		)
+		s.serveImage(w, r, req, expires)
 	}
 }
 
 // parseImageEncRequest decrypts the token of an encrypted image URL into an
-// ImageRequest and checks it. On a token that is missing, does not decrypt,
-// has expired or asks for something not valid, it writes an error response
-// and returns false.
+// image request and checks it, and returns it with the token's expiry. On a
+// token that is missing, does not decrypt, has expired or asks for something
+// not valid, it writes an error response and returns false.
 func (s *Handlers) parseImageEncRequest(
 	w http.ResponseWriter, r *http.Request,
-) (*imgcache.ImageRequest, bool) {
+) (*imagerequest.Request, time.Time, bool) {
 	// Extract token from URL
 	token := chi.URLParam(r, "token")
 	if token == "" {
 		s.respondError(w, "missing token", http.StatusBadRequest)
 
-		return nil, false
+		return nil, time.Time{}, false
 	}
 
 	// Decrypt and validate the payload
-	payload, err := s.encGen.Parse(token)
+	req, expires, err := s.encGen.Parse(token)
 	if err != nil {
 		if errors.Is(err, encurl.ErrExpired) {
 			s.log.Debug("encrypted URL expired", "error", err)
 			s.respondError(w, "URL has expired", http.StatusGone)
 
-			return nil, false
+			return nil, time.Time{}, false
 		}
 
-		s.log.Debug("failed to decrypt URL", "error", err)
+		s.log.Debug("invalid encrypted URL", "error", err)
 		s.respondError(w, "invalid encrypted URL", http.StatusBadRequest)
 
-		return nil, false
+		return nil, time.Time{}, false
 	}
 
-	// Convert payload to ImageRequest
-	req := payload.ToImageRequest()
-
 	// Apply the same dimension and fit-mode bounds as the plain image
 	// route: a sealed payload is trusted for its origin, not for staying
-	// within limits, so an over-limit size or unknown fit mode is a 400
-	// here rather than an out-of-memory or a 500 from the processor.
-	err = imgcache.ValidateImageRequest(req)
+	// within limits. This refuses an over-limit size before the source is
+	// fetched. An unknown fit mode is a 400 here rather than a 500 from the
+	// processor.
+	err = imagerequest.ValidateImageRequest(req)
 	if err != nil {
 		s.log.Debug("encrypted URL failed validation", "error", err)
 		s.respondError(w, "invalid encrypted URL: "+err.Error(),
 			http.StatusBadRequest)
 
-		return nil, false
+		return nil, time.Time{}, false
 	}
 
-	return req, true
-}
-
-// handleImageError converts image service errors to HTTP responses.
-func (s *Handlers) handleImageError(w http.ResponseWriter, err error) {
-	switch {
-	case errors.Is(err, httpfetcher.ErrSSRFBlocked):
-		s.respondError(w, "forbidden", http.StatusForbidden)
-	case errors.Is(err, httpfetcher.ErrUpstreamError):
-		s.respondError(w, "upstream error", http.StatusBadGateway)
-	case errors.Is(err, httpfetcher.ErrUpstreamTimeout):
-		s.respondError(w, "upstream timeout", http.StatusGatewayTimeout)
-	case errors.Is(err, httpfetcher.ErrTooManyConnections),
-		errors.Is(err, imageprocessor.ErrTooManyImages),
-		errors.Is(err, imgcache.ErrProcessingTimedOut):
-		s.respondError(w, "server busy, try again later",
-			http.StatusServiceUnavailable)
-	case errors.Is(err, httpfetcher.ErrInvalidContentType),
-		errors.Is(err, imageprocessor.ErrUnsupportedInputFormat):
-		s.respondError(w, "unsupported source format",
-			http.StatusUnsupportedMediaType)
-	case errors.Is(err, imageprocessor.ErrOutputTooLarge):
-		s.respondError(w, fmt.Sprintf("size too large for the source: the side "+
-			"computed from its proportions is above %d",
-			imageprocessor.MaxOutputDimension), http.StatusBadRequest)
-	default:
-		s.log.Error("image request failed", "error", err)
-		s.respondError(w, "internal error", http.StatusInternalServerError)
-	}
+	return req, expires, true
 }

internal/handlers/imageenc_internal_test.go

@@ -6,11 +6,13 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"testing"
+	"time"
 
 	"github.com/go-chi/chi/v5"
 
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/seal"
 )
 
 // newEncTestServer builds a router serving the encrypted-URL route with a
@@ -20,11 +22,13 @@ import (
 func newEncTestServer(t *testing.T) (*encurl.Generator, http.Handler) {
 	t.Helper()
 
-	encGen, err := encurl.NewGenerator(testSigningKey)
+	keys, err := seal.DeriveKeys(testSigningKey)
 	if err != nil {
-		t.Fatalf("encurl.NewGenerator() error = %v", err)
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
 	}
 
+	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
+
 	h := &Handlers{
 		log:    slog.New(slog.DiscardHandler),
 		encGen: encGen,
@@ -54,12 +58,15 @@ func TestHandleImageEnc_OverLimitDimension_Returns400(t *testing.T) {
 
 	encGen, srv := newEncTestServer(t)
 
-	token, err := encGen.Generate(&encurl.Payload{
-		SourceHost: "cdn.example.com",
-		SourcePath: "/photo.jpg",
-		Width:      100000,
-		Height:     100000,
-	})
+	token, err := encGen.Generate(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: "cdn.example.com",
+			Path: "/photo.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Size: imagerequest.Size{Width: 100000, Height: 100000},
+		},
+	}, time.Time{})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
@@ -79,13 +86,16 @@ func TestHandleImageEnc_InvalidFitMode_Returns400(t *testing.T) {
 
 	encGen, srv := newEncTestServer(t)
 
-	token, err := encGen.Generate(&encurl.Payload{
-		SourceHost: "cdn.example.com",
-		SourcePath: "/photo.jpg",
-		Width:      800,
-		Height:     600,
-		FitMode:    imgcache.FitMode("bogus"),
-	})
+	token, err := encGen.Generate(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: "cdn.example.com",
+			Path: "/photo.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 800, Height: 600},
+			FitMode: imagerequest.Fit("bogus"),
+		},
+	}, time.Time{})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}

internal/handlers/imageenc_token_internal_test.go

@@ -9,6 +9,8 @@ import (
 	"time"
 
 	"sneak.berlin/go/pixa/internal/encurl"
+	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/seal"
 )
 
 // requireServedPhoto requires that rec answers 200 with the JPEG at photoPath
@@ -59,32 +61,34 @@ func TestHandleImageEnc_RejectedToken(t *testing.T) {
 
 	h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
 
-	photo := encurl.Payload{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Width:      50,
-		Height:     50,
+	photo := imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size: imagerequest.Size{Width: 50, Height: 50},
+		},
 	}
 
-	valid, err := h.encGen.Generate(&photo)
+	valid, err := h.encGen.Generate(&photo, time.Time{})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
 
-	expiredPhoto := photo
-	expiredPhoto.ExpiresAt = time.Now().Add(-time.Minute).Unix()
-
-	expired, err := h.encGen.Generate(&expiredPhoto)
+	expired, err := h.encGen.Generate(&photo, time.Now().Add(-time.Minute))
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}
 
-	otherGen, err := encurl.NewGenerator("another-signing-key-fedcba9876543210")
+	keys, err := seal.DeriveKeys("another-signing-key-fedcba9876543210")
 	if err != nil {
-		t.Fatalf("encurl.NewGenerator() error = %v", err)
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
 	}
 
-	otherKey, err := otherGen.Generate(&photo)
+	otherGen := encurl.NewGenerator(keys.EncryptedURLKey)
+
+	otherKey, err := otherGen.Generate(&photo, time.Time{})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}

internal/handlers/jpegxl_default_internal_test.go

@@ -14,7 +14,7 @@ import (
 	"github.com/davidbyttow/govips/v2/vips"
 
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/signature"
 )
 
@@ -58,16 +58,18 @@ func TestImageWithoutFormat_SignedAsJXL(t *testing.T) {
 	route := newImageRoute(t, newPhotoFetcher(t, signedHost))
 	expires := time.Now().Add(time.Hour)
 
-	sig := signature.New(testSigningKey).Sign(&signature.Request{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Width:      50,
-		Height:     50,
-		Format:     string(imgcache.FormatJXL),
-		Quality:    encurl.DefaultQuality,
-		FitMode:    string(imgcache.FitCover),
-		Expires:    expires,
-	})
+	sig := signature.New(testSigningKey).Sign(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 50, Height: 50},
+			Format:  imagerequest.FormatJXL,
+			Quality: encurl.DefaultQuality,
+			FitMode: imagerequest.FitCover,
+		},
+	}, expires)
 	query := fmt.Sprintf("?sig=%s&exp=%d", sig, expires.Unix())
 
 	for _, size := range []string{"50x50.jxl", "50x50"} {
@@ -83,12 +85,15 @@ func TestImageEncWithoutFormat_ServesJPEGXL(t *testing.T) {
 
 	h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
 
-	token, err := h.encGen.Generate(&encurl.Payload{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Width:      50,
-		Height:     50,
-	})
+	token, err := h.encGen.Generate(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size: imagerequest.Size{Width: 50, Height: 50},
+		},
+	}, time.Time{})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}

internal/handlers/jpegxl_internal_test.go

@@ -7,7 +7,7 @@ import (
 
 	"github.com/davidbyttow/govips/v2/vips"
 
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // jxlType is the content type of JPEG XL.
@@ -22,14 +22,14 @@ func TestFormatForAccept_JPEGXL(t *testing.T) {
 	tests := []struct {
 		name   string
 		accept string
-		want   imgcache.ImageFormat
+		want   imagerequest.Format
 	}{
 		{"JPEG XL-capable browser",
-			"image/jxl,image/avif,image/webp,image/*,*/*;q=0.8", imgcache.FormatJXL},
-		{"JPEG XL only", jxlType, imgcache.FormatJXL},
+			"image/jxl,image/avif,image/webp,image/*,*/*;q=0.8", imagerequest.FormatJXL},
+		{"JPEG XL only", jxlType, imagerequest.FormatJXL},
 		{"JPEG XL with a lower q than AVIF", "image/avif,image/jxl;q=0.5",
-			imgcache.FormatJXL},
-		{"q=0 on JPEG XL", "image/jxl;q=0,image/avif,*/*", imgcache.FormatAVIF},
+			imagerequest.FormatJXL},
+		{"q=0 on JPEG XL", "image/jxl;q=0,image/avif,*/*", imagerequest.FormatAVIF},
 	}
 
 	for _, tt := range tests {

internal/handlers/referer_blocklist_internal_test.go

@@ -10,10 +10,15 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
+	"github.com/prometheus/client_golang/prometheus"
 	"sneak.berlin/go/pixa/internal/allowlist"
 	"sneak.berlin/go/pixa/internal/encurl"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/seal"
+	"sneak.berlin/go/pixa/internal/signature"
 )
 
 // blockedReferer is a page on leech.example, which newRefererRoutes puts on
@@ -29,11 +34,11 @@ type countingFetcher struct {
 
 // Fetch counts the fetch and passes it on.
 func (f *countingFetcher) Fetch(
-	ctx context.Context, url string,
+	ctx context.Context, source imagerequest.Source,
 ) (*httpfetcher.FetchResult, error) {
 	f.fetches.Add(1)
 
-	return f.Fetcher.Fetch(ctx, url)
+	return f.Fetcher.Fetch(ctx, source)
 }
 
 // newRefererRoutes returns both image routes of a Handlers whose
@@ -50,30 +55,38 @@ func newRefererRoutes(t *testing.T) (http.Handler, *Handlers, *countingFetcher)
 	cache, err := imgcache.NewCache(setupTestDB(t), imgcache.CacheConfig{
 		StateDir:    t.TempDir(),
 		NegativeTTL: 5 * time.Minute,
-	})
+		MaxBytes:    1 << 30,
+	}, prometheus.NewRegistry())
 	if err != nil {
 		t.Fatalf("imgcache.NewCache() error = %v", err)
 	}
 
 	svc, err := imgcache.NewService(&imgcache.ServiceConfig{
-		Cache:      cache,
-		Fetcher:    fetcher,
-		SigningKey: testSigningKey,
-		Allowlist:  []string{allowlistedHost},
+		Cache:   cache,
+		Fetcher: fetcher,
+		Processor: imageprocessor.New(imageprocessor.Params{
+			MaxInputBytes:           50 << 20,
+			MaxConcurrentProcessing: 2,
+		}),
+		MaxResponseSize: 50 << 20,
 	})
 	if err != nil {
 		t.Fatalf("imgcache.NewService() error = %v", err)
 	}
 
-	encGen, err := encurl.NewGenerator(testSigningKey)
+	keys, err := seal.DeriveKeys(testSigningKey)
 	if err != nil {
-		t.Fatalf("encurl.NewGenerator() error = %v", err)
+		t.Fatalf("seal.DeriveKeys() error = %v", err)
 	}
 
+	encGen := encurl.NewGenerator(keys.EncryptedURLKey)
+
 	h := &Handlers{
-		log:    slog.New(slog.DiscardHandler),
-		imgSvc: svc,
-		encGen: encGen,
+		log:       slog.New(slog.DiscardHandler),
+		imgSvc:    svc,
+		encGen:    encGen,
+		signer:    signature.New(testSigningKey),
+		allowlist: allowlist.New([]string{allowlistedHost}),
 		refererBlocklist: allowlist.New(
 			[]string{"leech.example", ".hotlinker.example"}),
 	}

internal/handlers/request_id_internal_test.go

@@ -13,26 +13,26 @@ import (
 
 	"github.com/go-chi/chi/v5/middleware"
 
-	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // signedPhotoURL returns a signed /v1/image/ URL, valid for a minute, for the
-// JPEG at photoPath on signedHost at 50x50, made with h's image service.
-func signedPhotoURL(t *testing.T, h *Handlers) string {
+// JPEG at photoPath on signedHost at 50x50. It is signed with testSigningKey,
+// the key the handlers that newSignedHostServer builds check signatures with.
+// It takes a Handlers it does not use, so that it has the type of encPhotoURL.
+func signedPhotoURL(t *testing.T, _ *Handlers) string {
 	t.Helper()
 
-	signedURL, err := h.imgSvc.GenerateSignedURL("", &imgcache.ImageRequest{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Size:       imgcache.Size{Width: 50, Height: 50},
-		Format:     imgcache.FormatJPEG,
+	return generateSignedURL(testSigningKey, &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatJPEG,
+		},
 	}, time.Minute)
-	if err != nil {
-		t.Fatalf("GenerateSignedURL() error = %v", err)
-	}
-
-	return signedURL
 }
 
 // encPhotoURL returns an encrypted /v1/e/ URL, which never expires, for the
@@ -40,13 +40,16 @@ func signedPhotoURL(t *testing.T, h *Handlers) string {
 func encPhotoURL(t *testing.T, h *Handlers) string {
 	t.Helper()
 
-	token, err := h.encGen.Generate(&encurl.Payload{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Width:      50,
-		Height:     50,
-		Format:     imgcache.FormatJPEG,
-	})
+	token, err := h.encGen.Generate(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatJPEG,
+		},
+	}, time.Time{})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
 	}

internal/handlers/server_busy_internal_test.go

@@ -11,51 +11,48 @@ import (
 
 	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/imgcache"
 )
 
-// TestServerBusyAnswers503 checks that both image routes answer 503 with
-// a clear error when the image service gives up waiting for a free upstream
-// connection or processing slot, wrapped as the service wraps them.
+// TestServerBusyAnswers503 checks that respondImageError, which answers the
+// errors of both image routes, answers 503 with a clear error when the image
+// service gives up waiting for a free upstream connection or processing slot,
+// wrapped as the service wraps them.
 func TestServerBusyAnswers503(t *testing.T) {
 	t.Parallel()
 
 	h := &Handlers{log: slog.New(slog.DiscardHandler)}
-	req := &imgcache.ImageRequest{SourceHost: "img.example.com", SourcePath: "/a.jpg"}
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{Host: "img.example.com", Path: "/a.jpg"},
+	}
 
 	for _, err := range []error{
 		fmt.Errorf("upstream fetch failed: %w", httpfetcher.ErrTooManyConnections),
 		fmt.Errorf("image processing failed: %w", imageprocessor.ErrTooManyImages),
 	} {
-		plain := httptest.NewRecorder()
-		h.respondImageError(plain, req, err)
+		rec := httptest.NewRecorder()
+		h.respondImageError(rec, req, err)
 
-		encrypted := httptest.NewRecorder()
-		h.handleImageError(encrypted, err)
+		if rec.Code != http.StatusServiceUnavailable {
+			t.Errorf("for %v: status = %d, want %d",
+				err, rec.Code, http.StatusServiceUnavailable)
+		}
 
-		for route, rec := range map[string]*httptest.ResponseRecorder{
-			"/v1/image/": plain, "/v1/e/": encrypted,
-		} {
-			if rec.Code != http.StatusServiceUnavailable {
-				t.Errorf("%s for %v: status = %d, want %d",
-					route, err, rec.Code, http.StatusServiceUnavailable)
-			}
-
-			if !strings.Contains(rec.Body.String(), "server busy, try again later") {
-				t.Errorf("%s for %v: body = %q, want the server busy error",
-					route, err, rec.Body.String())
-			}
+		if !strings.Contains(rec.Body.String(), "server busy, try again later") {
+			t.Errorf("for %v: body = %q, want the server busy error",
+				err, rec.Body.String())
 		}
 	}
 }
 
-// TestProcessingTimedOutAnswers503 checks that respondImageError and
-// handleImageError, which answer the errors of the two image routes, answer
-// 503 with the server busy error when the image service reports that
-// processing stopped at the deadline of the request doing it, wrapped as the
-// service wraps it. A request that waited for that processing gets this error
-// while its own deadline may have time left. The request's source only goes
-// into a log line, so it is left empty.
+// TestProcessingTimedOutAnswers503 checks that respondImageError, which
+// answers the errors of both image routes, answers 503 with the server busy
+// error when the image service reports that processing stopped at the
+// deadline of the request doing it, wrapped as the service wraps it. A request
+// that waited for that processing gets this error while its own deadline may
+// have time left. The request's source only goes into a log line, so it is
+// left empty.
 func TestProcessingTimedOutAnswers503(t *testing.T) {
 	t.Parallel()
 
@@ -63,25 +60,15 @@ func TestProcessingTimedOutAnswers503(t *testing.T) {
 	err := fmt.Errorf("%w: failed to encode: %w",
 		imgcache.ErrProcessingTimedOut, context.DeadlineExceeded)
 
-	plain := httptest.NewRecorder()
-	h.respondImageError(plain, &imgcache.ImageRequest{}, err)
+	rec := httptest.NewRecorder()
+	h.respondImageError(rec, &imagerequest.Request{}, err)
+	t.Logf("status = %d, body = %q", rec.Code, rec.Body.String())
 
-	encrypted := httptest.NewRecorder()
-	h.handleImageError(encrypted, err)
+	if rec.Code != http.StatusServiceUnavailable {
+		t.Errorf("status = %d, want %d", rec.Code, http.StatusServiceUnavailable)
+	}
 
-	for name, rec := range map[string]*httptest.ResponseRecorder{
-		"respondImageError": plain, "handleImageError": encrypted,
-	} {
-		t.Logf("%s: status = %d, body = %q", name, rec.Code, rec.Body.String())
-
-		if rec.Code != http.StatusServiceUnavailable {
-			t.Errorf("%s: status = %d, want %d",
-				name, rec.Code, http.StatusServiceUnavailable)
-		}
-
-		if !strings.Contains(rec.Body.String(), "server busy, try again later") {
-			t.Errorf("%s: body = %q, want the server busy error",
-				name, rec.Body.String())
-		}
+	if !strings.Contains(rec.Body.String(), "server busy, try again later") {
+		t.Errorf("body = %q, want the server busy error", rec.Body.String())
 	}
 }

internal/handlers/unsupported_source_internal_test.go

@@ -10,18 +10,21 @@ import (
 
 	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imageprocessor"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
-// TestUnsupportedSourceFormatAnswers415 checks that both image routes answer
-// 415 with a clear error when the upstream answers with a content type pixa
-// does not accept, such as SVG, and when orig is asked of a source in a
-// format the processor cannot name, wrapped as the service wraps them.
+// TestUnsupportedSourceFormatAnswers415 checks that respondImageError, which
+// answers the errors of both image routes, answers 415 with a clear error when
+// the upstream answers with a content type pixa does not accept, such as SVG,
+// and when orig is asked of a source in a format the processor cannot name,
+// wrapped as the service wraps them.
 func TestUnsupportedSourceFormatAnswers415(t *testing.T) {
 	t.Parallel()
 
 	h := &Handlers{log: slog.New(slog.DiscardHandler)}
-	req := &imgcache.ImageRequest{SourceHost: "img.example.com", SourcePath: "/a.svg"}
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{Host: "img.example.com", Path: "/a.svg"},
+	}
 
 	for _, err := range []error{
 		fmt.Errorf("upstream fetch failed: %w: image/svg+xml",
@@ -29,26 +32,18 @@ func TestUnsupportedSourceFormatAnswers415(t *testing.T) {
 		fmt.Errorf("image processing failed: %w: unknown",
 			imageprocessor.ErrUnsupportedInputFormat),
 	} {
-		plain := httptest.NewRecorder()
-		h.respondImageError(plain, req, err)
+		rec := httptest.NewRecorder()
+		h.respondImageError(rec, req, err)
+		t.Logf("for %v: %d %s", err, rec.Code, rec.Body.String())
 
-		encrypted := httptest.NewRecorder()
-		h.handleImageError(encrypted, err)
+		if rec.Code != http.StatusUnsupportedMediaType {
+			t.Errorf("for %v: status = %d, want %d",
+				err, rec.Code, http.StatusUnsupportedMediaType)
+		}
 
-		for route, rec := range map[string]*httptest.ResponseRecorder{
-			"HandleImage": plain, "HandleImageEnc": encrypted,
-		} {
-			t.Logf("%s for %v: %d %s", route, err, rec.Code, rec.Body.String())
-
-			if rec.Code != http.StatusUnsupportedMediaType {
-				t.Errorf("%s for %v: status = %d, want %d",
-					route, err, rec.Code, http.StatusUnsupportedMediaType)
-			}
-
-			if !strings.Contains(rec.Body.String(), "unsupported source format") {
-				t.Errorf("%s for %v: body = %q, want the unsupported source format error",
-					route, err, rec.Body.String())
-			}
+		if !strings.Contains(rec.Body.String(), "unsupported source format") {
+			t.Errorf("for %v: body = %q, want the unsupported source format error",
+				err, rec.Body.String())
 		}
 	}
 }

internal/handlers/validate_signature_internal_test.go

@@ -0,0 +1,211 @@
+package handlers
+
+import (
+	"testing"
+	"time"
+
+	"sneak.berlin/go/pixa/internal/allowlist"
+	"sneak.berlin/go/pixa/internal/signature"
+)
+
+// Addresses the port tests below put on the allowlist.
+const (
+	allowlistedIPv4 = "203.0.113.5"
+	allowlistedIPv6 = "2001:db8::1"
+)
+
+// newSignatureChecker returns Handlers that check signatures with
+// testSigningKey and have allowlistHosts on their allowlist, as New builds
+// them from signing_key and allowlist_hosts.
+func newSignatureChecker(allowlistHosts ...string) *Handlers {
+	return &Handlers{
+		signer:    signature.New(testSigningKey),
+		allowlist: allowlist.New(allowlistHosts),
+	}
+}
+
+func TestValidateSignature_NonAllowlistedHost_NoSignature(t *testing.T) {
+	t.Parallel()
+
+	h := newSignatureChecker(allowlistedHost)
+
+	// Should fail validation - not allowlisted and no signature
+	err := h.validateSignature(photoRequest(signedHost), "", time.Time{})
+	if err == nil {
+		t.Error("validateSignature() expected error for non-allowlisted " +
+			"host without signature")
+	}
+}
+
+func TestValidateSignature_NonAllowlistedHost_ValidSignature(t *testing.T) {
+	t.Parallel()
+
+	h := newSignatureChecker(allowlistedHost)
+	req := photoRequest(signedHost)
+
+	// Generate a valid signature
+	expires := time.Now().Add(time.Hour)
+	sig := signature.New(testSigningKey).Sign(req, expires)
+
+	// Should pass validation
+	err := h.validateSignature(req, sig, expires)
+	if err != nil {
+		t.Errorf("validateSignature() error = %v", err)
+	}
+}
+
+func TestValidateSignature_NonAllowlistedHost_ExpiredSignature(t *testing.T) {
+	t.Parallel()
+
+	h := newSignatureChecker(allowlistedHost)
+	req := photoRequest(signedHost)
+
+	// Generate an expired signature
+	expires := time.Now().Add(-time.Hour)
+	sig := signature.New(testSigningKey).Sign(req, expires)
+
+	// Should fail validation
+	err := h.validateSignature(req, sig, expires)
+	if err == nil {
+		t.Error("validateSignature() expected error for expired signature")
+	}
+}
+
+func TestValidateSignature_NonAllowlistedHost_InvalidSignature(t *testing.T) {
+	t.Parallel()
+
+	h := newSignatureChecker(allowlistedHost)
+
+	// Should fail validation
+	err := h.validateSignature(photoRequest(signedHost), "invalid-signature",
+		time.Now().Add(time.Hour))
+	if err == nil {
+		t.Error("validateSignature() expected error for invalid signature")
+	}
+}
+
+// TestValidateSignature_NoAllowlist checks that with no host on the
+// allowlist, a request without a signature fails validation.
+func TestValidateSignature_NoAllowlist(t *testing.T) {
+	t.Parallel()
+
+	h := newSignatureChecker()
+
+	err := h.validateSignature(photoRequest(signedHost), "", time.Time{})
+	if err == nil {
+		t.Error("validateSignature() expected error when no host is allowlisted")
+	}
+}
+
+// TestValidateSignature_SignatureExactHostMatch verifies that
+// validateSignature enforces exact host matching for signatures. A
+// signature for one host must not verify for a different host, even
+// if they share a domain suffix.
+func TestValidateSignature_SignatureExactHostMatch(t *testing.T) {
+	t.Parallel()
+
+	h := newSignatureChecker()
+
+	// Sign a request for signedHost
+	signedReq := photoRequest(signedHost)
+	expires := time.Now().Add(time.Hour)
+	sig := signature.New(testSigningKey).Sign(signedReq, expires)
+
+	// The original request should pass validation
+	t.Run("exact host passes", func(t *testing.T) {
+		t.Parallel()
+
+		err := h.validateSignature(signedReq, sig, expires)
+		if err != nil {
+			t.Errorf("validateSignature() exact host failed: %v", err)
+		}
+	})
+
+	// Try to reuse the signature with different hosts
+	tests := []struct {
+		name string
+		host string
+	}{
+		{"parent domain", "example.com"},
+		{"sibling subdomain", "images.example.com"},
+		{"deeper subdomain", "a." + signedHost},
+		{"evil suffix domain", signedHost + ".evil.com"},
+		{"prefixed host", "evil" + signedHost},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name+" rejected", func(t *testing.T) {
+			t.Parallel()
+
+			err := h.validateSignature(photoRequest(tt.host), sig, expires)
+			if err == nil {
+				t.Errorf("validateSignature() should reject signature for "+
+					"host %q (signed for %q)", tt.host, signedHost)
+			}
+		})
+	}
+}
+
+// TestValidateSignature_HostWithPortNeedsSignature verifies that a host
+// followed by a port, or by a colon with no port, matches no allowlist entry,
+// so that a request for it without a signature is refused, while the same
+// host with no port is allowlisted.
+func TestValidateSignature_HostWithPortNeedsSignature(t *testing.T) {
+	t.Parallel()
+
+	h := newSignatureChecker(allowlistedHost, allowlistedIPv4, allowlistedIPv6)
+
+	tests := []struct {
+		host        string
+		allowlisted bool
+	}{
+		{allowlistedHost, true},
+		{allowlistedHost + ":8443", false},
+		{allowlistedHost + ":443", false},
+		{allowlistedHost + ":", false},
+		{allowlistedIPv4, true},
+		{allowlistedIPv4 + ":8080", false},
+		{"[" + allowlistedIPv6 + "]", true},
+		{"[" + allowlistedIPv6 + "]:8443", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.host, func(t *testing.T) {
+			t.Parallel()
+
+			err := h.validateSignature(photoRequest(tt.host), "", time.Time{})
+			t.Logf("validateSignature() for host %q with no signature: %v",
+				tt.host, err)
+
+			if allowlisted := err == nil; allowlisted != tt.allowlisted {
+				t.Errorf("host %q served without a signature = %v, want %v",
+					tt.host, allowlisted, tt.allowlisted)
+			}
+		})
+	}
+}
+
+// TestValidateSignature_UnbracketedIPv6PortNeedsSignature verifies that an
+// allowlisted IPv6 address written without brackets and followed by a port,
+// or by a colon with no port, needs a signature. Go's URL type reads
+// 2001:db8::1:8443 as the host 2001:db8::1 with the port 8443.
+func TestValidateSignature_UnbracketedIPv6PortNeedsSignature(t *testing.T) {
+	t.Parallel()
+
+	h := newSignatureChecker(allowlistedIPv6)
+
+	for _, host := range []string{allowlistedIPv6 + ":8443", allowlistedIPv6 + ":"} {
+		t.Run(host, func(t *testing.T) {
+			t.Parallel()
+
+			err := h.validateSignature(photoRequest(host), "", time.Time{})
+			t.Logf("validateSignature() for host %q with no signature: %v",
+				host, err)
+
+			if err == nil {
+				t.Errorf("host %q served without a signature, want refused",
+					host)
+			}
+		})
+	}
+}

internal/httpfetcher/blocked_networks_internal_test.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"net/netip"
 	"testing"
+	"time"
 )
 
 // TestIsPrivateIPBlocksSpecialRanges covers the internal and special-use
@@ -70,12 +71,15 @@ func transportOf(t *testing.T, f *HTTPFetcher) *http.Transport {
 func TestDialerEnforcesBlockedNetworks(t *testing.T) {
 	t.Parallel()
 
-	cfg := DefaultConfig()
-	// TEST-NET-2 (198.51.100.0/24) is public to the built-in check, so
-	// blocking it can only come from the operator-supplied list.
-	cfg.BlockedNetworks = []netip.Prefix{netip.MustParsePrefix("198.51.100.0/24")}
-
-	transport := transportOf(t, New(cfg))
+	transport := transportOf(t, New(&Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        64,
+		// TEST-NET-2 (198.51.100.0/24) is public to the built-in check, so
+		// blocking it can only come from the operator-supplied list.
+		BlockedNetworks: []netip.Prefix{netip.MustParsePrefix("198.51.100.0/24")},
+	}))
 
 	blocked := []string{
 		"198.51.100.5:80", // operator-supplied range

internal/httpfetcher/dial_context_internal_test.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"net"
 	"testing"
+	"time"
 )
 
 // TestNewUsesCheckedDialerWithoutDialContext checks that a fetcher built
@@ -13,7 +14,12 @@ func TestNewUsesCheckedDialerWithoutDialContext(t *testing.T) {
 	t.Parallel()
 
 	srv := startUpstream(t)
-	transport := transportOf(t, New(DefaultConfig()))
+	transport := transportOf(t, New(&Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        64,
+	}))
 
 	addr := srv.Listener.Addr().String()
 
@@ -32,21 +38,25 @@ func TestDialContextReplacesOnlyTheDialer(t *testing.T) {
 	srv := startUpstream(t)
 	dialer := &recordingDialer{target: srv.Listener.Addr().String()}
 
-	cfg := DefaultConfig()
-	cfg.AllowHTTP = true
-	cfg.DialContext = dialer.dialContext
-	f := New(cfg)
+	f := New(&Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		AllowHTTP:             true,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        64,
+		DialContext:           dialer.dialContext,
+	})
 
 	if body := fetchBody(t, f, "/image"); body != imagePayload {
 		t.Errorf("body = %q, want %q", body, imagePayload)
 	}
 
-	_, err := f.Fetch(testContext(t), "http://127.0.0.1/image")
+	_, err := f.Fetch(testContext(t), imageSourceOn("127.0.0.1"))
 	if !errors.Is(err, ErrSSRFBlocked) {
 		t.Errorf("Fetch(loopback URL) error = %v, want ErrSSRFBlocked", err)
 	}
 
-	_, err = f.Fetch(testContext(t), upstreamURL("/redirect/private"))
+	_, err = f.Fetch(testContext(t), upstreamSource("/redirect/private"))
 	if !errors.Is(err, ErrSSRFBlocked) {
 		t.Errorf("Fetch(/redirect/private) error = %v, want ErrSSRFBlocked", err)
 	}

internal/httpfetcher/fetch_internal_test.go

@@ -14,6 +14,8 @@ import (
 	"sync"
 	"testing"
 	"time"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // testPublicHost is a TEST-NET-1 (RFC 5737) literal. isPrivateIP treats it as
@@ -29,9 +31,9 @@ const imagePayload = "fake-jpeg-bytes"
 // would mean SSRF protection let a forbidden target reach the transport.
 var errUnexpectedDial = errors.New("unexpected dial target")
 
-// upstreamURL builds a fetch URL on the fake public host for the given path.
-func upstreamURL(path string) string {
-	return "http://" + testPublicHost + path
+// upstreamSource returns the source at path on the fake public host.
+func upstreamSource(path string) imagerequest.Source {
+	return imagerequest.Source{Host: testPublicHost, Path: path}
 }
 
 // recordingDialer records every address the transport asks it to dial and
@@ -120,7 +122,12 @@ func newServerFetcher(
 	t.Helper()
 
 	if cfg == nil {
-		cfg = DefaultConfig()
+		cfg = &Config{
+			Timeout:               30 * time.Second,
+			MaxResponseSize:       50 << 20,
+			MaxConnectionsPerHost: 20,
+			MaxConnections:        64,
+		}
 	}
 
 	cfg.AllowHTTP = true
@@ -153,7 +160,7 @@ func testContext(t *testing.T) context.Context {
 func fetchImage(t *testing.T, f *HTTPFetcher, path string) *FetchResult {
 	t.Helper()
 
-	res, err := f.Fetch(testContext(t), upstreamURL(path))
+	res, err := f.Fetch(testContext(t), upstreamSource(path))
 	if err != nil {
 		t.Fatalf("Fetch(%s) error = %v", path, err)
 	}
@@ -165,7 +172,7 @@ func fetchImage(t *testing.T, f *HTTPFetcher, path string) *FetchResult {
 func fetchExpectError(t *testing.T, f *HTTPFetcher, path string) error {
 	t.Helper()
 
-	res, err := f.Fetch(testContext(t), upstreamURL(path))
+	res, err := f.Fetch(testContext(t), upstreamSource(path))
 	if err == nil {
 		_ = res.Content.Close()
 
@@ -217,7 +224,7 @@ func TestFetchRedirectToPrivateIPBlocked(t *testing.T) {
 	srv := startUpstream(t)
 	f, dialer := newServerFetcher(t, srv, nil)
 
-	_, err := f.Fetch(testContext(t), upstreamURL("/redirect/private"))
+	_, err := f.Fetch(testContext(t), upstreamSource("/redirect/private"))
 	if !errors.Is(err, ErrSSRFBlocked) {
 		t.Fatalf("Fetch() error = %v, want ErrSSRFBlocked", err)
 	}
@@ -280,8 +287,12 @@ func TestFetchMaxResponseSizeEnforced(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := DefaultConfig()
-	cfg.MaxResponseSize = 8
+	cfg := &Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       8,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        64,
+	}
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
@@ -310,8 +321,12 @@ func fetchWithMaxResponseSize(
 	srv := httptest.NewServer(handler)
 	t.Cleanup(srv.Close)
 
-	cfg := DefaultConfig()
-	cfg.MaxResponseSize = maxResponseSize
+	cfg := &Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       maxResponseSize,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        64,
+	}
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
@@ -436,8 +451,12 @@ func TestFetchSemaphoreReleasedOnError(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := DefaultConfig()
-	cfg.MaxConnectionsPerHost = 1
+	cfg := &Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 1,
+		MaxConnections:        64,
+	}
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
@@ -466,8 +485,12 @@ func assertSlotReleasedByClose(
 
 	srv := startUpstream(t)
 
-	cfg := DefaultConfig()
-	cfg.MaxConnectionsPerHost = 1
+	cfg := &Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 1,
+		MaxConnections:        64,
+	}
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
@@ -524,7 +547,7 @@ func TestFetchSemaphoreReleasedOnPartialReadClose(t *testing.T) {
 	})
 }
 
-// The dial-time re-resolution in ssrfSafeDialer is what closes the DNS
+// The dial-time re-resolution in dialSSRFSafe is what closes the DNS
 // rebinding window: even if validateURL saw a public answer earlier, the
 // dialer independently re-checks the address it is about to connect to. A full
 // rebinding simulation (a resolver returning public, then private) would mean
@@ -544,9 +567,9 @@ func TestSSRFSafeDialerBlocksPrivateTarget(t *testing.T) {
 		t.Run(addr, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := ssrfSafeDialer(context.Background(), "tcp", addr)
+			_, err := dialSSRFSafe(context.Background(), "tcp", addr, nil)
 			if !errors.Is(err, ErrSSRFBlocked) {
-				t.Errorf("ssrfSafeDialer(%q) = %v, want ErrSSRFBlocked", addr, err)
+				t.Errorf("dialSSRFSafe(%q) = %v, want ErrSSRFBlocked", addr, err)
 			}
 		})
 	}
@@ -560,7 +583,7 @@ func TestSSRFSafeDialerAllowsPublicTarget(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
 
-	_, err := ssrfSafeDialer(ctx, "tcp", testPublicHost+":80")
+	_, err := dialSSRFSafe(ctx, "tcp", testPublicHost+":80", nil)
 	if err == nil {
 		t.Fatal("expected a dial error for an unreachable public target")
 	}
@@ -569,3 +592,53 @@ func TestSSRFSafeDialerAllowsPublicTarget(t *testing.T) {
 		t.Errorf("public target was SSRF-blocked: %v", err)
 	}
 }
+
+// TestFetchSchemeFollowsAllowHTTP checks that the fetcher fetches a source
+// over https, on port 443, unless AllowHTTP is set, and then over http, on
+// port 80. The test server speaks plain HTTP, so only the fetch over http
+// succeeds.
+func TestFetchSchemeFollowsAllowHTTP(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		allowHTTP bool
+		wantAddr  string
+	}{
+		{false, net.JoinHostPort(testPublicHost, "443")},
+		{true, net.JoinHostPort(testPublicHost, "80")},
+	}
+
+	for _, tt := range tests {
+		t.Run(fmt.Sprintf("AllowHTTP %v", tt.allowHTTP), func(t *testing.T) {
+			t.Parallel()
+
+			srv := startUpstream(t)
+			dialer := &recordingDialer{target: srv.Listener.Addr().String()}
+
+			f := New(&Config{
+				Timeout:               30 * time.Second,
+				MaxResponseSize:       50 << 20,
+				AllowHTTP:             tt.allowHTTP,
+				MaxConnectionsPerHost: 20,
+				MaxConnections:        64,
+				DialContext:           dialer.dialContext,
+			})
+
+			res, err := f.Fetch(testContext(t), upstreamSource("/image"))
+			if err == nil {
+				_ = res.Content.Close()
+			}
+
+			dialed := dialer.dialedAddrs()
+			t.Logf("Fetch(): error %v, dialed %v", err, dialed)
+
+			if served := err == nil; served != tt.allowHTTP {
+				t.Errorf("served = %v, want %v", served, tt.allowHTTP)
+			}
+
+			if len(dialed) != 1 || dialed[0] != tt.wantAddr {
+				t.Errorf("dialed %v, want only %s", dialed, tt.wantAddr)
+			}
+		})
+	}
+}

internal/httpfetcher/httpfetcher.go

@@ -20,20 +20,20 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5/middleware"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // Fetcher configuration constants.
 const (
-	DefaultFetchTimeout          = 30 * time.Second
-	DefaultMaxResponseSize       = 50 << 20 // 50MB
-	DefaultTLSTimeout            = 10 * time.Second
-	DefaultMaxIdleConns          = 100
-	DefaultIdleConnTimeout       = 90 * time.Second
-	DefaultMaxRedirects          = 10
-	DefaultMaxConnectionsPerHost = 20
-	DefaultMaxConnections        = 64
+	DefaultTLSTimeout      = 10 * time.Second
+	DefaultMaxIdleConns    = 100
+	DefaultIdleConnTimeout = 90 * time.Second
+	DefaultMaxRedirects    = 10
 )
 
+// userAgent is the User-Agent header sent to upstream servers.
+const userAgent = "pixa/1.0"
+
 // ConnectionWaitTimeout is how long Fetch waits for a free connection when
 // MaxConnections fetches are already in progress.
 const ConnectionWaitTimeout = 10 * time.Second
@@ -59,15 +59,17 @@ const (
 // builtinBlockedPrefixes are internal or special-use ranges that Go's
 // net.IP predicates (IsPrivate, IsLinkLocalUnicast, and the like) do not
 // already cover. They are always blocked, in addition to any
-// operator-supplied networks. IPv4-mapped IPv6 addresses are unmapped
-// before matching, so these IPv4 ranges are caught in both forms.
+// operator-supplied networks. IPv4-mapped and IPv4-compatible IPv6
+// addresses are read as the IPv4 address they hold before matching, so
+// these IPv4 ranges are caught in all three forms.
 //
 //nolint:gochecknoglobals // immutable built-in blocklist
 var builtinBlockedPrefixes = []netip.Prefix{
-	netip.MustParsePrefix("100.64.0.0/10"), // RFC 6598 CGNAT / carrier-grade NAT
-	netip.MustParsePrefix("192.0.0.0/24"),  // RFC 6890 IETF protocol assignments
-	netip.MustParsePrefix("198.18.0.0/15"), // RFC 2544 benchmarking range
-	netip.MustParsePrefix("64:ff9b::/96"),  // RFC 6052 NAT64 (maps onto IPv4)
+	netip.MustParsePrefix("100.64.0.0/10"),  // RFC 6598 CGNAT / carrier-grade NAT
+	netip.MustParsePrefix("192.0.0.0/24"),   // RFC 6890 IETF protocol assignments
+	netip.MustParsePrefix("198.18.0.0/15"),  // RFC 2544 benchmarking range
+	netip.MustParsePrefix("64:ff9b::/96"),   // RFC 6052 NAT64 (maps onto IPv4)
+	netip.MustParsePrefix("64:ff9b:1::/48"), // RFC 8215 local-use NAT64 (maps onto IPv4)
 }
 
 // Fetcher errors.
@@ -90,8 +92,8 @@ var (
 
 // Fetcher retrieves content from upstream origins.
 type Fetcher interface {
-	// Fetch retrieves content from the given URL.
-	Fetch(ctx context.Context, url string) (*FetchResult, error)
+	// Fetch retrieves the content of the source image.
+	Fetch(ctx context.Context, source imagerequest.Source) (*FetchResult, error)
 }
 
 // FetchResult contains the result of fetching from upstream.
@@ -118,17 +120,28 @@ type FetchResult struct {
 	TLSCipherSuite string
 }
 
-// Config holds configuration for the upstream fetcher.
+// allowedContentTypes returns the content types an upstream response may
+// have, which Fetch also sends as its Accept header.
+func allowedContentTypes() []string {
+	return []string{
+		contentTypeJPEG,
+		contentTypePNG,
+		contentTypeGIF,
+		contentTypeWebP,
+		contentTypeAVIF,
+		contentTypeJXL,
+	}
+}
+
+// Config holds configuration for the upstream fetcher. Every field but
+// AllowHTTP, BlockedNetworks and DialContext must be set.
 type Config struct {
 	// Timeout for upstream requests.
 	Timeout time.Duration
 	// MaxResponseSize is the maximum allowed response body size.
 	MaxResponseSize int64
-	// UserAgent to send to upstream servers.
-	UserAgent string
-	// AllowedContentTypes is an allow list of MIME types to accept.
-	AllowedContentTypes []string
-	// AllowHTTP allows non-TLS connections (for testing only).
+	// AllowHTTP makes the fetcher fetch sources over http instead of https,
+	// and follow redirects to http (for testing only).
 	AllowHTTP bool
 	// MaxConnectionsPerHost limits concurrent connections to each upstream host.
 	MaxConnectionsPerHost int
@@ -145,26 +158,6 @@ type Config struct {
 	DialContext func(ctx context.Context, network, addr string) (net.Conn, error)
 }
 
-// DefaultConfig returns a Config with sensible defaults.
-func DefaultConfig() *Config {
-	return &Config{
-		Timeout:         DefaultFetchTimeout,
-		MaxResponseSize: DefaultMaxResponseSize,
-		UserAgent:       "pixa/1.0",
-		AllowedContentTypes: []string{
-			contentTypeJPEG,
-			contentTypePNG,
-			contentTypeGIF,
-			contentTypeWebP,
-			contentTypeAVIF,
-			contentTypeJXL,
-		},
-		AllowHTTP:             false,
-		MaxConnectionsPerHost: DefaultMaxConnectionsPerHost,
-		MaxConnections:        DefaultMaxConnections,
-	}
-}
-
 // HTTPFetcher implements Fetcher with SSRF protection and connection limits
 // per host and for all hosts together.
 type HTTPFetcher struct {
@@ -192,10 +185,6 @@ type hostSemaphore struct {
 
 // New creates a new HTTPFetcher with SSRF protection.
 func New(config *Config) *HTTPFetcher {
-	if config == nil {
-		config = DefaultConfig()
-	}
-
 	// Unless config.DialContext replaces it, the transport connects with
 	// the SSRF-safe dialer, which re-resolves and re-checks at connect time
 	// (closing the DNS-rebinding window) against both the built-in ranges
@@ -224,7 +213,7 @@ func New(config *Config) *HTTPFetcher {
 			}
 
 			// Validate the redirect target
-			err := validateURL(req.Context(), req.URL.String(), config.AllowHTTP)
+			err := validateURL(req.Context(), req.URL, config.AllowHTTP)
 			if err != nil {
 				return fmt.Errorf("redirect blocked: %w", err)
 			}
@@ -242,18 +231,22 @@ func New(config *Config) *HTTPFetcher {
 	}
 }
 
-// Fetch retrieves content from the given URL with SSRF protection. When
-// MaxConnections fetches are already in progress, it waits up to
-// ConnectionWaitTimeout for one to finish, then fails with
-// ErrTooManyConnections.
-func (f *HTTPFetcher) Fetch(ctx context.Context, url string) (*FetchResult, error) {
+// Fetch retrieves the source image with SSRF protection, over https, or over
+// http when AllowHTTP is set. When MaxConnections fetches are already in
+// progress, it waits up to ConnectionWaitTimeout for one to finish, then
+// fails with ErrTooManyConnections.
+func (f *HTTPFetcher) Fetch(
+	ctx context.Context, source imagerequest.Source,
+) (*FetchResult, error) {
+	sourceURL := source.URL(f.config.AllowHTTP)
+
 	// Validate URL before making request
-	err := validateURL(ctx, url, f.config.AllowHTTP)
+	err := validateURL(ctx, sourceURL, f.config.AllowHTTP)
 	if err != nil {
 		return nil, err
 	}
 
-	release, err := f.acquireConnection(ctx, extractHost(url))
+	release, err := f.acquireConnection(ctx, source.Host)
 	if err != nil {
 		return nil, err
 	}
@@ -267,19 +260,14 @@ func (f *HTTPFetcher) Fetch(ctx context.Context, url string) (*FetchResult, erro
 		}
 	}()
 
-	parsedURL, err := neturl.Parse(url)
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse URL: %w", err)
-	}
-
 	req := &http.Request{
 		Method: http.MethodGet,
-		URL:    parsedURL,
+		URL:    sourceURL,
 		Header: make(http.Header),
 	}
 
-	req.Header.Set("User-Agent", f.config.UserAgent)
-	req.Header.Set("Accept", strings.Join(f.config.AllowedContentTypes, ", "))
+	req.Header.Set("User-Agent", userAgent)
+	req.Header.Set("Accept", strings.Join(allowedContentTypes(), ", "))
 
 	// The ID of the request this fetch serves, so the fetch can be found in
 	// the upstream host's logs
@@ -458,7 +446,7 @@ func (f *HTTPFetcher) isAllowedContentType(contentType string) bool {
 	// Extract the MIME type without parameters
 	mediaType := strings.TrimSpace(strings.Split(contentType, ";")[0])
 
-	for _, allowed := range f.config.AllowedContentTypes {
+	for _, allowed := range allowedContentTypes() {
 		if strings.EqualFold(mediaType, allowed) {
 			return true
 		}
@@ -468,23 +456,18 @@ func (f *HTTPFetcher) isAllowedContentType(contentType string) bool {
 }
 
 // validateURL checks if a URL is safe to fetch (not internal/private).
-func validateURL(ctx context.Context, rawURL string, allowHTTP bool) error {
-	if !allowHTTP && !strings.HasPrefix(rawURL, "https://") {
+func validateURL(ctx context.Context, fetchURL *neturl.URL, allowHTTP bool) error {
+	if !allowHTTP && fetchURL.Scheme != "https" {
 		return ErrUnsupportedScheme
 	}
 
-	// Parse to extract host
-	host := extractHost(rawURL)
+	// Hostname drops any port, and the brackets of an IPv6 address whether
+	// or not a port follows them
+	host := fetchURL.Hostname()
 	if host == "" {
 		return ErrInvalidHost
 	}
 
-	// Remove port if present
-	h, _, err := net.SplitHostPort(host)
-	if err == nil {
-		host = h
-	}
-
 	// Block obvious localhost patterns
 	if isLocalhost(host) {
 		return ErrSSRFBlocked
@@ -506,25 +489,6 @@ func validateURL(ctx context.Context, rawURL string, allowHTTP bool) error {
 	return nil
 }
 
-// extractHost extracts the host from a URL string.
-func extractHost(rawURL string) string {
-	// Simple extraction without full URL parsing
-	url := rawURL
-	if idx := strings.Index(url, "://"); idx != -1 {
-		url = url[idx+3:]
-	}
-
-	if idx := strings.Index(url, "/"); idx != -1 {
-		url = url[:idx]
-	}
-
-	if idx := strings.Index(url, "?"); idx != -1 {
-		url = url[:idx]
-	}
-
-	return url
-}
-
 // isLocalhost checks if the host is localhost.
 func isLocalhost(host string) bool {
 	host = strings.ToLower(host)
@@ -543,6 +507,9 @@ func isPrivateIP(ip net.IP) bool {
 		return true
 	}
 
+	// An IPv4-compatible IPv6 address is judged as the IPv4 address it holds
+	ip = ipv4CompatibleToIPv4(ip)
+
 	// Check for loopback
 	if ip.IsLoopback() {
 		return true
@@ -594,7 +561,12 @@ func isPrivateIP(ip net.IP) bool {
 }
 
 // isBlockedIP reports whether ip is refused, either by the built-in
-// internal-range check or by one of the operator-supplied prefixes.
+// internal-range check or by one of the operator-supplied prefixes. An
+// IPv4-compatible address (in ::/96) is refused when a prefix contains the
+// address as written or the IPv4 address it holds. An IPv4-mapped address (in
+// ::ffff:0:0/96) is matched only as the IPv4 address it holds: Go keeps a
+// plain IPv4 address in that form too, and an IPv6 prefix such as ::/0 must
+// not refuse every IPv4 address.
 func isBlockedIP(ip net.IP, blocked []netip.Prefix) bool {
 	if isPrivateIP(ip) {
 		return true
@@ -607,16 +579,26 @@ func isBlockedIP(ip net.IP, blocked []netip.Prefix) bool {
 
 	addr = addr.Unmap()
 
+	// ip read as IPv4 where it is or holds an IPv4 address, otherwise the
+	// zero netip.Addr, which no prefix contains. Matching asIPv4 as well as
+	// addr refuses more only for an IPv4-compatible address.
+	asIPv4, _ := netip.AddrFromSlice(ipv4CompatibleToIPv4(ip).To4())
+
 	return slices.ContainsFunc(blocked, func(prefix netip.Prefix) bool {
-		return prefix.Contains(addr)
+		return prefix.Contains(addr) || prefix.Contains(asIPv4)
 	})
 }
 
-// ssrfSafeDialer validates IP addresses against the built-in blocked ranges
-// before connecting. New wraps dialSSRFSafe with the operator-supplied
-// blocklist; this entry point enforces the built-in ranges alone.
-func ssrfSafeDialer(ctx context.Context, network, addr string) (net.Conn, error) {
-	return dialSSRFSafe(ctx, network, addr, nil)
+// ipv4CompatibleToIPv4 returns the IPv4 address that an IPv4-compatible IPv6
+// address (in ::/96, such as ::127.0.0.1) holds in its last four bytes, and
+// any other address unchanged.
+func ipv4CompatibleToIPv4(ip net.IP) net.IP {
+	addr, ok := netip.AddrFromSlice(ip)
+	if ok && netip.MustParsePrefix("::/96").Contains(addr) {
+		return ip[12:]
+	}
+
+	return ip
 }
 
 // dialSSRFSafe re-resolves addr and refuses to connect to any built-in

internal/httpfetcher/httpfetcher_internal_test.go

@@ -5,62 +5,26 @@ import (
 	"errors"
 	"io"
 	"net"
+	"net/url"
 	"testing"
 	"testing/fstest"
+	"time"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // testHost is the hostname used by mock fetch tests.
 const testHost = "example.com"
 
-func TestDefaultConfig(t *testing.T) {
-	t.Parallel()
-
-	cfg := DefaultConfig()
-
-	if cfg.Timeout != DefaultFetchTimeout {
-		t.Errorf("Timeout = %v, want %v", cfg.Timeout, DefaultFetchTimeout)
-	}
-
-	if cfg.MaxResponseSize != DefaultMaxResponseSize {
-		t.Errorf("MaxResponseSize = %d, want %d", cfg.MaxResponseSize, DefaultMaxResponseSize)
-	}
-
-	if cfg.MaxConnectionsPerHost != DefaultMaxConnectionsPerHost {
-		t.Errorf("MaxConnectionsPerHost = %d, want %d",
-			cfg.MaxConnectionsPerHost, DefaultMaxConnectionsPerHost)
-	}
-
-	if cfg.AllowHTTP {
-		t.Error("AllowHTTP should default to false")
-	}
-
-	if len(cfg.AllowedContentTypes) == 0 {
-		t.Error("AllowedContentTypes should not be empty")
-	}
-}
-
-func TestNewWithNilConfigUsesDefaults(t *testing.T) {
-	t.Parallel()
-
-	f := New(nil)
-
-	if f == nil {
-		t.Fatal("New(nil) returned nil")
-	}
-
-	if f.config == nil {
-		t.Fatal("config should be populated from DefaultConfig")
-	}
-
-	if f.config.Timeout != DefaultFetchTimeout {
-		t.Errorf("Timeout = %v, want %v", f.config.Timeout, DefaultFetchTimeout)
-	}
-}
-
 func TestIsAllowedContentType(t *testing.T) {
 	t.Parallel()
 
-	f := New(DefaultConfig())
+	f := New(&Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        64,
+	})
 
 	tests := []struct {
 		contentType string
@@ -88,33 +52,6 @@ func TestIsAllowedContentType(t *testing.T) {
 	}
 }
 
-func TestExtractHost(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		url  string
-		want string
-	}{
-		{"https://example.com/path", testHost},
-		{"http://example.com:8080/path", "example.com:8080"},
-		{"https://example.com", testHost},
-		{"https://example.com?q=1", testHost},
-		{"example.com/path", testHost},
-		{"", ""},
-	}
-
-	for _, tc := range tests {
-		t.Run(tc.url, func(t *testing.T) {
-			t.Parallel()
-
-			got := extractHost(tc.url)
-			if got != tc.want {
-				t.Errorf("extractHost(%q) = %q, want %q", tc.url, got, tc.want)
-			}
-		})
-	}
-}
-
 func TestIsLocalhost(t *testing.T) {
 	t.Parallel()
 
@@ -186,10 +123,48 @@ func TestIsPrivateIP(t *testing.T) {
 	}
 }
 
+// TestIsPrivateIPJudgesEmbeddedIPv4Address checks IPv6 addresses that hold an
+// IPv4 address in their last four bytes: the IPv4-compatible form (::/96) and
+// the NAT64 form (64:ff9b::/96). One holding a loopback, private or
+// link-local IPv4 address is refused as that address is, and one holding a
+// public IPv4 address in the IPv4-compatible form passes.
+func TestIsPrivateIPJudgesEmbeddedIPv4Address(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		ip   string
+		want bool
+	}{
+		{"::127.0.0.1", true},       // loopback
+		{"::10.0.0.1", true},        // private
+		{"::169.254.169.254", true}, // link-local
+		{"64:ff9b::7f00:1", true},   // NAT64 form of 127.0.0.1
+		{"::8.8.8.8", false},        // public
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.ip, func(t *testing.T) {
+			t.Parallel()
+
+			ip := net.ParseIP(tc.ip)
+			if ip == nil {
+				t.Fatalf("failed to parse IP %q", tc.ip)
+			}
+
+			got := isPrivateIP(ip)
+			t.Logf("isPrivateIP(%s) = %v", ip, got)
+
+			if got != tc.want {
+				t.Errorf("isPrivateIP(%q) = %v, want %v", tc.ip, got, tc.want)
+			}
+		})
+	}
+}
+
 func TestValidateURL_RejectsNonHTTPS(t *testing.T) {
 	t.Parallel()
 
-	err := validateURL(t.Context(), "http://example.com/path", false)
+	err := validateURL(t.Context(), &url.URL{Scheme: "http", Host: testHost}, false)
 	if !errors.Is(err, ErrUnsupportedScheme) {
 		t.Errorf("validateURL http = %v, want ErrUnsupportedScheme", err)
 	}
@@ -199,7 +174,8 @@ func TestValidateURL_AllowsHTTPWhenConfigured(t *testing.T) {
 	t.Parallel()
 
 	// Use a host that won't resolve (explicit .invalid TLD) so we don't hit DNS.
-	err := validateURL(t.Context(), "http://nonexistent.invalid/path", true)
+	err := validateURL(t.Context(),
+		&url.URL{Scheme: "http", Host: "nonexistent.invalid"}, true)
 	// We expect a host resolution error, not ErrUnsupportedScheme.
 	if errors.Is(err, ErrUnsupportedScheme) {
 		t.Error("validateURL with AllowHTTP should not return ErrUnsupportedScheme")
@@ -209,7 +185,7 @@ func TestValidateURL_AllowsHTTPWhenConfigured(t *testing.T) {
 func TestValidateURL_RejectsLocalhost(t *testing.T) {
 	t.Parallel()
 
-	err := validateURL(t.Context(), "https://localhost/path", false)
+	err := validateURL(t.Context(), &url.URL{Scheme: "https", Host: "localhost"}, false)
 	if !errors.Is(err, ErrSSRFBlocked) {
 		t.Errorf("validateURL localhost = %v, want ErrSSRFBlocked", err)
 	}
@@ -218,7 +194,7 @@ func TestValidateURL_RejectsLocalhost(t *testing.T) {
 func TestValidateURL_EmptyHost(t *testing.T) {
 	t.Parallel()
 
-	err := validateURL(t.Context(), "https:///path", false)
+	err := validateURL(t.Context(), &url.URL{Scheme: "https"}, false)
 	if !errors.Is(err, ErrInvalidHost) {
 		t.Errorf("validateURL empty host = %v, want ErrInvalidHost", err)
 	}
@@ -233,7 +209,8 @@ func TestMockFetcher_FetchesFile(t *testing.T) {
 
 	m := NewMock(mockFS)
 
-	result, err := m.Fetch(context.Background(), "https://example.com/images/photo.jpg")
+	result, err := m.Fetch(context.Background(),
+		imagerequest.Source{Host: testHost, Path: "/images/photo.jpg"})
 	if err != nil {
 		t.Fatalf("Fetch() error = %v", err)
 	}
@@ -264,7 +241,8 @@ func TestMockFetcher_MissingFileReturnsUpstreamError(t *testing.T) {
 	mockFS := fstest.MapFS{}
 	m := NewMock(mockFS)
 
-	_, err := m.Fetch(context.Background(), "https://example.com/missing.jpg")
+	_, err := m.Fetch(context.Background(),
+		imagerequest.Source{Host: testHost, Path: "/missing.jpg"})
 	if !errors.Is(err, ErrUpstreamError) {
 		t.Errorf("Fetch() error = %v, want ErrUpstreamError", err)
 	}
@@ -281,7 +259,7 @@ func TestMockFetcher_RespectsContextCancellation(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
 
-	_, err := m.Fetch(ctx, "https://example.com/photo.jpg")
+	_, err := m.Fetch(ctx, imagerequest.Source{Host: testHost, Path: "/photo.jpg"})
 	if !errors.Is(err, context.Canceled) {
 		t.Errorf("Fetch() error = %v, want context.Canceled", err)
 	}

internal/httpfetcher/jpegxl_internal_test.go

@@ -1,16 +1,26 @@
 package httpfetcher
 
-import "testing"
+import (
+	"testing"
+	"time"
+)
 
 // TestJPEGXLContentType verifies that the fetcher accepts an upstream answer
-// of type image/jxl by default, and that the mock fetcher serves a .jxl file
-// as image/jxl.
+// of type image/jxl, and that the mock fetcher serves a .jxl file as
+// image/jxl.
 func TestJPEGXLContentType(t *testing.T) {
 	t.Parallel()
 
 	const jxlType = "image/jxl"
 
-	if !New(DefaultConfig()).isAllowedContentType(jxlType) {
+	f := New(&Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        64,
+	})
+
+	if !f.isAllowedContentType(jxlType) {
 		t.Errorf("isAllowedContentType(%q) = false, want true", jxlType)
 	}
 

internal/httpfetcher/max_connections_internal_test.go

@@ -8,22 +8,20 @@ import (
 	"sync"
 	"testing"
 	"time"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
-// imageURLOnPort is the fake upstream's image route on testPublicHost at
-// port. Each port is a different host to the per-host limit, while the test
-// dialer sends every port to the one test server.
-func imageURLOnPort(port int) string {
-	return "http://" + net.JoinHostPort(testPublicHost, strconv.Itoa(port)) +
-		"/image"
+// imageSourceOn is the fake upstream's image route on host.
+func imageSourceOn(host string) imagerequest.Source {
+	return imagerequest.Source{Host: host, Path: "/image"}
 }
 
-func TestDefaultConfigMaxConnections(t *testing.T) {
-	t.Parallel()
-
-	if got := DefaultConfig().MaxConnections; got != DefaultMaxConnections {
-		t.Errorf("MaxConnections = %d, want %d", got, DefaultMaxConnections)
-	}
+// imageSourceOnPort is the fake upstream's image route on testPublicHost at
+// port. Each port is a different host to the per-host limit, while the test
+// dialer sends every port to the one test server.
+func imageSourceOnPort(port int) imagerequest.Source {
+	return imageSourceOn(net.JoinHostPort(testPublicHost, strconv.Itoa(port)))
 }
 
 // TestFetchLimitsConnectionsToAllHostsTogether checks that MaxConnections
@@ -37,18 +35,22 @@ func TestFetchLimitsConnectionsToAllHostsTogether(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := DefaultConfig()
-	cfg.MaxConnections = 2
+	cfg := &Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        2,
+	}
 
 	f, _ := newServerFetcher(t, srv, cfg)
 	f.connectionWaitTimeout = 100 * time.Millisecond
 
-	first, err := f.Fetch(testContext(t), imageURLOnPort(81))
+	first, err := f.Fetch(testContext(t), imageSourceOnPort(81))
 	if err != nil {
 		t.Fatalf("first Fetch() error = %v", err)
 	}
 
-	second, err := f.Fetch(testContext(t), imageURLOnPort(82))
+	second, err := f.Fetch(testContext(t), imageSourceOnPort(82))
 	if err != nil {
 		t.Fatalf("second Fetch() error = %v", err)
 	}
@@ -57,7 +59,7 @@ func TestFetchLimitsConnectionsToAllHostsTogether(t *testing.T) {
 
 	start := time.Now()
 
-	_, err = f.Fetch(testContext(t), imageURLOnPort(83))
+	_, err = f.Fetch(testContext(t), imageSourceOnPort(83))
 	if !errors.Is(err, ErrTooManyConnections) {
 		t.Fatalf("third Fetch() error = %v, want ErrTooManyConnections", err)
 	}
@@ -76,7 +78,7 @@ func TestFetchLimitsConnectionsToAllHostsTogether(t *testing.T) {
 		t.Fatalf("close first body: %v", err)
 	}
 
-	third, err := f.Fetch(testContext(t), imageURLOnPort(83))
+	third, err := f.Fetch(testContext(t), imageSourceOnPort(83))
 	if err != nil {
 		t.Fatalf("Fetch() after a response was closed: error = %v", err)
 	}
@@ -94,12 +96,16 @@ func TestFetchFreesHostSlotWhenContextEndsWaitingForConnection(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := DefaultConfig()
-	cfg.MaxConnections = 1
+	cfg := &Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 20,
+		MaxConnections:        1,
+	}
 
 	f, _ := newServerFetcher(t, srv, cfg)
 
-	first, err := f.Fetch(testContext(t), imageURLOnPort(81))
+	first, err := f.Fetch(testContext(t), imageSourceOnPort(81))
 	if err != nil {
 		t.Fatalf("first Fetch() error = %v", err)
 	}
@@ -109,7 +115,7 @@ func TestFetchFreesHostSlotWhenContextEndsWaitingForConnection(t *testing.T) {
 	ctx, cancel := context.WithTimeout(t.Context(), 100*time.Millisecond)
 	defer cancel()
 
-	_, err = f.Fetch(ctx, imageURLOnPort(82))
+	_, err = f.Fetch(ctx, imageSourceOnPort(82))
 	if !errors.Is(err, context.DeadlineExceeded) {
 		t.Fatalf("second Fetch() error = %v, want context.DeadlineExceeded", err)
 	}
@@ -134,7 +140,7 @@ func TestFetchRemovesIdleHostSemaphores(t *testing.T) {
 
 	for i := range 100 {
 		wg.Go(func() {
-			res, err := f.Fetch(ctx, imageURLOnPort(1+i%50))
+			res, err := f.Fetch(ctx, imageSourceOnPort(1+i%50))
 			if err != nil {
 				t.Errorf("Fetch() error = %v", err)
 
@@ -163,19 +169,22 @@ func TestFetchRemovesHostSemaphoreWhenNoConnection(t *testing.T) {
 
 	srv := startUpstream(t)
 
-	cfg := DefaultConfig()
-	cfg.MaxConnections = 1
-	cfg.MaxConnectionsPerHost = 1
+	cfg := &Config{
+		Timeout:               30 * time.Second,
+		MaxResponseSize:       50 << 20,
+		MaxConnectionsPerHost: 1,
+		MaxConnections:        1,
+	}
 
 	f, _ := newServerFetcher(t, srv, cfg)
 	f.connectionWaitTimeout = 100 * time.Millisecond
 
-	open, err := f.Fetch(testContext(t), imageURLOnPort(81))
+	open, err := f.Fetch(testContext(t), imageSourceOnPort(81))
 	if err != nil {
 		t.Fatalf("first Fetch() error = %v", err)
 	}
 
-	_, err = f.Fetch(testContext(t), imageURLOnPort(82))
+	_, err = f.Fetch(testContext(t), imageSourceOnPort(82))
 	if !errors.Is(err, ErrTooManyConnections) {
 		t.Fatalf("Fetch() from another host: error = %v, "+
 			"want ErrTooManyConnections", err)
@@ -184,7 +193,7 @@ func TestFetchRemovesHostSemaphoreWhenNoConnection(t *testing.T) {
 	ctx, cancel := context.WithTimeout(t.Context(), 100*time.Millisecond)
 	defer cancel()
 
-	_, err = f.Fetch(ctx, imageURLOnPort(81))
+	_, err = f.Fetch(ctx, imageSourceOnPort(81))
 	if !errors.Is(err, context.DeadlineExceeded) {
 		t.Fatalf("Fetch() from the busy host: error = %v, "+
 			"want context.DeadlineExceeded", err)
@@ -196,7 +205,7 @@ func TestFetchRemovesHostSemaphoreWhenNoConnection(t *testing.T) {
 	ctx, cancel = context.WithTimeout(t.Context(), 100*time.Millisecond)
 	defer cancel()
 
-	_, err = f.Fetch(ctx, imageURLOnPort(83))
+	_, err = f.Fetch(ctx, imageSourceOnPort(83))
 	if !errors.Is(err, context.DeadlineExceeded) {
 		t.Fatalf("Fetch() from a host with nothing open: error = %v, "+
 			"want context.DeadlineExceeded", err)
@@ -219,15 +228,15 @@ func TestFetchReleasesConnectionOnError(t *testing.T) {
 	t.Parallel()
 
 	cases := []struct {
-		name string
-		url  string
-		want error
+		name   string
+		source imagerequest.Source
+		want   error
 	}{
-		{"upstream answers 500", upstreamURL("/status/500"), ErrUpstreamError},
-		{"upstream sends HTML", upstreamURL("/html"), ErrInvalidContentType},
+		{"upstream answers 500", upstreamSource("/status/500"), ErrUpstreamError},
+		{"upstream sends HTML", upstreamSource("/html"), ErrInvalidContentType},
 		// 198.51.100.7 (TEST-NET-2) passes the SSRF checks, and the test
 		// dialer refuses every host but testPublicHost.
-		{"connecting fails", "http://198.51.100.7/image", errUnexpectedDial},
+		{"connecting fails", imageSourceOn("198.51.100.7"), errUnexpectedDial},
 	}
 
 	for _, tc := range cases {
@@ -236,13 +245,17 @@ func TestFetchReleasesConnectionOnError(t *testing.T) {
 
 			srv := startUpstream(t)
 
-			cfg := DefaultConfig()
-			cfg.MaxConnections = 1
+			cfg := &Config{
+				Timeout:               30 * time.Second,
+				MaxResponseSize:       50 << 20,
+				MaxConnectionsPerHost: 20,
+				MaxConnections:        1,
+			}
 
 			f, _ := newServerFetcher(t, srv, cfg)
 			f.connectionWaitTimeout = 100 * time.Millisecond
 
-			_, err := f.Fetch(testContext(t), tc.url)
+			_, err := f.Fetch(testContext(t), tc.source)
 			if !errors.Is(err, tc.want) {
 				t.Fatalf("Fetch() error = %v, want %v", err, tc.want)
 			}

internal/httpfetcher/mock.go

@@ -7,14 +7,14 @@ import (
 	"io/fs"
 	"net/http"
 	"strings"
-)
 
-// errEmptyURLPath is returned when a mock URL has no usable path.
-var errEmptyURLPath = errors.New("empty URL path")
+	"sneak.berlin/go/pixa/internal/imagerequest"
+)
 
 // MockFetcher implements Fetcher using an embedded filesystem.
 // Files are organized as: hostname/path/to/file.ext
-// URLs like https://example.com/images/photo.jpg map to example.com/images/photo.jpg.
+// The source with host example.com and path /images/photo.jpg maps to
+// example.com/images/photo.jpg; the source query is ignored.
 type MockFetcher struct {
 	fs fs.FS
 }
@@ -24,8 +24,10 @@ func NewMock(fsys fs.FS) *MockFetcher {
 	return &MockFetcher{fs: fsys}
 }
 
-// Fetch retrieves content from the mock filesystem.
-func (m *MockFetcher) Fetch(ctx context.Context, url string) (*FetchResult, error) {
+// Fetch retrieves the source's content from the mock filesystem.
+func (m *MockFetcher) Fetch(
+	ctx context.Context, source imagerequest.Source,
+) (*FetchResult, error) {
 	// Check context cancellation
 	select {
 	case <-ctx.Done():
@@ -33,11 +35,7 @@ func (m *MockFetcher) Fetch(ctx context.Context, url string) (*FetchResult, erro
 	default:
 	}
 
-	// Parse URL to get filesystem path
-	path, err := urlToFSPath(url)
-	if err != nil {
-		return nil, err
-	}
+	path := source.Host + source.Path
 
 	// Open the file
 	f, err := m.fs.Open(path)
@@ -68,32 +66,6 @@ func (m *MockFetcher) Fetch(ctx context.Context, url string) (*FetchResult, erro
 	}, nil
 }
 
-// urlToFSPath converts a URL to a filesystem path.
-// https://example.com/images/photo.jpg -> example.com/images/photo.jpg
-func urlToFSPath(rawURL string) (string, error) {
-	// Strip scheme
-	url := rawURL
-	if idx := strings.Index(url, "://"); idx != -1 {
-		url = url[idx+3:]
-	}
-
-	// Remove query string
-	if idx := strings.Index(url, "?"); idx != -1 {
-		url = url[:idx]
-	}
-
-	// Remove fragment
-	if idx := strings.Index(url, "#"); idx != -1 {
-		url = url[:idx]
-	}
-
-	if url == "" {
-		return "", errEmptyURLPath
-	}
-
-	return url, nil
-}
-
 // detectContentTypeFromPath returns the MIME type based on file extension.
 func detectContentTypeFromPath(path string) string {
 	path = strings.ToLower(path)

internal/httpfetcher/request_id_internal_test.go

@@ -34,7 +34,7 @@ func TestFetchSendsRequestID(t *testing.T) {
 
 	ctx := context.WithValue(testContext(t), middleware.RequestIDKey, requestID)
 
-	res, err := f.Fetch(ctx, upstreamURL("/image"))
+	res, err := f.Fetch(ctx, upstreamSource("/image"))
 	if err != nil {
 		t.Fatalf("Fetch() error = %v", err)
 	}

internal/imageprocessor/avif_too_large_internal_test.go

@@ -0,0 +1,97 @@
+package imageprocessor
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"os"
+	"testing"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
+)
+
+// TestImageProcessor_RefusesAVIFAboveMaxPixels verifies that an AVIF output
+// of more than MaxAVIFOutputPixels is refused with ErrAVIFOutputTooLarge
+// before anything is decoded, whatever size and fit give it, the source's own
+// size included, and that an AVIF output of at most that many pixels, or one
+// in another format, is not. One input is a 64x32 PNG cut off in its pixel
+// data. The other is testdata/red.avif, a 4x4 AVIF, with the size in its
+// header changed to 4097x4096. libvips reads each input's size from its
+// header but fails when it decodes its pixel data, so a request that gets
+// that failure was not refused, and a refusal came before any decoding.
+func TestImageProcessor_RefusesAVIFAboveMaxPixels(t *testing.T) {
+	t.Parallel()
+
+	whole := createTestPNG(t, 64, 32)
+	cutOff := whole[:len(whole)/2]
+
+	largeAVIF, err := os.ReadFile("testdata/red.avif")
+	if err != nil {
+		t.Fatalf("failed to read test AVIF: %v", err)
+	}
+
+	// The ispe box gives the width and then the height, 4 bytes each, after
+	// the box's type and its 4 bytes of version and flags
+	ispe := bytes.Index(largeAVIF, []byte("ispe"))
+	binary.BigEndian.PutUint32(largeAVIF[ispe+8:], 4097)
+	binary.BigEndian.PutUint32(largeAVIF[ispe+12:], 4096)
+
+	tests := []struct {
+		name          string
+		input         []byte
+		format        imagerequest.Format
+		width, height int
+		fit           imagerequest.Fit
+		refused       bool
+	}{
+		{"AVIF at the limit", cutOff, imagerequest.FormatAVIF,
+			4096, 4096, imagerequest.FitCover, false},
+		{"AVIF above the limit", cutOff, imagerequest.FormatAVIF,
+			4096, 4097, imagerequest.FitCover, true},
+		{"WebP above the AVIF limit", cutOff, imagerequest.FormatWebP,
+			4096, 4097, imagerequest.FitCover, false},
+		// FitInside does not enlarge, so the output stays 64x32
+		{"AVIF inside a larger size", cutOff, imagerequest.FormatAVIF,
+			8192, 8192, imagerequest.FitInside, false},
+		// FitOutside scales 64x32 by 128 to cover 8192x1: 8192x4096
+		{"AVIF outside a smaller size", cutOff, imagerequest.FormatAVIF,
+			8192, 1, imagerequest.FitOutside, true},
+		// With no size, the output keeps the source's 4097x4096
+		{"AVIF of the source's size", largeAVIF, imagerequest.FormatAVIF,
+			0, 0, imagerequest.FitCover, true},
+		{"orig of an AVIF source", largeAVIF, imagerequest.FormatOriginal,
+			0, 0, imagerequest.FitCover, true},
+		{"JPEG of the source's size", largeAVIF, imagerequest.FormatJPEG,
+			0, 0, imagerequest.FitCover, false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := New(Params{
+				MaxInputBytes:           50 << 20,
+				MaxConcurrentProcessing: 1,
+			}).Process(t.Context(), bytes.NewReader(tt.input),
+				&imagerequest.Transform{
+					Size:    imagerequest.Size{Width: tt.width, Height: tt.height},
+					Format:  tt.format,
+					FitMode: tt.fit,
+				})
+			t.Logf("Process() error = %v", err)
+
+			if tt.refused {
+				if !errors.Is(err, ErrAVIFOutputTooLarge) {
+					t.Errorf("Process() error = %v, want %v", err, ErrAVIFOutputTooLarge)
+				}
+
+				return
+			}
+
+			if err == nil || errors.Is(err, ErrAVIFOutputTooLarge) {
+				t.Errorf("Process() error = %v, want the failure to decode "+
+					"the input", err)
+			}
+		})
+	}
+}

internal/imageprocessor/computed_side_internal_test.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"errors"
 	"testing"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // TestImageProcessor_RefusesComputedSideAboveMaximum verifies that a size
@@ -17,13 +19,17 @@ func TestImageProcessor_RefusesComputedSideAboveMaximum(t *testing.T) {
 	tests := []struct {
 		name                    string
 		inputWidth, inputHeight int
-		size                    Size
+		size                    imagerequest.Size
 		wantErr                 error
 	}{
-		{"width at the maximum", 4096, 1, Size{Height: 2}, nil},
-		{"width above the maximum", 4096, 1, Size{Height: 3}, ErrOutputTooLarge},
-		{"height at the maximum", 1, 4096, Size{Width: 2}, nil},
-		{"height above the maximum", 1, 4096, Size{Width: 3}, ErrOutputTooLarge},
+		{"width at the maximum", 4096, 1,
+			imagerequest.Size{Height: 2}, nil},
+		{"width above the maximum", 4096, 1,
+			imagerequest.Size{Height: 3}, ErrOutputTooLarge},
+		{"height at the maximum", 1, 4096,
+			imagerequest.Size{Width: 2}, nil},
+		{"height above the maximum", 1, 4096,
+			imagerequest.Size{Width: 3}, ErrOutputTooLarge},
 	}
 
 	for _, tt := range tests {
@@ -32,9 +38,16 @@ func TestImageProcessor_RefusesComputedSideAboveMaximum(t *testing.T) {
 
 			input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
 
-			result, err := New(Params{}).Process(t.Context(),
+			result, err := New(Params{
+				MaxInputBytes:           50 << 20,
+				MaxConcurrentProcessing: 1,
+			}).Process(t.Context(),
 				bytes.NewReader(input),
-				&Request{Size: tt.size, Format: FormatJPEG, FitMode: FitCover})
+				&imagerequest.Transform{
+					Size:    tt.size,
+					Format:  imagerequest.FormatJPEG,
+					FitMode: imagerequest.FitCover,
+				})
 			if result != nil {
 				t.Logf("Process() made %dx%d", result.Width, result.Height)
 
@@ -50,3 +63,79 @@ func TestImageProcessor_RefusesComputedSideAboveMaximum(t *testing.T) {
 		})
 	}
 }
+
+// TestImageProcessor_ComputedSideIsAtLeastOne verifies that, for a size with
+// one side 0, the side computed from the input's proportions is 1 where it
+// would round down to 0, and that Process makes that size in every fit mode
+// but FitOutside, which scales the input to cover the size and so can make
+// it longer. Each case checks the size targetDimensions gives before it
+// calls Process: with that side at 0, an 8192x1 input at 1300x0 makes
+// libvips ask for about 39 GB with FitCover.
+func TestImageProcessor_ComputedSideIsAtLeastOne(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name                    string
+		inputWidth, inputHeight int
+		size                    imagerequest.Size
+		wantWidth, wantHeight   int
+	}{
+		{"8192x1 at 100x0", 8192, 1, imagerequest.Size{Width: 100}, 100, 1},
+		{"8192x1 at 1300x0", 8192, 1, imagerequest.Size{Width: 1300}, 1300, 1},
+		{"8192x2 at 100x0", 8192, 2, imagerequest.Size{Width: 100}, 100, 1},
+		{"1x8192 at 0x100", 1, 8192, imagerequest.Size{Height: 100}, 1, 100},
+		{"1x8192 at 0x1300", 1, 8192, imagerequest.Size{Height: 1300}, 1, 1300},
+		{"2x8192 at 0x100", 2, 8192, imagerequest.Size{Height: 100}, 1, 100},
+	}
+
+	fits := []imagerequest.Fit{
+		imagerequest.FitCover, imagerequest.FitContain, imagerequest.FitFill,
+		imagerequest.FitInside, imagerequest.FitOutside,
+	}
+
+	for _, tt := range tests {
+		for _, fit := range fits {
+			t.Run(tt.name+" "+string(fit), func(t *testing.T) {
+				t.Parallel()
+
+				width, height, err := targetDimensions(tt.size,
+					tt.inputWidth, tt.inputHeight)
+				if err != nil || width != tt.wantWidth || height != tt.wantHeight {
+					t.Fatalf("targetDimensions() = %dx%d, %v, want %dx%d",
+						width, height, err, tt.wantWidth, tt.wantHeight)
+				}
+
+				input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
+
+				result, err := New(Params{
+					MaxInputBytes:           50 << 20,
+					MaxConcurrentProcessing: 1,
+				}).Process(t.Context(),
+					bytes.NewReader(input),
+					&imagerequest.Transform{
+						Size:    tt.size,
+						Format:  imagerequest.FormatJPEG,
+						FitMode: fit,
+					})
+				if err != nil {
+					t.Fatalf("Process() error = %v", err)
+				}
+
+				defer func() { _ = result.Content.Close() }()
+
+				t.Logf("Process() made %dx%d", result.Width, result.Height)
+
+				ok := result.Width == tt.wantWidth && result.Height == tt.wantHeight
+				if fit == imagerequest.FitOutside {
+					ok = result.Width >= tt.wantWidth && result.Height >= tt.wantHeight
+				}
+
+				if !ok {
+					t.Errorf("Process() made %dx%d, want %dx%d (at least, for %s)",
+						result.Width, result.Height, tt.wantWidth, tt.wantHeight,
+						imagerequest.FitOutside)
+				}
+			})
+		}
+	}
+}

internal/imageprocessor/deadline_internal_test.go

@@ -84,9 +84,9 @@ func checkProcessStopsAtDeadline(
 ) {
 	t.Helper()
 
-	proc := New(Params{MaxConcurrentProcessing: 1})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 
-	result, err := proc.Process(ctx, input, smallJPEGRequest())
+	result, err := proc.Process(ctx, input, smallJPEGTransform())
 	if result != nil {
 		t.Logf("Process() made a %dx%d image after its deadline passed",
 			result.Width, result.Height)

internal/imageprocessor/empty_format_internal_test.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"errors"
 	"testing"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // TestImageProcessor_EmptyFormatRefused verifies that a request with no format
@@ -12,8 +14,12 @@ import (
 func TestImageProcessor_EmptyFormatRefused(t *testing.T) {
 	t.Parallel()
 
-	_, err := New(Params{}).Process(
-		t.Context(), bytes.NewReader(createTestJPEG(t, 20, 20)), &Request{},
+	_, err := New(Params{
+		MaxInputBytes:           50 << 20,
+		MaxConcurrentProcessing: 1,
+	}).Process(
+		t.Context(), bytes.NewReader(createTestJPEG(t, 20, 20)),
+		&imagerequest.Transform{},
 	)
 	if !errors.Is(err, ErrUnsupportedOutputFormat) {
 		t.Errorf("Process() error = %v, want %v", err, ErrUnsupportedOutputFormat)

internal/imageprocessor/encoder_settings_internal_test.go

@@ -8,14 +8,20 @@ import (
 	"testing"
 
 	"github.com/davidbyttow/govips/v2/vips"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // processedSize runs input through Process and returns the output's size in
 // bytes.
-func processedSize(t *testing.T, input []byte, req *Request) int64 {
+func processedSize(
+	t *testing.T, input []byte, transform *imagerequest.Transform,
+) int64 {
 	t.Helper()
 
-	result, err := New(Params{}).Process(t.Context(), bytes.NewReader(input), req)
+	result, err := New(Params{
+		MaxInputBytes:           50 << 20,
+		MaxConcurrentProcessing: 1,
+	}).Process(t.Context(), bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -68,7 +74,8 @@ func TestImageProcessor_PNGIsCompressed(t *testing.T) {
 		}
 	}
 
-	size := processedSize(t, encodePNG(t, flat), &Request{Format: FormatPNG})
+	size := processedSize(t, encodePNG(t, flat),
+		&imagerequest.Transform{Format: imagerequest.FormatPNG})
 
 	const rawBytes = width * height * 3
 	if size > rawBytes/10 {
@@ -77,27 +84,28 @@ func TestImageProcessor_PNGIsCompressed(t *testing.T) {
 	}
 }
 
-// TestImageProcessor_WebPAtDefaultEffort verifies that WebP is saved at
-// libvips' default effort, 4: the output is the size of the same image saved
-// at that effort.
-func TestImageProcessor_WebPAtDefaultEffort(t *testing.T) {
+// TestImageProcessor_WebPAtEffort2 verifies that WebP is saved at effort 2,
+// not libvips' default of 4: the output is the size of the same image saved
+// at effort 2.
+func TestImageProcessor_WebPAtEffort2(t *testing.T) {
 	t.Parallel()
 
 	input := createTestJPEG(t, 200, 150)
 
-	size := processedSize(t, input, &Request{Format: FormatWebP, Quality: 85})
+	size := processedSize(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatWebP, Quality: 85})
 
 	want, _, err := decode(t, input).ExportWebp(&vips.WebpExportParams{
 		StripMetadata:   true,
 		Quality:         85,
-		ReductionEffort: 4,
+		ReductionEffort: 2,
 	})
 	if err != nil {
 		t.Fatalf("ExportWebp() error = %v", err)
 	}
 
 	if size != int64(len(want)) {
-		t.Errorf("WebP output is %d bytes, want %d, the size at effort 4",
+		t.Errorf("WebP output is %d bytes, want %d, the size at effort 2",
 			size, len(want))
 	}
 }
@@ -126,7 +134,8 @@ func TestImageProcessor_AVIFAtEffort1(t *testing.T) {
 
 	input := encodePNG(t, source)
 
-	size := processedSize(t, input, &Request{Format: FormatAVIF, Quality: 85})
+	size := processedSize(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatAVIF, Quality: 85})
 
 	want, _, err := decode(t, input).ExportAvif(&vips.AvifExportParams{
 		StripMetadata: true,
@@ -143,3 +152,30 @@ func TestImageProcessor_AVIFAtEffort1(t *testing.T) {
 			"and 8 bits", size, len(want))
 	}
 }
+
+// TestImageProcessor_JPEGXLAtEffort4 verifies that JPEG XL is saved at
+// effort 4, not libvips' default of 7: the output is the size of the same
+// image saved at effort 4, with the distance exportJXL gives quality 85.
+func TestImageProcessor_JPEGXLAtEffort4(t *testing.T) {
+	t.Parallel()
+
+	input := createTestJPEG(t, 200, 150)
+
+	size := processedSize(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatJXL, Quality: 85})
+
+	params := vips.NewJxlExportParams()
+	params.Quality = 85
+	params.Distance = jxlDistance(85)
+	params.Effort = 4
+
+	want, _, err := decode(t, input).ExportJxl(params)
+	if err != nil {
+		t.Fatalf("ExportJxl() error = %v", err)
+	}
+
+	if size != int64(len(want)) {
+		t.Errorf("JPEG XL output is %d bytes, want %d, the size at effort 4",
+			size, len(want))
+	}
+}

internal/imageprocessor/fit_cover_internal_test.go

@@ -5,28 +5,29 @@ import (
 	"image"
 	"image/color"
 	"image/png"
+	"math"
 	"testing"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // TestImageProcessor_FitCoverServesThinSource verifies that FitCover serves
-// a thin source at the requested size. A source of 8192x64 or 8192x1 scaled
-// to cover 8192x8192 is 128 or 8192 times as long as the output on its long
-// side. The centre of an 8192x1 source with the proportions of 1x8192 is
-// 1/8192 of a pixel wide. Each case is also turned on its side.
+// a thin source at the requested size. An 8192x1 source scaled to cover
+// 8192x8192 is 8192 times as long as the output on its long side. The centre
+// of an 8192x1 source with the proportions of 1x8192 is 1/8192 of a pixel
+// wide. Each case is also turned on its side.
 func TestImageProcessor_FitCoverServesThinSource(t *testing.T) {
 	t.Parallel()
 
 	tests := []struct {
 		name                    string
 		inputWidth, inputHeight int
-		size                    Size
+		size                    imagerequest.Size
 	}{
-		{"8192x64 at 8192x8192", 8192, 64, Size{Width: 8192, Height: 8192}},
-		{"8192x1 at 8192x8192", 8192, 1, Size{Width: 8192, Height: 8192}},
-		{"8192x1 at 1x8192", 8192, 1, Size{Width: 1, Height: 8192}},
-		{"64x8192 at 8192x8192", 64, 8192, Size{Width: 8192, Height: 8192}},
-		{"1x8192 at 8192x8192", 1, 8192, Size{Width: 8192, Height: 8192}},
-		{"1x8192 at 8192x1", 1, 8192, Size{Width: 8192, Height: 1}},
+		{"8192x1 at 8192x8192", 8192, 1, imagerequest.Size{Width: 8192, Height: 8192}},
+		{"8192x1 at 1x8192", 8192, 1, imagerequest.Size{Width: 1, Height: 8192}},
+		{"1x8192 at 8192x8192", 1, 8192, imagerequest.Size{Width: 8192, Height: 8192}},
+		{"1x8192 at 8192x1", 1, 8192, imagerequest.Size{Width: 8192, Height: 1}},
 	}
 
 	for _, tt := range tests {
@@ -35,9 +36,16 @@ func TestImageProcessor_FitCoverServesThinSource(t *testing.T) {
 
 			input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
 
-			result, err := New(Params{}).Process(t.Context(),
+			result, err := New(Params{
+				MaxInputBytes:           50 << 20,
+				MaxConcurrentProcessing: 1,
+			}).Process(t.Context(),
 				bytes.NewReader(input),
-				&Request{Size: tt.size, Format: FormatJPEG, FitMode: FitCover})
+				&imagerequest.Transform{
+					Size:    tt.size,
+					Format:  imagerequest.FormatJPEG,
+					FitMode: imagerequest.FitCover,
+				})
 			if err != nil {
 				t.Fatalf("Process() error = %v", err)
 			}
@@ -101,12 +109,15 @@ func TestImageProcessor_FitCoverCropsTheCentre(t *testing.T) {
 
 			input := createBandsPNG(t, tt.inputWidth, tt.inputHeight)
 
-			result, err := New(Params{}).Process(t.Context(),
+			result, err := New(Params{
+				MaxInputBytes:           50 << 20,
+				MaxConcurrentProcessing: 1,
+			}).Process(t.Context(),
 				bytes.NewReader(input),
-				&Request{
-					Size:    Size{Width: 50, Height: 50},
-					Format:  FormatPNG,
-					FitMode: FitCover,
+				&imagerequest.Transform{
+					Size:    imagerequest.Size{Width: 50, Height: 50},
+					Format:  imagerequest.FormatPNG,
+					FitMode: imagerequest.FitCover,
 				})
 			if err != nil {
 				t.Fatalf("Process() error = %v", err)
@@ -141,3 +152,136 @@ func TestImageProcessor_FitCoverCropsTheCentre(t *testing.T) {
 		})
 	}
 }
+
+// The greys of createSquarePNG, and the grey halfway between them.
+const (
+	backgroundGrey = 192
+	squareGrey     = 64
+	halfwayGrey    = (backgroundGrey + squareGrey) / 2
+)
+
+// createSquarePNG creates a grey PNG side pixels square with a darker grey
+// square squareSide pixels wide in its centre.
+func createSquarePNG(t *testing.T, side, squareSide int) []byte {
+	t.Helper()
+
+	first := (side - squareSide) / 2
+	last := first + squareSide - 1
+
+	img := image.NewGray(image.Rect(0, 0, side, side))
+	for y := range side {
+		for x := range side {
+			grey := uint8(backgroundGrey)
+			if x >= first && x <= last && y >= first && y <= last {
+				grey = squareGrey
+			}
+
+			img.SetGray(x, y, color.Gray{Y: grey})
+		}
+	}
+
+	return encodePNG(t, img)
+}
+
+// squareLength returns how long the square is along greys, the greys of a
+// row or column of the output that crosses it: the distance between the
+// first and the last point where greys passes halfwayGrey, or 0 when there
+// is no such point. Resampling blurs the square's edges over several
+// pixels, and each point is placed between the two pixels on either side
+// of it in proportion to their greys, so the length is measured to a
+// fraction of a pixel.
+func squareLength(greys []float64) float64 {
+	first, last := -1.0, -1.0
+
+	for i := 1; i < len(greys); i++ {
+		before, after := greys[i-1], greys[i]
+		if (before > halfwayGrey) == (after > halfwayGrey) {
+			continue
+		}
+
+		point := float64(i-1) + (before-halfwayGrey)/(before-after)
+		if first < 0 {
+			first = point
+		}
+
+		last = point
+	}
+
+	return last - first
+}
+
+// TestImageProcessor_FitCoverKeepsProportions verifies that FitCover scales
+// both sides of the source by the same amount: a square in the centre of
+// the source comes out square. Its width and height are measured along the
+// output's middle row and column.
+func TestImageProcessor_FitCoverKeepsProportions(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name             string
+		side, squareSide int
+		size             imagerequest.Size
+	}{
+		{"16x16 at 100x60", 16, 8, imagerequest.Size{Width: 100, Height: 60}},
+		{"16x16 at 60x100", 16, 8, imagerequest.Size{Width: 60, Height: 100}},
+		{"10x10 at 100x35", 10, 2, imagerequest.Size{Width: 100, Height: 35}},
+		{"10x10 at 35x100", 10, 2, imagerequest.Size{Width: 35, Height: 100}},
+		{"64x64 at 300x100", 64, 16, imagerequest.Size{Width: 300, Height: 100}},
+		{"64x64 at 100x300", 64, 16, imagerequest.Size{Width: 100, Height: 300}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			input := createSquarePNG(t, tt.side, tt.squareSide)
+
+			result, err := New(Params{
+				MaxInputBytes:           50 << 20,
+				MaxConcurrentProcessing: 1,
+			}).Process(t.Context(),
+				bytes.NewReader(input),
+				&imagerequest.Transform{
+					Size:    tt.size,
+					Format:  imagerequest.FormatPNG,
+					FitMode: imagerequest.FitCover,
+				})
+			if err != nil {
+				t.Fatalf("Process() error = %v", err)
+			}
+
+			defer func() { _ = result.Content.Close() }()
+
+			output, err := png.Decode(result.Content)
+			if err != nil {
+				t.Fatalf("failed to decode output: %v", err)
+			}
+
+			bounds := output.Bounds()
+			if bounds.Dx() != tt.size.Width || bounds.Dy() != tt.size.Height {
+				t.Fatalf("Process() made %dx%d, want %dx%d",
+					bounds.Dx(), bounds.Dy(), tt.size.Width, tt.size.Height)
+			}
+
+			row := make([]float64, bounds.Dx())
+			for x := range row {
+				r, _, _, _ := output.At(x, bounds.Dy()/2).RGBA()
+				row[x] = float64(r >> 8)
+			}
+
+			column := make([]float64, bounds.Dy())
+			for y := range column {
+				r, _, _, _ := output.At(bounds.Dx()/2, y).RGBA()
+				column[y] = float64(r >> 8)
+			}
+
+			width, height := squareLength(row), squareLength(column)
+			t.Logf("square is %.2f wide and %.2f high", width, height)
+
+			if width == 0 || math.Abs(width-height) > 0.5 {
+				t.Errorf("square is %.2f wide and %.2f high, want it square",
+					width, height)
+			}
+		})
+	}
+}

internal/imageprocessor/fit_outside_internal_test.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"errors"
 	"testing"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // TestImageProcessor_RefusesFitOutsideAboveMaximum verifies that FitOutside,
@@ -17,15 +19,20 @@ func TestImageProcessor_RefusesFitOutsideAboveMaximum(t *testing.T) {
 	tests := []struct {
 		name                    string
 		inputWidth, inputHeight int
-		size                    Size
+		size                    imagerequest.Size
 		// wantWidth and wantHeight are the output's, 0 for a refusal
 		wantWidth, wantHeight int
 	}{
-		{"width above the maximum", 3000, 600, Size{Width: 1, Height: 8192}, 0, 0},
-		{"height above the maximum", 600, 3000, Size{Width: 8192, Height: 1}, 0, 0},
-		{"width at the maximum", 1024, 256, Size{Width: 1, Height: 2048}, 8192, 2048},
-		{"height at the maximum", 256, 1024, Size{Width: 2048, Height: 1}, 2048, 8192},
-		{"within the maximum", 3000, 600, Size{Width: 1, Height: 1200}, 6000, 1200},
+		{"width above the maximum", 3000, 600,
+			imagerequest.Size{Width: 1, Height: 8192}, 0, 0},
+		{"height above the maximum", 600, 3000,
+			imagerequest.Size{Width: 8192, Height: 1}, 0, 0},
+		{"width at the maximum", 1024, 256,
+			imagerequest.Size{Width: 1, Height: 2048}, 8192, 2048},
+		{"height at the maximum", 256, 1024,
+			imagerequest.Size{Width: 2048, Height: 1}, 2048, 8192},
+		{"within the maximum", 3000, 600,
+			imagerequest.Size{Width: 1, Height: 1200}, 6000, 1200},
 	}
 
 	for _, tt := range tests {
@@ -34,9 +41,16 @@ func TestImageProcessor_RefusesFitOutsideAboveMaximum(t *testing.T) {
 
 			input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
 
-			result, err := New(Params{}).Process(t.Context(),
+			result, err := New(Params{
+				MaxInputBytes:           50 << 20,
+				MaxConcurrentProcessing: 1,
+			}).Process(t.Context(),
 				bytes.NewReader(input),
-				&Request{Size: tt.size, Format: FormatJPEG, FitMode: FitOutside})
+				&imagerequest.Transform{
+					Size:    tt.size,
+					Format:  imagerequest.FormatJPEG,
+					FitMode: imagerequest.FitOutside,
+				})
 			if result != nil {
 				t.Logf("Process() made %dx%d", result.Width, result.Height)
 			}
@@ -60,3 +74,52 @@ func TestImageProcessor_RefusesFitOutsideAboveMaximum(t *testing.T) {
 		})
 	}
 }
+
+// TestImageProcessor_FitOutsideSideIsAtLeastOne verifies that FitOutside
+// keeps each side at 1 or more when it works both sides out again from the
+// larger scale. A side of 49 scaled to 1 is 49 times 1/49, which in floating
+// point is just under 1 and so rounded down to 0, a width libvips refuses.
+func TestImageProcessor_FitOutsideSideIsAtLeastOne(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name                    string
+		inputWidth, inputHeight int
+		size                    imagerequest.Size
+		wantWidth, wantHeight   int
+	}{
+		{"49x8192 at 0x100", 49, 8192, imagerequest.Size{Height: 100}, 1, 167},
+		{"49x49 at 1x1", 49, 49, imagerequest.Size{Width: 1, Height: 1}, 1, 1},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			input := createTestJPEG(t, tt.inputWidth, tt.inputHeight)
+
+			result, err := New(Params{
+				MaxInputBytes:           50 << 20,
+				MaxConcurrentProcessing: 1,
+			}).Process(t.Context(),
+				bytes.NewReader(input),
+				&imagerequest.Transform{
+					Size:    tt.size,
+					Format:  imagerequest.FormatJPEG,
+					FitMode: imagerequest.FitOutside,
+				})
+			if err != nil {
+				t.Fatalf("Process() error = %v", err)
+			}
+
+			defer func() { _ = result.Content.Close() }()
+
+			t.Logf("Process() made %dx%d", result.Width, result.Height)
+
+			if result.Width != tt.wantWidth || result.Height != tt.wantHeight {
+				t.Errorf("Process() made %dx%d, want %dx%d",
+					result.Width, result.Height, tt.wantWidth, tt.wantHeight)
+			}
+		})
+	}
+}

internal/imageprocessor/imageprocessor.go

@@ -11,7 +11,7 @@ import (
 	"time"
 
 	"github.com/davidbyttow/govips/v2/vips"
-	"sneak.berlin/go/pixa/internal/config"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // vipsOnce ensures vips is initialized exactly once.
@@ -54,49 +54,6 @@ func CheckJPEGXLSupport() error {
 	return nil
 }
 
-// Format represents supported output image formats.
-type Format string
-
-// Supported image output formats.
-const (
-	FormatOriginal Format = "orig"
-	FormatJPEG     Format = "jpeg"
-	FormatPNG      Format = "png"
-	FormatWebP     Format = "webp"
-	FormatAVIF     Format = "avif"
-	FormatJXL      Format = "jxl"
-	FormatGIF      Format = "gif"
-)
-
-// FitMode represents how to fit an image into requested dimensions.
-type FitMode string
-
-// Supported image fit modes.
-const (
-	FitCover   FitMode = "cover"
-	FitContain FitMode = "contain"
-	FitFill    FitMode = "fill"
-	FitInside  FitMode = "inside"
-	FitOutside FitMode = "outside"
-)
-
-// ErrInvalidFitMode is returned when an invalid fit mode is provided.
-var ErrInvalidFitMode = errors.New("invalid fit mode")
-
-// Size represents requested image dimensions.
-type Size struct {
-	Width  int
-	Height int
-}
-
-// Request holds the parameters for image processing.
-type Request struct {
-	Size    Size
-	Format  Format
-	Quality int
-	FitMode FitMode
-}
-
 // Result contains the output of image processing.
 type Result struct {
 	// Content is the processed image data.
@@ -121,10 +78,6 @@ type Result struct {
 // Images larger than this are rejected to prevent DoS via decompression bombs.
 const MaxInputDimension = 8192
 
-// DefaultMaxInputBytes is the default maximum input size in bytes (50 MiB).
-// This matches the default upstream fetcher limit.
-const DefaultMaxInputBytes = 50 << 20
-
 // ErrInputTooLarge is returned when input image dimensions exceed MaxInputDimension.
 var ErrInputTooLarge = errors.New("input image dimensions exceed maximum")
 
@@ -133,8 +86,8 @@ var ErrInputTooLarge = errors.New("input image dimensions exceed maximum")
 var ErrInputDataTooLarge = errors.New("input data exceeds maximum allowed size")
 
 // MaxOutputDimension is the maximum width or height of an output image, and
-// so of a requested size (imgcache.MaxDimension).
-const MaxOutputDimension = 8192
+// so of a requested size (imagerequest.MaxDimension).
+const MaxOutputDimension = imagerequest.MaxDimension
 
 // ErrOutputTooLarge is returned, before resizing, when the output would have a
 // side above MaxOutputDimension: the side of a size with one side 0, computed
@@ -142,6 +95,19 @@ const MaxOutputDimension = 8192
 // requested size.
 var ErrOutputTooLarge = errors.New("output image dimensions exceed maximum")
 
+// MaxAVIFOutputPixels is the most pixels an AVIF output may have, so that an
+// encode takes at most 40 seconds of the default downstream_timeout of 60
+// seconds; AVIF is already at the lowest effort govips can set (avifEffort).
+// With one thread, as pixad runs libvips, saving 4096x4096, 8192x2048 or
+// 2048x8192 random pixels with an alpha channel takes up to about 34
+// seconds, the slowest at any quality and at 8 or 16 bits per sample, and
+// 5120x4096 at 8 bits already takes about 36.
+const MaxAVIFOutputPixels = 4096 * 4096
+
+// ErrAVIFOutputTooLarge is returned, before anything is decoded, when an AVIF
+// output would have more than MaxAVIFOutputPixels pixels.
+var ErrAVIFOutputTooLarge = errors.New("AVIF output has too many pixels")
+
 // ErrUnsupportedOutputFormat is returned when the requested output format is
 // not supported.
 var ErrUnsupportedOutputFormat = errors.New("unsupported output format")
@@ -171,50 +137,38 @@ type ImageProcessor struct {
 	processingWaitTimeout time.Duration
 }
 
-// Params holds configuration for creating an ImageProcessor.
-// Zero values use sensible defaults (MaxInputBytes defaults to DefaultMaxInputBytes).
+// Params holds configuration for creating an ImageProcessor. Both fields
+// must be at least 1.
 type Params struct {
 	// MaxInputBytes is the maximum allowed input size in bytes.
-	// If <= 0, DefaultMaxInputBytes is used.
 	MaxInputBytes int64
 	// MaxConcurrentProcessing is the most images processed at once.
-	// If <= 0, config.DefaultMaxConcurrentProcessing() is used.
 	MaxConcurrentProcessing int
 }
 
 // New creates a new image processor with the given parameters.
-// A zero-value Params{} uses sensible defaults.
 func New(params Params) *ImageProcessor {
 	initVips()
 
-	maxInputBytes := params.MaxInputBytes
-	if maxInputBytes <= 0 {
-		maxInputBytes = DefaultMaxInputBytes
-	}
-
-	maxConcurrentProcessing := params.MaxConcurrentProcessing
-	if maxConcurrentProcessing <= 0 {
-		maxConcurrentProcessing = config.DefaultMaxConcurrentProcessing()
-	}
-
 	return &ImageProcessor{
-		maxInputBytes:         maxInputBytes,
-		processingSemaphore:   make(chan struct{}, maxConcurrentProcessing),
+		maxInputBytes:         params.MaxInputBytes,
+		processingSemaphore:   make(chan struct{}, params.MaxConcurrentProcessing),
 		processingWaitTimeout: ProcessingWaitTimeout,
 	}
 }
 
-// Process transforms an image according to the request. When
+// Process transforms an image according to transform. When
 // MaxConcurrentProcessing images are already being processed, it waits up
 // to ProcessingWaitTimeout for one to finish, then fails with
 // ErrTooManyImages. When ctx has ended once Process has a slot, or before it
 // encodes, it returns ctx's error and gives the slot back. govips gives pixa
 // no way to stop libvips once an encode has begun, so an encode keeps its
-// slot until it finishes.
+// slot until it finishes. An AVIF output of more than MaxAVIFOutputPixels is
+// refused with ErrAVIFOutputTooLarge before anything is decoded.
 func (p *ImageProcessor) Process(
 	ctx context.Context,
 	input io.Reader,
-	req *Request,
+	transform *imagerequest.Transform,
 ) (*Result, error) {
 	release, err := p.acquireSlot(ctx)
 	if err != nil {
@@ -223,18 +177,9 @@ func (p *ImageProcessor) Process(
 
 	defer release()
 
-	// Read input with a size limit to prevent unbounded memory consumption.
-	// We read at most maxInputBytes+1 so we can detect if the input exceeds
-	// the limit without consuming additional memory.
-	limited := io.LimitReader(input, p.maxInputBytes+1)
-
-	data, err := io.ReadAll(limited)
+	data, err := p.readInput(input)
 	if err != nil {
-		return nil, fmt.Errorf("failed to read input: %w", err)
-	}
-
-	if int64(len(data)) > p.maxInputBytes {
-		return nil, ErrInputDataTooLarge
+		return nil, err
 	}
 
 	// govips picks the libvips loader from the input's first bytes with
@@ -272,27 +217,36 @@ func (p *ImageProcessor) Process(
 	}
 
 	// Determine target dimensions; too large ones are refused before resizing
-	targetWidth, targetHeight, err := targetDimensions(req.Size, origWidth, origHeight)
+	targetWidth, targetHeight, err := targetDimensions(transform.Size,
+		origWidth, origHeight)
+	if err != nil {
+		return nil, err
+	}
+
+	// orig is the source's own format; encode refuses an empty format
+	outputFormat := transform.Format
+	if outputFormat == imagerequest.FormatOriginal {
+		outputFormat = sourceFormat
+	}
+
+	// Determine output dimensions; too large ones are refused before
+	// resizing, which with FitCover already decodes the input
+	outputWidth, outputHeight, err := outputDimensions(origWidth, origHeight,
+		targetWidth, targetHeight, transform.FitMode, outputFormat)
 	if err != nil {
 		return nil, err
 	}
 
 	// Resize if needed
 	if targetWidth != origWidth || targetHeight != origHeight {
-		err := p.resize(img, targetWidth, targetHeight, req.FitMode)
+		err := p.resize(img, outputWidth, outputHeight, transform.FitMode)
 		if err != nil {
 			return nil, fmt.Errorf("failed to resize: %w", err)
 		}
 	}
 
-	// orig is the source's own format; encode refuses an empty format
-	outputFormat := req.Format
-	if outputFormat == FormatOriginal {
-		outputFormat = sourceFormat
-	}
-
 	// Encode to target format
-	output, err := p.encode(ctx, img, outputFormat, req.Quality)
+	output, err := p.encode(ctx, img, outputFormat, transform.Quality)
 	if err != nil {
 		return nil, fmt.Errorf("failed to encode: %w", err)
 	}
@@ -311,9 +265,13 @@ func (p *ImageProcessor) Process(
 
 // targetDimensions calculates the output dimensions for a requested size,
 // scaling proportionally when only one dimension is given and keeping the
-// original dimensions when both are zero. A side scaled proportionally can
-// come out above MaxOutputDimension, which is ErrOutputTooLarge.
-func targetDimensions(size Size, origWidth, origHeight int) (int, int, error) {
+// original dimensions when both are zero. A side scaled proportionally is
+// rounded down but kept at 1 or more, as for a thin image it would round
+// down to 0, a side of no pixels. It can come out above MaxOutputDimension,
+// which is ErrOutputTooLarge.
+func targetDimensions(
+	size imagerequest.Size, origWidth, origHeight int,
+) (int, int, error) {
 	width, height := size.Width, size.Height
 
 	switch {
@@ -322,10 +280,10 @@ func targetDimensions(size Size, origWidth, origHeight int) (int, int, error) {
 		return origWidth, origHeight, nil
 	case width == 0:
 		// Only height specified: calculate width proportionally
-		width = origWidth * height / origHeight
+		width = max(1, origWidth*height/origHeight)
 	case height == 0:
 		// Only width specified: calculate height proportionally
-		height = origHeight * width / origWidth
+		height = max(1, origHeight*width/origWidth)
 	}
 
 	if width > MaxOutputDimension || height > MaxOutputDimension {
@@ -346,46 +304,22 @@ const (
 	mimeJXL  = "image/jxl"
 )
 
-// SupportedInputFormats returns MIME types this processor can read.
-func (p *ImageProcessor) SupportedInputFormats() []string {
-	return []string{
-		mimeJPEG,
-		mimePNG,
-		mimeGIF,
-		mimeWebP,
-		mimeAVIF,
-		mimeJXL,
-	}
-}
-
-// SupportedOutputFormats returns formats this processor can write.
-func (p *ImageProcessor) SupportedOutputFormats() []Format {
-	return []Format{
-		FormatJPEG,
-		FormatPNG,
-		FormatGIF,
-		FormatWebP,
-		FormatAVIF,
-		FormatJXL,
-	}
-}
-
 // FormatToMIME converts a Format to its MIME type string.
-func FormatToMIME(format Format) string {
+func FormatToMIME(format imagerequest.Format) string {
 	switch format {
-	case FormatJPEG:
+	case imagerequest.FormatJPEG:
 		return mimeJPEG
-	case FormatPNG:
+	case imagerequest.FormatPNG:
 		return mimePNG
-	case FormatWebP:
+	case imagerequest.FormatWebP:
 		return mimeWebP
-	case FormatGIF:
+	case imagerequest.FormatGIF:
 		return mimeGIF
-	case FormatAVIF:
+	case imagerequest.FormatAVIF:
 		return mimeAVIF
-	case FormatJXL:
+	case imagerequest.FormatJXL:
 		return mimeJXL
-	case FormatOriginal:
+	case imagerequest.FormatOriginal, imagerequest.FormatAuto:
 		return "application/octet-stream"
 	default:
 		return "application/octet-stream"
@@ -443,6 +377,23 @@ func (p *ImageProcessor) acquireSlot(ctx context.Context) (func(), error) {
 	return release, nil
 }
 
+// readInput reads input with a size limit to prevent unbounded memory
+// consumption, refusing more than maxInputBytes with ErrInputDataTooLarge. It
+// reads at most maxInputBytes+1 so it can detect if the input exceeds the
+// limit without consuming additional memory.
+func (p *ImageProcessor) readInput(input io.Reader) ([]byte, error) {
+	data, err := io.ReadAll(io.LimitReader(input, p.maxInputBytes+1))
+	if err != nil {
+		return nil, fmt.Errorf("failed to read input: %w", err)
+	}
+
+	if int64(len(data)) > p.maxInputBytes {
+		return nil, ErrInputDataTooLarge
+	}
+
+	return data, nil
+}
+
 // detectFormat returns the format string for a govips image type.
 func (p *ImageProcessor) detectFormat(imageType vips.ImageType) string {
 	switch imageType {
@@ -455,9 +406,9 @@ func (p *ImageProcessor) detectFormat(imageType vips.ImageType) string {
 	case vips.ImageTypeWEBP:
 		return "webp"
 	case vips.ImageTypeAVIF, vips.ImageTypeHEIF:
-		return string(FormatAVIF)
+		return string(imagerequest.FormatAVIF)
 	case vips.ImageTypeJXL:
-		return string(FormatJXL)
+		return string(imagerequest.FormatJXL)
 	case vips.ImageTypeUnknown, vips.ImageTypeMagick, vips.ImageTypePDF,
 		vips.ImageTypeSVG, vips.ImageTypeTIFF, vips.ImageTypeBMP,
 		vips.ImageTypeJP2K:
@@ -467,98 +418,127 @@ func (p *ImageProcessor) detectFormat(imageType vips.ImageType) string {
 	}
 }
 
-// resize resizes the image according to the fit mode. With FitOutside one
-// side can come out larger than requested; when it would be above
-// MaxOutputDimension, resize returns ErrOutputTooLarge without resizing.
+// outputDimensions returns the dimensions resize gives an image of imgWidth x
+// imgHeight for the target dimensions and fit mode, without resizing it, and
+// refuses an output too large for format. With FitOutside one side can come
+// out larger than the target; when it would be above MaxOutputDimension,
+// outputDimensions returns ErrOutputTooLarge. An AVIF output of more than
+// MaxAVIFOutputPixels is ErrAVIFOutputTooLarge.
+func outputDimensions(
+	imgWidth, imgHeight, width, height int,
+	fit imagerequest.Fit, format imagerequest.Format,
+) (int, int, error) {
+	scaleW := float64(width) / float64(imgWidth)
+	scaleH := float64(height) / float64(imgHeight)
+	outputWidth, outputHeight := width, height
+
+	switch fit {
+	case imagerequest.FitCover, imagerequest.FitFill, "":
+		// Cover crops, and fill stretches, to exactly the target dimensions
+
+	case imagerequest.FitContain:
+		// Fit within the target dimensions, maintaining aspect ratio. Scaled
+		// by the smaller scale, the short side of a thin image can round
+		// down to 0, which libvips refuses as a width, so each side is at
+		// least 1.
+		scale := min(scaleW, scaleH)
+		outputWidth = max(1, int(float64(imgWidth)*scale))
+		outputHeight = max(1, int(float64(imgHeight)*scale))
+
+	case imagerequest.FitInside:
+		// Same as contain, but only shrink
+		scale := min(scaleW, scaleH, 1)
+		outputWidth = max(1, int(float64(imgWidth)*scale))
+		outputHeight = max(1, int(float64(imgHeight)*scale))
+
+	case imagerequest.FitOutside:
+		// The smallest dimension fits, the other may exceed the target. A
+		// side scaled to 1 can come out just under 1 in floating point, as
+		// 49 times 1/49 does, and round down to 0, which libvips refuses as
+		// a width, so each side is at least 1.
+		scale := max(scaleW, scaleH)
+		outputWidth = max(1, int(float64(imgWidth)*scale))
+		outputHeight = max(1, int(float64(imgHeight)*scale))
+
+	default:
+		return 0, 0, fmt.Errorf("%w: %s", imagerequest.ErrInvalidFitMode, fit)
+	}
+
+	// The side FitOutside scales past the target is held to the maximum too
+	if max(outputWidth, outputHeight) > MaxOutputDimension {
+		return 0, 0, fmt.Errorf("%w: %dx%d is above %d", ErrOutputTooLarge,
+			outputWidth, outputHeight, MaxOutputDimension)
+	}
+
+	if format == imagerequest.FormatAVIF &&
+		outputWidth*outputHeight > MaxAVIFOutputPixels {
+		return 0, 0, fmt.Errorf("%w: %dx%d is above %d pixels",
+			ErrAVIFOutputTooLarge, outputWidth, outputHeight, MaxAVIFOutputPixels)
+	}
+
+	return outputWidth, outputHeight, nil
+}
+
+// resize resizes the image to width x height, the dimensions
+// outputDimensions gives for the fit mode.
 func (p *ImageProcessor) resize(
-	img *vips.ImageRef, width, height int, fit FitMode,
+	img *vips.ImageRef, width, height int, fit imagerequest.Fit,
 ) error {
 	switch fit {
-	case FitCover, "":
+	case imagerequest.FitCover, "":
 		// Crop the centre and resize to fill exact dimensions (default)
 		return cropCentreAndResize(img, width, height)
 
-	case FitContain:
-		// Resize to fit within dimensions, maintaining aspect ratio
-		imgW, imgH := img.Width(), img.Height()
-		scaleW := float64(width) / float64(imgW)
-		scaleH := float64(height) / float64(imgH)
-		scale := min(scaleW, scaleH)
-		newW := int(float64(imgW) * scale)
-		newH := int(float64(imgH) * scale)
-
-		return img.Thumbnail(newW, newH, vips.InterestingNone)
-
-	case FitFill:
+	case imagerequest.FitFill:
 		// Resize to exact dimensions (may distort)
 		return img.ThumbnailWithSize(width, height, vips.InterestingNone, vips.SizeForce)
 
-	case FitInside:
-		// Same as contain, but only shrink
-		if img.Width() <= width && img.Height() <= height {
-			return nil // Already fits
+	case imagerequest.FitInside:
+		// outputDimensions keeps the dimensions of an image that already fits
+		if img.Width() == width && img.Height() == height {
+			return nil
 		}
 
-		imgW, imgH := img.Width(), img.Height()
-		scaleW := float64(width) / float64(imgW)
-		scaleH := float64(height) / float64(imgH)
-		scale := min(scaleW, scaleH)
-		newW := int(float64(imgW) * scale)
-		newH := int(float64(imgH) * scale)
+		return img.Thumbnail(width, height, vips.InterestingNone)
 
-		return img.Thumbnail(newW, newH, vips.InterestingNone)
-
-	case FitOutside:
-		// Resize so smallest dimension fits, may exceed target on other dimension
-		imgW, imgH := img.Width(), img.Height()
-		scaleW := float64(width) / float64(imgW)
-		scaleH := float64(height) / float64(imgH)
-		scale := max(scaleW, scaleH)
-		newW := int(float64(imgW) * scale)
-		newH := int(float64(imgH) * scale)
-
-		// The dimension that exceeds the target is held to the maximum too
-		if newW > MaxOutputDimension || newH > MaxOutputDimension {
-			return fmt.Errorf("%w: %dx%d is above %d", ErrOutputTooLarge,
-				newW, newH, MaxOutputDimension)
-		}
-
-		return img.Thumbnail(newW, newH, vips.InterestingNone)
+	case imagerequest.FitContain, imagerequest.FitOutside:
+		return img.Thumbnail(width, height, vips.InterestingNone)
 
 	default:
-		return fmt.Errorf("%w: %s", ErrInvalidFitMode, fit)
+		return fmt.Errorf("%w: %s", imagerequest.ErrInvalidFitMode, fit)
 	}
 }
 
-// cropCentreAndResize cuts img to its centre, the largest area it holds with
-// the proportions of width x height, and resizes that to width x height.
-// This is the crop libvips' thumbnail makes with InterestingCentre, but
-// libvips scales the whole image to cover the size and copies the result
-// into memory before it crops, and for a thin image that is far larger than
-// the image or the output: 8192x64 at 8192x8192 is 1048576x8192, about 24
-// GiB. Cropping first makes no image larger than img or the output.
+// cropCentreAndResize scales img by the same amount on both sides, the
+// least that makes it cover width x height, and cuts the centre width x
+// height out of it, as libvips' thumbnail does with InterestingCentre.
+// thumbnail alone scales the whole image and copies the result into memory
+// before it cuts, and for a thin image that is far larger than the image or
+// the output: 8192x64 at 8192x8192 is 1048576x8192, about 24 GiB. So the
+// centre is cut from img first, widened to whole pixels of img, which adds
+// less than one pixel of img on each side, and thumbnail scales and cuts
+// only that.
 func cropCentreAndResize(img *vips.ImageRef, width, height int) error {
 	imgW, imgH := img.Width(), img.Height()
 
 	// An image wider than the requested proportions keeps its height and
-	// loses width, any other keeps its width and loses height; the side
-	// shortened is rounded to the nearest pixel and is at least 1
-	cropW, cropH := imgW, imgH
+	// loses width down to imgH*width/height, any other keeps its width and
+	// loses height down to imgW*height/width. Half of what is lost comes
+	// off each side, rounded down to whole pixels, so the part kept holds
+	// all of the centre.
+	left, top := 0, 0
 	if imgW*height > imgH*width {
-		cropW = max(1, (imgH*width+height/2)/height)
+		left = (imgW*height - imgH*width) / (2 * height) //nolint:mnd // each side
 	} else {
-		cropH = max(1, (imgW*height+width/2)/width)
+		top = (imgH*width - imgW*height) / (2 * width) //nolint:mnd // each side
 	}
 
-	// Half of what is cut comes off each side
-	left, top := (imgW-cropW)/2, (imgH-cropH)/2 //nolint:mnd // half the cut
-
-	err := img.ExtractArea(left, top, cropW, cropH)
+	err := img.ExtractArea(left, top, imgW-2*left, imgH-2*top)
 	if err != nil {
 		return err
 	}
 
-	return img.ThumbnailWithSize(width, height, vips.InterestingNone, vips.SizeForce)
+	return img.Thumbnail(width, height, vips.InterestingCentre)
 }
 
 const defaultQuality = 85
@@ -567,7 +547,8 @@ const defaultQuality = 85
 // to stop libvips once an encode has begun, so when ctx has ended encode
 // returns ctx's error without beginning one.
 func (p *ImageProcessor) encode(
-	ctx context.Context, img *vips.ImageRef, format Format, quality int,
+	ctx context.Context, img *vips.ImageRef, format imagerequest.Format,
+	quality int,
 ) ([]byte, error) {
 	err := ctx.Err()
 	if err != nil {
@@ -590,25 +571,25 @@ func (p *ImageProcessor) encode(
 	}
 
 	switch format {
-	case FormatJPEG:
+	case imagerequest.FormatJPEG:
 		return exportJPEG(img, quality)
 
-	case FormatPNG:
+	case imagerequest.FormatPNG:
 		return exportPNG(img)
 
-	case FormatGIF:
+	case imagerequest.FormatGIF:
 		return exportGIF(img)
 
-	case FormatWebP:
+	case imagerequest.FormatWebP:
 		return exportWebP(img, quality)
 
-	case FormatAVIF:
+	case imagerequest.FormatAVIF:
 		return exportAVIF(img, quality)
 
-	case FormatJXL:
+	case imagerequest.FormatJXL:
 		return exportJXL(img, quality)
 
-	case FormatOriginal:
+	case imagerequest.FormatOriginal, imagerequest.FormatAuto:
 		return nil, fmt.Errorf("%w: %s", ErrUnsupportedOutputFormat, format)
 
 	default:
@@ -658,11 +639,16 @@ func exportGIF(img *vips.ImageRef) ([]byte, error) {
 	return output, err
 }
 
-// webpEffort is libvips' default WebP effort, from 0 (fastest) to 6.
-const webpEffort = 4
+// webpEffort is the WebP effort, from 0 (fastest) to 6. It is below libvips'
+// default of 4 so that an encode takes at most 40 seconds of the default
+// downstream_timeout of 60 seconds. With one thread, as pixad runs libvips,
+// saving an 8192x8192 image of random pixels with an alpha channel takes up
+// to about 23 seconds at 2, and up to about 16 without one, at any quality;
+// with an alpha channel, 3 takes about 50 seconds and 4 about 61.
+const webpEffort = 2
 
-// exportWebP encodes img as lossy WebP at quality and libvips' default
-// effort, without metadata.
+// exportWebP encodes img as lossy WebP at quality and webpEffort, without
+// metadata.
 func exportWebP(img *vips.ImageRef, quality int) ([]byte, error) {
 	output, _, err := img.ExportWebp(&vips.WebpExportParams{
 		StripMetadata:   true,
@@ -674,12 +660,13 @@ func exportWebP(img *vips.ImageRef, quality int) ([]byte, error) {
 }
 
 // avifEffort is the AVIF effort, from 0 (fastest) to 9; 1 is the lowest
-// govips can set. With one thread, as pixad runs libvips, 1 takes about 51
-// seconds to save an 8192x8192 RGB image of random pixels, and about 110
-// with an alpha channel, the worst case, against the default
-// downstream_timeout of 60 seconds. On an image of milder noise, which 1
-// saves in about 12 seconds, 2 takes nearly a minute and libvips' default,
-// 4, takes minutes.
+// govips can set. With one thread, as pixad runs libvips, 1 takes about 52
+// seconds to save an 8192x8192 RGB image of random pixels at quality 85,
+// and about 96 with an alpha channel, against the default
+// downstream_timeout of 60 seconds, so an AVIF output is held to
+// MaxAVIFOutputPixels. On an image of milder noise, which 1 saves in about
+// 12 seconds, 2 takes nearly a minute and libvips' default, 4, takes
+// minutes.
 const avifEffort = 1
 
 // avifBitdepth is the AVIF bit depth, 8 bits per sample for every image.
@@ -706,10 +693,18 @@ func exportAVIF(img *vips.ImageRef, quality int) ([]byte, error) {
 // JPEG that names none.
 const jxlResolution = 72 / 25.4
 
-// exportJXL encodes img as JPEG XL at quality, with libvips' default effort
-// and without metadata. govips sends libvips a distance, the JPEG XL
-// encoder's own measure of quality, along with the quality, and libvips then
-// uses the distance alone, so the quality is also given as a distance.
+// jxlEffort is the JPEG XL effort, from 1 (fastest) to 9. It is below
+// libvips' default of 7 so that an encode takes at most 40 seconds of the
+// default downstream_timeout of 60 seconds. With one thread, as pixad runs
+// libvips, saving an 8192x8192 image of random pixels with an alpha channel
+// takes up to about 27 seconds at 4, and up to about 13 without one, at any
+// quality; with an alpha channel, 5 takes about 43 seconds and 7 about 81.
+const jxlEffort = 4
+
+// exportJXL encodes img as JPEG XL at quality and jxlEffort, without
+// metadata. govips sends libvips a distance, the JPEG XL encoder's own
+// measure of quality, along with the quality, and libvips then uses the
+// distance alone, so the quality is also given as a distance.
 func exportJXL(img *vips.ImageRef, quality int) ([]byte, error) {
 	// libvips converts a CMYK image to sRGB before it saves WebP, AVIF or
 	// PNG, but cannot save one as JPEG XL. encode has already converted
@@ -748,6 +743,7 @@ func exportJXL(img *vips.ImageRef, quality int) ([]byte, error) {
 	params := vips.NewJxlExportParams()
 	params.Quality = quality
 	params.Distance = jxlDistance(quality)
+	params.Effort = jxlEffort
 
 	output, _, err := toSave.ExportJxl(params)
 	if err != nil {
@@ -775,20 +771,22 @@ func jxlDistance(quality int) float64 {
 
 // formatFromString converts a format string from detectFormat to Format. A
 // format detectFormat could not name is ErrUnsupportedInputFormat.
-func (p *ImageProcessor) formatFromString(format string) (Format, error) {
+func (p *ImageProcessor) formatFromString(
+	format string,
+) (imagerequest.Format, error) {
 	switch format {
 	case "jpeg":
-		return FormatJPEG, nil
+		return imagerequest.FormatJPEG, nil
 	case "png":
-		return FormatPNG, nil
+		return imagerequest.FormatPNG, nil
 	case "gif":
-		return FormatGIF, nil
+		return imagerequest.FormatGIF, nil
 	case "webp":
-		return FormatWebP, nil
-	case string(FormatAVIF):
-		return FormatAVIF, nil
-	case string(FormatJXL):
-		return FormatJXL, nil
+		return imagerequest.FormatWebP, nil
+	case string(imagerequest.FormatAVIF):
+		return imagerequest.FormatAVIF, nil
+	case string(imagerequest.FormatJXL):
+		return imagerequest.FormatJXL, nil
 	default:
 		return "", fmt.Errorf("%w: %s", ErrUnsupportedInputFormat, format)
 	}

internal/imageprocessor/imageprocessor_internal_test.go

@@ -15,6 +15,7 @@ import (
 	"testing"
 
 	"github.com/davidbyttow/govips/v2/vips"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 func TestMain(m *testing.M) {
@@ -87,7 +88,7 @@ func isAVIF(data []byte) bool {
 
 	brand := string(data[8:12])
 
-	return brand == string(FormatAVIF) || brand == "avis"
+	return brand == string(imagerequest.FormatAVIF) || brand == "avis"
 }
 
 // detectMIME is a minimal magic-byte detector for test assertions.
@@ -118,19 +119,19 @@ func detectMIME(data []byte) string {
 func TestImageProcessor_ResizeJPEG(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 800, 600)
 
-	req := &Request{
-		Size:    Size{Width: 400, Height: 300},
-		Format:  FormatJPEG,
+	transform := &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 400, Height: 300},
+		Format:  imagerequest.FormatJPEG,
 		Quality: 85,
-		FitMode: FitCover,
+		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -164,18 +165,18 @@ func TestImageProcessor_ResizeJPEG(t *testing.T) {
 func TestImageProcessor_ConvertToPNG(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 200, 150)
 
-	req := &Request{
-		Size:    Size{Width: 200, Height: 150},
-		Format:  FormatPNG,
-		FitMode: FitCover,
+	transform := &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 200, Height: 150},
+		Format:  imagerequest.FormatPNG,
+		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -196,23 +197,23 @@ func TestImageProcessor_ConvertToPNG(t *testing.T) {
 // processAndCheckSize processes a test JPEG of the given input dimensions
 // with the requested size and asserts the resulting dimensions.
 func processAndCheckSize(
-	t *testing.T, inputW, inputH int, size Size, wantW, wantH int,
+	t *testing.T, inputW, inputH int, size imagerequest.Size, wantW, wantH int,
 ) {
 	t.Helper()
 
-	proc := New(Params{})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
 	input := createTestJPEG(t, inputW, inputH)
 
-	req := &Request{
+	transform := &imagerequest.Transform{
 		Size:    size,
-		Format:  FormatJPEG,
+		Format:  imagerequest.FormatJPEG,
 		Quality: 85,
-		FitMode: FitCover,
+		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -232,27 +233,27 @@ func TestImageProcessor_OriginalSize(t *testing.T) {
 	t.Parallel()
 
 	// Width and height 0: keep original size
-	processAndCheckSize(t, 640, 480, Size{Width: 0, Height: 0}, 640, 480)
+	processAndCheckSize(t, 640, 480, imagerequest.Size{Width: 0, Height: 0}, 640, 480)
 }
 
 func TestImageProcessor_FitContain(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
 	// 800x400 image (2:1 aspect) into 400x400 box with contain
 	// Should result in 400x200 (maintaining aspect ratio)
 	input := createTestJPEG(t, 800, 400)
 
-	req := &Request{
-		Size:    Size{Width: 400, Height: 400},
-		Format:  FormatJPEG,
+	transform := &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 400, Height: 400},
+		Format:  imagerequest.FormatJPEG,
 		Quality: 85,
-		FitMode: FitContain,
+		FitMode: imagerequest.FitContain,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -270,7 +271,7 @@ func TestImageProcessor_ProportionalScale_WidthOnly(t *testing.T) {
 
 	// 800x600 image, request width=400 height=0
 	// Should scale proportionally to 400x300
-	processAndCheckSize(t, 800, 600, Size{Width: 400, Height: 0}, 400, 300)
+	processAndCheckSize(t, 800, 600, imagerequest.Size{Width: 400, Height: 0}, 400, 300)
 }
 
 func TestImageProcessor_ProportionalScale_HeightOnly(t *testing.T) {
@@ -278,24 +279,24 @@ func TestImageProcessor_ProportionalScale_HeightOnly(t *testing.T) {
 
 	// 800x600 image, request width=0 height=300
 	// Should scale proportionally to 400x300
-	processAndCheckSize(t, 800, 600, Size{Width: 0, Height: 300}, 400, 300)
+	processAndCheckSize(t, 800, 600, imagerequest.Size{Width: 0, Height: 300}, 400, 300)
 }
 
 func TestImageProcessor_ProcessPNG(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
 	input := createTestPNG(t, 400, 300)
 
-	req := &Request{
-		Size:    Size{Width: 200, Height: 150},
-		Format:  FormatPNG,
-		FitMode: FitCover,
+	transform := &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 200, Height: 150},
+		Format:  imagerequest.FormatPNG,
+		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -311,22 +312,6 @@ func TestImageProcessor_ProcessPNG(t *testing.T) {
 	}
 }
 
-func TestImageProcessor_SupportedFormats(t *testing.T) {
-	t.Parallel()
-
-	proc := New(Params{})
-
-	inputFormats := proc.SupportedInputFormats()
-	if len(inputFormats) == 0 {
-		t.Error("SupportedInputFormats() returned empty slice")
-	}
-
-	outputFormats := proc.SupportedOutputFormats()
-	if len(outputFormats) == 0 {
-		t.Error("SupportedOutputFormats() returned empty slice")
-	}
-}
-
 func TestImageProcessor_RejectsOversizedInput(t *testing.T) {
 	t.Parallel()
 
@@ -345,18 +330,18 @@ func TestImageProcessor_RejectsOversizedInput(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			proc := New(Params{})
+			proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 			ctx := context.Background()
 			input := createTestJPEG(t, tt.width, tt.height)
 
-			req := &Request{
-				Size:    Size{Width: 100, Height: 100},
-				Format:  FormatJPEG,
+			transform := &imagerequest.Transform{
+				Size:    imagerequest.Size{Width: 100, Height: 100},
+				Format:  imagerequest.FormatJPEG,
 				Quality: 85,
-				FitMode: FitCover,
+				FitMode: imagerequest.FitCover,
 			}
 
-			_, err := proc.Process(ctx, bytes.NewReader(input), req)
+			_, err := proc.Process(ctx, bytes.NewReader(input), transform)
 			if err == nil {
 				t.Error("Process() should reject oversized input images")
 			}
@@ -371,20 +356,20 @@ func TestImageProcessor_RejectsOversizedInput(t *testing.T) {
 func TestImageProcessor_AcceptsMaxDimensionInput(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
 	// Create an image at exactly MaxInputDimension - should be accepted
 	input := createTestJPEG(t, MaxInputDimension, 100)
 
-	req := &Request{
-		Size:    Size{Width: 100, Height: 100},
-		Format:  FormatJPEG,
+	transform := &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 100, Height: 100},
+		Format:  imagerequest.FormatJPEG,
 		Quality: 85,
-		FitMode: FitCover,
+		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf(
 			"Process() should accept images at MaxInputDimension, got error: %v",
@@ -397,22 +382,24 @@ func TestImageProcessor_AcceptsMaxDimensionInput(t *testing.T) {
 
 // encodeAndCheck processes a 200x150 test JPEG into a 100x75 output of the
 // given format and asserts the output MIME type and dimensions.
-func encodeAndCheck(t *testing.T, format Format, quality int, wantMIME string) {
+func encodeAndCheck(
+	t *testing.T, format imagerequest.Format, quality int, wantMIME string,
+) {
 	t.Helper()
 
-	proc := New(Params{})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
 	input := createTestJPEG(t, 200, 150)
 
-	req := &Request{
-		Size:    Size{Width: 100, Height: 75},
+	transform := &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 100, Height: 75},
 		Format:  format,
 		Quality: quality,
-		FitMode: FitCover,
+		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v, want nil", err)
 	}
@@ -443,13 +430,13 @@ func encodeAndCheck(t *testing.T, format Format, quality int, wantMIME string) {
 func TestImageProcessor_EncodeWebP(t *testing.T) {
 	t.Parallel()
 
-	encodeAndCheck(t, FormatWebP, 80, mimeWebP)
+	encodeAndCheck(t, imagerequest.FormatWebP, 80, mimeWebP)
 }
 
 func TestImageProcessor_DecodeAVIF(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
 	// Load test AVIF file
@@ -459,14 +446,14 @@ func TestImageProcessor_DecodeAVIF(t *testing.T) {
 	}
 
 	// Request resize and convert to JPEG
-	req := &Request{
-		Size:    Size{Width: 2, Height: 2},
-		Format:  FormatJPEG,
+	transform := &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 2, Height: 2},
+		Format:  imagerequest.FormatJPEG,
 		Quality: 85,
-		FitMode: FitCover,
+		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v, want nil (AVIF decoding should work)", err)
 	}
@@ -491,7 +478,7 @@ func TestImageProcessor_RejectsOversizedInputData(t *testing.T) {
 	// Create a processor with a very small byte limit
 	const limit = 1024
 
-	proc := New(Params{MaxInputBytes: limit})
+	proc := New(Params{MaxInputBytes: limit, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
 	// Create a valid JPEG that exceeds the byte limit
@@ -500,14 +487,14 @@ func TestImageProcessor_RejectsOversizedInputData(t *testing.T) {
 		t.Fatalf("test JPEG must exceed %d bytes, got %d", limit, len(input))
 	}
 
-	req := &Request{
-		Size:    Size{Width: 100, Height: 75},
-		Format:  FormatJPEG,
+	transform := &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 100, Height: 75},
+		Format:  imagerequest.FormatJPEG,
 		Quality: 85,
-		FitMode: FitCover,
+		FitMode: imagerequest.FitCover,
 	}
 
-	_, err := proc.Process(ctx, bytes.NewReader(input), req)
+	_, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err == nil {
 		t.Fatal("Process() should reject input exceeding maxInputBytes")
 	}
@@ -524,17 +511,17 @@ func TestImageProcessor_AcceptsInputWithinLimit(t *testing.T) {
 	input := createTestJPEG(t, 10, 10)
 	limit := int64(len(input)) * 10 // 10× headroom
 
-	proc := New(Params{MaxInputBytes: limit})
+	proc := New(Params{MaxInputBytes: limit, MaxConcurrentProcessing: 1})
 	ctx := context.Background()
 
-	req := &Request{
-		Size:    Size{Width: 10, Height: 10},
-		Format:  FormatJPEG,
+	transform := &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 10, Height: 10},
+		Format:  imagerequest.FormatJPEG,
 		Quality: 85,
-		FitMode: FitCover,
+		FitMode: imagerequest.FitCover,
 	}
 
-	result, err := proc.Process(ctx, bytes.NewReader(input), req)
+	result, err := proc.Process(ctx, bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v, want nil", err)
 	}
@@ -542,35 +529,24 @@ func TestImageProcessor_AcceptsInputWithinLimit(t *testing.T) {
 	defer func() { _ = result.Content.Close() }()
 }
 
-func TestImageProcessor_DefaultMaxInputBytes(t *testing.T) {
-	t.Parallel()
-
-	// Passing 0 should use the default
-	proc := New(Params{})
-	if proc.maxInputBytes != DefaultMaxInputBytes {
-		t.Errorf("maxInputBytes = %d, want %d", proc.maxInputBytes, DefaultMaxInputBytes)
-	}
-
-	// Passing negative should also use the default
-	proc = New(Params{MaxInputBytes: -1})
-	if proc.maxInputBytes != DefaultMaxInputBytes {
-		t.Errorf("maxInputBytes = %d, want %d", proc.maxInputBytes, DefaultMaxInputBytes)
-	}
-}
-
 func TestImageProcessor_EncodeAVIF(t *testing.T) {
 	t.Parallel()
 
-	encodeAndCheck(t, FormatAVIF, 85, mimeAVIF)
+	encodeAndCheck(t, imagerequest.FormatAVIF, 85, mimeAVIF)
 }
 
 // processAndDecode runs input through Process and decodes the output with
 // vips, so a test can inspect the image a client would receive.
-func processAndDecode(t *testing.T, input []byte, req *Request) *vips.ImageRef {
+func processAndDecode(
+	t *testing.T, input []byte, transform *imagerequest.Transform,
+) *vips.ImageRef {
 	t.Helper()
 
-	result, err := New(Params{}).Process(
-		context.Background(), bytes.NewReader(input), req,
+	result, err := New(Params{
+		MaxInputBytes:           50 << 20,
+		MaxConcurrentProcessing: 1,
+	}).Process(
+		context.Background(), bytes.NewReader(input), transform,
 	)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
@@ -614,15 +590,17 @@ func TestImageProcessor_StripsEXIF(t *testing.T) {
 		t.Fatal("testdata/gps-exif.jpg has no GPS latitude")
 	}
 
-	formats := []Format{
-		FormatJPEG, FormatPNG, FormatWebP, FormatAVIF, FormatGIF, FormatOriginal,
+	formats := []imagerequest.Format{
+		imagerequest.FormatJPEG, imagerequest.FormatPNG, imagerequest.FormatWebP,
+		imagerequest.FormatAVIF, imagerequest.FormatGIF, imagerequest.FormatOriginal,
 	}
 
 	for _, format := range formats {
 		t.Run(string(format), func(t *testing.T) {
 			t.Parallel()
 
-			output := processAndDecode(t, input, &Request{Format: format})
+			output := processAndDecode(t, input,
+				&imagerequest.Transform{Format: format})
 
 			if output.HasExif() {
 				t.Errorf("output has EXIF: %v", output.GetExif())
@@ -644,21 +622,21 @@ func TestImageProcessor_AppliesEXIFOrientation(t *testing.T) {
 
 	tests := []struct {
 		name  string
-		size  Size
+		size  imagerequest.Size
 		wantW int
 		wantH int
 	}{
-		{name: "original size", size: Size{}, wantW: 8, wantH: 16},
-		{name: "width only", size: Size{Width: 4}, wantW: 4, wantH: 8},
+		{name: "original size", size: imagerequest.Size{}, wantW: 8, wantH: 16},
+		{name: "width only", size: imagerequest.Size{Width: 4}, wantW: 4, wantH: 8},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			output := processAndDecode(t, input, &Request{
+			output := processAndDecode(t, input, &imagerequest.Transform{
 				Size:   tt.size,
-				Format: FormatPNG,
+				Format: imagerequest.FormatPNG,
 			})
 
 			if output.Width() != tt.wantW || output.Height() != tt.wantH {
@@ -694,7 +672,8 @@ func TestImageProcessor_ConvertsWideGamutToSRGB(t *testing.T) {
 		t.Fatalf("failed to read test JPEG: %v", err)
 	}
 
-	output := processAndDecode(t, input, &Request{Format: FormatPNG})
+	output := processAndDecode(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatPNG})
 
 	if output.HasICCProfile() {
 		t.Error("output has an ICC profile")

internal/imageprocessor/jpegxl_output_internal_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/davidbyttow/govips/v2/vips"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // TestImageProcessor_EncodeJPEGXL converts a JPEG to a smaller JPEG XL and
@@ -15,10 +16,16 @@ import (
 func TestImageProcessor_EncodeJPEGXL(t *testing.T) {
 	t.Parallel()
 
-	req := &Request{Size: Size{Width: 100, Height: 75}, Format: FormatJXL}
+	transform := &imagerequest.Transform{
+		Size:   imagerequest.Size{Width: 100, Height: 75},
+		Format: imagerequest.FormatJXL,
+	}
 
-	result, err := New(Params{}).Process(
-		t.Context(), bytes.NewReader(createTestJPEG(t, 200, 150)), req,
+	result, err := New(Params{
+		MaxInputBytes:           50 << 20,
+		MaxConcurrentProcessing: 1,
+	}).Process(
+		t.Context(), bytes.NewReader(createTestJPEG(t, 200, 150)), transform,
 	)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
@@ -60,8 +67,12 @@ func TestImageProcessor_JPEGXLQuality(t *testing.T) {
 	outputBytes := make(map[int]int64)
 
 	for _, quality := range []int{30, 90} {
-		result, err := New(Params{}).Process(t.Context(),
-			bytes.NewReader(input), &Request{Format: FormatJXL, Quality: quality})
+		result, err := New(Params{
+			MaxInputBytes:           50 << 20,
+			MaxConcurrentProcessing: 1,
+		}).Process(t.Context(),
+			bytes.NewReader(input),
+			&imagerequest.Transform{Format: imagerequest.FormatJXL, Quality: quality})
 		if err != nil {
 			t.Fatalf("Process() at quality %d error = %v", quality, err)
 		}
@@ -89,7 +100,8 @@ func TestImageProcessor_JPEGXLDropsSourceEXIF(t *testing.T) {
 		t.Fatalf("failed to read test JPEG: %v", err)
 	}
 
-	exif := processAndDecode(t, input, &Request{Format: FormatJXL}).GetExif()
+	exif := processAndDecode(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatJXL}).GetExif()
 
 	for _, field := range []string{
 		"exif-ifd0-Make", "exif-ifd0-Model", "exif-ifd2-BodySerialNumber",
@@ -115,7 +127,8 @@ func TestImageProcessor_JPEGXLDropsSourceResolution(t *testing.T) {
 		t.Fatalf("failed to read test JPEG: %v", err)
 	}
 
-	output := processAndDecode(t, input, &Request{Format: FormatJXL})
+	output := processAndDecode(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatJXL})
 
 	// libvips gives the resolution in pixels per millimetre.
 	xDPI := math.Round(output.ResX() * 25.4)
@@ -140,7 +153,8 @@ func TestImageProcessor_JPEGXLAppliesEXIFOrientation(t *testing.T) {
 		t.Fatalf("failed to read test JPEG: %v", err)
 	}
 
-	output := processAndDecode(t, input, &Request{Format: FormatJXL})
+	output := processAndDecode(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatJXL})
 
 	if output.Width() != 8 || output.Height() != 16 {
 		t.Fatalf("output is %dx%d, want 8x16", output.Width(), output.Height())
@@ -176,7 +190,8 @@ func TestImageProcessor_JPEGXLConvertsWideGamutToSRGB(t *testing.T) {
 		t.Fatalf("failed to read test JPEG: %v", err)
 	}
 
-	output := processAndDecode(t, input, &Request{Format: FormatJXL})
+	output := processAndDecode(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatJXL})
 
 	pixel, err := output.GetPoint(4, 4)
 	if err != nil {
@@ -203,7 +218,8 @@ func TestImageProcessor_JPEGXLFromCMYK(t *testing.T) {
 		t.Fatalf("failed to read test JPEG: %v", err)
 	}
 
-	output := processAndDecode(t, input, &Request{Format: FormatJXL})
+	output := processAndDecode(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatJXL})
 
 	if output.Bands() != 3 {
 		t.Fatalf("output has %d bands, want 3", output.Bands())

internal/imageprocessor/max_concurrent_processing_internal_test.go

@@ -5,12 +5,13 @@ import (
 	"context"
 	"errors"
 	"io"
-	"runtime"
 	"strings"
 	"sync"
 	"testing"
 	"testing/iotest"
 	"time"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // errTestReadFailed is the error the unreadable test input returns.
@@ -76,13 +77,13 @@ func (r *gatedReader) Read(p []byte) (int, error) {
 	return n, err
 }
 
-// smallJPEGRequest asks for a 5x5 JPEG.
-func smallJPEGRequest() *Request {
-	return &Request{
-		Size:    Size{Width: 5, Height: 5},
-		Format:  FormatJPEG,
+// smallJPEGTransform asks for a 5x5 JPEG.
+func smallJPEGTransform() *imagerequest.Transform {
+	return &imagerequest.Transform{
+		Size:    imagerequest.Size{Width: 5, Height: 5},
+		Format:  imagerequest.FormatJPEG,
 		Quality: 85,
-		FitMode: FitCover,
+		FitMode: imagerequest.FitCover,
 	}
 }
 
@@ -92,7 +93,7 @@ func processInBackground(
 	proc *ImageProcessor, reader *gatedReader, results chan<- error,
 ) {
 	go func() {
-		result, err := proc.Process(context.Background(), reader, smallJPEGRequest())
+		result, err := proc.Process(context.Background(), reader, smallJPEGTransform())
 		if err == nil {
 			_ = result.Content.Close()
 		}
@@ -115,47 +116,15 @@ func waitForEntries(t *testing.T, entered <-chan struct{}, count int) {
 	}
 }
 
-func TestNewDefaultsMaxConcurrentProcessingToHalfTheCPUs(t *testing.T) {
+func TestNewMakesMaxConcurrentProcessingSlots(t *testing.T) {
 	t.Parallel()
 
-	for _, limit := range []int{0, -1} {
-		proc := New(Params{MaxConcurrentProcessing: limit})
-		if got := cap(proc.processingSemaphore); got != max(runtime.GOMAXPROCS(0)/2, 1) {
-			t.Errorf("MaxConcurrentProcessing %d: %d slots, want %d, half the CPUs",
-				limit, got, max(runtime.GOMAXPROCS(0)/2, 1))
-		}
-	}
-
-	proc := New(Params{MaxConcurrentProcessing: 3})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 3})
 	if got := cap(proc.processingSemaphore); got != 3 {
 		t.Errorf("MaxConcurrentProcessing 3: %d slots, want 3", got)
 	}
 }
 
-// TestNewDefaultIsHalfTheCPUsAndAtLeastOne checks that New, given no
-// MaxConcurrentProcessing, makes one slot for every two CPUs Go uses,
-// rounded down, and one slot when Go uses one CPU.
-//
-//nolint:paralleltest // it sets GOMAXPROCS, which other tests read
-func TestNewDefaultIsHalfTheCPUsAndAtLeastOne(t *testing.T) {
-	cpusBefore := runtime.GOMAXPROCS(0)
-
-	t.Cleanup(func() { runtime.GOMAXPROCS(cpusBefore) })
-
-	for _, tc := range []struct{ cpus, want int }{
-		{1, 1}, {2, 1}, {3, 1}, {8, 4},
-	} {
-		runtime.GOMAXPROCS(tc.cpus)
-
-		got := cap(New(Params{}).processingSemaphore)
-		t.Logf("GOMAXPROCS %d: %d slots", tc.cpus, got)
-
-		if got != tc.want {
-			t.Errorf("GOMAXPROCS %d: %d slots, want %d", tc.cpus, got, tc.want)
-		}
-	}
-}
-
 // TestProcessNeverExceedsMaxConcurrentProcessing starts more Process calls
 // than MaxConcurrentProcessing allows and holds the first ones inside
 // Process until the test lets them go. No more than the limit may be
@@ -169,7 +138,7 @@ func TestProcessNeverExceedsMaxConcurrentProcessing(t *testing.T) {
 		calls = 6
 	)
 
-	proc := New(Params{MaxConcurrentProcessing: limit})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: limit})
 	input := createTestJPEG(t, 50, 50)
 
 	counter := &readingCounter{}
@@ -216,7 +185,7 @@ func TestProcessNeverExceedsMaxConcurrentProcessing(t *testing.T) {
 func TestProcessWaitsThenFailsWhenNoSlotFrees(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxConcurrentProcessing: 1})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 	proc.processingWaitTimeout = 100 * time.Millisecond
 
 	input := createTestJPEG(t, 10, 10)
@@ -237,7 +206,7 @@ func TestProcessWaitsThenFailsWhenNoSlotFrees(t *testing.T) {
 	start := time.Now()
 
 	_, err := proc.Process(context.Background(), bytes.NewReader(input),
-		smallJPEGRequest())
+		smallJPEGTransform())
 	if !errors.Is(err, ErrTooManyImages) {
 		t.Fatalf("Process() error = %v, want ErrTooManyImages", err)
 	}
@@ -263,38 +232,38 @@ func TestProcessReleasesSlotOnError(t *testing.T) {
 
 	valid := createTestJPEG(t, 10, 10)
 
-	unsupported := smallJPEGRequest()
+	unsupported := smallJPEGTransform()
 	unsupported.Format = "bmp"
 
 	cases := []struct {
-		name  string
-		input io.Reader
-		req   *Request
+		name      string
+		input     io.Reader
+		transform *imagerequest.Transform
 		// want is the error Process must return; nil means any error.
 		want error
 	}{
 		{
-			name:  "input cannot be read",
-			input: iotest.ErrReader(errTestReadFailed),
-			req:   smallJPEGRequest(),
-			want:  errTestReadFailed,
+			name:      "input cannot be read",
+			input:     iotest.ErrReader(errTestReadFailed),
+			transform: smallJPEGTransform(),
+			want:      errTestReadFailed,
 		},
 		{
-			name:  "input over the byte limit",
-			input: bytes.NewReader(createTestJPEG(t, 800, 600)),
-			req:   smallJPEGRequest(),
-			want:  ErrInputDataTooLarge,
+			name:      "input over the byte limit",
+			input:     bytes.NewReader(createTestJPEG(t, 800, 600)),
+			transform: smallJPEGTransform(),
+			want:      ErrInputDataTooLarge,
 		},
 		{
-			name:  "input not an image",
-			input: strings.NewReader("not an image"),
-			req:   smallJPEGRequest(),
+			name:      "input not an image",
+			input:     strings.NewReader("not an image"),
+			transform: smallJPEGTransform(),
 		},
 		{
-			name:  "output format not supported",
-			input: bytes.NewReader(valid),
-			req:   unsupported,
-			want:  ErrUnsupportedOutputFormat,
+			name:      "output format not supported",
+			input:     bytes.NewReader(valid),
+			transform: unsupported,
+			want:      ErrUnsupportedOutputFormat,
 		},
 	}
 
@@ -305,7 +274,7 @@ func TestProcessReleasesSlotOnError(t *testing.T) {
 			proc := New(Params{MaxInputBytes: 4096, MaxConcurrentProcessing: 1})
 			proc.processingWaitTimeout = 100 * time.Millisecond
 
-			_, err := proc.Process(context.Background(), tc.input, tc.req)
+			_, err := proc.Process(context.Background(), tc.input, tc.transform)
 			if err == nil || (tc.want != nil && !errors.Is(err, tc.want)) {
 				t.Fatalf("Process() error = %v, want %v", err, tc.want)
 			}
@@ -315,7 +284,7 @@ func TestProcessReleasesSlotOnError(t *testing.T) {
 			}
 
 			result, err := proc.Process(context.Background(), bytes.NewReader(valid),
-				smallJPEGRequest())
+				smallJPEGTransform())
 			if err != nil {
 				t.Fatalf("Process() after the error = %v, want nil", err)
 			}
@@ -332,7 +301,7 @@ func TestProcessReleasesSlotOnError(t *testing.T) {
 func TestWaitForProcessing(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{MaxConcurrentProcessing: 2})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 2})
 
 	gate := make(chan struct{})
 	entered := make(chan struct{}, 1)

internal/imageprocessor/orig_format_internal_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/davidbyttow/govips/v2/vips"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // TestImageProcessor_OrigOfUnnamedFormatRefused verifies that orig of a TIFF
@@ -26,8 +27,12 @@ func TestImageProcessor_OrigOfUnnamedFormatRefused(t *testing.T) {
 		t.Fatalf("failed to save test TIFF: %v", err)
 	}
 
-	result, err := New(Params{}).Process(
-		t.Context(), bytes.NewReader(tiff), &Request{Format: FormatOriginal},
+	result, err := New(Params{
+		MaxInputBytes:           50 << 20,
+		MaxConcurrentProcessing: 1,
+	}).Process(
+		t.Context(), bytes.NewReader(tiff),
+		&imagerequest.Transform{Format: imagerequest.FormatOriginal},
 	)
 	if result != nil {
 		t.Logf("Process() returned %s", result.ContentType)

internal/imageprocessor/source_formats_internal_test.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"io"
 	"testing"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // TestImageProcessor_LoadsEachSourceFormat verifies that an image in each of
@@ -12,13 +14,15 @@ import (
 func TestImageProcessor_LoadsEachSourceFormat(t *testing.T) {
 	t.Parallel()
 
-	proc := New(Params{})
+	proc := New(Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1})
 
-	for _, format := range []Format{
-		FormatJPEG, FormatPNG, FormatGIF, FormatWebP, FormatAVIF, FormatJXL,
+	for _, format := range []imagerequest.Format{
+		imagerequest.FormatJPEG, imagerequest.FormatPNG, imagerequest.FormatGIF,
+		imagerequest.FormatWebP, imagerequest.FormatAVIF, imagerequest.FormatJXL,
 	} {
 		saved, err := proc.Process(t.Context(),
-			bytes.NewReader(createTestPNG(t, 20, 20)), &Request{Format: format})
+			bytes.NewReader(createTestPNG(t, 20, 20)),
+			&imagerequest.Transform{Format: format})
 		if err != nil {
 			t.Fatalf("saving the test image as %s: %v", format, err)
 		}
@@ -29,7 +33,7 @@ func TestImageProcessor_LoadsEachSourceFormat(t *testing.T) {
 		}
 
 		result, err := proc.Process(t.Context(), bytes.NewReader(source),
-			&Request{Format: FormatOriginal})
+			&imagerequest.Transform{Format: imagerequest.FormatOriginal})
 		if err != nil {
 			t.Errorf("orig of the %s image: %v", format, err)
 

internal/imagerequest/imagerequest.go

@@ -0,0 +1,137 @@
+// Package imagerequest holds the image request type, its parts, its checks,
+// the parsing of the /v1/image/ path, the variant key, the source key and the
+// source's upstream URL. It imports no other package of this repo, so every
+// package that handles an image request can import it.
+package imagerequest
+
+import (
+	"errors"
+	"net/url"
+)
+
+// ErrInvalidFitMode is returned when an invalid fit mode is provided.
+var ErrInvalidFitMode = errors.New("invalid fit mode")
+
+// Format represents supported output image formats.
+type Format string
+
+// Supported image output formats.
+const (
+	FormatOriginal Format = "orig"
+	FormatJPEG     Format = "jpeg"
+	FormatPNG      Format = "png"
+	FormatWebP     Format = "webp"
+	FormatAVIF     Format = "avif"
+	FormatJXL      Format = "jxl"
+	FormatGIF      Format = "gif"
+
+	// FormatAuto stands for JPEG XL, AVIF, WebP or JPEG, chosen for each
+	// request from its Accept header once the URL's signature or token has
+	// been checked; it is never processed or cached as itself.
+	FormatAuto Format = "auto"
+)
+
+// Size represents requested image dimensions
+type Size struct {
+	Width  int
+	Height int
+}
+
+// OriginalSize returns true if this represents "keep original size"
+func (s Size) OriginalSize() bool {
+	return s.Width == 0 && s.Height == 0
+}
+
+// Fit represents how to fit image into requested dimensions.
+type Fit string
+
+// Supported image fit modes.
+const (
+	FitCover   Fit = "cover"
+	FitContain Fit = "contain"
+	FitFill    Fit = "fill"
+	FitInside  Fit = "inside"
+	FitOutside Fit = "outside"
+)
+
+// ValidateFitMode checks if the given fit mode is valid.
+// Returns ErrInvalidFitMode for unrecognized fit modes.
+func ValidateFitMode(fit Fit) error {
+	switch fit {
+	case FitCover, FitContain, FitFill, FitInside, FitOutside, "":
+		return nil
+	default:
+		return ErrInvalidFitMode
+	}
+}
+
+// ValidateImageRequest checks a request's width and height with
+// ValidateDimension and its fit mode with ValidateFitMode. Both the plain
+// /v1/image/ route and the encrypted /v1/e/ route validate through this
+// function so a request from either source enforces identical bounds.
+func ValidateImageRequest(req *Request) error {
+	err := ValidateDimension("width", req.Transform.Size.Width)
+	if err != nil {
+		return err
+	}
+
+	err = ValidateDimension("height", req.Transform.Size.Height)
+	if err != nil {
+		return err
+	}
+
+	return ValidateFitMode(req.Transform.FitMode)
+}
+
+// Request represents a request for a processed image: the source to fetch
+// and the transform to apply to it. It holds exactly what the variant key
+// covers.
+type Request struct {
+	// Source is what to fetch
+	Source Source
+	// Transform is what to do to it
+	Transform Transform
+}
+
+// Source is the image a request fetches from the origin.
+type Source struct {
+	// Host is the origin host (e.g., "cdn.example.com")
+	Host string
+	// Path is the path on the origin with its percent-escapes decoded, as
+	// url.URL's Path holds it (e.g., "/photos/my cat.jpg")
+	Path string
+	// Query is the optional query string for the origin URL as the URL
+	// writes it, percent-escapes included, as url.URL's RawQuery holds it
+	Query string
+}
+
+// Transform is what a request does to its source; the image processor
+// takes it alone.
+type Transform struct {
+	// Size is the requested output dimensions
+	Size Size
+	// Format is the requested output format
+	Format Format
+	// Quality is the output quality (1-100) for lossy formats
+	Quality int
+	// FitMode is how to fit the image into requested dimensions
+	FitMode Fit
+}
+
+// URL returns the source's upstream URL, with the scheme http when allowHTTP
+// is true and https otherwise. net/url writes its path percent-encoded again,
+// so each source path is one upstream path. Its query is the source query as
+// it is, with the characters escapeQuery encodes percent-encoded.
+func (s Source) URL(allowHTTP bool) *url.URL {
+	scheme := "https"
+	if allowHTTP {
+		scheme = "http"
+	}
+
+	return &url.URL{
+		Scheme:   scheme,
+		Host:     s.Host,
+		Path:     s.Path,
+		RawQuery: escapeQuery(s.Query),
+	}
+}

internal/imagerequest/sourcekey.go

@@ -0,0 +1,26 @@
+package imagerequest
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+)
+
+// SourceKey is a SHA256 hash identifying a cached source image (hex-encoded).
+type SourceKey string
+
+// Key returns the key the source is cached under, made as CacheKey makes a
+// variant key.
+// Format: sha256(host:path:query)
+// The path and query go through escapePercentAndColon, so that a ":" in
+// either cannot be taken for the one between them.
+func (s Source) Key() SourceKey {
+	data := fmt.Sprintf("%s:%s:%s",
+		s.Host,
+		escapePercentAndColon(s.Path),
+		escapePercentAndColon(s.Query),
+	)
+	h := sha256.Sum256([]byte(data))
+
+	return SourceKey(hex.EncodeToString(h[:]))
+}

internal/imagerequest/sourcekey_internal_test.go

@@ -0,0 +1,40 @@
+package imagerequest
+
+import "testing"
+
+// TestSourceKey_DiffersForEachSource checks that each source gets a key of
+// 64 hex characters, the same each time, and that no two of these sources
+// share one, also when they differ only by a ":" or "%" in the path or query.
+func TestSourceKey_DiffersForEachSource(t *testing.T) {
+	t.Parallel()
+
+	sources := []Source{
+		{Host: testHostCDN, Path: testPathCat},
+		{Host: testHostCDN, Path: testPathCat, Query: "v=2"},
+		{Host: "other.example.com", Path: testPathCat},
+		{Host: testHostCDN, Path: "/c:d"},
+		{Host: testHostCDN, Path: "/c", Query: "d:"},
+		{Host: testHostCDN, Path: "/c%3Ad"},
+	}
+
+	seen := make(map[SourceKey]Source)
+
+	for _, source := range sources {
+		key := source.Key()
+		t.Logf("Key() of %+v = %s", source, key)
+
+		if len(key) != 64 {
+			t.Errorf("Key() of %+v length = %d, want 64", source, len(key))
+		}
+
+		if again := source.Key(); again != key {
+			t.Errorf("Key() of %+v not deterministic: %s vs %s", source, key, again)
+		}
+
+		if earlier, found := seen[key]; found {
+			t.Errorf("Key() gave %+v and %+v the same key", earlier, source)
+		}
+
+		seen[key] = source
+	}
+}

internal/imagerequest/sourceurl_internal_test.go

@@ -0,0 +1,50 @@
+package imagerequest
+
+import "testing"
+
+func TestSource_URL_DefaultHTTPS(t *testing.T) {
+	t.Parallel()
+
+	source := Source{
+		Host:  testHostCDN,
+		Path:  testPathCat,
+		Query: "v=2",
+	}
+
+	got := source.URL(false).String()
+
+	want := "https://cdn.example.com/photos/cat.jpg?v=2"
+	if got != want {
+		t.Errorf("URL() = %q, want %q", got, want)
+	}
+}
+
+func TestSource_URL_AllowHTTP(t *testing.T) {
+	t.Parallel()
+
+	source := Source{
+		Host: "localhost:8080",
+		Path: testPathCat,
+	}
+
+	got := source.URL(true).String()
+
+	want := "http://localhost:8080/photos/cat.jpg"
+	if got != want {
+		t.Errorf("URL() = %q, want %q", got, want)
+	}
+}
+
+func TestSource_URL_AllowHTTPFalse(t *testing.T) {
+	t.Parallel()
+
+	source := Source{
+		Host: testHostCDN,
+		Path: "/img.jpg",
+	}
+
+	got := source.URL(false).String()
+	if got != "https://cdn.example.com/img.jpg" {
+		t.Errorf("URL() = %q, want https scheme", got)
+	}
+}

internal/imagerequest/urlparser.go

@@ -1,14 +1,13 @@
-package imgcache
+package imagerequest
 
 import (
 	"errors"
 	"fmt"
+	"net/netip"
 	"net/url"
 	"regexp"
 	"strconv"
 	"strings"
-
-	"sneak.berlin/go/pixa/internal/imageprocessor"
 )
 
 // URL parsing errors.
@@ -24,11 +23,13 @@ var (
 )
 
 // MaxDimension is the maximum allowed width or height, the same as the image
-// processor's maximum for an output image.
-const MaxDimension = imageprocessor.MaxOutputDimension
+// processor's maximum for an output image (imageprocessor.MaxOutputDimension).
+const MaxDimension = 8192
 
 // ValidateDimension checks one requested width or height; name ("width" or
-// "height") appears in the error. 0 means "original size" and is valid.
+// "height") appears in the error. 0 is valid: that side is then worked out from
+// the source's proportions and the other requested side, rounded down but at
+// least 1, or is the source's own side when the other side is 0 too.
 func ValidateDimension(name string, value int) error {
 	if value < 0 {
 		return fmt.Errorf("%w: %s is negative", ErrInvalidSize, name)
@@ -50,42 +51,26 @@ var sizeFormatRegex = regexp.MustCompile(
 // percentEscapeRegex matches one percent-escape, such as "%2e"
 var percentEscapeRegex = regexp.MustCompile(`%[0-9A-Fa-f]{2}`)
 
-// ParsedURL contains the parsed components of an image proxy URL.
-type ParsedURL struct {
-	// Host is the source origin host (e.g., "cdn.example.com")
-	Host string
-	// Path is the path on the origin (e.g., "/photos/cat.jpg")
-	Path string
-	// Query is the optional query string for the origin
-	Query string
-	// Size is the requested output dimensions
-	Size Size
-	// Format is the requested output format
-	Format ImageFormat
-}
+// queryEscapeRegex matches a percent-escape, or one character that a browser
+// percent-encodes in the query of an http or https URL: one outside the
+// printable ASCII characters "!" to "~", such as a space, a control character
+// or a character outside ASCII, or one of `"#'<>`. A "%" that does not begin a
+// percent-escape matches too.
+var queryEscapeRegex = regexp.MustCompile(`%[0-9A-Fa-f]{2}|[^!-~]|["#'<>%]`)
 
-// ParseImagePath parses an image URL's path after /v1/image/, decoded once:
-// <host>/<path>/<size>.<format>, or <host>/<path>/<size> for JPEG XL.
-// Examples:
-//   - cdn.example.com/photos/cat.jpg/800x600.webp
-//   - cdn.example.com/photos/cat.jpg/0x0.jpeg
-//   - cdn.example.com/photos/cat.jpg/orig.png
-//   - cdn.example.com/photos/cat.jpg/800x600
-func ParseImagePath(path string) (*ParsedURL, error) {
-	// Strip leading slash if present (chi may include it)
-	path = strings.TrimPrefix(path, "/")
-	if path == "" {
-		return nil, ErrMissingHost
-	}
-
-	return parseImageComponents(path)
-}
+// hostRegex matches the forms the host of an image URL may take: a host name
+// or an IPv4 address (letters, digits, "-", "_" and "."), or an IPv6 address
+// in brackets (hex digits, ":" and "."), either one optionally followed by ":"
+// and a port, which may be empty. Its one group holds the text in brackets,
+// which parseImageComponents also checks is an IPv6 address.
+var hostRegex = regexp.MustCompile(
+	`^(?:[A-Za-z0-9_.-]+|\[([0-9A-Fa-f:.]+)\])(?::[0-9]*)?$`)
 
 // ParseImageURL parses an image URL's path, decoded once as r.URL.Path holds
 // it: /v1/image/<host>/<path>/<size>.<format>, or /v1/image/<host>/<path>/<size>
 // for JPEG XL. A source query follows the source path after a "?", which the
 // URL writes as %3F.
-func ParseImageURL(urlPath string) (*ParsedURL, error) {
+func ParseImageURL(urlPath string) (*Request, error) {
 	// Remove the /v1/image/ prefix
 	const prefix = "/v1/image/"
 	if !strings.HasPrefix(urlPath, prefix) {
@@ -102,7 +87,7 @@ func ParseImageURL(urlPath string) (*ParsedURL, error) {
 
 // parseImageComponents parses <host>/<path>/<size>.<format>, or
 // <host>/<path>/<size> for JPEG XL.
-func parseImageComponents(remainder string) (*ParsedURL, error) {
+func parseImageComponents(remainder string) (*Request, error) {
 	// Find the last path segment, which holds "size" or "size.format"
 	lastSlash := strings.LastIndex(remainder, "/")
 	if lastSlash == -1 {
@@ -141,10 +126,20 @@ func parseImageComponents(remainder string) (*ParsedURL, error) {
 		return nil, ErrMissingHost
 	}
 
-	// A URL reads what comes before "@" as a user name and password, and the
-	// rest as the host
-	if strings.Contains(host, "@") {
-		return nil, fmt.Errorf("%w: %q holds @", ErrInvalidHost, host)
+	// Later steps put the host unparsed into the allowlist check, the cache key
+	// and the upstream URL, so only the forms hostRegex describes are accepted
+	hostMatch := hostRegex.FindStringSubmatch(host)
+	if hostMatch == nil {
+		return nil, fmt.Errorf("%w: %q", ErrInvalidHost, host)
+	}
+
+	// The allowlist check and the fetcher drop the brackets, so brackets
+	// around anything but an IPv6 address would give a host a second spelling
+	if inBrackets := hostMatch[1]; inBrackets != "" {
+		addr, err := netip.ParseAddr(inBrackets)
+		if err != nil || !addr.Is6() {
+			return nil, fmt.Errorf("%w: %q", ErrInvalidHost, host)
+		}
 	}
 
 	// Host names do not depend on letter case, so the allowlist, the upstream
@@ -152,9 +147,19 @@ func parseImageComponents(remainder string) (*ParsedURL, error) {
 	// host
 	host = strings.ToLower(host)
 
-	// Extract query string if present in path
+	// A "#" starts a URL's fragment, so neither the source path nor the source
+	// query may hold one
+	if strings.Contains(path, "#") {
+		return nil, fmt.Errorf(
+			`%w: the source path or query holds a "#"`, ErrInvalidPath)
+	}
+
+	// Extract query string if present in path. It is the source URL's query
+	// as that URL writes it. A character a URL's query cannot hold as it is,
+	// such as a space written %20 in the image URL, is percent-encoded here,
+	// so the query is signed and cached as it is sent upstream
 	if qIndex := strings.Index(path, "?"); qIndex != -1 {
-		query = path[qIndex+1:]
+		query = escapeQuery(path[qIndex+1:])
 		path = path[:qIndex]
 	}
 
@@ -170,12 +175,9 @@ func parseImageComponents(remainder string) (*ParsedURL, error) {
 		path = "/" + path
 	}
 
-	return &ParsedURL{
-		Host:   host,
-		Path:   path,
-		Query:  query,
-		Size:   size,
-		Format: format,
+	return &Request{
+		Source:    Source{Host: host, Path: path, Query: query},
+		Transform: Transform{Size: size, Format: format},
 	}, nil
 }
 
@@ -243,8 +245,22 @@ func decodePercentEscapes(s string) string {
 	})
 }
 
+// escapeQuery returns a source query as a URL's query holds it: each
+// character that queryEscapeRegex names, such as a space, percent-encoded,
+// and the rest, the query's percent-escapes included, kept as they are. The
+// result is unchanged by a second escapeQuery.
+func escapeQuery(query string) string {
+	return queryEscapeRegex.ReplaceAllStringFunc(query, func(match string) string {
+		if percentEscapeRegex.MatchString(match) {
+			return match
+		}
+
+		return url.PathEscape(match)
+	})
+}
+
 // parseSizeFormat parses strings like "800x600.webp", "orig.png" or "800x600"
-func parseSizeFormat(s string) (Size, ImageFormat, error) {
+func parseSizeFormat(s string) (Size, Format, error) {
 	matches := sizeFormatRegex.FindStringSubmatch(s)
 	if matches == nil {
 		return Size{}, "", ErrInvalidSize
@@ -298,8 +314,8 @@ func parseSizeFormat(s string) (Size, ImageFormat, error) {
 	return size, format, nil
 }
 
-// parseFormat converts a format string to ImageFormat.
-func parseFormat(s string) (ImageFormat, error) {
+// parseFormat converts a format string to Format.
+func parseFormat(s string) (Format, error) {
 	switch strings.ToLower(s) {
 	case "orig", "original":
 		return FormatOriginal, nil
@@ -321,14 +337,3 @@ func parseFormat(s string) (ImageFormat, error) {
 		return "", fmt.Errorf("%w: %s", ErrInvalidFormat, s)
 	}
 }
-
-// ToImageRequest converts a ParsedURL to an ImageRequest.
-func (p *ParsedURL) ToImageRequest() *ImageRequest {
-	return &ImageRequest{
-		SourceHost:  p.Host,
-		SourcePath:  p.Path,
-		SourceQuery: p.Query,
-		Size:        p.Size,
-		Format:      p.Format,
-	}
-}

internal/imagerequest/urlparser_internal_test.go

@@ -1,33 +1,41 @@
-package imgcache
+package imagerequest
 
 import (
 	"errors"
 	"testing"
 )
 
-// assertParsedURL compares all fields of a parsed URL against the
-// expected value.
-func assertParsedURL(t *testing.T, got, want *ParsedURL) {
+// Shared test fixture strings.
+const (
+	testHostCDN     = "cdn.example.com"
+	testHostExample = "example.com"
+	testPathCat     = "/photos/cat.jpg"
+)
+
+// assertRequest compares the source host, path and query and the size and
+// format of got against want.
+func assertRequest(t *testing.T, got, want *Request) {
 	t.Helper()
 
-	if got.Host != want.Host {
-		t.Errorf("Host = %q, want %q", got.Host, want.Host)
+	if got.Source.Host != want.Source.Host {
+		t.Errorf("Host = %q, want %q", got.Source.Host, want.Source.Host)
 	}
 
-	if got.Path != want.Path {
-		t.Errorf("Path = %q, want %q", got.Path, want.Path)
+	if got.Source.Path != want.Source.Path {
+		t.Errorf("Path = %q, want %q", got.Source.Path, want.Source.Path)
 	}
 
-	if got.Query != want.Query {
-		t.Errorf("Query = %q, want %q", got.Query, want.Query)
+	if got.Source.Query != want.Source.Query {
+		t.Errorf("Query = %q, want %q", got.Source.Query, want.Source.Query)
 	}
 
-	if got.Size != want.Size {
-		t.Errorf("Size = %v, want %v", got.Size, want.Size)
+	if got.Transform.Size != want.Transform.Size {
+		t.Errorf("Size = %v, want %v", got.Transform.Size, want.Transform.Size)
 	}
 
-	if got.Format != want.Format {
-		t.Errorf("Format = %q, want %q", got.Format, want.Format)
+	if got.Transform.Format != want.Transform.Format {
+		t.Errorf("Format = %q, want %q",
+			got.Transform.Format, want.Transform.Format)
 	}
 }
 
@@ -37,62 +45,64 @@ func TestParseImageURL(t *testing.T) {
 	tests := []struct {
 		name  string
 		input string
-		want  *ParsedURL
+		want  *Request
 	}{
 		{
 			name:  "basic path with size",
 			input: "/v1/image/cdn.example.com/photos/cat.jpg/800x600.webp",
-			want: &ParsedURL{
-				Host: testHostCDN, Path: testPathCat,
-				Size: Size{Width: 800, Height: 600}, Format: FormatWebP,
+			want: &Request{
+				Source:    Source{Host: testHostCDN, Path: testPathCat},
+				Transform: Transform{Size: Size{Width: 800, Height: 600}, Format: FormatWebP},
 			},
 		},
 		{
 			name:  "original size with 0x0",
 			input: "/v1/image/cdn.example.com/photos/cat.jpg/0x0.jpeg",
-			want: &ParsedURL{
-				Host: testHostCDN, Path: testPathCat,
-				Size: Size{Width: 0, Height: 0}, Format: FormatJPEG,
+			want: &Request{
+				Source:    Source{Host: testHostCDN, Path: testPathCat},
+				Transform: Transform{Size: Size{Width: 0, Height: 0}, Format: FormatJPEG},
 			},
 		},
 		{
 			name:  "original size with orig keyword",
 			input: "/v1/image/cdn.example.com/photos/cat.jpg/orig.png",
-			want: &ParsedURL{
-				Host: testHostCDN, Path: testPathCat,
-				Size: Size{Width: 0, Height: 0}, Format: FormatPNG,
+			want: &Request{
+				Source:    Source{Host: testHostCDN, Path: testPathCat},
+				Transform: Transform{Size: Size{Width: 0, Height: 0}, Format: FormatPNG},
 			},
 		},
 		{
 			name:  "path with query string",
 			input: "/v1/image/cdn.example.com/photos/cat.jpg?arg1=val1&arg2=val2/800x600.webp",
-			want: &ParsedURL{
-				Host: testHostCDN, Path: testPathCat, Query: "arg1=val1&arg2=val2",
-				Size: Size{Width: 800, Height: 600}, Format: FormatWebP,
+			want: &Request{
+				Source: Source{
+					Host: testHostCDN, Path: testPathCat, Query: "arg1=val1&arg2=val2",
+				},
+				Transform: Transform{Size: Size{Width: 800, Height: 600}, Format: FormatWebP},
 			},
 		},
 		{
 			name:  "deep nested path",
 			input: "/v1/image/cdn.example.com/a/b/c/d/image.jpg/1920x1080.avif",
-			want: &ParsedURL{
-				Host: testHostCDN, Path: "/a/b/c/d/image.jpg",
-				Size: Size{Width: 1920, Height: 1080}, Format: FormatAVIF,
+			want: &Request{
+				Source:    Source{Host: testHostCDN, Path: "/a/b/c/d/image.jpg"},
+				Transform: Transform{Size: Size{Width: 1920, Height: 1080}, Format: FormatAVIF},
 			},
 		},
 		{
 			name:  "jpg alias for jpeg",
 			input: "/v1/image/example.com/img.png/100x100.jpg",
-			want: &ParsedURL{
-				Host: testHostExample, Path: "/img.png",
-				Size: Size{Width: 100, Height: 100}, Format: FormatJPEG,
+			want: &Request{
+				Source:    Source{Host: testHostExample, Path: "/img.png"},
+				Transform: Transform{Size: Size{Width: 100, Height: 100}, Format: FormatJPEG},
 			},
 		},
 		{
 			name:  "gif format",
 			input: "/v1/image/example.com/animated.gif/200x200.gif",
-			want: &ParsedURL{
-				Host: testHostExample, Path: "/animated.gif",
-				Size: Size{Width: 200, Height: 200}, Format: FormatGIF,
+			want: &Request{
+				Source:    Source{Host: testHostExample, Path: "/animated.gif"},
+				Transform: Transform{Size: Size{Width: 200, Height: 200}, Format: FormatGIF},
 			},
 		},
 	}
@@ -106,7 +116,7 @@ func TestParseImageURL(t *testing.T) {
 				t.Fatalf("ParseImageURL() unexpected error = %v", err)
 			}
 
-			assertParsedURL(t, got, tt.want)
+			assertRequest(t, got, tt.want)
 		})
 	}
 }
@@ -121,8 +131,8 @@ func TestParseImageURL_AutoFormat(t *testing.T) {
 		t.Fatalf("ParseImageURL() error = %v", err)
 	}
 
-	if got.Format != FormatAuto {
-		t.Errorf("Format = %q, want %q", got.Format, FormatAuto)
+	if got.Transform.Format != FormatAuto {
+		t.Errorf("Format = %q, want %q", got.Transform.Format, FormatAuto)
 	}
 }
 
@@ -182,135 +192,49 @@ func TestParseImageURL_Errors(t *testing.T) {
 	}
 }
 
-func TestParseImagePath(t *testing.T) {
-	t.Parallel()
-
-	// ParseImagePath is for chi wildcard capture (no /v1/image/ prefix)
-	tests := []struct {
-		name    string
-		input   string
-		want    *ParsedURL
-		wantErr bool
-	}{
-		{
-			name:  "chi wildcard capture",
-			input: "cdn.example.com/photos/cat.jpg/800x600.webp",
-			want: &ParsedURL{
-				Host:   testHostCDN,
-				Path:   testPathCat,
-				Size:   Size{Width: 800, Height: 600},
-				Format: FormatWebP,
-			},
-		},
-		{
-			name:  "with leading slash from chi",
-			input: "/cdn.example.com/photos/cat.jpg/800x600.webp",
-			want: &ParsedURL{
-				Host:   testHostCDN,
-				Path:   testPathCat,
-				Size:   Size{Width: 800, Height: 600},
-				Format: FormatWebP,
-			},
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			got, err := ParseImagePath(tt.input)
-			if (err != nil) != tt.wantErr {
-				t.Errorf("ParseImagePath() error = %v, wantErr %v", err, tt.wantErr)
-
-				return
-			}
-
-			if err != nil {
-				return
-			}
-
-			assertParsedURL(t, got, tt.want)
-		})
-	}
-}
-
-// TestParseImagePath_LowerCasesHost verifies that the host is lower-cased, so
+// TestParseImageURL_LowerCasesHost verifies that the host is lower-cased, so
 // that every spelling of its letter case is the same host to the allowlist,
 // the upstream connection limits and the cache, and that the path keeps its
 // case.
-func TestParseImagePath_LowerCasesHost(t *testing.T) {
+func TestParseImageURL_LowerCasesHost(t *testing.T) {
 	t.Parallel()
 
-	got, err := ParseImagePath("CDN.Example.COM/Photos/Cat.jpg/800x600.webp")
+	got, err := ParseImageURL("/v1/image/CDN.Example.COM/Photos/Cat.jpg/800x600.webp")
 	if err != nil {
-		t.Fatalf("ParseImagePath() error = %v", err)
+		t.Fatalf("ParseImageURL() error = %v", err)
 	}
 
-	t.Logf("parsed host %q, path %q", got.Host, got.Path)
+	t.Logf("parsed host %q, path %q", got.Source.Host, got.Source.Path)
 
-	if got.Host != testHostCDN {
-		t.Errorf("Host = %q, want %q", got.Host, testHostCDN)
+	if got.Source.Host != testHostCDN {
+		t.Errorf("Host = %q, want %q", got.Source.Host, testHostCDN)
 	}
 
-	if got.Path != "/Photos/Cat.jpg" {
-		t.Errorf("Path = %q, want %q", got.Path, "/Photos/Cat.jpg")
+	if got.Source.Path != "/Photos/Cat.jpg" {
+		t.Errorf("Path = %q, want %q", got.Source.Path, "/Photos/Cat.jpg")
 	}
 }
 
-// TestParseImagePath_RefusesUserinfo verifies that a host holding "@" is
+// TestParseImageURL_RefusesUserinfo verifies that a host holding "@" is
 // refused: a URL reads what comes before the "@" as a user name and password
 // and the rest as the host.
-func TestParseImagePath_RefusesUserinfo(t *testing.T) {
+func TestParseImageURL_RefusesUserinfo(t *testing.T) {
 	t.Parallel()
 
 	for _, input := range []string{
-		"user@cdn.example.com/photos/cat.jpg/800x600.webp",
-		"user:password@cdn.example.com/photos/cat.jpg/800x600.webp",
+		"/v1/image/user@cdn.example.com/photos/cat.jpg/800x600.webp",
+		"/v1/image/user:password@cdn.example.com/photos/cat.jpg/800x600.webp",
 	} {
-		got, err := ParseImagePath(input)
-		t.Logf("ParseImagePath(%q) = %+v, error = %v", input, got, err)
+		got, err := ParseImageURL(input)
+		t.Logf("ParseImageURL(%q) = %+v, error = %v", input, got, err)
 
 		if !errors.Is(err, ErrInvalidHost) {
-			t.Errorf("ParseImagePath(%q) error = %v, want %v",
+			t.Errorf("ParseImageURL(%q) error = %v, want %v",
 				input, err, ErrInvalidHost)
 		}
 	}
 }
 
-func TestParsedURL_ToImageRequest(t *testing.T) {
-	t.Parallel()
-
-	parsed := &ParsedURL{
-		Host:   testHostCDN,
-		Path:   testPathCat,
-		Query:  "version=2",
-		Size:   Size{Width: 800, Height: 600},
-		Format: FormatWebP,
-	}
-
-	req := parsed.ToImageRequest()
-
-	if req.SourceHost != parsed.Host {
-		t.Errorf("SourceHost = %q, want %q", req.SourceHost, parsed.Host)
-	}
-
-	if req.SourcePath != parsed.Path {
-		t.Errorf("SourcePath = %q, want %q", req.SourcePath, parsed.Path)
-	}
-
-	if req.SourceQuery != parsed.Query {
-		t.Errorf("SourceQuery = %q, want %q", req.SourceQuery, parsed.Query)
-	}
-
-	if req.Size != parsed.Size {
-		t.Errorf("Size = %v, want %v", req.Size, parsed.Size)
-	}
-
-	if req.Format != parsed.Format {
-		t.Errorf("Format = %q, want %q", req.Format, parsed.Format)
-	}
-}
-
 func TestParseImageURL_PathTraversal(t *testing.T) {
 	t.Parallel()
 
@@ -331,6 +255,10 @@ func TestParseImageURL_PathTraversal(t *testing.T) {
 			name:  "parent in middle of path",
 			input: "/v1/image/cdn.example.com/photos/../../../etc/passwd/800x600.jpeg",
 		},
+		{
+			name:  "parent directory in path",
+			input: "/v1/image/cdn.example.com/photos/../secret/800x600.jpeg",
+		},
 		{
 			name:  "encoded parent directory",
 			input: "/v1/image/cdn.example.com/photos/%2e%2e/secret/800x600.jpeg",
@@ -373,40 +301,6 @@ func TestParseImageURL_PathTraversal(t *testing.T) {
 	}
 }
 
-func TestParseImagePath_PathTraversal(t *testing.T) {
-	t.Parallel()
-
-	// Test path traversal via ParseImagePath (chi wildcard)
-	tests := []struct {
-		name  string
-		input string
-	}{
-		{
-			name:  "parent directory in path",
-			input: "cdn.example.com/photos/../secret/800x600.jpeg",
-		},
-		{
-			name:  "encoded traversal",
-			input: "cdn.example.com/photos/%2e%2e/secret/800x600.jpeg",
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			_, err := ParseImagePath(tt.input)
-			if err == nil {
-				t.Error("ParseImagePath() should reject path traversal attempts")
-			}
-
-			if !errors.Is(err, ErrPathTraversal) {
-				t.Errorf("ParseImagePath() error = %v, want ErrPathTraversal", err)
-			}
-		})
-	}
-}
-
 // TestParseImageURL_SourceURLHoldingPercent25 verifies that a source path and
 // a source query holding %25, the percent-escape of a literal "%", are
 // accepted as they are, although decoding them once more leaves a "%" that
@@ -417,22 +311,24 @@ func TestParseImageURL_SourceURLHoldingPercent25(t *testing.T) {
 	tests := []struct {
 		name  string
 		input string
-		want  *ParsedURL
+		want  *Request
 	}{
 		{
 			name:  "path",
 			input: "/v1/image/cdn.example.com/sale/50%25off.jpg/800x600.webp",
-			want: &ParsedURL{
-				Host: testHostCDN, Path: "/sale/50%25off.jpg",
-				Size: Size{Width: 800, Height: 600}, Format: FormatWebP,
+			want: &Request{
+				Source:    Source{Host: testHostCDN, Path: "/sale/50%25off.jpg"},
+				Transform: Transform{Size: Size{Width: 800, Height: 600}, Format: FormatWebP},
 			},
 		},
 		{
 			name:  "query",
 			input: "/v1/image/cdn.example.com/photos/cat.jpg?discount=50%25/800x600.webp",
-			want: &ParsedURL{
-				Host: testHostCDN, Path: testPathCat, Query: "discount=50%25",
-				Size: Size{Width: 800, Height: 600}, Format: FormatWebP,
+			want: &Request{
+				Source: Source{
+					Host: testHostCDN, Path: testPathCat, Query: "discount=50%25",
+				},
+				Transform: Transform{Size: Size{Width: 800, Height: 600}, Format: FormatWebP},
 			},
 		},
 	}
@@ -446,7 +342,7 @@ func TestParseImageURL_SourceURLHoldingPercent25(t *testing.T) {
 				t.Fatalf("ParseImageURL() unexpected error = %v", err)
 			}
 
-			assertParsedURL(t, got, tt.want)
+			assertRequest(t, got, tt.want)
 		})
 	}
 }

internal/imagerequest/validate_internal_test.go

@@ -1,4 +1,4 @@
-package imgcache
+package imagerequest
 
 import (
 	"errors"
@@ -10,35 +10,43 @@ func TestValidateImageRequest(t *testing.T) {
 
 	tests := []struct {
 		name    string
-		req     ImageRequest
+		req     Request
 		wantErr error
 	}{
 		{
 			name: "within bounds",
-			req:  ImageRequest{Size: Size{Width: 800, Height: 600}, FitMode: FitCover},
+			req: Request{Transform: Transform{
+				Size: Size{Width: 800, Height: 600}, FitMode: FitCover,
+			}},
 		},
 		{
 			name: "original size and empty fit",
-			req:  ImageRequest{Size: Size{Width: 0, Height: 0}},
+			req:  Request{Transform: Transform{Size: Size{Width: 0, Height: 0}}},
 		},
 		{
-			name:    "width over limit",
-			req:     ImageRequest{Size: Size{Width: MaxDimension + 1, Height: 600}},
+			name: "width over limit",
+			req: Request{Transform: Transform{
+				Size: Size{Width: MaxDimension + 1, Height: 600},
+			}},
 			wantErr: ErrDimensionTooLarge,
 		},
 		{
-			name:    "height over limit",
-			req:     ImageRequest{Size: Size{Width: 800, Height: MaxDimension + 1}},
+			name: "height over limit",
+			req: Request{Transform: Transform{
+				Size: Size{Width: 800, Height: MaxDimension + 1},
+			}},
 			wantErr: ErrDimensionTooLarge,
 		},
 		{
 			name:    "negative width",
-			req:     ImageRequest{Size: Size{Width: -1, Height: 600}},
+			req:     Request{Transform: Transform{Size: Size{Width: -1, Height: 600}}},
 			wantErr: ErrInvalidSize,
 		},
 		{
-			name:    "invalid fit mode",
-			req:     ImageRequest{Size: Size{Width: 800, Height: 600}, FitMode: "bogus"},
+			name: "invalid fit mode",
+			req: Request{Transform: Transform{
+				Size: Size{Width: 800, Height: 600}, FitMode: "bogus",
+			}},
 			wantErr: ErrInvalidFitMode,
 		},
 	}

internal/imagerequest/variantkey.go

@@ -0,0 +1,39 @@
+package imagerequest
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"strings"
+)
+
+// VariantKey is a SHA256 hash identifying a specific image variant (hex-encoded).
+type VariantKey string
+
+// CacheKey generates a unique key for a request variant.
+// Format: sha256(host:path:query:width:height:format:quality:fit_mode)
+// The path and query go through escapePercentAndColon, so that a ":" in
+// either cannot be taken for the one between them.
+func CacheKey(req *Request) VariantKey {
+	data := fmt.Sprintf("%s:%s:%s:%d:%d:%s:%d:%s",
+		req.Source.Host,
+		escapePercentAndColon(req.Source.Path),
+		escapePercentAndColon(req.Source.Query),
+		req.Transform.Size.Width,
+		req.Transform.Size.Height,
+		req.Transform.Format,
+		req.Transform.Quality,
+		req.Transform.FitMode,
+	)
+	h := sha256.Sum256([]byte(data))
+
+	return VariantKey(hex.EncodeToString(h[:]))
+}
+
+// escapePercentAndColon returns s with each "%" written as "%25" and each
+// ":" as "%3A", so that the result holds no ":".
+func escapePercentAndColon(s string) string {
+	s = strings.ReplaceAll(s, "%", "%25")
+
+	return strings.ReplaceAll(s, ":", "%3A")
+}

internal/imagerequest/variantkey_internal_test.go

@@ -0,0 +1,142 @@
+package imagerequest
+
+import "testing"
+
+func TestCacheKey(t *testing.T) {
+	t.Parallel()
+
+	req1 := &Request{
+		Source: Source{Host: testHostCDN, Path: testPathCat, Query: ""},
+		Transform: Transform{
+			Size: Size{Width: 800, Height: 600}, Format: FormatWebP,
+			Quality: 85, FitMode: FitCover,
+		},
+	}
+
+	req2 := &Request{
+		Source: Source{Host: testHostCDN, Path: testPathCat, Query: ""},
+		Transform: Transform{
+			Size: Size{Width: 800, Height: 600}, Format: FormatWebP,
+			Quality: 85, FitMode: FitCover,
+		},
+	}
+
+	// Same request should produce same key
+	key1 := CacheKey(req1)
+	key2 := CacheKey(req2)
+
+	if key1 != key2 {
+		t.Errorf("CacheKey() not deterministic: %s vs %s", key1, key2)
+	}
+
+	// Key should be 64 hex chars
+	if len(string(key1)) != 64 {
+		t.Errorf("CacheKey() length = %d, want 64", len(string(key1)))
+	}
+
+	// Different size should produce different key
+	req3 := &Request{
+		Source: Source{Host: testHostCDN, Path: testPathCat, Query: ""},
+		Transform: Transform{
+			Size: Size{Width: 400, Height: 300}, Format: FormatWebP, // Different size
+			Quality: 85, FitMode: FitCover,
+		},
+	}
+
+	key3 := CacheKey(req3)
+	if key1 == key3 {
+		t.Error("CacheKey() produced same key for different sizes")
+	}
+
+	// Different format should produce different key
+	req4 := &Request{
+		Source: Source{Host: testHostCDN, Path: testPathCat, Query: ""},
+		Transform: Transform{
+			Size: Size{Width: 800, Height: 600}, Format: FormatPNG, // Different format
+			Quality: 85, FitMode: FitCover,
+		},
+	}
+
+	key4 := CacheKey(req4)
+	if key1 == key4 {
+		t.Error("CacheKey() produced same key for different formats")
+	}
+
+	// Different quality should produce different key
+	req5 := &Request{
+		Source: Source{Host: testHostCDN, Path: testPathCat, Query: ""},
+		Transform: Transform{
+			Size: Size{Width: 800, Height: 600}, Format: FormatWebP,
+			Quality: 50, FitMode: FitCover, // Different quality
+		},
+	}
+
+	key5 := CacheKey(req5)
+	if key1 == key5 {
+		t.Error("CacheKey() produced same key for different quality")
+	}
+}
+
+// TestCacheKey_ColonOrPercentInPathOrQuery checks that two different source
+// URLs whose path or query holds ":" or "%" get different keys.
+func TestCacheKey_ColonOrPercentInPathOrQuery(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name          string
+		path1, query1 string
+		path2, query2 string
+	}{
+		{
+			name:  "colon moved from path to query",
+			path1: "/a:b", query1: "",
+			path2: "/a", query2: "b:",
+		},
+		{
+			name:  "colon in path and its percent-encoding",
+			path1: "/a:b", query1: "",
+			path2: "/a%3Ab", query2: "",
+		},
+	}
+
+	for _, tt := range cases {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			key1 := CacheKey(&Request{
+				Source: Source{
+					Host:  testHostCDN,
+					Path:  tt.path1,
+					Query: tt.query1,
+				},
+				Transform: Transform{
+					Size:    Size{Width: 800, Height: 600},
+					Format:  FormatWebP,
+					Quality: 85,
+					FitMode: FitCover,
+				},
+			})
+			key2 := CacheKey(&Request{
+				Source: Source{
+					Host:  testHostCDN,
+					Path:  tt.path2,
+					Query: tt.query2,
+				},
+				Transform: Transform{
+					Size:    Size{Width: 800, Height: 600},
+					Format:  FormatWebP,
+					Quality: 85,
+					FitMode: FitCover,
+				},
+			})
+
+			t.Logf("CacheKey() of path %q query %q = %s", tt.path1, tt.query1, key1)
+			t.Logf("CacheKey() of path %q query %q = %s", tt.path2, tt.query2, key2)
+
+			if key1 == key2 {
+				t.Errorf("CacheKey() gave path %q query %q and path %q query %q "+
+					"the same key", tt.path1, tt.query1, tt.path2, tt.query2)
+			}
+		})
+	}
+}

internal/imgcache/cache.go

@@ -2,35 +2,23 @@ package imgcache
 
 import (
 	"context"
-	"crypto/sha256"
 	"database/sql"
-	"encoding/hex"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
 	"log/slog"
 	"path/filepath"
-	"sync"
-	"sync/atomic"
 	"time"
 
-	lru "github.com/hashicorp/golang-lru/v2"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"github.com/prometheus/client_golang/prometheus"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
-// Cache errors.
-var (
-	ErrCacheMiss     = errors.New("cache miss")
-	ErrNegativeCache = errors.New("negative cache hit")
-)
-
-// HTTP status code for successful fetch.
-const httpStatusOK = 200
-
-// metaCacheSize is how many variants' content types metaCache holds. A
-// variant not among them is served as before, reading its .meta file.
-const metaCacheSize = 10000
+// maxPendingAccessTimes is how many access times of variants served from
+// the cache, and how many of cached sources a miss used, may each wait to be
+// written, at about 80 bytes each. An access time handed over while that
+// many of its kind wait is dropped.
+const maxPendingAccessTimes = 10000
 
 // cleanExpiredBatchSize is the most expired negative cache rows one
 // statement of CleanExpired deletes. Each batch is a statement of its
@@ -44,23 +32,12 @@ type CacheConfig struct {
 	NegativeTTL time.Duration
 
 	// MaxBytes is the disk cache size limit in bytes that eviction
-	// enforces. Zero means no limit is enforced (no eviction).
+	// enforces. Zero turns the disk cache off entirely: no cache
+	// directories are created, lookups always miss, stores are no-ops,
+	// and the eviction goroutine only removes the expired negative cache
+	// rows.
 	MaxBytes int64
 
-	// UseDefaultMaxBytes makes NewCache replace MaxBytes with the
-	// default limit: 75% of the sum of the space free on the filesystem
-	// holding the cache and the bytes the cache already holds, at least
-	// DefaultCacheMaxBytesFloor. The config layer sets this when the
-	// operator omits cache_max_bytes.
-	UseDefaultMaxBytes bool
-
-	// DisableDiskCache turns the disk cache off entirely: no cache
-	// directories are created, lookups always miss, stores are
-	// no-ops, and the eviction goroutine only removes the expired
-	// negative cache rows. The config layer sets this when the
-	// operator configures cache_max_bytes: 0.
-	DisableDiskCache bool
-
 	// Logger receives accounting and eviction log output. A nil
 	// Logger means slog.Default().
 	Logger *slog.Logger
@@ -68,16 +45,11 @@ type CacheConfig struct {
 
 // Cache implements the caching layer for the image proxy.
 type Cache struct {
-	db          *sql.DB
-	srcContent  *ContentStorage  // source images by content hash
-	variants    *VariantStorage  // processed variants by cache key
-	srcMetadata *MetadataStorage // source metadata by host/path
-	config      CacheConfig
-	log         *slog.Logger
-
-	// disabled means the disk cache is turned off entirely: lookups
-	// always miss, stores are no-ops, and no eviction runs.
-	disabled bool
+	db         *sql.DB
+	srcContent *ContentStorage // source images by source key
+	variants   *VariantStorage // processed variants by cache key
+	config     CacheConfig
+	log        *slog.Logger
 
 	// Eviction machinery. The channels are created in NewCache so
 	// stores can signal write pressure without racing StartEviction.
@@ -87,47 +59,30 @@ type Cache struct {
 	evictionDone     chan struct{}
 	evictionCancel   context.CancelFunc
 
-	// The pending counts: hits, misses, upstream fetches and transforms
-	// whose write to the database missed its request's deadline, kept
-	// here until they are written by the goroutine that
-	// StartPendingCountWrites starts. As for eviction, the channels are
-	// created in NewCache: pendingCountsAdded wakes that goroutine, and
-	// pendingCountsDone is closed when it returns. pendingCountsCancel,
-	// set by StartPendingCountWrites, cancels its context, which tells it
-	// to finish.
-	pendingHits               atomic.Int64
-	pendingMisses             atomic.Int64
-	pendingUpstreamFetches    atomic.Int64
-	pendingUpstreamFetchBytes atomic.Int64
-	pendingTransforms         atomic.Int64
-	pendingCountsAdded        chan struct{}
-	pendingCountsDone         chan struct{}
-	pendingCountsCancel       context.CancelFunc
+	// pendingVariantAccessTimes holds the variants served from the cache,
+	// and pendingSourceAccessTimes the cached sources a miss used, whose
+	// access time is still to be written by the goroutine that
+	// StartPendingAccessTimeWrites starts, so that no request waits for the
+	// database to record it. As for eviction, the channels are created in
+	// NewCache, so that requests can hand over access times before that
+	// goroutine starts; pendingAccessTimesDone is closed when it returns.
+	// pendingAccessTimesCancel, set by StartPendingAccessTimeWrites,
+	// cancels its context, which tells it to finish.
+	pendingVariantAccessTimes chan imagerequest.VariantKey
+	pendingSourceAccessTimes  chan imagerequest.SourceKey
+	pendingAccessTimesDone    chan struct{}
+	pendingAccessTimesCancel  context.CancelFunc
 
-	// Held through each write of the pending counts, and by
-	// readHitAndMissCounts to read them
-	pendingCountsWriteMutex sync.Mutex
-
-	// metaCache holds the content types of the variants most recently
-	// stored or served, so a hit does not read the variant's .meta file.
-	// It never stands in for the variant file, which is always opened.
-	metaCache *lru.Cache[VariantKey, string]
-
-	// contentLocks serializes StoreSource and evictSourceBlob per
-	// content hash, closing the race window between an eviction's row
-	// deletion and its file unlink against a concurrent store of
-	// identical content.
-	contentLocks *contentLock
-
-	// evictSourceBlobTestHook, when set, is invoked by evictSourceBlob
-	// after its row-deletion transaction commits and before the
-	// content file is unlinked. It exists solely so tests can
-	// deterministically pause inside that window to exercise
-	// concurrent stores against it; production code leaves it nil.
-	evictSourceBlobTestHook func(ContentHash)
+	// The counts of what the cache does, made and registered by
+	// registerCounters (see counters.go)
+	cacheHits          prometheus.Counter
+	cacheMisses        prometheus.Counter
+	upstreamFetches    prometheus.Counter
+	upstreamFetchBytes prometheus.Counter
+	transforms         prometheus.Counter
 
 	// reconciliationPageSize is the most rows one read of a content table
-	// returns in the reconciliation pass and in Stats. newCache sets it to
+	// returns in the reconciliation pass. NewCache sets it to
 	// defaultReconciliationPageSize; tests set it smaller.
 	reconciliationPageSize int
 
@@ -138,43 +93,37 @@ type Cache struct {
 	reconciliationReadTestHook func(rows int)
 }
 
-// NewCache creates a new cache instance.
-func NewCache(db *sql.DB, config CacheConfig) (*Cache, error) {
-	return newCache(db, config, defaultFreeSpaceProbe)
-}
-
-// newCache is NewCache with the free-space probe passed in, so tests
-// can fake the free space the default limit is worked out from.
-func newCache(
-	db *sql.DB, config CacheConfig, probe FreeSpaceProbeFunc,
+// NewCache creates a new cache instance and registers its counters on
+// metricsRegistry. pixad passes Prometheus' default registry, the one
+// /metrics serves. It makes no database call.
+func NewCache(
+	db *sql.DB, config CacheConfig, metricsRegistry prometheus.Registerer,
 ) (*Cache, error) {
 	log := config.Logger
 	if log == nil {
 		log = slog.Default()
 	}
 
-	metaCache, err := lru.New[VariantKey, string](metaCacheSize)
-	if err != nil {
-		return nil, fmt.Errorf("failed to create variant content type cache: %w", err)
-	}
-
 	c := &Cache{
 		db:               db,
 		config:           config,
 		log:              log,
-		disabled:         config.DisableDiskCache,
 		evictionPressure: make(chan struct{}, 1),
 		evictionDone:     make(chan struct{}),
-		metaCache:        metaCache,
-		contentLocks:     newContentLock(),
 
-		pendingCountsAdded: make(chan struct{}, 1),
-		pendingCountsDone:  make(chan struct{}),
+		pendingVariantAccessTimes: make(chan imagerequest.VariantKey, maxPendingAccessTimes),
+		pendingSourceAccessTimes:  make(chan imagerequest.SourceKey, maxPendingAccessTimes),
+		pendingAccessTimesDone:    make(chan struct{}),
 
 		reconciliationPageSize: defaultReconciliationPageSize,
 	}
 
-	if c.disabled {
+	err := c.registerCounters(metricsRegistry)
+	if err != nil {
+		return nil, err
+	}
+
+	if config.MaxBytes == 0 {
 		return c, nil
 	}
 
@@ -186,180 +135,80 @@ func newCache(
 	}
 
 	variants, err := NewVariantStorage(
-		filepath.Join(config.StateDir, "cache", "variants"), log,
+		filepath.Join(config.StateDir, "cache", "variants"),
 	)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create variant storage: %w", err)
 	}
 
-	srcMetadata, err := NewMetadataStorage(
-		filepath.Join(config.StateDir, "cache", "metadata"),
-	)
-	if err != nil {
-		return nil, fmt.Errorf("failed to create source metadata storage: %w", err)
-	}
-
 	c.srcContent = srcContent
 	c.variants = variants
-	c.srcMetadata = srcMetadata
-
-	if config.UseDefaultMaxBytes {
-		limit, err := c.computeDefaultMaxBytes(context.Background(), probe)
-		if err != nil {
-			return nil, err
-		}
-
-		c.config.MaxBytes = limit
-
-		log.Info("computed default cache size limit from free space and cache contents",
-			"cache_max_bytes", limit,
-			"cache_dir", filepath.Join(config.StateDir, "cache"),
-		)
-	}
 
 	return c, nil
 }
 
-// LookupResult contains the result of a cache lookup.
-type LookupResult struct {
-	Hit         bool
-	CacheKey    VariantKey
-	ContentType string
-	SizeBytes   int64
-	CacheStatus CacheStatus
-}
-
-// Lookup checks if a processed variant exists on disk. Hits touch the
-// variant's LRU timestamp; a disabled cache always misses.
-func (c *Cache) Lookup(ctx context.Context, req *ImageRequest) (*LookupResult, error) {
-	cacheKey := CacheKey(req)
-
-	// Check variant storage directly - no DB needed for cache hits
-	if !c.disabled && c.variants.Exists(cacheKey) {
-		c.touchVariant(ctx, cacheKey)
-
-		return &LookupResult{
-			Hit:         true,
-			CacheKey:    cacheKey,
-			CacheStatus: CacheHit,
-		}, nil
-	}
-
-	return &LookupResult{
-		Hit:         false,
-		CacheKey:    cacheKey,
-		CacheStatus: CacheMiss,
-	}, nil
-}
-
-// GetVariant returns a reader, size, and content type for a cached
-// variant. The content type comes from metaCache, or else from the
-// variant's .meta file and is then kept in metaCache. A variant with
-// no .meta file is served as application/octet-stream, which is not
-// kept.
-func (c *Cache) GetVariant(cacheKey VariantKey) (io.ReadCloser, int64, string, error) {
-	if c.disabled {
+// GetVariant opens a cached variant and returns a reader, its size and its
+// content type, read from the variant file's first bytes. It opens that one
+// file and makes no database call. A variant not in the cache, or any
+// variant of a disabled cache, is ErrNotFound; a variant file whose first
+// bytes are not those of an output format is another error.
+func (c *Cache) GetVariant(
+	cacheKey imagerequest.VariantKey,
+) (io.ReadCloser, int64, string, error) {
+	if c.config.MaxBytes == 0 {
 		return nil, 0, "", ErrNotFound
 	}
 
-	contentType, known := c.metaCache.Get(cacheKey)
-	if !known {
-		return c.loadVariantWithMeta(cacheKey)
-	}
-
-	reader, size, err := c.variants.LoadWithSize(cacheKey)
-	if err != nil {
-		// The file is gone, e.g. deleted outside pixa
-		c.metaCache.Remove(cacheKey)
-
-		return nil, 0, "", err
-	}
-
-	return reader, size, contentType, nil
+	return c.variants.LoadWithContentType(cacheKey)
 }
 
-// StoreSource stores fetched source content and metadata. On a
-// disabled cache it is a no-op returning an empty hash.
+// StoreSource stores fetched source content: it writes the file named by
+// the source's key, then the source's row. When the row cannot be written
+// the file is removed and the store fails, as a file with no row is never
+// served or evicted; if that removal fails too, the next reconciliation
+// pass removes the file. On a disabled cache it is a no-op returning an
+// empty key.
 func (c *Cache) StoreSource(
 	ctx context.Context,
-	req *ImageRequest,
+	req *imagerequest.Request,
 	content io.Reader,
-	result *httpfetcher.FetchResult,
-) (ContentHash, error) {
-	if c.disabled {
+) (imagerequest.SourceKey, error) {
+	if c.config.MaxBytes == 0 {
 		return "", nil
 	}
 
-	// Hash the content ourselves (rather than via srcContent.Store,
-	// which would hash internally) so the content hash is known before
-	// any file or database work happens: that lets the entire store be
-	// serialized, per hash, against a concurrent eviction of the same
-	// content below.
 	data, err := io.ReadAll(content)
 	if err != nil {
 		return "", fmt.Errorf("failed to read source content: %w", err)
 	}
 
-	sum := sha256.Sum256(data)
-	contentHash := ContentHash(hex.EncodeToString(sum[:]))
+	key := req.Source.Key()
 
-	// Hold the content hash's lock for the whole store operation. A
-	// concurrent eviction of this exact hash (the real SHA-256 dedup
-	// case: a different source path whose bytes hash identically)
-	// deletes the accounting rows and unlinks the file inside the same
-	// lock, so the two can never interleave: either this store
-	// completes first (and a subsequent eviction removes it together
-	// with its rows and file, correctly), or eviction completes first
-	// (and this store finds the file already gone and recreates it
-	// fresh) — never a fresh row left pointing at a file eviction is
-	// mid-unlink on.
-	unlock := c.contentLocks.Lock(string(contentHash))
-	defer unlock()
-
-	size, err := c.srcContent.StoreHashed(contentHash, data)
+	size, err := c.srcContent.Store(key, data)
 	if err != nil {
 		return "", fmt.Errorf("failed to store source content: %w", err)
 	}
 
-	// Store in database
-	pathHash := HashPath(req.SourcePath + "?" + req.SourceQuery)
-
-	headersJSON, err := json.Marshal(result.Headers)
-	if err != nil {
-		return "", fmt.Errorf("failed to marshal response headers: %w", err)
-	}
-
 	_, err = c.db.ExecContext(ctx, `
-		INSERT INTO source_content (content_hash, content_type, size_bytes)
-		VALUES (?, ?, ?)
-		ON CONFLICT(content_hash) DO NOTHING
-	`, contentHash, result.ContentType, size)
+		INSERT INTO source_content (source_key, size_bytes)
+		VALUES (?, ?)
+		ON CONFLICT(source_key) DO UPDATE SET
+			size_bytes = excluded.size_bytes,
+			last_accessed_at = CURRENT_TIMESTAMP
+	`, string(key), size)
 	if err != nil {
+		deleteErr := c.srcContent.Delete(key)
+		if deleteErr != nil {
+			c.log.Warn("failed to remove source file whose row was not written",
+				"source_key", key, "error", deleteErr)
+		}
+
 		return "", fmt.Errorf("failed to insert source content: %w", err)
 	}
 
-	_, err = c.db.ExecContext(ctx, `
-		INSERT INTO source_metadata
-			(source_host, source_path, source_query, path_hash,
-			 content_hash, status_code, content_type, response_headers)
-		VALUES (?, ?, ?, ?, ?, ?, ?, ?)
-		ON CONFLICT(source_host, source_path, source_query) DO UPDATE SET
-			content_hash = excluded.content_hash,
-			status_code = excluded.status_code,
-			content_type = excluded.content_type,
-			response_headers = excluded.response_headers,
-			fetched_at = CURRENT_TIMESTAMP
-	`, req.SourceHost, req.SourcePath, req.SourceQuery, pathHash,
-		contentHash, httpStatusOK, result.ContentType, string(headersJSON))
-	if err != nil {
-		return "", fmt.Errorf("failed to insert source metadata: %w", err)
-	}
-
-	c.writeMetadataSidecar(req, pathHash, contentHash, result)
-
 	c.notifyWritePressure()
 
-	return contentHash, nil
+	return key, nil
 }
 
 // StoreVariant stores a processed variant by its cache key and records
@@ -367,27 +216,24 @@ func (c *Cache) StoreSource(
 // accounting insert is best-effort (the startup reconciliation pass
 // adopts any variant file that misses its accounting row).
 func (c *Cache) StoreVariant(
-	ctx context.Context, cacheKey VariantKey, content io.Reader, contentType string,
+	ctx context.Context, cacheKey imagerequest.VariantKey, content io.Reader,
 ) error {
-	if c.disabled {
+	if c.config.MaxBytes == 0 {
 		return nil
 	}
 
-	size, err := c.variants.Store(cacheKey, content, contentType)
+	size, err := c.variants.Store(cacheKey, content)
 	if err != nil {
 		return err
 	}
 
-	c.metaCache.Add(cacheKey, contentType)
-
 	_, err = c.db.ExecContext(ctx, `
-		INSERT INTO variant_content (cache_key, size_bytes, content_type)
-		VALUES (?, ?, ?)
+		INSERT INTO variant_content (cache_key, size_bytes)
+		VALUES (?, ?)
 		ON CONFLICT(cache_key) DO UPDATE SET
 			size_bytes = excluded.size_bytes,
-			content_type = excluded.content_type,
 			last_accessed_at = CURRENT_TIMESTAMP
-	`, string(cacheKey), size, contentType)
+	`, string(cacheKey), size)
 	if err != nil {
 		c.log.Warn("failed to record variant in size accounting",
 			"cache_key", cacheKey, "error", err)
@@ -399,60 +245,53 @@ func (c *Cache) StoreVariant(
 }
 
 // LookupSource checks if we have cached source content for a request.
-// Returns the content hash and content type if found, or empty values
-// if not. Hits touch the blob's LRU timestamp; a disabled cache always
-// reports no cached source.
+// Returns the source key if found, or an empty key if not; a row whose
+// file is missing is not found. A source found has its access time
+// handed to the background writer without waiting (see
+// touchSourceContent); a disabled cache always reports no cached source.
 func (c *Cache) LookupSource(
-	ctx context.Context, req *ImageRequest,
-) (ContentHash, string, error) {
-	if c.disabled {
-		return "", "", nil
+	ctx context.Context, req *imagerequest.Request,
+) (imagerequest.SourceKey, error) {
+	if c.config.MaxBytes == 0 {
+		return "", nil
 	}
 
-	var hashStr, contentType string
+	key := req.Source.Key()
+
+	var rowExists bool
 
 	err := c.db.QueryRowContext(ctx, `
-		SELECT content_hash, content_type FROM source_metadata
-		WHERE source_host = ? AND source_path = ? AND source_query = ?
-	`, req.SourceHost, req.SourcePath, req.SourceQuery).Scan(&hashStr, &contentType)
-
-	if errors.Is(err, sql.ErrNoRows) {
-		return "", "", nil
-	}
-
+		SELECT EXISTS(SELECT 1 FROM source_content WHERE source_key = ?)
+	`, string(key)).Scan(&rowExists)
 	if err != nil {
-		return "", "", fmt.Errorf("failed to lookup source: %w", err)
+		return "", fmt.Errorf("failed to lookup source: %w", err)
 	}
 
-	contentHash := ContentHash(hashStr)
+	if !rowExists {
+		return "", nil
+	}
 
 	// Verify the content file exists
-	if !c.srcContent.Exists(contentHash) {
-		return "", "", nil
+	if !c.srcContent.Exists(key) {
+		return "", nil
 	}
 
-	c.touchSourceContent(ctx, contentHash)
+	c.touchSourceContent(key)
 
-	return contentHash, contentType, nil
+	return key, nil
 }
 
 // StoreNegative stores a negative cache entry for a failed fetch.
-func (c *Cache) StoreNegative(
-	ctx context.Context, req *ImageRequest, statusCode int, errMsg string,
-) error {
+func (c *Cache) StoreNegative(ctx context.Context, req *imagerequest.Request) error {
 	expiresAt := time.Now().UTC().Add(c.config.NegativeTTL)
 
 	_, err := c.db.ExecContext(ctx, `
 		INSERT INTO negative_cache
-			(source_host, source_path, source_query, status_code,
-			 error_message, expires_at)
-		VALUES (?, ?, ?, ?, ?, ?)
+			(source_host, source_path, source_query, expires_at)
+		VALUES (?, ?, ?, ?)
 		ON CONFLICT(source_host, source_path, source_query) DO UPDATE SET
-			status_code = excluded.status_code,
-			error_message = excluded.error_message,
-			fetched_at = CURRENT_TIMESTAMP,
 			expires_at = excluded.expires_at
-	`, req.SourceHost, req.SourcePath, req.SourceQuery, statusCode, errMsg, expiresAt)
+	`, req.Source.Host, req.Source.Path, req.Source.Query, expiresAt)
 	if err != nil {
 		return fmt.Errorf("failed to insert negative cache: %w", err)
 	}
@@ -460,33 +299,16 @@ func (c *Cache) StoreNegative(
 	return nil
 }
 
-// GetSourceMetadataID returns the source metadata ID for a request.
-func (c *Cache) GetSourceMetadataID(
-	ctx context.Context, req *ImageRequest,
-) (int64, error) {
-	var id int64
-
-	err := c.db.QueryRowContext(ctx, `
-		SELECT id FROM source_metadata
-		WHERE source_host = ? AND source_path = ? AND source_query = ?
-	`, req.SourceHost, req.SourcePath, req.SourceQuery).Scan(&id)
-	if err != nil {
-		return 0, fmt.Errorf("failed to get source metadata ID: %w", err)
-	}
-
-	return id, nil
-}
-
-// GetSourceContent returns a reader for cached source content by its hash,
+// GetSourceContent returns a reader for cached source content by its key,
 // and the content's size in bytes.
 func (c *Cache) GetSourceContent(
-	contentHash ContentHash,
+	key imagerequest.SourceKey,
 ) (io.ReadCloser, int64, error) {
-	if c.disabled {
+	if c.config.MaxBytes == 0 {
 		return nil, 0, ErrNotFound
 	}
 
-	return c.srcContent.LoadWithSize(contentHash)
+	return c.srcContent.LoadWithSize(key)
 }
 
 // CleanExpired removes the negative cache rows past their expiry, one
@@ -512,241 +334,72 @@ func (c *Cache) CleanExpired(ctx context.Context) error {
 	}
 }
 
-// Stats returns cache statistics.
-func (c *Cache) Stats(ctx context.Context) (*CacheStats, error) {
-	var stats CacheStats
-
-	err := c.readHitAndMissCounts(ctx, &stats)
-	if err != nil && !errors.Is(err, sql.ErrNoRows) {
-		return nil, fmt.Errorf("failed to get cache stats: %w", err)
-	}
-
-	// Count and size the cached source images and processed variants from
-	// their tables. A disabled cache holds none, whatever rows an earlier
-	// run left.
-	if !c.disabled {
-		err = c.db.QueryRowContext(ctx, `
-			SELECT (SELECT COUNT(*) FROM source_content)
-			     + (SELECT COUNT(*) FROM variant_content)
-		`).Scan(&stats.TotalItems)
-		if err != nil {
-			c.log.Warn("failed to count cache items for stats", "error", err)
-		}
-
-		stats.TotalSizeBytes, err = c.sumContentSizeBytes(ctx)
-		if err != nil {
-			c.log.Warn("failed to sum cache size for stats", "error", err)
-		}
-	}
-
-	// Compute hit rate as a ratio
-	if stats.HitCount+stats.MissCount > 0 {
-		stats.HitRate = float64(stats.HitCount) / float64(stats.HitCount+stats.MissCount)
-	}
-
-	return &stats, nil
-}
-
 // IncrementStats counts a cache hit or miss, and an upstream fetch that read
 // fetchBytes bytes, as IncrementUpstreamFetch does. Like the other Increment
-// methods, it writes to the database with ctx's deadline but not its
-// cancellation, so an ended request is still counted but does not wait for
-// the database past its deadline; a count not written by then becomes a
-// pending count (see StartPendingCountWrites).
-func (c *Cache) IncrementStats(ctx context.Context, hit bool, fetchBytes int64) {
-	countCtx, cancel := withoutCancelKeepingDeadline(ctx)
-	defer cancel()
-
-	var err error
-
-	pendingCount := &c.pendingMisses
-
+// methods, it only adds to the cache's Prometheus counters in memory (see
+// counters.go), so it never waits for the database or fails.
+func (c *Cache) IncrementStats(hit bool, fetchBytes int64) {
 	if hit {
-		pendingCount = &c.pendingHits
-
-		_, err = c.db.ExecContext(countCtx, `
-			UPDATE cache_stats
-			SET hit_count = hit_count + 1,
-			    last_updated_at = CURRENT_TIMESTAMP
-			WHERE id = 1
-		`)
+		c.cacheHits.Inc()
 	} else {
-		_, err = c.db.ExecContext(countCtx, `
-			UPDATE cache_stats
-			SET miss_count = miss_count + 1,
-			    last_updated_at = CURRENT_TIMESTAMP
-			WHERE id = 1
-		`)
+		c.cacheMisses.Inc()
 	}
 
-	switch {
-	case errors.Is(err, context.DeadlineExceeded):
-		c.addPendingCount(pendingCount, 1)
-	case err != nil:
-		c.log.Warn("failed to count cache hit or miss", "hit", hit, "error", err)
-	}
-
-	c.IncrementUpstreamFetch(ctx, fetchBytes)
+	c.IncrementUpstreamFetch(fetchBytes)
 }
 
 // IncrementUpstreamFetch counts one upstream fetch that read fetchBytes bytes.
 // A fetch that read no bytes is not counted.
-func (c *Cache) IncrementUpstreamFetch(ctx context.Context, fetchBytes int64) {
+func (c *Cache) IncrementUpstreamFetch(fetchBytes int64) {
 	if fetchBytes <= 0 {
 		return
 	}
 
-	countCtx, cancel := withoutCancelKeepingDeadline(ctx)
-	defer cancel()
-
-	_, err := c.db.ExecContext(countCtx, `
-		UPDATE cache_stats
-		SET upstream_fetch_count = upstream_fetch_count + 1,
-		    upstream_fetch_bytes = upstream_fetch_bytes + ?,
-		    last_updated_at = CURRENT_TIMESTAMP
-		WHERE id = 1
-	`, fetchBytes)
-
-	switch {
-	case errors.Is(err, context.DeadlineExceeded):
-		c.addPendingCount(&c.pendingUpstreamFetches, 1)
-		c.addPendingCount(&c.pendingUpstreamFetchBytes, fetchBytes)
-	case err != nil:
-		c.log.Warn("failed to count upstream fetch",
-			"fetch_bytes", fetchBytes, "error", err)
-	}
+	c.upstreamFetches.Inc()
+	c.upstreamFetchBytes.Add(float64(fetchBytes))
 }
 
 // IncrementTransformCount counts one image transcoded by the image processor.
-func (c *Cache) IncrementTransformCount(ctx context.Context) {
-	countCtx, cancel := withoutCancelKeepingDeadline(ctx)
-	defer cancel()
+func (c *Cache) IncrementTransformCount() {
+	c.transforms.Inc()
+}
 
-	_, err := c.db.ExecContext(countCtx, `
-		UPDATE cache_stats
-		SET transform_count = transform_count + 1,
-		    last_updated_at = CURRENT_TIMESTAMP
-		WHERE id = 1
-	`)
-
-	switch {
-	case errors.Is(err, context.DeadlineExceeded):
-		c.addPendingCount(&c.pendingTransforms, 1)
-	case err != nil:
-		c.log.Warn("failed to count transform", "error", err)
+// touchVariant hands the access time of a variant served from the cache to
+// the goroutine StartPendingAccessTimeWrites starts, which writes it in its
+// next batch. It never waits: while maxPendingAccessTimes access times of
+// variants wait to be written, this one is dropped, and the variant only
+// looks colder to eviction.
+func (c *Cache) touchVariant(cacheKey imagerequest.VariantKey) {
+	select {
+	case c.pendingVariantAccessTimes <- cacheKey:
+	default:
 	}
 }
 
-// readHitAndMissCounts sets the hit and miss counts of stats to those of the
-// cache_stats row plus the pending hits and misses (see
-// StartPendingCountWrites). It holds pendingCountsWriteMutex, so that no
-// write of the pending counts falls between the two reads.
-func (c *Cache) readHitAndMissCounts(ctx context.Context, stats *CacheStats) error {
-	c.pendingCountsWriteMutex.Lock()
-	defer c.pendingCountsWriteMutex.Unlock()
-
-	err := c.db.QueryRowContext(ctx, `
-		SELECT hit_count, miss_count
-		FROM cache_stats WHERE id = 1
-	`).Scan(&stats.HitCount, &stats.MissCount)
-
-	stats.HitCount += c.pendingHits.Load()
-	stats.MissCount += c.pendingMisses.Load()
-
-	return err
-}
-
-// loadVariantWithMeta is GetVariant for a variant metaCache does not
-// hold: it reads the content type from the variant's .meta file and
-// keeps it in metaCache, unless a StoreVariant has put one there
-// meanwhile, as the store's is newer. A read that finds no .meta file,
-// as one can when the store's .meta write failed or an eviction removed
-// the file after the read opened the variant, serves
-// application/octet-stream and keeps nothing, so metaCache only ever
-// holds a type read from a .meta file or passed to StoreVariant.
-func (c *Cache) loadVariantWithMeta(
-	cacheKey VariantKey,
-) (io.ReadCloser, int64, string, error) {
-	reader, size, contentType, err := c.variants.LoadWithMeta(cacheKey)
-	if err != nil {
-		return nil, 0, "", err
-	}
-
-	if contentType == "" {
-		return reader, size, fallbackContentType, nil
-	}
-
-	c.metaCache.ContainsOrAdd(cacheKey, contentType)
-
-	return reader, size, contentType, nil
-}
-
-// writeMetadataSidecar writes the JSON metadata sidecar of a stored source.
-// A failure is logged and is otherwise non-fatal; the metadata is in the
-// database.
-func (c *Cache) writeMetadataSidecar(
-	req *ImageRequest,
-	pathHash PathHash,
-	contentHash ContentHash,
-	result *httpfetcher.FetchResult,
-) {
-	meta := &SourceMetadata{
-		Host:            req.SourceHost,
-		Path:            req.SourcePath,
-		Query:           req.SourceQuery,
-		ContentHash:     string(contentHash),
-		StatusCode:      result.StatusCode,
-		ContentType:     result.ContentType,
-		ContentLength:   result.ContentLength,
-		ResponseHeaders: result.Headers,
-		FetchedAt:       time.Now().UTC().Unix(),
-		FetchDurationMs: result.FetchDurationMs,
-		RemoteAddr:      result.RemoteAddr,
-	}
-
-	err := c.srcMetadata.Store(req.SourceHost, pathHash, meta)
-	if err != nil {
-		c.log.Warn("failed to write metadata sidecar",
-			"host", req.SourceHost, "path_hash", pathHash, "error", err)
+// touchSourceContent hands the access time of a cached source a miss used to
+// the goroutine StartPendingAccessTimeWrites starts, which writes it in its
+// next batch. It never waits: while maxPendingAccessTimes access times of
+// sources wait to be written, this one is dropped, and the source only looks
+// colder to eviction.
+func (c *Cache) touchSourceContent(key imagerequest.SourceKey) {
+	select {
+	case c.pendingSourceAccessTimes <- key:
+	default:
 	}
 }
 
-// touchVariant updates the LRU timestamp of a variant, best-effort:
-// a failed touch only makes the entry look colder to eviction.
-func (c *Cache) touchVariant(ctx context.Context, cacheKey VariantKey) {
-	_, err := c.db.ExecContext(ctx, `
-		UPDATE variant_content SET last_accessed_at = CURRENT_TIMESTAMP
-		WHERE cache_key = ?
-	`, string(cacheKey))
-	if err != nil {
-		c.log.Debug("failed to touch variant LRU timestamp",
-			"cache_key", cacheKey, "error", err)
-	}
-}
-
-// touchSourceContent updates the LRU timestamp of a source content
-// blob, best-effort: a failed touch only makes the blob look colder.
-func (c *Cache) touchSourceContent(ctx context.Context, contentHash ContentHash) {
-	_, err := c.db.ExecContext(ctx, `
-		UPDATE source_content SET last_accessed_at = CURRENT_TIMESTAMP
-		WHERE content_hash = ?
-	`, string(contentHash))
-	if err != nil {
-		c.log.Debug("failed to touch source content LRU timestamp",
-			"content_hash", contentHash, "error", err)
-	}
-}
-
-// checkNegativeCache checks if a request is in the negative cache.
+// checkNegativeCache checks if a request is in the negative cache. It only
+// reads: a row past its expiry is not a hit, and the eviction goroutine
+// deletes it with the other expired rows (see CleanExpired).
 func (c *Cache) checkNegativeCache(
-	ctx context.Context, req *ImageRequest,
+	ctx context.Context, req *imagerequest.Request,
 ) (bool, error) {
 	var expiresAt time.Time
 
 	err := c.db.QueryRowContext(ctx, `
 		SELECT expires_at FROM negative_cache
 		WHERE source_host = ? AND source_path = ? AND source_query = ?
-	`, req.SourceHost, req.SourcePath, req.SourceQuery).Scan(&expiresAt)
+	`, req.Source.Host, req.Source.Path, req.Source.Query).Scan(&expiresAt)
 
 	if errors.Is(err, sql.ErrNoRows) {
 		return false, nil
@@ -756,22 +409,9 @@ func (c *Cache) checkNegativeCache(
 		return false, fmt.Errorf("failed to check negative cache: %w", err)
 	}
 
-	// Check if expired
-	if time.Now().After(expiresAt) {
-		// Clean up expired entry
-		_, err = c.db.ExecContext(ctx, `
-			DELETE FROM negative_cache
-			WHERE source_host = ? AND source_path = ? AND source_query = ?
-		`, req.SourceHost, req.SourcePath, req.SourceQuery)
-		if err != nil {
-			c.log.Warn("failed to delete expired negative cache entry",
-				"host", req.SourceHost, "path", req.SourcePath, "error", err)
-		}
+	expired := time.Now().After(expiresAt)
 
-		return false, nil
-	}
-
-	return true, nil
+	return !expired, nil
 }
 
 // cleanExpiredBatch deletes up to cleanExpiredBatchSize negative cache

internal/imgcache/cache_hit_internal_test.go

@@ -0,0 +1,303 @@
+package imgcache
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"image/color"
+	"io"
+	"os"
+	"testing"
+	"time"
+
+	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
+	"sneak.berlin/go/pixa/internal/magic"
+)
+
+// TestGetVariant_ContentTypeFromFirstBytes stores an image in each output
+// format as a variant and checks that GetVariant serves it whole with the
+// content type of its format, read from the file.
+func TestGetVariant_ContentTypeFromFirstBytes(t *testing.T) {
+	t.Parallel()
+
+	cache, _ := newEvictionTestCache(t, 1<<30)
+	processor := imageprocessor.New(imageprocessor.Params{
+		MaxInputBytes:           50 << 20,
+		MaxConcurrentProcessing: 1,
+	})
+	source := generateTestJPEG(t, 40, 30, color.RGBA{200, 40, 40, 255})
+
+	for _, format := range []imagerequest.Format{
+		imagerequest.FormatJPEG, imagerequest.FormatPNG, imagerequest.FormatGIF,
+		imagerequest.FormatWebP, imagerequest.FormatAVIF, imagerequest.FormatJXL,
+	} {
+		result, err := processor.Process(t.Context(), bytes.NewReader(source),
+			&imagerequest.Transform{
+				Size:    imagerequest.Size{Width: 20, Height: 15},
+				Format:  format,
+				Quality: 85,
+				FitMode: imagerequest.FitCover,
+			})
+		if err != nil {
+			t.Fatalf("making a %s image: %v", format, err)
+		}
+
+		image, err := io.ReadAll(result.Content)
+		if err != nil {
+			t.Fatalf("reading the %s image: %v", format, err)
+		}
+
+		key := imagerequest.VariantKey("aabbccdd10" + string(format))
+
+		err = cache.StoreVariant(t.Context(), key, bytes.NewReader(image))
+		if err != nil {
+			t.Fatalf("StoreVariant(%s) error = %v", format, err)
+		}
+
+		reader, size, contentType, err := cache.GetVariant(key)
+		if err != nil {
+			t.Fatalf("GetVariant(%s) error = %v", format, err)
+		}
+
+		served, err := io.ReadAll(reader)
+		_ = reader.Close()
+
+		if err != nil {
+			t.Fatalf("reading the %s variant: %v", format, err)
+		}
+
+		t.Logf("%s: %d bytes served as %s", format, size, contentType)
+
+		if want := imageprocessor.FormatToMIME(format); contentType != want {
+			t.Errorf("%s variant content type = %q, want %q", format, contentType, want)
+		}
+
+		if size != int64(len(image)) || !bytes.Equal(served, image) {
+			t.Errorf("%s variant served %d bytes, size %d, want the %d bytes stored",
+				format, len(served), size, len(image))
+		}
+	}
+}
+
+// TestGetVariant_RefusesFileOfNoOutputFormat checks that GetVariant refuses
+// a variant file whose first bytes are not those of an output format, with
+// an error other than ErrNotFound, and that a variant with no file, or any
+// variant of a disabled cache, is ErrNotFound.
+func TestGetVariant_RefusesFileOfNoOutputFormat(t *testing.T) {
+	t.Parallel()
+
+	cache, _ := newEvictionTestCache(t, 1<<30)
+	jpegImage := generateTestJPEG(t, 10, 10, color.RGBA{0, 0, 255, 255})
+
+	tests := []struct {
+		name    string
+		content []byte
+		wantErr error
+	}{
+		{"text", []byte("this is text, not an image"), magic.ErrUnknownFormat},
+		{"SVG", []byte(`<svg xmlns="http://www.w3.org/2000/svg"></svg>`),
+			errNotAnOutputFormat},
+		{"JPEG cut to 10 bytes", jpegImage[:10], io.EOF},
+		{"empty", nil, io.EOF},
+	}
+
+	for i, tt := range tests {
+		key := imagerequest.VariantKey(fmt.Sprintf("aabbccdd20%02d", i))
+
+		_, err := cache.variants.Store(key, bytes.NewReader(tt.content))
+		if err != nil {
+			t.Fatalf("%s: storing the variant file: %v", tt.name, err)
+		}
+
+		reader, _, contentType, err := cache.GetVariant(key)
+		t.Logf("%s: GetVariant() error = %v", tt.name, err)
+
+		if reader != nil || contentType != "" || !errors.Is(err, tt.wantErr) {
+			t.Errorf("%s: GetVariant() = reader %v, content type %q, error %v; "+
+				"want no reader and %v", tt.name, reader, contentType, err, tt.wantErr)
+		}
+	}
+
+	reader, _, _, err := cache.GetVariant(testVariantKeyFour)
+	if reader != nil || !errors.Is(err, ErrNotFound) {
+		t.Errorf("GetVariant() of a variant with no file = reader %v, error %v; "+
+			"want no reader and %v", reader, err, ErrNotFound)
+	}
+
+	disabled, _ := newEvictionTestCache(t, 0)
+
+	reader, _, _, err = disabled.GetVariant(testVariantKeyOne)
+	if reader != nil || !errors.Is(err, ErrNotFound) {
+		t.Errorf("GetVariant() on a disabled cache = reader %v, error %v; "+
+			"want no reader and %v", reader, err, ErrNotFound)
+	}
+}
+
+// TestService_Get_MakesAgainVariantOfNoOutputFormat replaces a cached
+// variant's file with text, and checks that the next request is a miss
+// answered with the variant made again, and the one after a hit.
+func TestService_Get_MakesAgainVariantOfNoOutputFormat(t *testing.T) {
+	t.Parallel()
+
+	svc, fixtures := SetupTestService(t)
+	req := photoVariant(fixtures, 85, imagerequest.FitCover)
+
+	want, _ := getImage(t, svc, req)
+
+	path := svc.cache.variants.keyToPath(imagerequest.CacheKey(req))
+
+	err := os.WriteFile(path, []byte("this is text, not an image"), StorageFilePerm)
+	if err != nil {
+		t.Fatalf("replacing the variant file: %v", err)
+	}
+
+	got, status := getImage(t, svc, req)
+	t.Logf("after the replacement: %d bytes, %s", len(got), status)
+
+	if status != CacheMiss || !bytes.Equal(got, want) {
+		t.Errorf("after the replacement: Get() = %d bytes, %s; want the %d bytes "+
+			"made again, %s", len(got), status, len(want), CacheMiss)
+	}
+
+	got, status = getImage(t, svc, req)
+
+	if status != CacheHit || !bytes.Equal(got, want) {
+		t.Errorf("next request: Get() = %d bytes, %s; want the %d bytes, %s",
+			len(got), status, len(want), CacheHit)
+	}
+}
+
+// TestService_Get_HitWaitsForNoDatabaseWrite holds the database's one
+// connection while a cached variant is requested. The hit must be answered
+// while the connection is still held, and its access time must reach the
+// database once it is free.
+func TestService_Get_HitWaitsForNoDatabaseWrite(t *testing.T) {
+	t.Parallel()
+
+	svc, fixtures := SetupTestService(t)
+	req := photoVariant(fixtures, 85, imagerequest.FitCover)
+	key := imagerequest.CacheKey(req)
+
+	getImage(t, svc, req)
+
+	// Each connection to an in-memory SQLite database opens a new, empty one,
+	// so the goroutine that writes the access times must share the
+	// connection that holds the schema.
+	svc.cache.db.SetMaxOpenConns(1)
+	svc.cache.StartPendingAccessTimeWrites()
+
+	defer func() { _ = svc.cache.StopPendingAccessTimeWrites(t.Context()) }()
+
+	anHourAgo := time.Now().Add(-time.Hour)
+	setVariantLastAccessed(t, svc.cache, key, anHourAgo)
+
+	releaseDatabase := holdDatabase(t, svc.cache)
+	defer releaseDatabase()
+
+	results := startGet(t.Context(), svc, req)
+
+	select {
+	case got := <-results:
+		if got.err != nil {
+			t.Fatalf("Get() of the cached variant error = %v", got.err)
+		}
+	case <-time.After(pendingAccessTimesWait):
+		t.Fatal("the cache hit waited for the database")
+	}
+
+	releaseDatabase()
+
+	deadline := time.Now().Add(pendingAccessTimesWait)
+
+	for countRows(t, svc.cache, `
+		SELECT COUNT(*) FROM variant_content
+		WHERE cache_key = ? AND last_accessed_at > ?
+	`, string(key), anHourAgo.UTC().Format(sqliteTimestampFormat)) == 0 {
+		if time.Now().After(deadline) {
+			t.Fatal("the hit's access time was not written")
+		}
+
+		time.Sleep(10 * time.Millisecond)
+	}
+}
+
+// TestTouchVariantAndTouchSourceContent_DropAccessTimesPastTheLimit hands one
+// more access time of a variant, and one more of a source, than may wait to
+// be written. touchVariant and touchSourceContent must return each time
+// without waiting, and the last of each must be dropped.
+func TestTouchVariantAndTouchSourceContent_DropAccessTimesPastTheLimit(t *testing.T) {
+	t.Parallel()
+
+	cache, _ := newEvictionTestCache(t, 1<<30)
+
+	done := make(chan struct{})
+
+	go func() {
+		defer close(done)
+
+		for range maxPendingAccessTimes + 1 {
+			cache.touchVariant(testVariantKeyOne)
+			cache.touchSourceContent("aabbccdd3001")
+		}
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(pendingAccessTimesWait):
+		t.Fatal("touchVariant or touchSourceContent waited once the access " +
+			"times reached the limit")
+	}
+
+	if waiting := len(cache.pendingVariantAccessTimes); waiting != maxPendingAccessTimes {
+		t.Errorf("%d access times of variants wait to be written, want %d",
+			waiting, maxPendingAccessTimes)
+	}
+
+	if waiting := len(cache.pendingSourceAccessTimes); waiting != maxPendingAccessTimes {
+		t.Errorf("%d access times of sources wait to be written, want %d",
+			waiting, maxPendingAccessTimes)
+	}
+}
+
+// TestStopPendingAccessTimeWrites_WritesPendingAccessTimes hands the access
+// time of one of two variants, three times, then stops the goroutine that
+// writes them, which never started. The stop must write that access time and
+// leave the other variant's.
+func TestStopPendingAccessTimeWrites_WritesPendingAccessTimes(t *testing.T) {
+	t.Parallel()
+
+	cache, _ := newEvictionTestCache(t, 1<<30)
+	anHourAgo := time.Now().Add(-time.Hour)
+
+	for _, key := range []imagerequest.VariantKey{testVariantKeyOne, testVariantKeyTwo} {
+		storeEvictionTestVariant(t, cache, key, []byte("variant bytes"))
+		setVariantLastAccessed(t, cache, key, anHourAgo)
+	}
+
+	for range 3 {
+		cache.touchVariant(testVariantKeyOne)
+	}
+
+	err := cache.StopPendingAccessTimeWrites(t.Context())
+	if err != nil {
+		t.Fatalf("StopPendingAccessTimeWrites() error = %v", err)
+	}
+
+	for key, wantTouched := range map[imagerequest.VariantKey]int{
+		testVariantKeyOne: 1, testVariantKeyTwo: 0,
+	} {
+		touched := countRows(t, cache, `
+			SELECT COUNT(*) FROM variant_content
+			WHERE cache_key = ? AND last_accessed_at > ?
+		`, string(key), anHourAgo.UTC().Format(sqliteTimestampFormat))
+		if touched != wantTouched {
+			t.Errorf("variant %s: %d rows with a new access time, want %d",
+				key, touched, wantTouched)
+		}
+	}
+
+	if waiting := len(cache.pendingVariantAccessTimes); waiting != 0 {
+		t.Errorf("%d access times still wait to be written, want 0", waiting)
+	}
+}

internal/imgcache/cache_internal_test.go

@@ -1,15 +1,14 @@
 package imgcache
 
 import (
-	"bytes"
 	"context"
 	"database/sql"
 	"os"
 	"testing"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
 	_ "modernc.org/sqlite"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
 )
 
 func setupTestDB(t *testing.T) *sql.DB {
@@ -23,67 +22,18 @@ func setupTestDB(t *testing.T) *sql.DB {
 	// Create schema
 	schema := `
 		CREATE TABLE source_content (
-			content_hash TEXT PRIMARY KEY,
-			content_type TEXT NOT NULL,
+			source_key TEXT PRIMARY KEY,
 			size_bytes INTEGER NOT NULL,
-			fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP
-		);
-		CREATE TABLE source_metadata (
-			id INTEGER PRIMARY KEY AUTOINCREMENT,
-			source_host TEXT NOT NULL,
-			source_path TEXT NOT NULL,
-			source_query TEXT NOT NULL DEFAULT '',
-			path_hash TEXT NOT NULL,
-			content_hash TEXT,
-			status_code INTEGER NOT NULL,
-			content_type TEXT,
-			response_headers TEXT,
-			fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
-			expires_at DATETIME,
-			etag TEXT,
-			last_modified TEXT,
-			UNIQUE(source_host, source_path, source_query)
-		);
-		CREATE TABLE output_content (
-			content_hash TEXT PRIMARY KEY,
-			content_type TEXT NOT NULL,
-			size_bytes INTEGER NOT NULL,
-			fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP
-		);
-		CREATE TABLE request_cache (
-			id INTEGER PRIMARY KEY AUTOINCREMENT,
-			cache_key TEXT NOT NULL UNIQUE,
-			source_metadata_id INTEGER NOT NULL,
-			output_hash TEXT NOT NULL,
-			width INTEGER NOT NULL,
-			height INTEGER NOT NULL,
-			format TEXT NOT NULL,
-			quality INTEGER NOT NULL DEFAULT 85,
-			fit_mode TEXT NOT NULL DEFAULT 'cover',
-			fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
-			access_count INTEGER NOT NULL DEFAULT 1
+			last_accessed_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
 		);
 		CREATE TABLE negative_cache (
 			id INTEGER PRIMARY KEY AUTOINCREMENT,
 			source_host TEXT NOT NULL,
 			source_path TEXT NOT NULL,
 			source_query TEXT NOT NULL DEFAULT '',
-			status_code INTEGER NOT NULL,
-			error_message TEXT,
-			fetched_at DATETIME DEFAULT CURRENT_TIMESTAMP,
 			expires_at DATETIME NOT NULL,
 			UNIQUE(source_host, source_path, source_query)
 		);
-		CREATE TABLE cache_stats (
-			id INTEGER PRIMARY KEY CHECK (id = 1),
-			hit_count INTEGER NOT NULL DEFAULT 0,
-			miss_count INTEGER NOT NULL DEFAULT 0,
-			upstream_fetch_count INTEGER NOT NULL DEFAULT 0,
-			upstream_fetch_bytes INTEGER NOT NULL DEFAULT 0,
-			transform_count INTEGER NOT NULL DEFAULT 0,
-			last_updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
-		);
-		INSERT INTO cache_stats (id) VALUES (1);
 	`
 
 	_, err = db.ExecContext(t.Context(), schema)
@@ -94,361 +44,6 @@ func setupTestDB(t *testing.T) *sql.DB {
 	return db
 }
 
-func setupTestCache(t *testing.T) *Cache {
-	t.Helper()
-
-	tmpDir := t.TempDir()
-	db := setupTestDB(t)
-
-	cache, err := NewCache(db, CacheConfig{
-		StateDir:    tmpDir,
-		NegativeTTL: 5 * time.Minute,
-	})
-	if err != nil {
-		t.Fatalf("failed to create cache: %v", err)
-	}
-
-	return cache
-}
-
-func TestCache_LookupMiss(t *testing.T) {
-	t.Parallel()
-
-	cache := setupTestCache(t)
-	ctx := context.Background()
-
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: testPathCat,
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
-	}
-
-	result, err := cache.Lookup(ctx, req)
-	if err != nil {
-		t.Fatalf("Lookup() error = %v", err)
-	}
-
-	if result.Hit {
-		t.Error("Lookup() hit = true, want false for cache miss")
-	}
-
-	if result.CacheStatus != CacheMiss {
-		t.Errorf("Lookup() status = %v, want %v", result.CacheStatus, CacheMiss)
-	}
-}
-
-func TestCache_StoreAndLookup(t *testing.T) {
-	t.Parallel()
-
-	cache := setupTestCache(t)
-	ctx := context.Background()
-
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: testPathCat,
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
-	}
-
-	// Store source content
-	sourceContent := []byte("fake jpeg data")
-	fetchResult := &httpfetcher.FetchResult{
-		ContentType: testContentTypeJPEG,
-		Headers:     map[string][]string{testHeaderContentType: {testContentTypeJPEG}},
-	}
-
-	contentHash, err := cache.StoreSource(
-		ctx, req, bytes.NewReader(sourceContent), fetchResult)
-	if err != nil {
-		t.Fatalf("StoreSource() error = %v", err)
-	}
-
-	if contentHash == "" {
-		t.Error("StoreSource() returned empty hash")
-	}
-
-	// Store variant
-	cacheKey := CacheKey(req)
-	outputContent := []byte("fake webp data")
-
-	err = cache.StoreVariant(
-		t.Context(), cacheKey, bytes.NewReader(outputContent), "image/webp")
-	if err != nil {
-		t.Fatalf("StoreVariant() error = %v", err)
-	}
-
-	// Now lookup should hit
-	result, err := cache.Lookup(ctx, req)
-	if err != nil {
-		t.Fatalf("Lookup() error = %v", err)
-	}
-
-	if !result.Hit {
-		t.Error("Lookup() hit = false, want true after store")
-	}
-
-	if result.CacheStatus != CacheHit {
-		t.Errorf("Lookup() status = %v, want %v", result.CacheStatus, CacheHit)
-	}
-
-	if result.CacheKey == "" {
-		t.Error("Lookup() returned empty cache key")
-	}
-}
-
-func TestCache_NegativeCache(t *testing.T) {
-	t.Parallel()
-
-	cache := setupTestCache(t)
-	ctx := context.Background()
-
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/notfound.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-	}
-
-	// Store negative cache entry
-	err := cache.StoreNegative(ctx, req, 404, "not found")
-	if err != nil {
-		t.Fatalf("StoreNegative() error = %v", err)
-	}
-
-	// Lookup should return miss (negative cache is checked at service level)
-	result, err := cache.Lookup(ctx, req)
-	if err != nil {
-		t.Fatalf("Lookup() error = %v", err)
-	}
-
-	if result.Hit {
-		t.Error("Lookup() hit = true, want false for negative cache entry")
-	}
-}
-
-func TestCache_NegativeCacheExpiry(t *testing.T) {
-	t.Parallel()
-
-	tmpDir := t.TempDir()
-	db := setupTestDB(t)
-
-	// Very short negative TTL for testing
-	cache, err := NewCache(db, CacheConfig{
-		StateDir:    tmpDir,
-		NegativeTTL: 1 * time.Millisecond,
-	})
-	if err != nil {
-		t.Fatalf("failed to create cache: %v", err)
-	}
-
-	ctx := context.Background()
-
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/expired.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-	}
-
-	// Store negative cache entry
-	err = cache.StoreNegative(ctx, req, 404, "not found")
-	if err != nil {
-		t.Fatalf("StoreNegative() error = %v", err)
-	}
-
-	// Wait for expiry
-	time.Sleep(10 * time.Millisecond)
-
-	// Lookup should return miss after expiry
-	result, err := cache.Lookup(ctx, req)
-	if err != nil {
-		t.Fatalf("Lookup() error = %v, want nil after expiry", err)
-	}
-
-	if result.Hit {
-		t.Error("Lookup() hit = true, want false after negative cache expiry")
-	}
-}
-
-func TestCache_VariantLookup(t *testing.T) {
-	t.Parallel()
-
-	cache := setupTestCache(t)
-	ctx := context.Background()
-
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/variant.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
-	}
-
-	// Store variant
-	cacheKey := CacheKey(req)
-	outputContent := []byte("output data")
-
-	err := cache.StoreVariant(
-		t.Context(), cacheKey, bytes.NewReader(outputContent), "image/webp")
-	if err != nil {
-		t.Fatalf("StoreVariant() error = %v", err)
-	}
-
-	// First lookup
-	result1, err := cache.Lookup(ctx, req)
-	if err != nil {
-		t.Fatalf("Lookup() first error = %v", err)
-	}
-
-	if !result1.Hit {
-		t.Error("Lookup() first hit = false")
-	}
-
-	// Second lookup should also hit (from disk)
-	result2, err := cache.Lookup(ctx, req)
-	if err != nil {
-		t.Fatalf("Lookup() second error = %v", err)
-	}
-
-	if !result2.Hit {
-		t.Error("Lookup() second hit = false")
-	}
-
-	if result1.CacheKey != result2.CacheKey {
-		t.Error("Lookup() returned different cache keys")
-	}
-}
-
-func TestCache_GetVariant_ReturnsContentType(t *testing.T) {
-	t.Parallel()
-
-	cache := setupTestCache(t)
-	ctx := context.Background()
-
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/variantct.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
-	}
-
-	// Store variant
-	cacheKey := CacheKey(req)
-	outputContent := []byte("output webp data")
-
-	err := cache.StoreVariant(
-		t.Context(), cacheKey, bytes.NewReader(outputContent), "image/webp")
-	if err != nil {
-		t.Fatalf("StoreVariant() error = %v", err)
-	}
-
-	// Lookup
-	result, err := cache.Lookup(ctx, req)
-	if err != nil {
-		t.Fatalf("Lookup() error = %v", err)
-	}
-
-	if !result.Hit {
-		t.Fatal("Lookup() hit = false, want true")
-	}
-
-	// GetVariant should return content type
-	reader, size, contentType, err := cache.GetVariant(result.CacheKey)
-	if err != nil {
-		t.Fatalf("GetVariant() error = %v", err)
-	}
-
-	defer func() { _ = reader.Close() }()
-
-	if contentType != "image/webp" {
-		t.Errorf("GetVariant() ContentType = %q, want %q", contentType, "image/webp")
-	}
-
-	if size != int64(len(outputContent)) {
-		t.Errorf("GetVariant() size = %d, want %d", size, len(outputContent))
-	}
-}
-
-func TestCache_GetVariant(t *testing.T) {
-	t.Parallel()
-
-	cache := setupTestCache(t)
-	ctx := context.Background()
-
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/output.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
-	}
-
-	// Store variant
-	cacheKey := CacheKey(req)
-	outputContent := []byte("the actual output content")
-
-	err := cache.StoreVariant(
-		t.Context(), cacheKey, bytes.NewReader(outputContent), "image/webp")
-	if err != nil {
-		t.Fatalf("StoreVariant() error = %v", err)
-	}
-
-	// Lookup to get cache key
-	result, err := cache.Lookup(ctx, req)
-	if err != nil {
-		t.Fatalf("Lookup() error = %v", err)
-	}
-
-	// Get variant content
-	reader, _, _, err := cache.GetVariant(result.CacheKey)
-	if err != nil {
-		t.Fatalf("GetVariant() error = %v", err)
-	}
-
-	defer func() { _ = reader.Close() }()
-
-	buf := make([]byte, 100)
-	n, _ := reader.Read(buf)
-
-	if !bytes.Equal(buf[:n], outputContent) {
-		t.Errorf("GetVariant() content = %q, want %q", buf[:n], outputContent)
-	}
-}
-
-func TestCache_Stats(t *testing.T) {
-	t.Parallel()
-
-	cache := setupTestCache(t)
-	ctx := context.Background()
-
-	// Increment some stats
-	cache.IncrementStats(ctx, true, 0)
-	cache.IncrementStats(ctx, true, 0)
-	cache.IncrementStats(ctx, false, 1024)
-
-	stats, err := cache.Stats(ctx)
-	if err != nil {
-		t.Fatalf("Stats() error = %v", err)
-	}
-
-	if stats.HitCount != 2 {
-		t.Errorf("Stats() HitCount = %d, want 2", stats.HitCount)
-	}
-
-	if stats.MissCount != 1 {
-		t.Errorf("Stats() MissCount = %d, want 1", stats.MissCount)
-	}
-}
-
 func TestCache_CleanExpired(t *testing.T) {
 	t.Parallel()
 
@@ -458,15 +53,16 @@ func TestCache_CleanExpired(t *testing.T) {
 	cache, _ := NewCache(db, CacheConfig{
 		StateDir:    tmpDir,
 		NegativeTTL: 1 * time.Millisecond,
-	})
+		MaxBytes:    1 << 30,
+	}, prometheus.NewRegistry())
 
 	ctx := context.Background()
 
 	// Insert expired negative cache entry directly
 	_, err := db.ExecContext(ctx, `
 		INSERT INTO negative_cache
-			(source_host, source_path, source_query, status_code, expires_at)
-		VALUES ('example.com', '/old.jpg', '', 404, datetime('now', '-1 hour'))
+			(source_host, source_path, source_query, expires_at)
+		VALUES ('example.com', '/old.jpg', '', datetime('now', '-1 hour'))
 	`)
 	if err != nil {
 		t.Fatalf("failed to insert test data: %v", err)
@@ -509,7 +105,8 @@ func TestCache_StorageDirectoriesCreated(t *testing.T) {
 
 	_, err := NewCache(db, CacheConfig{
 		StateDir: tmpDir,
-	})
+		MaxBytes: 1 << 30,
+	}, prometheus.NewRegistry())
 	if err != nil {
 		t.Fatalf("NewCache() error = %v", err)
 	}
@@ -518,7 +115,6 @@ func TestCache_StorageDirectoriesCreated(t *testing.T) {
 	dirs := []string{
 		"cache/sources",
 		"cache/variants",
-		"cache/metadata",
 	}
 
 	for _, dir := range dirs {

internal/imgcache/cache_usage_internal_test.go

@@ -5,6 +5,8 @@ import (
 	"strconv"
 	"strings"
 	"testing"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // TestEvictionReadsTheUsageTotal adds, stores again, resizes and evicts
@@ -29,10 +31,10 @@ func TestEvictionReadsTheUsageTotal(t *testing.T) {
 	storeEvictionTestVariant(t, cache, testVariantKeyTwo,
 		bytes.Repeat([]byte{0x75}, 200))
 
-	// pixa never changes a source's size, but a statement that does must
-	// change the total too.
+	// Storing a source URL again changes its size, so the total must
+	// follow a statement that changes it.
 	_, err := cache.db.ExecContext(ctx,
-		`UPDATE source_content SET size_bytes = 900 WHERE content_hash = ?`,
+		`UPDATE source_content SET size_bytes = 900 WHERE source_key = ?`,
 		string(kept))
 	if err != nil {
 		t.Fatalf("failed to change the source's size: %v", err)
@@ -153,8 +155,9 @@ func TestUsageTotalNotCorrectedFromAnOlderSum(t *testing.T) {
 // pass. No read the pass makes of a content table, to check its rows or
 // to sum them, may cover more than two rows, so a request's query waits
 // for one page at most. Between them the reads must still cover every
-// row of both tables twice, once to check it and once to sum it, and the
-// sum must put a wrong total right.
+// variant row twice, once to check it and once to sum it, and every
+// source row once, as source rows are read only to sum them, and the sum
+// must put a wrong total right.
 func TestReconciliationReadsAPageAtATime(t *testing.T) {
 	t.Parallel()
 
@@ -171,7 +174,8 @@ func TestReconciliationReadsAPageAtATime(t *testing.T) {
 
 		storeEvictionTestSource(t, cache, "pages.example.com",
 			"/"+strconv.Itoa(i)+".jpg", bytes.Repeat(content, 100))
-		storeEvictionTestVariant(t, cache, VariantKey("aabbccdd000"+strconv.Itoa(i)),
+		storeEvictionTestVariant(t, cache,
+			imagerequest.VariantKey("aabbccdd000"+strconv.Itoa(i)),
 			bytes.Repeat(content, 10))
 	}
 
@@ -204,9 +208,10 @@ func TestReconciliationReadsAPageAtATime(t *testing.T) {
 		coveredRows += rows
 	}
 
-	// Ten rows, each read once to check it and once to sum it.
-	if coveredRows != 20 {
-		t.Errorf("the reads covered %d rows in all, want 20", coveredRows)
+	// Five variant rows, each read once to check it and once to sum it,
+	// and five source rows, read only to sum them.
+	if coveredRows != 15 {
+		t.Errorf("the reads covered %d rows in all, want 15", coveredRows)
 	}
 
 	usage, err := cache.UsageBytes(ctx)

internal/imgcache/cachesize.go

@@ -1,85 +0,0 @@
-package imgcache
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"math"
-	"path/filepath"
-	"syscall"
-)
-
-// DefaultCacheMaxBytesFloor is the minimum computed default for the
-// cache_max_bytes setting: 500 MiB. The floor applies only to the
-// computed default (when the key is omitted from the configuration),
-// never to explicitly configured values.
-const DefaultCacheMaxBytesFloor int64 = 524288000
-
-// freeSpaceFractionNumerator and freeSpaceFractionDenominator express
-// the 75% share used for the computed default limit as integer
-// arithmetic (dividing before multiplying avoids overflow).
-const (
-	freeSpaceFractionNumerator   uint64 = 3
-	freeSpaceFractionDenominator uint64 = 4
-)
-
-var errNegativeBlockSize = errors.New("statfs reported negative block size")
-
-// FreeSpaceProbeFunc reports the number of free bytes available on the
-// filesystem containing path. It is a function type so tests can
-// inject a fake probe instead of depending on the host disk.
-type FreeSpaceProbeFunc func(path string) (uint64, error)
-
-// defaultFreeSpaceProbe reports free filesystem bytes via statfs on
-// the given path, as available to unprivileged processes.
-func defaultFreeSpaceProbe(path string) (uint64, error) {
-	var stat syscall.Statfs_t
-
-	err := syscall.Statfs(path, &stat)
-	if err != nil {
-		return 0, err
-	}
-
-	if stat.Bsize < 0 {
-		return 0, fmt.Errorf("%w %d for %q", errNegativeBlockSize, stat.Bsize, path)
-	}
-
-	blockSize := uint64(stat.Bsize)
-
-	return stat.Bavail * blockSize, nil
-}
-
-// computeDefaultMaxBytes returns the default cache size limit: 75% of
-// the sum of the free bytes probe reports for <state_dir>/cache/ and
-// the bytes the cache already holds, with a floor of
-// DefaultCacheMaxBytesFloor. Counting what the cache holds keeps the
-// limit from shrinking as the cache fills.
-func (c *Cache) computeDefaultMaxBytes(
-	ctx context.Context, probe FreeSpaceProbeFunc,
-) (int64, error) {
-	cacheDir := filepath.Join(c.config.StateDir, "cache")
-
-	freeBytes, err := probe(cacheDir)
-	if err != nil {
-		return 0, fmt.Errorf(
-			"default cache_max_bytes: cannot determine free space for %q: %w",
-			cacheDir, err)
-	}
-
-	usedBytes, err := c.UsageBytes(ctx)
-	if err != nil {
-		return 0, err
-	}
-
-	// Both terms are at most math.MaxInt64, so the sum cannot overflow.
-	//nolint:gosec // G115: UsageBytes returns the total cache usage, never negative
-	spaceBytes := min(freeBytes, math.MaxInt64) + uint64(usedBytes)
-
-	computed := spaceBytes / freeSpaceFractionDenominator * freeSpaceFractionNumerator
-	computed = min(computed, math.MaxInt64)
-
-	limit := int64(computed)
-	limit = max(limit, DefaultCacheMaxBytesFloor)
-
-	return limit, nil
-}

internal/imgcache/cachesize_internal_test.go

@@ -1,188 +0,0 @@
-package imgcache
-
-import (
-	"errors"
-	"os"
-	"path/filepath"
-	"strings"
-	"testing"
-)
-
-// Static errors returned by the stub free-space probes below.
-var (
-	errTestStatfsFailed     = errors.New("statfs failed")
-	errTestProbeNotExpected = errors.New("probe must not be called")
-)
-
-// TestComputeDefaultMaxBytesCountsWhatTheCacheHolds verifies that the
-// default limit is 75% of the free space plus what the cache already
-// holds, so a cache filled to its limit keeps that limit across a
-// restart instead of shrinking to 75% of the space left free.
-func TestComputeDefaultMaxBytesCountsWhatTheCacheHolds(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<30)
-
-	// Empty cache, 4 GiB free -> 3 GiB default.
-	got, err := cache.computeDefaultMaxBytes(t.Context(),
-		func(string) (uint64, error) { return 4294967296, nil })
-	if err != nil {
-		t.Fatalf("computeDefaultMaxBytes returned error: %v", err)
-	}
-
-	t.Logf("default for an empty cache with 4 GiB free: %d", got)
-
-	if got != 3221225472 {
-		t.Errorf("default for an empty cache = %d, want 3221225472 (75%% of 4 GiB)",
-			got)
-	}
-
-	// The cache now holds those 3 GiB, which leaves 1 GiB free.
-	_, err = cache.db.ExecContext(t.Context(),
-		`INSERT INTO variant_content (cache_key, size_bytes, content_type)
-		 VALUES (?, ?, ?)`,
-		string(testVariantKeyOne), 3221225472, testContentTypeWebP,
-	)
-	if err != nil {
-		t.Fatalf("failed to insert variant accounting row: %v", err)
-	}
-
-	got, err = cache.computeDefaultMaxBytes(t.Context(),
-		func(string) (uint64, error) { return 1073741824, nil })
-	if err != nil {
-		t.Fatalf("computeDefaultMaxBytes returned error: %v", err)
-	}
-
-	t.Logf("default for a cache holding 3 GiB with 1 GiB free: %d", got)
-
-	if got != 3221225472 {
-		t.Errorf("default for a cache holding 3 GiB with 1 GiB free = %d, "+
-			"want 3221225472 (75%% of 1 GiB + 3 GiB)", got)
-	}
-}
-
-// TestComputeDefaultMaxBytesAppliesFloor verifies that when 75% of the
-// free space plus what the cache holds is below 500 MiB, the default
-// is floored at DefaultCacheMaxBytesFloor.
-func TestComputeDefaultMaxBytesAppliesFloor(t *testing.T) {
-	t.Parallel()
-
-	cases := []struct {
-		name      string
-		freeBytes uint64
-	}{
-		{name: "100 MiB free", freeBytes: 104857600},
-		{name: "zero free", freeBytes: 0},
-		{name: "just below floor threshold", freeBytes: 699050665},
-	}
-
-	for _, tc := range cases {
-		t.Run(tc.name, func(t *testing.T) {
-			t.Parallel()
-
-			cache, _ := newEvictionTestCache(t, 1<<30)
-
-			got, err := cache.computeDefaultMaxBytes(t.Context(),
-				func(string) (uint64, error) { return tc.freeBytes, nil })
-			if err != nil {
-				t.Fatalf("computeDefaultMaxBytes returned error: %v", err)
-			}
-
-			if got != DefaultCacheMaxBytesFloor {
-				t.Errorf("computeDefaultMaxBytes = %d, want floor %d",
-					got, DefaultCacheMaxBytesFloor)
-			}
-		})
-	}
-}
-
-// TestComputeDefaultMaxBytesPropagatesProbeError verifies that a
-// failing free-space probe produces an error naming cache_max_bytes,
-// instead of a silently wrong default.
-func TestComputeDefaultMaxBytesPropagatesProbeError(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<30)
-
-	_, err := cache.computeDefaultMaxBytes(t.Context(),
-		func(string) (uint64, error) { return 0, errTestStatfsFailed })
-	if err == nil {
-		t.Fatal("probe failure must produce an error, got nil")
-	}
-
-	t.Logf("got expected error: %v", err)
-
-	if !strings.Contains(err.Error(), "cache_max_bytes") {
-		t.Errorf("error %q does not name cache_max_bytes", err.Error())
-	}
-}
-
-// TestNewCacheComputesDefaultMaxBytesWhenAsked verifies that with
-// UseDefaultMaxBytes set, the cache's limit becomes the computed
-// default, and that the probe is pointed at <state_dir>/cache/, which
-// must be created first so statfs measures the right filesystem.
-func TestNewCacheComputesDefaultMaxBytesWhenAsked(t *testing.T) {
-	t.Parallel()
-
-	stateDir := t.TempDir()
-	wantCacheDir := filepath.Join(stateDir, "cache")
-
-	var probedPath string
-
-	// 4 GiB free -> 3 GiB default.
-	probe := func(path string) (uint64, error) {
-		probedPath = path
-
-		info, err := os.Stat(path)
-		if err != nil || !info.IsDir() {
-			t.Errorf("cache directory %q was not created before probing: info=%v err=%v",
-				path, info, err)
-		}
-
-		return 4294967296, nil
-	}
-
-	cache, err := newCache(evictionTestDB(t), CacheConfig{
-		StateDir:           stateDir,
-		UseDefaultMaxBytes: true,
-	}, probe)
-	if err != nil {
-		t.Fatalf("newCache returned error: %v", err)
-	}
-
-	if cache.config.MaxBytes != 3221225472 {
-		t.Errorf("MaxBytes = %d, want computed default 3221225472",
-			cache.config.MaxBytes)
-	}
-
-	if probedPath != wantCacheDir {
-		t.Errorf("free space probed at %q, want cache directory %q",
-			probedPath, wantCacheDir)
-	}
-}
-
-// TestNewCacheKeepsExplicitMaxBytes verifies that without
-// UseDefaultMaxBytes the cache keeps MaxBytes exactly as given and
-// never consults the free-space probe.
-func TestNewCacheKeepsExplicitMaxBytes(t *testing.T) {
-	t.Parallel()
-
-	probe := func(string) (uint64, error) {
-		t.Error("free-space probe must not be consulted for explicit values")
-
-		return 0, errTestProbeNotExpected
-	}
-
-	cache, err := newCache(evictionTestDB(t), CacheConfig{
-		StateDir: t.TempDir(),
-		MaxBytes: 1024,
-	}, probe)
-	if err != nil {
-		t.Fatalf("newCache returned error: %v", err)
-	}
-
-	if cache.config.MaxBytes != 1024 {
-		t.Errorf("MaxBytes = %d, want explicit 1024 (no floor, no recompute)",
-			cache.config.MaxBytes)
-	}
-}

internal/imgcache/concurrent_misses_internal_test.go

@@ -16,6 +16,7 @@ import (
 	"github.com/getsentry/sentry-go"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/magic"
 )
 
@@ -35,7 +36,7 @@ type heldFetcher struct {
 }
 
 func (f *heldFetcher) Fetch(
-	ctx context.Context, url string,
+	ctx context.Context, source imagerequest.Source,
 ) (*httpfetcher.FetchResult, error) {
 	f.fetches.Add(1)
 
@@ -47,7 +48,7 @@ func (f *heldFetcher) Fetch(
 		return nil, ctx.Err()
 	}
 
-	return f.upstream.Fetch(ctx, url)
+	return f.upstream.Fetch(ctx, source)
 }
 
 // releaseFetches lets every held fetch, and every later one, go on.
@@ -78,16 +79,22 @@ func setupHeldFetchService(t *testing.T) (*Service, *TestFixtures, *heldFetcher)
 }
 
 // photoVariant asks for the test photo, 100x100, at 50x25 as a JPEG of the
-// given quality and fit mode. Each call returns a new request, as Get writes
-// to the request it is given.
-func photoVariant(fixtures *TestFixtures, quality int, fit FitMode) *ImageRequest {
-	return &ImageRequest{
-		SourceHost: fixtures.GoodHost,
-		SourcePath: testPathPhoto,
-		Size:       Size{Width: 50, Height: 25},
-		Format:     FormatJPEG,
-		Quality:    quality,
-		FitMode:    fit,
+// given quality and fit mode. Each call returns a new request, which a test
+// may change.
+func photoVariant(
+	fixtures *TestFixtures, quality int, fit imagerequest.Fit,
+) *imagerequest.Request {
+	return &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: fixtures.GoodHost,
+			Path: testPathPhoto,
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 50, Height: 25},
+			Format:  imagerequest.FormatJPEG,
+			Quality: quality,
+			FitMode: fit,
+		},
 	}
 }
 
@@ -100,7 +107,7 @@ type getResult struct {
 // startGet calls Get in a goroutine of its own and delivers what it returned
 // on the channel.
 func startGet(
-	ctx context.Context, svc *Service, req *ImageRequest,
+	ctx context.Context, svc *Service, req *imagerequest.Request,
 ) <-chan getResult {
 	results := make(chan getResult, 1)
 
@@ -146,7 +153,7 @@ func TestService_Get_ConcurrentMissesShareOneFetch(t *testing.T) {
 	pending := make([]<-chan getResult, 0, requests)
 	for range requests {
 		pending = append(pending,
-			startGet(t.Context(), svc, photoVariant(fixtures, 85, FitCover)))
+			startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover)))
 	}
 
 	<-fetcher.started
@@ -184,9 +191,9 @@ func TestService_Get_ConcurrentMissesShareOneFetch(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	want := cacheStatsCounters{0, requests, 1, int64(len(photo)), 1}
+	want := counterValues{0, requests, 1, int64(len(photo)), 1}
 
-	if got := readCacheStatsCounters(t, svc.cache); got != want {
+	if got := readCounters(svc.cache); got != want {
 		t.Errorf("counters = %+v, want %+v", got, want)
 	}
 }
@@ -199,9 +206,11 @@ func TestService_Get_ConcurrentVariantsStayApart(t *testing.T) {
 
 	svc, fixtures, fetcher := setupHeldFetchService(t)
 
-	cover := startGet(t.Context(), svc, photoVariant(fixtures, 85, FitCover))
-	lowQuality := startGet(t.Context(), svc, photoVariant(fixtures, 40, FitCover))
-	contain := startGet(t.Context(), svc, photoVariant(fixtures, 85, FitContain))
+	cover := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
+	lowQuality := startGet(t.Context(), svc,
+		photoVariant(fixtures, 40, imagerequest.FitCover))
+	contain := startGet(t.Context(), svc,
+		photoVariant(fixtures, 85, imagerequest.FitContain))
 
 	for range 3 {
 		select {
@@ -253,12 +262,12 @@ func TestService_Get_WaiterStopsWhenItsContextEnds(t *testing.T) {
 
 	svc, fixtures, fetcher := setupHeldFetchService(t)
 
-	first := startGet(t.Context(), svc, photoVariant(fixtures, 85, FitCover))
+	first := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 
 	<-fetcher.started
 
 	waiterCtx, cancelWaiter := context.WithCancel(t.Context())
-	waiter := startGet(waiterCtx, svc, photoVariant(fixtures, 85, FitCover))
+	waiter := startGet(waiterCtx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 
 	time.Sleep(arrivalWait)
 	cancelWaiter()
@@ -300,11 +309,11 @@ func TestService_Get_FirstRequestLeavingKeepsTheWork(t *testing.T) {
 	svc, fixtures, fetcher := setupHeldFetchService(t)
 
 	firstCtx, cancelFirst := context.WithCancel(t.Context())
-	first := startGet(firstCtx, svc, photoVariant(fixtures, 85, FitCover))
+	first := startGet(firstCtx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 
 	<-fetcher.started
 
-	second := startGet(t.Context(), svc, photoVariant(fixtures, 85, FitCover))
+	second := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 
 	time.Sleep(arrivalWait)
 	cancelFirst()
@@ -331,8 +340,7 @@ func TestService_Get_FirstRequestLeavingKeepsTheWork(t *testing.T) {
 // TestService_Get_ConcurrentMissesShareAFailure has several requests for an
 // image that cannot be served arrive while its fetch is held: the one fetch
 // answers all of them with its error. The request after them is answered from
-// the negative cache when the failure is kept there, and fetches again when it
-// is not.
+// the negative cache, where the failure is kept.
 func TestService_Get_ConcurrentMissesShareAFailure(t *testing.T) {
 	t.Parallel()
 
@@ -346,8 +354,8 @@ func TestService_Get_ConcurrentMissesShareAFailure(t *testing.T) {
 		{"upstream answers 404, kept in the negative cache",
 			"/images/missing.jpg", httpfetcher.ErrUpstreamError,
 			ErrNegativeCached, 1},
-		{"source fails the magic byte check, not kept",
-			"/images/text.png", magic.ErrUnknownFormat, magic.ErrUnknownFormat, 2},
+		{"source fails the magic byte check, kept in the negative cache",
+			"/images/text.png", magic.ErrUnknownFormat, ErrNegativeCached, 1},
 	}
 
 	for _, tc := range tests {
@@ -356,9 +364,9 @@ func TestService_Get_ConcurrentMissesShareAFailure(t *testing.T) {
 
 			svc, fixtures, fetcher := setupHeldFetchService(t)
 
-			request := func() *ImageRequest {
-				req := photoVariant(fixtures, 85, FitCover)
-				req.SourcePath = tc.path
+			request := func() *imagerequest.Request {
+				req := photoVariant(fixtures, 85, imagerequest.FitCover)
+				req.Source.Path = tc.path
 
 				return req
 			}
@@ -400,7 +408,7 @@ func TestService_Get_EndedRequestFetchesNothing(t *testing.T) {
 	ctx, cancel := context.WithCancel(t.Context())
 	cancel()
 
-	_, err := svc.Get(ctx, photoVariant(fixtures, 85, FitCover))
+	_, err := svc.Get(ctx, photoVariant(fixtures, 85, imagerequest.FitCover))
 	if !errors.Is(err, context.Canceled) {
 		t.Errorf("Get() error = %v, want %v", err, context.Canceled)
 	}
@@ -424,7 +432,7 @@ func TestService_Get_ReturnsByItsDeadline(t *testing.T) {
 	ctx, cancel := context.WithTimeout(t.Context(), timeout)
 	defer cancel()
 
-	results := startGet(ctx, svc, photoVariant(fixtures, 85, FitCover))
+	results := startGet(ctx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 
 	select {
 	case got := <-results:
@@ -447,7 +455,7 @@ func TestService_Get_WaiterGetsProcessingTimedOut(t *testing.T) {
 
 	svc, fixtures, fetcher := setupHeldFetchService(t)
 	svc.processor = imageprocessor.New(
-		imageprocessor.Params{MaxConcurrentProcessing: 1},
+		imageprocessor.Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1},
 	)
 
 	holdProcessingSlot(t, svc.processor)
@@ -457,11 +465,11 @@ func TestService_Get_WaiterGetsProcessingTimedOut(t *testing.T) {
 	firstCtx, cancelFirst := context.WithTimeout(t.Context(), firstTimeout)
 	defer cancelFirst()
 
-	first := startGet(firstCtx, svc, photoVariant(fixtures, 85, FitCover))
+	first := startGet(firstCtx, svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 
 	<-fetcher.started
 
-	waiter := startGet(t.Context(), svc, photoVariant(fixtures, 85, FitCover))
+	waiter := startGet(t.Context(), svc, photoVariant(fixtures, 85, imagerequest.FitCover))
 
 	time.Sleep(arrivalWait)
 	fetcher.releaseFetches()
@@ -481,7 +489,7 @@ func TestService_Get_WaiterGetsProcessingTimedOut(t *testing.T) {
 type panickingFetcher struct{}
 
 func (panickingFetcher) Fetch(
-	context.Context, string,
+	context.Context, imagerequest.Source,
 ) (*httpfetcher.FetchResult, error) {
 	panic("upstream fetcher panicked")
 }
@@ -504,7 +512,7 @@ func TestService_Get_PanicBecomesAnError(t *testing.T) {
 			}
 		}()
 
-		_, err = svc.Get(t.Context(), photoVariant(fixtures, 85, FitCover))
+		_, err = svc.Get(t.Context(), photoVariant(fixtures, 85, imagerequest.FitCover))
 	}()
 
 	if err == nil || !strings.Contains(err.Error(), "upstream fetcher panicked") {
@@ -541,7 +549,7 @@ func TestService_Get_PanicIsReportedToSentry(t *testing.T) {
 			}
 		}()
 
-		_, _ = svc.Get(ctx, photoVariant(fixtures, 85, FitCover))
+		_, _ = svc.Get(ctx, photoVariant(fixtures, 85, imagerequest.FitCover))
 	}()
 
 	events := transport.Events()

internal/imgcache/contentlock.go

@@ -1,64 +0,0 @@
-package imgcache
-
-import "sync"
-
-// contentLock provides per-key mutual exclusion for content-hash keyed
-// operations. StoreSource and evictSourceBlob each hold a content
-// hash's lock for the full duration of their file-plus-accounting-row
-// work, so a store and an eviction racing on identical content bytes
-// (the real SHA-256 content-addressed dedup case, not a contrived one)
-// can never interleave: the unlink of an evicted blob's file can never
-// race the creation of a fresh database row for a concurrently
-// re-stored copy of the same content. Entries are removed once no
-// goroutine holds or is waiting for them, so a long-running process
-// does not accumulate memory proportional to the number of distinct
-// content hashes it has ever seen.
-type contentLock struct {
-	mu      sync.Mutex
-	entries map[string]*contentLockEntry
-}
-
-// contentLockEntry is one key's exclusion lock plus a count of
-// goroutines currently holding or waiting to acquire it, used to know
-// when it is safe to remove the entry from the map.
-type contentLockEntry struct {
-	mu    sync.Mutex
-	count int
-}
-
-// newContentLock creates an empty contentLock.
-func newContentLock() *contentLock {
-	return &contentLock{entries: make(map[string]*contentLockEntry)}
-}
-
-// Lock acquires exclusive access for key, blocking until it is
-// available, and returns a function that releases it. The caller must
-// invoke the returned function exactly once to release the lock.
-func (c *contentLock) Lock(key string) func() {
-	c.mu.Lock()
-
-	entry, ok := c.entries[key]
-	if !ok {
-		entry = &contentLockEntry{}
-		c.entries[key] = entry
-	}
-
-	entry.count++
-
-	c.mu.Unlock()
-
-	entry.mu.Lock()
-
-	return func() {
-		entry.mu.Unlock()
-
-		c.mu.Lock()
-
-		entry.count--
-		if entry.count == 0 {
-			delete(c.entries, key)
-		}
-
-		c.mu.Unlock()
-	}
-}

internal/imgcache/contentlock_internal_test.go

@@ -1,142 +0,0 @@
-package imgcache
-
-import (
-	"sync"
-	"sync/atomic"
-	"testing"
-	"time"
-)
-
-// TestContentLockExcludesSameKey verifies that two goroutines locking
-// the same key never run their critical sections concurrently.
-func TestContentLockExcludesSameKey(t *testing.T) {
-	t.Parallel()
-
-	lock := newContentLock()
-
-	var (
-		active  atomic.Int32
-		maxSeen int32
-		wg      sync.WaitGroup
-	)
-
-	const goroutines = 20
-
-	wg.Add(goroutines)
-
-	for range goroutines {
-		go func() {
-			defer wg.Done()
-
-			unlock := lock.Lock("same-key")
-			defer unlock()
-
-			n := active.Add(1)
-
-			for {
-				seen := atomic.LoadInt32(&maxSeen)
-				if n <= seen || atomic.CompareAndSwapInt32(&maxSeen, seen, n) {
-					break
-				}
-			}
-
-			time.Sleep(time.Millisecond)
-
-			active.Add(-1)
-		}()
-	}
-
-	wg.Wait()
-
-	if maxSeen != 1 {
-		t.Errorf("max concurrent holders of the same key = %d, want 1", maxSeen)
-	}
-}
-
-// TestContentLockAllowsDifferentKeys verifies that locking distinct
-// keys does not serialize unrelated work: all goroutines must be able
-// to enter their critical sections at once, proven by every one of
-// them reaching the rendezvous point before any is allowed to
-// proceed.
-func TestContentLockAllowsDifferentKeys(t *testing.T) {
-	t.Parallel()
-
-	lock := newContentLock()
-
-	const goroutines = 20
-
-	var (
-		wg      sync.WaitGroup
-		inside  atomic.Int32
-		reached = make(chan struct{}, goroutines)
-	)
-
-	wg.Add(goroutines)
-
-	release := make(chan struct{})
-
-	for i := range goroutines {
-		key := string(rune('a' + i))
-
-		go func() {
-			defer wg.Done()
-
-			unlock := lock.Lock(key)
-			defer unlock()
-
-			inside.Add(1)
-
-			reached <- struct{}{}
-
-			<-release
-		}()
-	}
-
-	// Every goroutine must reach the rendezvous point (i.e. acquire its
-	// own key's lock) without needing any other to release first. If
-	// keys were incorrectly serialized onto one underlying lock, only
-	// one would get here and this would time out.
-	for i := range goroutines {
-		select {
-		case <-reached:
-		case <-time.After(2 * time.Second):
-			t.Fatalf("only %d/%d goroutines locking distinct keys made progress; "+
-				"keys may be incorrectly serialized", i, goroutines)
-		}
-	}
-
-	if n := inside.Load(); n != goroutines {
-		t.Errorf("goroutines inside their critical section = %d, want %d",
-			n, goroutines)
-	}
-
-	close(release)
-	wg.Wait()
-}
-
-// TestContentLockRemovesEntryAfterUnlock verifies that the internal
-// entries map does not grow without bound: once no goroutine holds or
-// awaits a key, its entry is removed.
-func TestContentLockRemovesEntryAfterUnlock(t *testing.T) {
-	t.Parallel()
-
-	lock := newContentLock()
-
-	unlock := lock.Lock("k")
-
-	lock.mu.Lock()
-	if _, ok := lock.entries["k"]; !ok {
-		lock.mu.Unlock()
-		t.Fatal("entry missing while lock is held")
-	}
-	lock.mu.Unlock()
-
-	unlock()
-
-	lock.mu.Lock()
-	defer lock.mu.Unlock()
-
-	if _, ok := lock.entries["k"]; ok {
-		t.Error("entry for key still present after the last holder unlocked")
-	}
-}

internal/imgcache/counters.go

@@ -0,0 +1,45 @@
+package imgcache
+
+import (
+	"fmt"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// registerCounters makes the cache's counters and registers them on
+// metricsRegistry. The counters are kept in memory, so adding to one waits
+// for nothing and makes no database call. It fails when metricsRegistry
+// already holds counters of the same names.
+func (c *Cache) registerCounters(metricsRegistry prometheus.Registerer) error {
+	c.cacheHits = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "pixa_cache_hits_total",
+		Help: "Image requests served from the cache.",
+	})
+	c.cacheMisses = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "pixa_cache_misses_total",
+		Help: "Image requests not served from the cache.",
+	})
+	c.upstreamFetches = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "pixa_upstream_fetches_total",
+		Help: "Fetches of a source image from upstream that read any bytes.",
+	})
+	c.upstreamFetchBytes = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "pixa_upstream_fetch_bytes_total",
+		Help: "Bytes read from upstream by fetches of source images.",
+	})
+	c.transforms = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "pixa_transforms_total",
+		Help: "Images the image processor transformed.",
+	})
+
+	for _, counter := range []prometheus.Counter{
+		c.cacheHits, c.cacheMisses, c.upstreamFetches, c.upstreamFetchBytes, c.transforms,
+	} {
+		err := metricsRegistry.Register(counter)
+		if err != nil {
+			return fmt.Errorf("failed to register the cache's counters: %w", err)
+		}
+	}
+
+	return nil
+}

internal/imgcache/counters_internal_test.go

@@ -0,0 +1,87 @@
+package imgcache
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+// counterValues holds the values of a cache's counters.
+type counterValues struct {
+	hitCount           int64
+	missCount          int64
+	upstreamFetchCount int64
+	upstreamFetchBytes int64
+	transformCount     int64
+}
+
+// readCounters reads cache's counters.
+func readCounters(cache *Cache) counterValues {
+	return counterValues{
+		hitCount:           int64(testutil.ToFloat64(cache.cacheHits)),
+		missCount:          int64(testutil.ToFloat64(cache.cacheMisses)),
+		upstreamFetchCount: int64(testutil.ToFloat64(cache.upstreamFetches)),
+		upstreamFetchBytes: int64(testutil.ToFloat64(cache.upstreamFetchBytes)),
+		transformCount:     int64(testutil.ToFloat64(cache.transforms)),
+	}
+}
+
+// TestNewCache_RegistersItsCountersOnItsRegistry checks that NewCache
+// registers the cache's counters on the registry it is given, under the
+// names README.md gives them.
+func TestNewCache_RegistersItsCountersOnItsRegistry(t *testing.T) {
+	t.Parallel()
+
+	registry := prometheus.NewRegistry()
+
+	_, err := NewCache(evictionTestDB(t),
+		CacheConfig{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
+	if err != nil {
+		t.Fatalf("NewCache() error = %v", err)
+	}
+
+	names := []string{
+		"pixa_cache_hits_total",
+		"pixa_cache_misses_total",
+		"pixa_upstream_fetches_total",
+		"pixa_upstream_fetch_bytes_total",
+		"pixa_transforms_total",
+	}
+
+	count, err := testutil.GatherAndCount(registry, names...)
+	if err != nil {
+		t.Fatalf("testutil.GatherAndCount() error = %v", err)
+	}
+
+	if count != len(names) {
+		t.Errorf("%d of the counters %v are on the registry, want %d",
+			count, names, len(names))
+	}
+}
+
+// TestNewCache_FailsWhenItsCountersCannotBeRegistered makes a second cache
+// on the registry of a first. Its counters have the same names, so the
+// registry refuses them, and NewCache must return that error.
+func TestNewCache_FailsWhenItsCountersCannotBeRegistered(t *testing.T) {
+	t.Parallel()
+
+	registry := prometheus.NewRegistry()
+
+	_, err := NewCache(evictionTestDB(t),
+		CacheConfig{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
+	if err != nil {
+		t.Fatalf("NewCache() of the first cache error = %v", err)
+	}
+
+	_, err = NewCache(evictionTestDB(t),
+		CacheConfig{StateDir: t.TempDir(), MaxBytes: 1 << 30}, registry)
+	t.Logf("NewCache() of the second cache error = %v", err)
+
+	var alreadyRegistered prometheus.AlreadyRegisteredError
+	if !errors.As(err, &alreadyRegistered) {
+		t.Errorf("NewCache() of the second cache error = %v, want %T",
+			err, alreadyRegistered)
+	}
+}

internal/imgcache/eviction.go

@@ -3,7 +3,6 @@ package imgcache
 import (
 	"context"
 	"database/sql"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"io/fs"
@@ -11,6 +10,8 @@ import (
 	"path/filepath"
 	"strings"
 	"time"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // DefaultEvictionInterval is how often the background evictor checks
@@ -18,6 +19,14 @@ import (
 // write-pressure wakeups triggered by stores.
 const DefaultEvictionInterval = 5 * time.Minute
 
+// reconciliationWaitFactor is how many times as long as a
+// reconciliation pass took the eviction loop waits at least, after that
+// pass ends, before it starts the next one. A pass reads a row and stats a
+// file for every cached file, so its time grows with the cache; waiting
+// ten times as long keeps reconciliation to at most a tenth of the time,
+// however large the cache is.
+const reconciliationWaitFactor = 10
+
 // evictionBatchSize is how many LRU candidates of each class (variants
 // and source blobs) one eviction pass fetches from the database.
 const evictionBatchSize = 100
@@ -42,27 +51,26 @@ const sqliteTimestampLayout = "2006-01-02 15:04:05"
 // writes (".tmp-*" patterns in the storage layer).
 const tempFilePrefix = ".tmp-"
 
-// variantMetaSuffix is the sidecar suffix VariantStorage writes next
-// to each variant file.
-const variantMetaSuffix = ".meta"
-
-// fallbackContentType is the content type given to a variant file that
-// has no readable .meta sidecar, when it is served or reconciled.
-const fallbackContentType = "application/octet-stream"
-
 // UsageBytes returns the total number of bytes of cache content
-// tracked in the database (source content blobs plus processed
-// variants). It reads the total the database keeps up to date as rows
-// are added and removed, so it neither scans the cache directories nor
-// sums the tables.
+// tracked in the database, as the package function UsageBytes does, or 0
+// when the disk cache is off.
 func (c *Cache) UsageBytes(ctx context.Context) (int64, error) {
-	if c.disabled {
+	if c.config.MaxBytes == 0 {
 		return 0, nil
 	}
 
+	return UsageBytes(ctx, c.db)
+}
+
+// UsageBytes returns the total number of bytes of cache content tracked
+// in db (source content blobs plus processed variants). It reads the
+// total the database keeps up to date as rows are added and removed, so
+// it neither scans the cache directories nor sums the tables. pixad reads
+// it before it builds the cache, to work out the default cache_max_bytes.
+func UsageBytes(ctx context.Context, db *sql.DB) (int64, error) {
 	var total int64
 
-	err := c.db.QueryRowContext(ctx,
+	err := db.QueryRowContext(ctx,
 		`SELECT total_size_bytes FROM cache_usage WHERE id = 1`,
 	).Scan(&total)
 	if err != nil {
@@ -74,20 +82,20 @@ func (c *Cache) UsageBytes(ctx context.Context) (int64, error) {
 
 // evictionCandidate is one LRU eviction victim candidate: either a
 // processed variant (isVariant true, identified by cacheKey) or a
-// source content blob (identified by contentHash).
+// source content blob (identified by sourceKey).
 type evictionCandidate struct {
 	isVariant      bool
-	cacheKey       VariantKey
-	contentHash    ContentHash
+	cacheKey       imagerequest.VariantKey
+	sourceKey      imagerequest.SourceKey
 	sizeBytes      int64
 	lastAccessedAt string
 }
 
 // EvictToLimit evicts least-recently-used cache entries until total
 // tracked usage is at or below the configured MaxBytes limit. It is a
-// no-op when the cache is disabled or no limit is configured.
+// no-op when the cache is disabled.
 func (c *Cache) EvictToLimit(ctx context.Context) error {
-	if c.disabled || c.config.MaxBytes <= 0 {
+	if c.config.MaxBytes == 0 {
 		return nil
 	}
 
@@ -150,7 +158,7 @@ func (c *Cache) evictBatch(ctx context.Context, excessBytes int64) (int64, error
 
 			c.log.Warn("failed to evict cache entry",
 				"cache_key", candidate.cacheKey,
-				"content_hash", candidate.contentHash,
+				"source_key", candidate.sourceKey,
 				"error", err,
 			)
 
@@ -169,7 +177,7 @@ func (c *Cache) evictCandidate(ctx context.Context, candidate evictionCandidate)
 		return c.evictVariant(ctx, candidate.cacheKey)
 	}
 
-	return c.evictSourceBlob(ctx, candidate.contentHash)
+	return c.evictSourceBlob(ctx, candidate.sourceKey)
 }
 
 // evictionCandidates returns up to evictionBatchSize variants and
@@ -232,7 +240,7 @@ func (c *Cache) variantCandidates(ctx context.Context) ([]evictionCandidate, err
 			return nil, fmt.Errorf("failed to scan variant candidate: %w", err)
 		}
 
-		candidate.cacheKey = VariantKey(key)
+		candidate.cacheKey = imagerequest.VariantKey(key)
 		candidates = append(candidates, candidate)
 	}
 
@@ -249,9 +257,9 @@ func (c *Cache) variantCandidates(ctx context.Context) ([]evictionCandidate, err
 // SQLite reads the rows in order from that column's index instead of
 // sorting the whole table.
 const sourceCandidatesQuery = `
-	SELECT content_hash, size_bytes, last_accessed_at
+	SELECT source_key, size_bytes, last_accessed_at
 	FROM source_content
-	ORDER BY last_accessed_at ASC, content_hash ASC
+	ORDER BY last_accessed_at ASC, source_key ASC
 	LIMIT ?`
 
 // sourceCandidates returns the least recently used source blobs.
@@ -268,14 +276,14 @@ func (c *Cache) sourceCandidates(ctx context.Context) ([]evictionCandidate, erro
 	for rows.Next() {
 		var candidate evictionCandidate
 
-		var hash string
+		var key string
 
-		err := rows.Scan(&hash, &candidate.sizeBytes, &candidate.lastAccessedAt)
+		err := rows.Scan(&key, &candidate.sizeBytes, &candidate.lastAccessedAt)
 		if err != nil {
 			return nil, fmt.Errorf("failed to scan source candidate: %w", err)
 		}
 
-		candidate.contentHash = ContentHash(hash)
+		candidate.sourceKey = imagerequest.SourceKey(key)
 		candidates = append(candidates, candidate)
 	}
 
@@ -288,19 +296,16 @@ func (c *Cache) sourceCandidates(ctx context.Context) ([]evictionCandidate, erro
 }
 
 // evictVariant removes one variant: accounting row first, then the
-// content and .meta files, so the database never references a deleted
-// file. The metaCache entry goes before the files; a GetVariant that
-// read them just before may put it back, and the next GetVariant then
-// fails to open the file and removes it again.
-func (c *Cache) evictVariant(ctx context.Context, cacheKey VariantKey) error {
+// file, so the database never references a deleted file.
+func (c *Cache) evictVariant(
+	ctx context.Context, cacheKey imagerequest.VariantKey,
+) error {
 	_, err := c.db.ExecContext(ctx,
 		`DELETE FROM variant_content WHERE cache_key = ?`, string(cacheKey))
 	if err != nil {
 		return fmt.Errorf("failed to delete variant accounting row: %w", err)
 	}
 
-	c.metaCache.Remove(cacheKey)
-
 	err = c.variants.Delete(cacheKey)
 	if err != nil {
 		return err
@@ -309,117 +314,18 @@ func (c *Cache) evictVariant(ctx context.Context, cacheKey VariantKey) error {
 	return nil
 }
 
-// sourceReference identifies one source_metadata row's JSON sidecar.
-type sourceReference struct {
-	host     string
-	pathHash PathHash
-}
-
-// evictSourceBlob removes one source content blob. All source_metadata
-// rows referencing the blob are deleted together with its
-// source_content row in a single transaction BEFORE the file is
-// unlinked: a blob referenced by multiple source paths is only ever
-// removed together with all of its references, and database rows never
-// point at deleted files. The JSON metadata sidecars for the removed
-// rows are deleted afterwards.
-//
-// The whole operation holds the content hash's lock (the same one
-// StoreSource holds for its full store), so a concurrent store of
-// identical content bytes can never observe the file gone but a row
-// still present, or insert a fresh row between this transaction's
-// commit and the file unlink below: it either runs entirely before
-// this eviction starts, or is blocked until this eviction (row
-// deletion and unlink together) has fully completed.
-func (c *Cache) evictSourceBlob(ctx context.Context, contentHash ContentHash) error {
-	unlock := c.contentLocks.Lock(string(contentHash))
-	defer unlock()
-
-	references, err := c.sourceReferences(ctx, contentHash)
-	if err != nil {
-		return err
-	}
-
-	tx, err := c.db.BeginTx(ctx, nil)
-	if err != nil {
-		return fmt.Errorf("failed to begin eviction transaction: %w", err)
-	}
-
-	defer func() { _ = tx.Rollback() }()
-
-	_, err = tx.ExecContext(ctx,
-		`DELETE FROM source_metadata WHERE content_hash = ?`, string(contentHash))
-	if err != nil {
-		return fmt.Errorf("failed to delete source metadata rows: %w", err)
-	}
-
-	_, err = tx.ExecContext(ctx,
-		`DELETE FROM source_content WHERE content_hash = ?`, string(contentHash))
+// evictSourceBlob removes one source: its row first, then its file, as
+// evictVariant does for a variant. It holds no lock: a store of the same
+// source in between can leave the source's row with no file, which
+// LookupSource treats as a miss.
+func (c *Cache) evictSourceBlob(ctx context.Context, key imagerequest.SourceKey) error {
+	_, err := c.db.ExecContext(ctx,
+		`DELETE FROM source_content WHERE source_key = ?`, string(key))
 	if err != nil {
 		return fmt.Errorf("failed to delete source content row: %w", err)
 	}
 
-	err = tx.Commit()
-	if err != nil {
-		return fmt.Errorf("failed to commit eviction transaction: %w", err)
-	}
-
-	if c.evictSourceBlobTestHook != nil {
-		c.evictSourceBlobTestHook(contentHash)
-	}
-
-	// Only after the rows are gone may the files be removed.
-	for _, reference := range references {
-		err := c.srcMetadata.Delete(reference.host, reference.pathHash)
-		if err != nil {
-			c.log.Warn("failed to delete metadata sidecar",
-				"host", reference.host, "path_hash", reference.pathHash, "error", err)
-		}
-	}
-
-	err = c.srcContent.Delete(contentHash)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-// sourceReferences lists the metadata sidecar locations of every
-// source_metadata row referencing the given blob.
-func (c *Cache) sourceReferences(
-	ctx context.Context, contentHash ContentHash,
-) ([]sourceReference, error) {
-	rows, err := c.db.QueryContext(ctx, `
-		SELECT source_host, path_hash FROM source_metadata WHERE content_hash = ?
-	`, string(contentHash))
-	if err != nil {
-		return nil, fmt.Errorf("failed to query source references: %w", err)
-	}
-
-	defer func() { _ = rows.Close() }()
-
-	var references []sourceReference
-
-	for rows.Next() {
-		var reference sourceReference
-
-		var pathHash string
-
-		err := rows.Scan(&reference.host, &pathHash)
-		if err != nil {
-			return nil, fmt.Errorf("failed to scan source reference: %w", err)
-		}
-
-		reference.pathHash = PathHash(pathHash)
-		references = append(references, reference)
-	}
-
-	err = rows.Err()
-	if err != nil {
-		return nil, fmt.Errorf("source reference iteration failed: %w", err)
-	}
-
-	return references, nil
+	return c.srcContent.Delete(key)
 }
 
 // notifyWritePressure wakes the background evictor after a store, so
@@ -427,7 +333,7 @@ func (c *Cache) sourceReferences(
 // storing request. The notification channel has capacity one and drops
 // when a wakeup is already pending.
 func (c *Cache) notifyWritePressure() {
-	if c.disabled || c.config.MaxBytes <= 0 {
+	if c.config.MaxBytes == 0 {
 		return
 	}
 
@@ -438,10 +344,12 @@ func (c *Cache) notifyWritePressure() {
 }
 
 // StartEviction launches the background eviction goroutine, which
-// reconciles the database accounting with the cache directories and
 // removes the expired negative cache rows at startup and again on every
-// periodic tick thereafter, and evicts to the configured limit on the
-// given periodic interval and on write-pressure notifications. On a
+// periodic tick thereafter, reconciles the database accounting with the
+// cache directories at startup and again on the first periodic tick
+// that comes at least ten times as long after a reconciliation pass
+// ended as that pass took, and evicts to the configured limit on the given
+// periodic interval and on write-pressure notifications. On a
 // disabled cache it only removes the expired negative cache rows, as
 // the negative cache is used either way. It is a no-op when already
 // started. The goroutine outlives the caller, so it runs with its own
@@ -482,7 +390,7 @@ func (c *Cache) StopEviction(ctx context.Context) error {
 func (c *Cache) evictionLoop(ctx context.Context, interval time.Duration) {
 	defer close(c.evictionDone)
 
-	c.runReconciliationPass(ctx)
+	nextReconciliation := c.runReconciliationPass(ctx)
 	c.runCleanExpired(ctx)
 	c.runEvictionPass(ctx)
 
@@ -494,16 +402,20 @@ func (c *Cache) evictionLoop(ctx context.Context, interval time.Duration) {
 		case <-ctx.Done():
 			return
 		case <-ticker.C:
-			// Reconciliation walks the cache directories, so it only
-			// runs on the periodic ticker rather than on every
-			// write-pressure wakeup, keeping it off the per-store hot
-			// path. Reusing the eviction interval itself (rather than a
-			// separate, longer one) is a deliberate choice: it is the
-			// simplest option that still bounds how long a store's
-			// best-effort accounting insert can stay silently
-			// unaccounted for to one interval, on a process that is
-			// already running this loop regardless.
-			c.runReconciliationPass(ctx)
+			// Reconciliation walks the cache directories and reads a
+			// row for every file, so it runs only on the periodic
+			// ticker rather than on every write-pressure wakeup, and
+			// only on the first tick at or after nextReconciliation,
+			// which is ten times as long after the last pass ended as
+			// that pass took. Passes then never run back to back,
+			// however long one takes. A file whose best-effort
+			// accounting insert failed in a store stays unaccounted for
+			// until the next pass, up to about one eviction interval
+			// plus ten times the last pass's time.
+			if !time.Now().Before(nextReconciliation) {
+				nextReconciliation = c.runReconciliationPass(ctx)
+			}
+
 			c.runCleanExpired(ctx)
 		case <-c.evictionPressure:
 		}
@@ -527,17 +439,25 @@ func (c *Cache) runEvictionPass(ctx context.Context) {
 }
 
 // runReconciliationPass runs one reconciliation pass, logging failures
-// instead of propagating them (the loop must keep running). It does
-// nothing once ctx is cancelled.
-func (c *Cache) runReconciliationPass(ctx context.Context) {
+// instead of propagating them (the loop must keep running), and returns
+// the earliest time the next pass may start: reconciliationWaitFactor
+// times as long after this pass ended as it took. It does nothing once
+// ctx is cancelled.
+func (c *Cache) runReconciliationPass(ctx context.Context) time.Time {
 	if ctx.Err() != nil {
-		return
+		return time.Now()
 	}
 
+	started := time.Now()
+
 	err := c.reconcileAccounting(ctx)
 	if err != nil {
 		c.log.Warn("cache accounting reconciliation failed", "error", err)
 	}
+
+	ended := time.Now()
+
+	return ended.Add(reconciliationWaitFactor * ended.Sub(started))
 }
 
 // runCleanExpired runs CleanExpired, logging a failure instead of
@@ -556,21 +476,23 @@ func (c *Cache) runCleanExpired(ctx context.Context) {
 
 // reconcileAccounting synchronizes the database size accounting with
 // the actual contents of the cache directories. It runs at startup and
-// again on every periodic eviction tick thereafter, off the request
+// then on the first periodic eviction tick that comes at least ten times
+// as long after the last pass ended as that pass took, off the request
 // hot path: it adopts variant files that predate the accounting table
 // (or whose accounting insert failed, e.g. StoreVariant's best-effort
-// insert under transient DB contention), drops accounting rows whose
-// files are missing, removes source blob files the database does not
-// know (and rows whose files are gone), removes source and variant files
-// that are empty or not the size their rows record, sweeps stale temp
-// files left behind by crashed writes, and last checks the total cache
-// usage against the tables. It reads the tables a page at a time.
+// insert under transient DB contention), drops variant accounting rows
+// whose files are missing, removes source blob files the database does
+// not know, removes source and variant files that are empty or not the
+// size their rows record, sweeps stale temp files left behind by crashed
+// writes, and last checks the total cache usage against the tables. It
+// reads the tables a page at a time.
 // Running it periodically, not just once, bounds how long such drift can
-// accumulate unaccounted for on a long-running process to one eviction
-// interval. Once ctx is cancelled, it stops at the next file or row and
-// returns ctx's error.
+// accumulate unaccounted for on a long-running process to about one
+// eviction interval plus ten times the last pass's time.
+// Once ctx is cancelled, it stops at the next file or row and returns
+// ctx's error.
 func (c *Cache) reconcileAccounting(ctx context.Context) error {
-	if c.disabled {
+	if c.config.MaxBytes == 0 {
 		return nil
 	}
 
@@ -589,20 +511,19 @@ func (c *Cache) reconcileAccounting(ctx context.Context) error {
 		return err
 	}
 
-	err = c.reconcileSourceRows(ctx)
-	if err != nil {
-		return err
-	}
-
 	return c.reconcileUsageTotal(ctx)
 }
 
-// reconcileVariantFiles walks the variant storage directory, checking
-// each variant file against its accounting row (reconcileVariantFile)
-// and sweeping stale temp files.
-func (c *Cache) reconcileVariantFiles(ctx context.Context) error {
+// reconcileFiles walks baseDir, one of the cache's storage directories,
+// sweeping stale temp files and passing each other file, with its name, to
+// reconcileFile. Once ctx is cancelled it stops at the next file and
+// returns ctx's error.
+func (c *Cache) reconcileFiles(
+	ctx context.Context, baseDir string,
+	reconcileFile func(path string, entry fs.DirEntry, name string) error,
+) error {
 	return filepath.WalkDir(
-		c.variants.baseDir,
+		baseDir,
 		func(path string, entry fs.DirEntry, err error) error {
 			if ctx.Err() != nil {
 				return ctx.Err()
@@ -620,22 +541,28 @@ func (c *Cache) reconcileVariantFiles(ctx context.Context) error {
 				return nil
 			}
 
-			if strings.HasSuffix(name, variantMetaSuffix) {
-				return nil
-			}
-
-			return c.reconcileVariantFile(ctx, path, entry, VariantKey(name))
+			return reconcileFile(path, entry, name)
 		},
 	)
 }
 
+// reconcileVariantFiles walks the variant storage directory, checking
+// each variant file against its accounting row (reconcileVariantFile)
+// and sweeping stale temp files.
+func (c *Cache) reconcileVariantFiles(ctx context.Context) error {
+	return c.reconcileFiles(ctx, c.variants.baseDir,
+		func(path string, entry fs.DirEntry, name string) error {
+			return c.reconcileVariantFile(ctx, path, entry, imagerequest.VariantKey(name))
+		})
+}
+
 // reconcileVariantFile checks one variant file against its accounting
 // row. A file without a row is adopted into the accounting, unless it is
 // empty. A file that is empty, or not the size its row records, as a
 // crash or a restored snapshot can leave it, is removed with its row and
 // a warning naming it, so the variant is converted again.
 func (c *Cache) reconcileVariantFile(
-	ctx context.Context, path string, entry fs.DirEntry, cacheKey VariantKey,
+	ctx context.Context, path string, entry fs.DirEntry, cacheKey imagerequest.VariantKey,
 ) error {
 	info, err := entry.Info()
 	if err != nil {
@@ -650,7 +577,7 @@ func (c *Cache) reconcileVariantFile(
 
 	switch {
 	case errors.Is(err, sql.ErrNoRows) && info.Size() > 0:
-		return c.adoptVariantFile(ctx, path, info, cacheKey)
+		return c.adoptVariantFile(ctx, info, cacheKey)
 	case err != nil && !errors.Is(err, sql.ErrNoRows):
 		return fmt.Errorf("failed to check variant accounting row: %w", err)
 	case info.Size() > 0 && info.Size() == recordedSize:
@@ -667,16 +594,14 @@ func (c *Cache) reconcileVariantFile(
 // adoptVariantFile inserts an accounting row for a variant file that
 // has none, using the file's size and modification time.
 func (c *Cache) adoptVariantFile(
-	ctx context.Context, path string, info fs.FileInfo, cacheKey VariantKey,
+	ctx context.Context, info fs.FileInfo, cacheKey imagerequest.VariantKey,
 ) error {
 	modTime := info.ModTime().UTC().Format(sqliteTimestampLayout)
-	contentType := c.variantContentTypeFromSidecar(path)
 
 	_, err := c.db.ExecContext(ctx, `
-		INSERT INTO variant_content
-			(cache_key, size_bytes, content_type, created_at, last_accessed_at)
-		VALUES (?, ?, ?, ?, ?)
-	`, string(cacheKey), info.Size(), contentType, modTime, modTime)
+		INSERT INTO variant_content (cache_key, size_bytes, last_accessed_at)
+		VALUES (?, ?, ?)
+	`, string(cacheKey), info.Size(), modTime)
 	if err != nil {
 		return fmt.Errorf("failed to adopt variant file into accounting: %w", err)
 	}
@@ -687,27 +612,10 @@ func (c *Cache) adoptVariantFile(
 	return nil
 }
 
-// variantContentTypeFromSidecar reads the content type from a variant
-// .meta sidecar, falling back to application/octet-stream.
-func (c *Cache) variantContentTypeFromSidecar(variantPath string) string {
-	//nolint:gosec // path from cache walk
-	metaData, err := os.ReadFile(variantPath + variantMetaSuffix)
-	if err != nil {
-		return fallbackContentType
-	}
-
-	var meta VariantMeta
-	if json.Unmarshal(metaData, &meta) != nil || meta.ContentType == "" {
-		return fallbackContentType
-	}
-
-	return meta.ContentType
-}
-
 // reconcileVariantRows drops accounting rows whose variant files are
 // missing, so the database never references deleted content.
 func (c *Cache) reconcileVariantRows(ctx context.Context) error {
-	var after VariantKey
+	var after imagerequest.VariantKey
 
 	for {
 		keys, err := c.variantKeysAfter(ctx, after)
@@ -748,9 +656,9 @@ func (c *Cache) reconcileVariantRows(ctx context.Context) error {
 // variantKeysAfter returns, in order, up to c.reconciliationPageSize
 // tracked variant cache keys that sort after the given one.
 func (c *Cache) variantKeysAfter(
-	ctx context.Context, after VariantKey,
-) ([]VariantKey, error) {
-	return queryStringColumn[VariantKey](ctx, c.db, `
+	ctx context.Context, after imagerequest.VariantKey,
+) ([]imagerequest.VariantKey, error) {
+	return queryStringColumn[imagerequest.VariantKey](ctx, c.db, `
 		SELECT cache_key FROM variant_content
 		WHERE cache_key > ? ORDER BY cache_key LIMIT ?
 	`, "variant keys", "variant key", string(after), c.reconciliationPageSize)
@@ -795,38 +703,20 @@ func queryStringColumn[T ~string](
 // each blob file against its source_content row (reconcileSourceFile)
 // and sweeping stale temp files.
 func (c *Cache) reconcileSourceFiles(ctx context.Context) error {
-	return filepath.WalkDir(
-		c.srcContent.baseDir,
-		func(path string, entry fs.DirEntry, err error) error {
-			if ctx.Err() != nil {
-				return ctx.Err()
-			}
-
-			if err != nil || entry.IsDir() {
-				return err
-			}
-
-			name := entry.Name()
-
-			if strings.HasPrefix(name, tempFilePrefix) {
-				c.sweepStaleTempFile(path, entry)
-
-				return nil
-			}
-
-			return c.reconcileSourceFile(ctx, path, entry, ContentHash(name))
-		},
-	)
+	return c.reconcileFiles(ctx, c.srcContent.baseDir,
+		func(path string, entry fs.DirEntry, name string) error {
+			return c.reconcileSourceFile(ctx, path, entry, imagerequest.SourceKey(name))
+		})
 }
 
 // reconcileSourceFile checks one source blob file against its
-// source_content row. A file without a row is removed: it is
-// unreachable, as source lookups always go through source_metadata. A
-// file that is empty, or not the size its row records, as a crash or a
-// restored snapshot can leave it, is removed with its rows and a warning
-// naming it, so the source is fetched again.
+// source_content row. A file without a row is removed, as no lookup
+// serves it and no eviction removes it. A file that is empty, or not the
+// size its row records, as a crash or a restored snapshot can leave it,
+// is removed with its row and a warning naming it, so the source is
+// fetched again.
 func (c *Cache) reconcileSourceFile(
-	ctx context.Context, path string, entry fs.DirEntry, contentHash ContentHash,
+	ctx context.Context, path string, entry fs.DirEntry, key imagerequest.SourceKey,
 ) error {
 	info, err := entry.Info()
 	if err != nil {
@@ -836,13 +726,13 @@ func (c *Cache) reconcileSourceFile(
 	var recordedSize int64
 
 	err = c.db.QueryRowContext(ctx,
-		`SELECT size_bytes FROM source_content WHERE content_hash = ?`,
-		string(contentHash),
+		`SELECT size_bytes FROM source_content WHERE source_key = ?`,
+		string(key),
 	).Scan(&recordedSize)
 
 	switch {
 	case errors.Is(err, sql.ErrNoRows):
-		return c.removeUntrackedSourceFile(ctx, path, contentHash)
+		return c.removeUntrackedSourceFile(path, key)
 	case err != nil:
 		return fmt.Errorf("failed to check source content row: %w", err)
 	case info.Size() > 0 && info.Size() == recordedSize:
@@ -853,96 +743,34 @@ func (c *Cache) reconcileSourceFile(
 	c.log.Warn("removing damaged cached source file", "path", path,
 		"file_bytes", info.Size(), "recorded_bytes", recordedSize)
 
-	return c.evictSourceBlob(ctx, contentHash)
+	return c.evictSourceBlob(ctx, key)
 }
 
 // removeUntrackedSourceFile deletes a source blob file that has no
-// source_content row. Any source_metadata rows referencing the hash
-// are removed first so no row ever points at a deleted file.
+// source_content row.
 func (c *Cache) removeUntrackedSourceFile(
-	ctx context.Context, path string, contentHash ContentHash,
+	path string, key imagerequest.SourceKey,
 ) error {
-	_, err := c.db.ExecContext(ctx,
-		`DELETE FROM source_metadata WHERE content_hash = ?`, string(contentHash))
-	if err != nil {
-		return fmt.Errorf("failed to delete metadata rows for untracked blob: %w", err)
-	}
-
-	err = os.Remove(path)
+	err := os.Remove(path)
 	if err != nil && !os.IsNotExist(err) {
 		return fmt.Errorf("failed to remove untracked source file: %w", err)
 	}
 
-	c.log.Info("removed untracked source content file", "content_hash", contentHash)
+	c.log.Info("removed untracked source content file", "source_key", key)
 
 	return nil
 }
 
-// reconcileSourceRows removes source_content rows (and their metadata
-// references and sidecars) whose blob files are missing on disk.
-func (c *Cache) reconcileSourceRows(ctx context.Context) error {
-	var after ContentHash
-
-	for {
-		hashes, err := c.sourceContentHashesAfter(ctx, after)
-		if err != nil {
-			return err
-		}
-
-		if c.reconciliationReadTestHook != nil {
-			c.reconciliationReadTestHook(len(hashes))
-		}
-
-		if len(hashes) == 0 {
-			return nil
-		}
-
-		for _, hash := range hashes {
-			if ctx.Err() != nil {
-				return ctx.Err()
-			}
-
-			if c.srcContent.Exists(hash) {
-				continue
-			}
-
-			// The blob file is already gone; evictSourceBlob removes the
-			// rows and sidecars and tolerates the missing file.
-			err := c.evictSourceBlob(ctx, hash)
-			if err != nil {
-				return err
-			}
-
-			c.log.Info("dropped rows for missing source content file", "content_hash", hash)
-		}
-
-		after = hashes[len(hashes)-1]
-	}
-}
-
-// sourceContentHashesAfter returns, in order, up to
-// c.reconciliationPageSize tracked source content hashes that sort after
-// the given one.
-func (c *Cache) sourceContentHashesAfter(
-	ctx context.Context, after ContentHash,
-) ([]ContentHash, error) {
-	return queryStringColumn[ContentHash](ctx, c.db, `
-		SELECT content_hash FROM source_content
-		WHERE content_hash > ? ORDER BY content_hash LIMIT ?
-	`, "source content hashes", "content hash", string(after),
-		c.reconciliationPageSize)
-}
-
 // Each of these queries sums size_bytes over the next page of rows of
 // one content table, the rows that sort after a key, and returns the
 // page's last key, the sum and the number of rows in the page. Past the
 // last row the page has no rows and the key is NULL.
 const (
 	sourceSizePageQuery = `
-		SELECT MAX(content_hash), COALESCE(SUM(size_bytes), 0), COUNT(*)
+		SELECT MAX(source_key), COALESCE(SUM(size_bytes), 0), COUNT(*)
 		FROM (
-			SELECT content_hash, size_bytes FROM source_content
-			WHERE content_hash > ? ORDER BY content_hash LIMIT ?
+			SELECT source_key, size_bytes FROM source_content
+			WHERE source_key > ? ORDER BY source_key LIMIT ?
 		)`
 	variantSizePageQuery = `
 		SELECT MAX(cache_key), COALESCE(SUM(size_bytes), 0), COUNT(*)

internal/imgcache/eviction_internal_test.go

@@ -10,12 +10,14 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
-	_ "modernc.org/sqlite"
+	"github.com/prometheus/client_golang/prometheus"
+	"modernc.org/sqlite"
 	"sneak.berlin/go/pixa/internal/database"
-	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // sqliteTimestampFormat matches the format SQLite's CURRENT_TIMESTAMP
@@ -27,10 +29,10 @@ const sqliteTimestampFormat = "2006-01-02 15:04:05"
 // keys reused across the eviction tests, in the order the tests store
 // them.
 const (
-	testVariantKeyOne   VariantKey = "aabbccdd0001"
-	testVariantKeyTwo   VariantKey = "aabbccdd0002"
-	testVariantKeyThree VariantKey = "aabbccdd0003"
-	testVariantKeyFour  VariantKey = "aabbccdd0004"
+	testVariantKeyOne   imagerequest.VariantKey = "aabbccdd0001"
+	testVariantKeyTwo   imagerequest.VariantKey = "aabbccdd0002"
+	testVariantKeyThree imagerequest.VariantKey = "aabbccdd0003"
+	testVariantKeyFour  imagerequest.VariantKey = "aabbccdd0004"
 )
 
 // evictionTestDB creates an in-memory SQLite database with the real
@@ -64,16 +66,12 @@ func newEvictionTestCache(t *testing.T, maxBytes int64) (*Cache, string) {
 	tmpDir := t.TempDir()
 	db := evictionTestDB(t)
 
-	// maxBytes zero mirrors the production mapping of
-	// cache_max_bytes: 0 (handlers sets DisableDiskCache); at the
-	// CacheConfig layer itself a zero MaxBytes means "no limit" for
-	// backwards compatibility with existing fixtures.
+	// maxBytes zero turns the disk cache off, as cache_max_bytes: 0 does.
 	cache, err := NewCache(db, CacheConfig{
-		StateDir:         tmpDir,
-		NegativeTTL:      5 * time.Minute,
-		MaxBytes:         maxBytes,
-		DisableDiskCache: maxBytes == 0,
-	})
+		StateDir:    tmpDir,
+		NegativeTTL: 5 * time.Minute,
+		MaxBytes:    maxBytes,
+	}, prometheus.NewRegistry())
 	if err != nil {
 		t.Fatalf("failed to create cache: %v", err)
 	}
@@ -82,47 +80,42 @@ func newEvictionTestCache(t *testing.T, maxBytes int64) (*Cache, string) {
 }
 
 // storeEvictionTestSource stores content as a fetched source for
-// host/path and returns the resulting content hash.
+// host/path and returns the resulting source key.
 func storeEvictionTestSource(
 	t *testing.T, cache *Cache, host, path string, content []byte,
-) ContentHash {
+) imagerequest.SourceKey {
 	t.Helper()
 
-	req := &ImageRequest{
-		SourceHost: host,
-		SourcePath: path,
-		Format:     FormatJPEG,
-		Quality:    85,
-		FitMode:    FitCover,
-	}
-
-	result := &httpfetcher.FetchResult{
-		StatusCode:    200,
-		ContentType:   testContentTypeJPEG,
-		ContentLength: int64(len(content)),
-		Headers: map[string][]string{
-			testHeaderContentType: {testContentTypeJPEG},
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: host,
+			Path: path,
+		},
+		Transform: imagerequest.Transform{
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
 		},
 	}
 
-	hash, err := cache.StoreSource(
-		context.Background(), req, bytes.NewReader(content), result,
+	key, err := cache.StoreSource(
+		context.Background(), req, bytes.NewReader(content),
 	)
 	if err != nil {
 		t.Fatalf("StoreSource(%s%s) failed: %v", host, path, err)
 	}
 
-	return hash
+	return key
 }
 
 // storeEvictionTestVariant stores content as a processed variant under
 // the given cache key.
 func storeEvictionTestVariant(
-	t *testing.T, cache *Cache, key VariantKey, content []byte,
+	t *testing.T, cache *Cache, key imagerequest.VariantKey, content []byte,
 ) {
 	t.Helper()
 
-	err := cache.StoreVariant(t.Context(), key, bytes.NewReader(content), "image/webp")
+	err := cache.StoreVariant(t.Context(), key, bytes.NewReader(content))
 	if err != nil {
 		t.Fatalf("StoreVariant(%s) failed: %v", key, err)
 	}
@@ -131,7 +124,7 @@ func storeEvictionTestVariant(
 // setVariantLastAccessed backdates the last access time of a tracked
 // variant, to make LRU ordering deterministic in tests.
 func setVariantLastAccessed(
-	t *testing.T, cache *Cache, key VariantKey, when time.Time,
+	t *testing.T, cache *Cache, key imagerequest.VariantKey, when time.Time,
 ) {
 	t.Helper()
 
@@ -157,13 +150,13 @@ func setVariantLastAccessed(
 // setSourceLastAccessed backdates the last access time of a tracked
 // source content blob.
 func setSourceLastAccessed(
-	t *testing.T, cache *Cache, hash ContentHash, when time.Time,
+	t *testing.T, cache *Cache, key imagerequest.SourceKey, when time.Time,
 ) {
 	t.Helper()
 
 	res, err := cache.db.ExecContext(t.Context(),
-		`UPDATE source_content SET last_accessed_at = ? WHERE content_hash = ?`,
-		when.UTC().Format(sqliteTimestampFormat), string(hash),
+		`UPDATE source_content SET last_accessed_at = ? WHERE source_key = ?`,
+		when.UTC().Format(sqliteTimestampFormat), string(key),
 	)
 	if err != nil {
 		t.Fatalf("failed to set source last_accessed_at: %v", err)
@@ -175,7 +168,7 @@ func setSourceLastAccessed(
 	}
 
 	if affected != 1 {
-		t.Fatalf("source %s has no accounting row (affected=%d)", hash, affected)
+		t.Fatalf("source %s has no accounting row (affected=%d)", key, affected)
 	}
 }
 
@@ -200,32 +193,31 @@ func assertNoDanglingReferences(t *testing.T, cache *Cache) {
 	t.Helper()
 
 	rows, err := cache.db.QueryContext(t.Context(),
-		`SELECT content_hash FROM source_metadata
-		 WHERE content_hash IS NOT NULL AND content_hash != ''`,
+		`SELECT source_key FROM source_content`,
 	)
 	if err != nil {
-		t.Fatalf("failed to query source_metadata: %v", err)
+		t.Fatalf("failed to query source_content: %v", err)
 	}
 
 	defer func() { _ = rows.Close() }()
 
 	for rows.Next() {
-		var hash string
+		var key string
 
-		err := rows.Scan(&hash)
+		err := rows.Scan(&key)
 		if err != nil {
-			t.Fatalf("failed to scan content_hash: %v", err)
+			t.Fatalf("failed to scan source_key: %v", err)
 		}
 
-		if !cache.srcContent.Exists(ContentHash(hash)) {
-			t.Errorf("source_metadata references content %s but the file is missing",
-				hash)
+		if !cache.srcContent.Exists(imagerequest.SourceKey(key)) {
+			t.Errorf("source_content references content %s but the file is missing",
+				key)
 		}
 	}
 
 	err = rows.Err()
 	if err != nil {
-		t.Fatalf("source_metadata iteration failed: %v", err)
+		t.Fatalf("source_content iteration failed: %v", err)
 	}
 
 	variantRows, err := cache.db.QueryContext(t.Context(),
@@ -244,7 +236,7 @@ func assertNoDanglingReferences(t *testing.T, cache *Cache) {
 			t.Fatalf("failed to scan cache_key: %v", err)
 		}
 
-		if !cache.variants.Exists(VariantKey(key)) {
+		if !cache.variants.Exists(imagerequest.VariantKey(key)) {
 			t.Errorf("variant_content references key %s but the file is missing", key)
 		}
 	}
@@ -308,33 +300,6 @@ func TestUsageBytesAccountsSourceAndVariantBytes(t *testing.T) {
 	}
 }
 
-func TestUsageBytesCountsMultiReferencedBlobOnce(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<30)
-
-	content := bytes.Repeat([]byte{0xCC}, 1200)
-
-	hashOne := storeEvictionTestSource(t, cache,
-		"src.example.com", "/one.jpg", content)
-	hashTwo := storeEvictionTestSource(t, cache,
-		"src.example.com", "/two.jpg", content)
-
-	if hashOne != hashTwo {
-		t.Fatalf("identical content produced different hashes: %s vs %s",
-			hashOne, hashTwo)
-	}
-
-	usage, err := cache.UsageBytes(context.Background())
-	if err != nil {
-		t.Fatalf("UsageBytes failed: %v", err)
-	}
-
-	if usage != 1200 {
-		t.Errorf("UsageBytes = %d, want 1200 (deduplicated blob counted once)", usage)
-	}
-}
-
 func TestEvictToLimitEvictsLeastRecentlyUsedFirst(t *testing.T) {
 	t.Parallel()
 
@@ -343,7 +308,7 @@ func TestEvictToLimitEvictsLeastRecentlyUsedFirst(t *testing.T) {
 	cache, _ := newEvictionTestCache(t, limit)
 
 	now := time.Now()
-	keys := []VariantKey{
+	keys := []imagerequest.VariantKey{
 		testVariantKeyOne, testVariantKeyTwo,
 		testVariantKeyThree, testVariantKeyFour,
 	}
@@ -388,102 +353,15 @@ func TestEvictToLimitEvictsLeastRecentlyUsedFirst(t *testing.T) {
 	assertNoDanglingReferences(t, cache)
 }
 
-func TestEvictionRemovesMultiReferencedBlobTogetherWithAllReferences(t *testing.T) {
-	t.Parallel()
-
-	const limit = 1000
-
-	cache, _ := newEvictionTestCache(t, limit)
-
-	now := time.Now()
-
-	// One 800-byte blob referenced by two source paths.
-	sharedContent := bytes.Repeat([]byte{0xDD}, 800)
-	sharedHash := storeEvictionTestSource(t, cache,
-		"src.example.com", "/a.jpg", sharedContent)
-
-	h := storeEvictionTestSource(t, cache,
-		"src.example.com", "/b.jpg", sharedContent)
-	if h != sharedHash {
-		t.Fatalf("identical content produced different hashes: %s vs %s",
-			h, sharedHash)
-	}
-
-	// A newer 600-byte blob referenced by one source path.
-	recentHash := storeEvictionTestSource(t, cache, "src.example.com", "/c.jpg",
-		bytes.Repeat([]byte{0xEE}, 600))
-
-	setSourceLastAccessed(t, cache, sharedHash, now.Add(-2*time.Hour))
-	setSourceLastAccessed(t, cache, recentHash, now.Add(-time.Minute))
-
-	err := cache.EvictToLimit(context.Background())
-	if err != nil {
-		t.Fatalf("EvictToLimit failed: %v", err)
-	}
-
-	usage, err := cache.UsageBytes(context.Background())
-	if err != nil {
-		t.Fatalf("UsageBytes failed: %v", err)
-	}
-
-	if usage > limit {
-		t.Errorf("usage after eviction = %d, want <= %d", usage, limit)
-	}
-
-	// The multi-referenced blob must be gone from disk, from
-	// source_content, and from BOTH source_metadata rows: references
-	// are removed together with the blob, never left dangling.
-	if cache.srcContent.Exists(sharedHash) {
-		t.Errorf("evicted blob %s still exists on disk", sharedHash)
-	}
-
-	if n := countRows(t, cache,
-		`SELECT COUNT(*) FROM source_content WHERE content_hash = ?`, string(sharedHash),
-	); n != 0 {
-		t.Errorf("evicted blob %s still has %d source_content rows", sharedHash, n)
-	}
-
-	if n := countRows(t, cache,
-		`SELECT COUNT(*) FROM source_metadata WHERE content_hash = ?`, string(sharedHash),
-	); n != 0 {
-		t.Errorf("evicted blob %s still has %d source_metadata references", sharedHash, n)
-	}
-
-	// The JSON metadata sidecars for both referencing paths must be
-	// removed along with the rows.
-	for _, path := range []string{"/a.jpg", "/b.jpg"} {
-		pathHash := HashPath(path + "?")
-		if cache.srcMetadata.Exists("src.example.com", pathHash) {
-			t.Errorf("metadata sidecar for %s must be removed with its row", path)
-		}
-	}
-
-	// The more recently used blob survives fully intact.
-	if !cache.srcContent.Exists(recentHash) {
-		t.Errorf("recently used blob %s must survive eviction", recentHash)
-	}
-
-	if n := countRows(t, cache,
-		`SELECT COUNT(*) FROM source_metadata WHERE content_hash = ?`, string(recentHash),
-	); n != 1 {
-		t.Errorf("recently used blob %s has %d source_metadata rows, want 1",
-			recentHash, n)
-	}
-
-	assertNoDanglingReferences(t, cache)
-}
-
 func TestEvictionKeepsEverythingWhenUnderLimit(t *testing.T) {
 	t.Parallel()
 
 	cache, _ := newEvictionTestCache(t, 1<<30)
 
 	content := bytes.Repeat([]byte{0xDF}, 800)
-	hash := storeEvictionTestSource(t, cache, "src.example.com", "/a.jpg", content)
-
-	h := storeEvictionTestSource(t, cache, "src.example.com", "/b.jpg", content)
-	if h != hash {
-		t.Fatalf("identical content produced different hashes: %s vs %s", h, hash)
+	keys := []imagerequest.SourceKey{
+		storeEvictionTestSource(t, cache, "src.example.com", "/a.jpg", content),
+		storeEvictionTestSource(t, cache, "src.example.com", "/b.jpg", content),
 	}
 
 	storeEvictionTestVariant(t, cache, testVariantKeyOne,
@@ -494,14 +372,16 @@ func TestEvictionKeepsEverythingWhenUnderLimit(t *testing.T) {
 		t.Fatalf("EvictToLimit failed: %v", err)
 	}
 
-	if !cache.srcContent.Exists(hash) {
-		t.Errorf("blob %s must not be evicted while usage is under the limit", hash)
-	}
+	for _, key := range keys {
+		if !cache.srcContent.Exists(key) {
+			t.Errorf("source %s must not be evicted while usage is under the limit", key)
+		}
 
-	if n := countRows(t, cache,
-		`SELECT COUNT(*) FROM source_metadata WHERE content_hash = ?`, string(hash),
-	); n != 2 {
-		t.Errorf("blob %s has %d source_metadata rows, want 2", hash, n)
+		if n := countRows(t, cache,
+			`SELECT COUNT(*) FROM source_content WHERE source_key = ?`, string(key),
+		); n != 1 {
+			t.Errorf("source %s has %d source_content rows, want 1", key, n)
+		}
 	}
 
 	if !cache.variants.Exists(testVariantKeyOne) {
@@ -516,12 +396,16 @@ func TestZeroMaxBytesDisablesDiskCache(t *testing.T) {
 
 	cache, tmpDir := newEvictionTestCache(t, 0)
 
-	req := &ImageRequest{
-		SourceHost: "src.example.com",
-		SourcePath: "/a.jpg",
-		Format:     FormatJPEG,
-		Quality:    85,
-		FitMode:    FitCover,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: "src.example.com",
+			Path: "/a.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
 	}
 
 	assertDisabledCacheWritesAreNoOps(t, cache, req)
@@ -533,62 +417,45 @@ func TestZeroMaxBytesDisablesDiskCache(t *testing.T) {
 // assertDisabledCacheWritesAreNoOps verifies that stores against a
 // disabled cache report success without recording anything.
 func assertDisabledCacheWritesAreNoOps(
-	t *testing.T, cache *Cache, req *ImageRequest,
+	t *testing.T, cache *Cache, req *imagerequest.Request,
 ) {
 	t.Helper()
 
 	ctx := t.Context()
 
 	err := cache.StoreVariant(
-		ctx, CacheKey(req), bytes.NewReader([]byte("data")), "image/webp",
+		ctx, imagerequest.CacheKey(req), bytes.NewReader([]byte("data")),
 	)
 	if err != nil {
 		t.Fatalf("StoreVariant on disabled cache must be a no-op, got error: %v", err)
 	}
 
-	result := &httpfetcher.FetchResult{
-		StatusCode:    200,
-		ContentType:   testContentTypeJPEG,
-		ContentLength: 4,
-		Headers:       map[string][]string{},
-	}
-
-	hash, err := cache.StoreSource(ctx, req, bytes.NewReader([]byte("data")), result)
+	key, err := cache.StoreSource(ctx, req, bytes.NewReader([]byte("data")))
 	if err != nil {
 		t.Fatalf("StoreSource on disabled cache must be a no-op, got error: %v", err)
 	}
 
-	if hash != "" {
-		t.Errorf("StoreSource on disabled cache returned hash %q, want empty", hash)
+	if key != "" {
+		t.Errorf("StoreSource on disabled cache returned key %q, want empty", key)
 	}
 }
 
 // assertDisabledCacheReadsAlwaysMiss verifies that lookups against a
 // disabled cache never report a hit.
 func assertDisabledCacheReadsAlwaysMiss(
-	t *testing.T, cache *Cache, req *ImageRequest,
+	t *testing.T, cache *Cache, req *imagerequest.Request,
 ) {
 	t.Helper()
 
 	ctx := t.Context()
 
-	lookup, err := cache.Lookup(ctx, req)
-	if err != nil {
-		t.Fatalf("Lookup on disabled cache failed: %v", err)
-	}
-
-	if lookup.Hit {
-		t.Error("Lookup on disabled cache must always miss")
-	}
-
-	srcHash, srcType, err := cache.LookupSource(ctx, req)
+	key, err := cache.LookupSource(ctx, req)
 	if err != nil {
 		t.Fatalf("LookupSource on disabled cache failed: %v", err)
 	}
 
-	if srcHash != "" || srcType != "" {
-		t.Errorf("LookupSource on disabled cache = (%q, %q), want empty",
-			srcHash, srcType)
+	if key != "" {
+		t.Errorf("LookupSource on disabled cache = %q, want empty", key)
 	}
 }
 
@@ -609,10 +476,6 @@ func assertDisabledCacheTracksNothing(t *testing.T, cache *Cache) {
 	if n := countRows(t, cache, `SELECT COUNT(*) FROM source_content`); n != 0 {
 		t.Errorf("disabled cache wrote %d source_content rows, want 0", n)
 	}
-
-	if n := countRows(t, cache, `SELECT COUNT(*) FROM source_metadata`); n != 0 {
-		t.Errorf("disabled cache wrote %d source_metadata rows, want 0", n)
-	}
 }
 
 // assertDisabledCacheWroteNothingToDisk verifies that a disabled cache
@@ -661,7 +524,7 @@ func TestEvictionRunsUnderWritePressure(t *testing.T) {
 	cache.StartEviction(time.Hour)
 	defer func() { _ = cache.StopEviction(t.Context()) }()
 
-	keys := []VariantKey{
+	keys := []imagerequest.VariantKey{
 		testVariantKeyOne, testVariantKeyTwo, testVariantKeyThree,
 	}
 	fills := []byte{0x11, 0x12, 0x13}
@@ -715,7 +578,7 @@ func TestEvictionRunsOnPeriodicSchedule(t *testing.T) {
 		time.Sleep(10 * time.Millisecond)
 	}
 
-	keys := []VariantKey{
+	keys := []imagerequest.VariantKey{
 		testVariantKeyOne, testVariantKeyTwo, testVariantKeyThree,
 	}
 	fills := []byte{0x21, 0x22, 0x23}
@@ -723,7 +586,7 @@ func TestEvictionRunsOnPeriodicSchedule(t *testing.T) {
 	for i, key := range keys {
 		content := bytes.Repeat([]byte{fills[i]}, 1000)
 
-		_, err = cache.variants.Store(key, bytes.NewReader(content), "image/webp")
+		_, err = cache.variants.Store(key, bytes.NewReader(content))
 		if err != nil {
 			t.Fatalf("failed to store variant file: %v", err)
 		}
@@ -775,7 +638,7 @@ func TestStartEvictionReconcilesAccountingWithDisk(t *testing.T) {
 	untracked := bytes.Repeat([]byte{0x31}, 1000)
 
 	_, err := cache.variants.Store(
-		testVariantKeyOne, bytes.NewReader(untracked), "image/webp",
+		testVariantKeyOne, bytes.NewReader(untracked),
 	)
 	if err != nil {
 		t.Fatalf("failed to store untracked variant file: %v", err)
@@ -783,9 +646,8 @@ func TestStartEvictionReconcilesAccountingWithDisk(t *testing.T) {
 
 	// An accounting row whose file is missing must be dropped.
 	_, err = cache.db.ExecContext(t.Context(),
-		`INSERT INTO variant_content (cache_key, size_bytes, content_type)
-		 VALUES (?, ?, ?)`,
-		"deadbeef0001", 700, "image/webp",
+		`INSERT INTO variant_content (cache_key, size_bytes) VALUES (?, ?)`,
+		"deadbeef0001", 700,
 	)
 	if err != nil {
 		t.Fatalf("failed to insert stale variant accounting row: %v", err)
@@ -877,7 +739,7 @@ func TestPeriodicReconciliationAdoptsFileThatAppearsAfterStartup(t *testing.T) {
 	untracked := bytes.Repeat([]byte{0x41}, 900)
 
 	_, err = cache.variants.Store(
-		"aabbccdd0099", bytes.NewReader(untracked), "image/webp",
+		"aabbccdd0099", bytes.NewReader(untracked),
 	)
 	if err != nil {
 		t.Fatalf("failed to store untracked variant file: %v", err)
@@ -918,6 +780,89 @@ func TestPeriodicReconciliationAdoptsFileThatAppearsAfterStartup(t *testing.T) {
 	}
 }
 
+// TestReconciliationPassesAreSpacedByTenTimesTheirTime makes the hook
+// called after every read of the reconciliation pass sleep 10 ms, runs
+// the eviction loop on a 10 ms interval, and records when each of those
+// calls starts and ends. A pass starts before its first call and ends
+// after its last, so the time from the first call's start to the last
+// call's end is at most the pass's time. The next pass's first call must
+// start at least ten times that long after the last call ended.
+func TestReconciliationPassesAreSpacedByTenTimesTheirTime(t *testing.T) {
+	t.Parallel()
+
+	cache, _ := newEvictionTestCache(t, 1<<30)
+
+	// A pass made here, before the loop starts, counts the reads one
+	// pass makes on this empty cache, so the reads recorded below can be
+	// split into passes.
+	readsPerPass := 0
+	cache.reconciliationReadTestHook = func(int) { readsPerPass++ }
+
+	err := cache.reconcileAccounting(t.Context())
+	if err != nil {
+		t.Fatalf("reconcileAccounting failed: %v", err)
+	}
+
+	t.Logf("one reconciliation pass makes %d reads", readsPerPass)
+
+	if readsPerPass == 0 {
+		t.Fatal("a reconciliation pass made no read")
+	}
+
+	// The pass at startup and two after it.
+	const passes = 3
+
+	type read struct{ start, end time.Time }
+
+	// The channel holds every read the test looks at, so none of those
+	// is dropped; reads after them are, and never block the loop.
+	reads := make(chan read, passes*readsPerPass)
+
+	cache.reconciliationReadTestHook = func(int) {
+		start := time.Now()
+
+		time.Sleep(10 * time.Millisecond)
+
+		select {
+		case reads <- read{start: start, end: time.Now()}:
+		default:
+		}
+	}
+
+	cache.StartEviction(10 * time.Millisecond)
+	defer func() { _ = cache.StopEviction(t.Context()) }()
+
+	recorded := make([]read, 0, passes*readsPerPass)
+	timeout := time.After(15 * time.Second)
+
+	for len(recorded) < passes*readsPerPass {
+		select {
+		case r := <-reads:
+			recorded = append(recorded, r)
+		case <-timeout:
+			t.Fatalf("saw %d reconciliation reads in 15 s, want %d (%d passes)",
+				len(recorded), passes*readsPerPass, passes)
+		}
+	}
+
+	for pass := range passes - 1 {
+		first := recorded[pass*readsPerPass]
+		last := recorded[(pass+1)*readsPerPass-1]
+		next := recorded[(pass+1)*readsPerPass]
+
+		passTime := last.end.Sub(first.start)
+		wait := next.start.Sub(last.end)
+
+		t.Logf("pass %d took at least %v, and the next pass started %v after it",
+			pass+1, passTime, wait)
+
+		if wait < 10*passTime {
+			t.Errorf("pass %d took at least %v, and the next pass started %v "+
+				"after it, want at least %v", pass+1, passTime, wait, 10*passTime)
+		}
+	}
+}
+
 // TestStopEvictionInterruptsPassInProgress holds the test database's
 // only connection, so the startup reconciliation pass waits for it, and
 // checks that StopEviction stops that pass instead of waiting for the
@@ -972,9 +917,15 @@ func TestStopEvictionInterruptsPassInProgress(t *testing.T) {
 }
 
 // TestEvictToLimitStopsAtNextCandidateOnceCancelled cancels the context
-// while the oldest of three source blobs is being evicted, and checks that
-// EvictToLimit then returns context.Canceled without evicting the other
-// two or logging a warning for either of them.
+// once the oldest of three sources is evicted, while the next one waits
+// for the database, and checks that EvictToLimit then returns
+// context.Canceled, with that source gone and the other two kept, and
+// logs no warning. The test database has one connection. When the
+// deletion of the oldest source's row commits, a commit hook holds the
+// deletion until the test waits for the connection, so the test takes it
+// as soon as the deletion is done. The eviction of the next source then
+// waits for the connection, and the test cancels the context while it
+// waits.
 func TestEvictToLimitStopsAtNextCandidateOnceCancelled(t *testing.T) {
 	t.Parallel()
 
@@ -984,7 +935,7 @@ func TestEvictToLimitStopsAtNextCandidateOnceCancelled(t *testing.T) {
 
 	cache.log = slog.New(slog.NewJSONHandler(&logBuf, nil))
 
-	hashes := []ContentHash{
+	keys := []imagerequest.SourceKey{
 		storeEvictionTestSource(t, cache, "cancel.example.com", "/a.jpg",
 			bytes.Repeat([]byte{0x61}, 1000)),
 		storeEvictionTestSource(t, cache, "cancel.example.com", "/b.jpg",
@@ -995,69 +946,155 @@ func TestEvictToLimitStopsAtNextCandidateOnceCancelled(t *testing.T) {
 
 	base := time.Now().Add(-time.Hour)
 
-	for i, hash := range hashes {
-		setSourceLastAccessed(t, cache, hash, base.Add(time.Duration(i)*time.Minute))
+	for i, key := range keys {
+		setSourceLastAccessed(t, cache, key, base.Add(time.Duration(i)*time.Minute))
 	}
 
+	waitsBefore := cache.db.Stats().WaitCount
+	oldestRowDeleted := make(chan struct{})
+
+	var oldestRowDeletedOnce sync.Once
+
+	setCommitHook(t, cache, func() int32 {
+		oldestRowDeletedOnce.Do(func() {
+			close(oldestRowDeleted)
+
+			deadline := time.Now().Add(5 * time.Second)
+
+			for cache.db.Stats().WaitCount == waitsBefore && time.Now().Before(deadline) {
+				time.Sleep(time.Millisecond)
+			}
+		})
+
+		return 0
+	})
+
 	ctx, cancel := context.WithCancel(t.Context())
 	defer cancel()
 
-	cache.evictSourceBlobTestHook = func(ContentHash) { cancel() }
+	evicted := make(chan error, 1)
 
-	err := cache.EvictToLimit(ctx)
+	go func() { evicted <- cache.EvictToLimit(ctx) }()
+
+	select {
+	case <-oldestRowDeleted:
+	case err := <-evicted:
+		t.Fatalf("EvictToLimit() returned %v without deleting a row", err)
+	case <-time.After(5 * time.Second):
+		t.Fatal("EvictToLimit never deleted a row")
+	}
+
+	releaseDatabase := holdDatabase(t, cache)
+	defer releaseDatabase()
+
+	waitForConnectionWaits(t, cache.db, waitsBefore+2)
+	cancel()
+
+	err := <-evicted
 	t.Logf("EvictToLimit() error = %v", err)
 	t.Logf("log output: %s", logBuf.String())
 
+	// The checks below read the database, so the connection goes back.
+	releaseDatabase()
+
+	setCommitHook(t, cache, nil)
+
 	if !errors.Is(err, context.Canceled) {
 		t.Errorf("EvictToLimit() error = %v, want context.Canceled", err)
 	}
 
-	if cache.srcContent.Exists(hashes[0]) {
-		t.Errorf("source blob %s, evicted when the context was cancelled, "+
-			"is still on disk", hashes[0])
-	}
-
-	for _, hash := range hashes[1:] {
-		if !cache.srcContent.Exists(hash) {
-			t.Errorf("source blob %s was evicted after the context was cancelled", hash)
-		}
-	}
+	assertOnlyOldestSourceEvicted(t, cache, keys)
 
 	if strings.Contains(logBuf.String(), `"level":"WARN"`) {
 		t.Errorf("EvictToLimit logged a warning after the context was cancelled")
 	}
+}
+
+// setCommitHook makes the SQLite driver call hook each time a write on
+// the test database's one connection commits, or stops it when hook is
+// nil.
+func setCommitHook(t *testing.T, cache *Cache, hook sqlite.CommitHookFn) {
+	t.Helper()
+
+	conn, err := cache.db.Conn(t.Context())
+	if err != nil {
+		t.Fatalf("failed to take the database connection: %v", err)
+	}
+
+	defer func() { _ = conn.Close() }()
+
+	err = conn.Raw(func(driverConn any) error {
+		hooks, ok := driverConn.(sqlite.HookRegisterer)
+		if !ok {
+			t.Fatalf("the database connection is a %T, which takes no hooks",
+				driverConn)
+		}
+
+		hooks.RegisterCommitHook(hook)
+
+		return nil
+	})
+	if err != nil {
+		t.Fatalf("failed to set the commit hook: %v", err)
+	}
+}
+
+// assertOnlyOldestSourceEvicted checks that the first of keys has neither
+// its file nor its row, and that every other one has both.
+func assertOnlyOldestSourceEvicted(
+	t *testing.T, cache *Cache, keys []imagerequest.SourceKey,
+) {
+	t.Helper()
+
+	if cache.srcContent.Exists(keys[0]) {
+		t.Errorf("source %s, evicted when the context was cancelled, "+
+			"is still on disk", keys[0])
+	}
+
+	for _, key := range keys[1:] {
+		if !cache.srcContent.Exists(key) {
+			t.Errorf("source %s was evicted after the context was cancelled", key)
+		}
+
+		if n := countRows(t, cache,
+			`SELECT COUNT(*) FROM source_content WHERE source_key = ?`, string(key),
+		); n != 1 {
+			t.Errorf("source %s, kept, has %d source_content rows, want 1", key, n)
+		}
+	}
 
 	assertNoDanglingReferences(t, cache)
 }
 
-// TestStopEvictionReturnsWhenItsContextEnds pauses an eviction pass where
-// cancellation cannot reach it, after a source blob's rows are deleted and
-// before its file is removed, and checks that StopEviction returns its
-// context's error when that context ends instead of waiting for the pass.
-// Once the pass goes on, the goroutine exits and no row points at a
-// missing file.
+// TestStopEvictionReturnsWhenItsContextEnds pauses the startup
+// reconciliation pass in the hook called after each of its reads, where
+// cancellation cannot reach it, and checks that StopEviction returns an
+// error wrapping its context's error when that context ends, instead of
+// waiting for the pass. Once the pass goes on, the goroutine exits, and a
+// second StopEviction returns nil.
 func TestStopEvictionReturnsWhenItsContextEnds(t *testing.T) {
 	t.Parallel()
 
-	cache, _ := newEvictionTestCache(t, 1)
+	cache, _ := newEvictionTestCache(t, 1<<30)
 
 	paused := make(chan struct{})
 	resume := make(chan struct{})
 
-	cache.evictSourceBlobTestHook = func(ContentHash) {
-		close(paused)
-		<-resume
-	}
+	var pauseOnce sync.Once
 
-	hash := storeEvictionTestSource(t, cache, "stop.example.com", "/a.jpg",
-		bytes.Repeat([]byte{0x61}, 1000))
+	cache.reconciliationReadTestHook = func(int) {
+		pauseOnce.Do(func() {
+			close(paused)
+			<-resume
+		})
+	}
 
 	cache.StartEviction(time.Hour)
 
 	select {
 	case <-paused:
 	case <-time.After(5 * time.Second):
-		t.Fatal("the eviction pass never reached the source blob")
+		t.Fatal("the reconciliation pass never made a read")
 	}
 
 	ctx, cancel := context.WithTimeout(t.Context(), 50*time.Millisecond)
@@ -1076,12 +1113,6 @@ func TestStopEvictionReturnsWhenItsContextEnds(t *testing.T) {
 	if err != nil {
 		t.Fatalf("second StopEviction() error = %v, want nil", err)
 	}
-
-	assertNoDanglingReferences(t, cache)
-
-	if cache.srcContent.Exists(hash) {
-		t.Errorf("source blob %s is still on disk after its rows were deleted", hash)
-	}
 }
 
 // TestReconciliationWalksStopOnceCancelled checks that both directory
@@ -1153,125 +1184,3 @@ func TestReconciliationPassLogsNoWarningOnceCancelled(t *testing.T) {
 		t.Errorf("runReconciliationPass logged a warning with a cancelled context")
 	}
 }
-
-// TestEvictSourceBlobExcludesConcurrentStoreOfIdenticalContent exercises
-// the exact TOCTOU window between evictSourceBlob's row-deletion
-// transaction commit and its content file unlink: a concurrent
-// StoreSource for a different source path whose content hashes to the
-// same value (real SHA-256 dedup, not a contrived case) must not be
-// able to insert a fresh row referencing the file while eviction is
-// mid-unlink, and must not lose its own store once eviction has fully
-// released the content hash.
-func TestEvictSourceBlobExcludesConcurrentStoreOfIdenticalContent(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<30)
-	ctx := context.Background()
-
-	content := bytes.Repeat([]byte{0x55}, 400)
-
-	hash := storeEvictionTestSource(t, cache,
-		"race.example.com", "/first.jpg", content)
-
-	proceed := make(chan struct{})
-	storeAttempted := make(chan struct{})
-
-	cache.evictSourceBlobTestHook = func(gotHash ContentHash) {
-		if gotHash != hash {
-			t.Errorf("test hook invoked for hash %s, want %s", gotHash, hash)
-		}
-
-		close(storeAttempted)
-		<-proceed
-	}
-
-	evictDone := make(chan error, 1)
-
-	go func() {
-		evictDone <- cache.evictSourceBlob(ctx, hash)
-	}()
-
-	// Wait until eviction has committed its delete transaction and is
-	// paused (inside the test hook) immediately before unlinking the
-	// content file: exactly the window the review flagged.
-	<-storeAttempted
-
-	storeDone := storeIdenticalContentConcurrently(ctx, cache, content)
-
-	// The concurrent store must not be able to complete while eviction
-	// still holds the content hash (i.e. before the file is unlinked):
-	// if it could, it would insert a row referencing a file about to be
-	// removed out from under it.
-	select {
-	case err := <-storeDone:
-		t.Fatalf("StoreSource for identical content completed (err=%v) while eviction "+
-			"still held the content hash open between commit and unlink; the store and "+
-			"the evict of identical content are not mutually exclusive", err)
-	case <-time.After(200 * time.Millisecond):
-		// Expected: the store is blocked behind eviction's exclusion.
-	}
-
-	close(proceed)
-
-	err := <-evictDone
-	if err != nil {
-		t.Fatalf("evictSourceBlob failed: %v", err)
-	}
-
-	err = <-storeDone
-	if err != nil {
-		t.Fatalf("StoreSource failed: %v", err)
-	}
-
-	assertNoDanglingReferences(t, cache)
-
-	dupHash, _, err := cache.LookupSource(ctx, &ImageRequest{
-		SourceHost: "race.example.com",
-		SourcePath: "/dup.jpg",
-	})
-	if err != nil {
-		t.Fatalf("LookupSource failed: %v", err)
-	}
-
-	if dupHash == "" {
-		t.Fatal("re-stored blob was lost: the store legitimately ran after eviction " +
-			"released the content hash and must have recreated the file and row")
-	}
-
-	if !cache.srcContent.Exists(dupHash) {
-		t.Errorf("source_content/source_metadata references %s but its file is missing",
-			dupHash)
-	}
-}
-
-// storeIdenticalContentConcurrently starts a StoreSource for a second
-// source path whose body hashes to the same content hash, returning the
-// channel its error is delivered on.
-func storeIdenticalContentConcurrently(
-	ctx context.Context, cache *Cache, content []byte,
-) chan error {
-	storeDone := make(chan error, 1)
-
-	go func() {
-		req := &ImageRequest{
-			SourceHost: "race.example.com",
-			SourcePath: "/dup.jpg",
-			Format:     FormatJPEG,
-			Quality:    85,
-			FitMode:    FitCover,
-		}
-		result := &httpfetcher.FetchResult{
-			StatusCode:    200,
-			ContentType:   testContentTypeJPEG,
-			ContentLength: int64(len(content)),
-			Headers: map[string][]string{
-				testHeaderContentType: {testContentTypeJPEG},
-			},
-		}
-
-		_, err := cache.StoreSource(ctx, req, bytes.NewReader(content), result)
-		storeDone <- err
-	}()
-
-	return storeDone
-}

internal/imgcache/imgcache.go

@@ -1,127 +1,7 @@
-// Package imgcache provides interfaces and types for the image caching proxy.
+// Package imgcache provides types for the image caching proxy.
 package imgcache
 
-import (
-	"context"
-	"errors"
-	"io"
-	"time"
-)
-
-// ErrInvalidFitMode is returned when an invalid fit mode is provided.
-var ErrInvalidFitMode = errors.New("invalid fit mode")
-
-// ImageFormat represents supported output image formats.
-type ImageFormat string
-
-// Supported image output formats.
-const (
-	FormatOriginal ImageFormat = "orig"
-	FormatJPEG     ImageFormat = "jpeg"
-	FormatPNG      ImageFormat = "png"
-	FormatWebP     ImageFormat = "webp"
-	FormatAVIF     ImageFormat = "avif"
-	FormatJXL      ImageFormat = "jxl"
-	FormatGIF      ImageFormat = "gif"
-
-	// FormatAuto stands for JPEG XL, AVIF, WebP or JPEG, chosen for each
-	// request from its Accept header once the URL's signature or token has
-	// been checked; it is never processed or cached as itself.
-	FormatAuto ImageFormat = "auto"
-)
-
-// Size represents requested image dimensions
-type Size struct {
-	Width  int
-	Height int
-}
-
-// OriginalSize returns true if this represents "keep original size"
-func (s Size) OriginalSize() bool {
-	return s.Width == 0 && s.Height == 0
-}
-
-// FitMode represents how to fit image into requested dimensions.
-type FitMode string
-
-// Supported image fit modes.
-const (
-	FitCover   FitMode = "cover"
-	FitContain FitMode = "contain"
-	FitFill    FitMode = "fill"
-	FitInside  FitMode = "inside"
-	FitOutside FitMode = "outside"
-)
-
-// ValidateFitMode checks if the given fit mode is valid.
-// Returns ErrInvalidFitMode for unrecognized fit modes.
-func ValidateFitMode(fit FitMode) error {
-	switch fit {
-	case FitCover, FitContain, FitFill, FitInside, FitOutside, "":
-		return nil
-	default:
-		return ErrInvalidFitMode
-	}
-}
-
-// ValidateImageRequest checks a request's width and height with
-// ValidateDimension and its fit mode with ValidateFitMode. Both the plain
-// /v1/image/ route and the encrypted /v1/e/ route validate through this
-// function so a request from either source enforces identical bounds.
-func ValidateImageRequest(req *ImageRequest) error {
-	err := ValidateDimension("width", req.Size.Width)
-	if err != nil {
-		return err
-	}
-
-	err = ValidateDimension("height", req.Size.Height)
-	if err != nil {
-		return err
-	}
-
-	return ValidateFitMode(req.FitMode)
-}
-
-// ImageRequest represents a request for a processed image
-type ImageRequest struct {
-	// SourceHost is the origin host (e.g., "cdn.example.com")
-	SourceHost string
-	// SourcePath is the path on the origin (e.g., "/photos/cat.jpg")
-	SourcePath string
-	// SourceQuery is the optional query string for the origin URL
-	SourceQuery string
-	// Size is the requested output dimensions
-	Size Size
-	// Format is the requested output format
-	Format ImageFormat
-	// Quality is the output quality (1-100) for lossy formats
-	Quality int
-	// FitMode is how to fit the image into requested dimensions
-	FitMode FitMode
-	// Signature is the HMAC signature for non-allowlisted hosts
-	Signature string
-	// Expires is when the URL expires: the exp of a signed URL, or the expiry
-	// of an encrypted URL; the zero time if it has none
-	Expires time.Time
-	// AllowHTTP indicates whether HTTP (non-TLS) is allowed for this request
-	AllowHTTP bool
-}
-
-// SourceURL returns the full upstream URL to fetch.
-// Uses http:// scheme when AllowHTTP is true, otherwise https://.
-func (r *ImageRequest) SourceURL() string {
-	scheme := "https"
-	if r.AllowHTTP {
-		scheme = "http"
-	}
-
-	url := scheme + "://" + r.SourceHost + r.SourcePath
-	if r.SourceQuery != "" {
-		url += "?" + r.SourceQuery
-	}
-
-	return url
-}
+import "io"
 
 // ImageResponse represents a processed image ready to serve
 type ImageResponse struct {
@@ -133,9 +13,7 @@ type ImageResponse struct {
 	ContentType string
 	// ETag is the entity tag for caching
 	ETag string
-	// LastModified is when the content was last modified
-	LastModified time.Time
-	// CacheStatus indicates HIT, MISS, or STALE
+	// CacheStatus indicates HIT or MISS
 	CacheStatus CacheStatus
 	// FetchedBytes is the number of bytes fetched from upstream (0 if cache hit)
 	FetchedBytes int64
@@ -146,35 +24,6 @@ type CacheStatus string
 
 // Cache status values for response headers.
 const (
-	CacheHit   CacheStatus = "HIT"
-	CacheMiss  CacheStatus = "MISS"
-	CacheStale CacheStatus = "STALE"
+	CacheHit  CacheStatus = "HIT"
+	CacheMiss CacheStatus = "MISS"
 )
-
-// ImageCache is the main interface for the image caching proxy
-type ImageCache interface {
-	// Get retrieves a processed image, fetching and processing if necessary
-	Get(ctx context.Context, req *ImageRequest) (*ImageResponse, error)
-
-	// Warm pre-fetches and caches an image without returning it
-	Warm(ctx context.Context, req *ImageRequest) error
-
-	// Stats returns cache statistics
-	Stats(ctx context.Context) (*CacheStats, error)
-}
-
-// CacheStats contains cache statistics
-type CacheStats struct {
-	// TotalItems is the number of cached source images plus processed
-	// variants
-	TotalItems int64
-	// TotalSizeBytes is the total size of cached source images and
-	// processed variants
-	TotalSizeBytes int64
-	// HitCount is the number of cache hits
-	HitCount int64
-	// MissCount is the number of cache misses
-	MissCount int64
-	// HitRate is HitCount / (HitCount + MissCount)
-	HitRate float64
-}

internal/imgcache/max_concurrent_processing_internal_test.go

@@ -9,18 +9,23 @@ import (
 	"time"
 
 	"sneak.berlin/go/pixa/internal/imageprocessor"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // widthOnlyRequest asks for the test photo at width, its height scaled to
 // keep the photo's aspect ratio.
-func widthOnlyRequest(fixtures *TestFixtures, width int) *ImageRequest {
-	return &ImageRequest{
-		SourceHost: fixtures.GoodHost,
-		SourcePath: testPathPhoto,
-		Size:       Size{Width: width},
-		Format:     FormatJPEG,
-		Quality:    85,
-		FitMode:    FitCover,
+func widthOnlyRequest(fixtures *TestFixtures, width int) *imagerequest.Request {
+	return &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: fixtures.GoodHost,
+			Path: testPathPhoto,
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: width},
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
 	}
 }
 
@@ -36,7 +41,7 @@ func holdProcessingSlot(
 	input, feed := io.Pipe()
 
 	go func() {
-		_, _ = proc.Process(t.Context(), input, &imageprocessor.Request{})
+		_, _ = proc.Process(t.Context(), input, &imagerequest.Transform{})
 	}()
 
 	_, err := feed.Write([]byte{0})
@@ -61,7 +66,7 @@ func TestService_Get_WaitsForSlotBeforeReadingCachedSource(t *testing.T) {
 
 	svc, fixtures := SetupTestService(t)
 	svc.processor = imageprocessor.New(
-		imageprocessor.Params{MaxConcurrentProcessing: 1},
+		imageprocessor.Params{MaxInputBytes: 50 << 20, MaxConcurrentProcessing: 1},
 	)
 
 	// A first request caches the photo as a source.
@@ -72,11 +77,11 @@ func TestService_Get_WaitsForSlotBeforeReadingCachedSource(t *testing.T) {
 
 	_ = resp.Content.Close()
 
-	contentHash, _, err := svc.cache.LookupSource(t.Context(),
+	sourceKey, err := svc.cache.LookupSource(t.Context(),
 		widthOnlyRequest(fixtures, 50))
-	if err != nil || contentHash == "" {
+	if err != nil || sourceKey == "" {
 		t.Fatalf("LookupSource() = %q, %v; want the cached source",
-			contentHash, err)
+			sourceKey, err)
 	}
 
 	release := holdProcessingSlot(t, svc.processor)
@@ -98,7 +103,7 @@ func TestService_Get_WaitsForSlotBeforeReadingCachedSource(t *testing.T) {
 	// before waiting, it would have read it by now.
 	time.Sleep(100 * time.Millisecond)
 
-	err = os.WriteFile(svc.cache.srcContent.hashToPath(contentHash),
+	err = os.WriteFile(svc.cache.srcContent.keyToPath(sourceKey),
 		generateTestJPEG(t, 100, 50, color.RGBA{0, 0, 255, 255}), 0o600)
 	if err != nil {
 		t.Fatalf("failed to rewrite the cached source: %v", err)

internal/imgcache/metacache_internal_test.go

@@ -1,349 +0,0 @@
-package imgcache
-
-import (
-	"bytes"
-	"encoding/json"
-	"errors"
-	"fmt"
-	"io"
-	"os"
-	"sync"
-	"testing"
-	"time"
-)
-
-// webpRequest returns a request for a 100x100 WebP variant of path.
-func webpRequest(path string) *ImageRequest {
-	return &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: path,
-		Size:       Size{Width: 100, Height: 100},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
-	}
-}
-
-// assertVariantServed checks that GetVariant serves key with the given
-// content and the image/webp content type storeEvictionTestVariant stores.
-func assertVariantServed(t *testing.T, cache *Cache, key VariantKey, content []byte) {
-	t.Helper()
-
-	reader, size, contentType, err := cache.GetVariant(key)
-	if err != nil {
-		t.Fatalf("GetVariant(%s) error = %v", key, err)
-	}
-
-	defer func() { _ = reader.Close() }()
-
-	got, err := io.ReadAll(reader)
-	if err != nil {
-		t.Fatalf("reading variant %s: %v", key, err)
-	}
-
-	if !bytes.Equal(got, content) {
-		t.Errorf("GetVariant(%s) content = %q, want %q", key, got, content)
-	}
-
-	if size != int64(len(content)) {
-		t.Errorf("GetVariant(%s) size = %d, want %d", key, size, len(content))
-	}
-
-	if contentType != testContentTypeWebP {
-		t.Errorf("GetVariant(%s) content type = %q, want %q",
-			key, contentType, testContentTypeWebP)
-	}
-}
-
-// assertVariantNotFound checks that GetVariant refuses key with
-// ErrNotFound.
-func assertVariantNotFound(t *testing.T, cache *Cache, key VariantKey) {
-	t.Helper()
-
-	reader, _, _, err := cache.GetVariant(key)
-	if err == nil {
-		_ = reader.Close()
-	}
-
-	if !errors.Is(err, ErrNotFound) {
-		t.Errorf("GetVariant(%s) error = %v, want ErrNotFound", key, err)
-	}
-}
-
-// assertLookupMisses checks that Lookup reports request as a miss.
-func assertLookupMisses(t *testing.T, cache *Cache, request *ImageRequest) {
-	t.Helper()
-
-	lookup, err := cache.Lookup(t.Context(), request)
-	if err != nil {
-		t.Fatalf("Lookup(%s) error = %v", request.SourcePath, err)
-	}
-
-	if lookup.Hit {
-		t.Errorf("Lookup(%s) is a hit, want a miss", request.SourcePath)
-	}
-}
-
-// renameFile renames the file at from to to.
-func renameFile(t *testing.T, from, to string) {
-	t.Helper()
-
-	err := os.Rename(from, to)
-	if err != nil {
-		t.Fatalf("renaming %s: %v", from, err)
-	}
-}
-
-// TestSecondHitDoesNotReadMetaFile checks that once a variant has been
-// stored or read, a hit takes its content type from memory: with the
-// .meta file deleted, GetVariant must still return the stored content
-// type rather than the application/octet-stream it uses without one.
-func TestSecondHitDoesNotReadMetaFile(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<20)
-	content := []byte("webp variant bytes")
-
-	storeEvictionTestVariant(t, cache, testVariantKeyOne, content)
-
-	// A second Cache on the same state directory starts with nothing in
-	// memory, as pixad does after a restart, so its first read uses the
-	// .meta file.
-	restarted, err := NewCache(cache.db, cache.config)
-	if err != nil {
-		t.Fatalf("NewCache() error = %v", err)
-	}
-
-	assertVariantServed(t, restarted, testVariantKeyOne, content)
-
-	err = os.Remove(cache.variants.keyToPath(testVariantKeyOne) + ".meta")
-	if err != nil {
-		t.Fatalf("removing .meta file: %v", err)
-	}
-
-	assertVariantServed(t, cache, testVariantKeyOne, content)
-	assertVariantServed(t, restarted, testVariantKeyOne, content)
-}
-
-// TestReadDuringStoreKeepsStoredContentType checks that a GetVariant
-// which began before StoreVariant finished cannot replace the content
-// type the store kept in memory. Such a read can find the variant file
-// but not yet its .meta file, and so gets application/octet-stream. The
-// test deletes the .meta file after the store, then runs the part of
-// GetVariant that comes after its check of memory.
-func TestReadDuringStoreKeepsStoredContentType(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<20)
-	content := []byte("webp variant bytes")
-
-	storeEvictionTestVariant(t, cache, testVariantKeyOne, content)
-
-	err := os.Remove(cache.variants.keyToPath(testVariantKeyOne) + ".meta")
-	if err != nil {
-		t.Fatalf("removing .meta file: %v", err)
-	}
-
-	reader, _, contentType, err := cache.loadVariantWithMeta(testVariantKeyOne)
-	if err != nil {
-		t.Fatalf("loadVariantWithMeta(%s) error = %v", testVariantKeyOne, err)
-	}
-
-	_ = reader.Close()
-
-	t.Logf("the read without a .meta file got content type %q", contentType)
-
-	assertVariantServed(t, cache, testVariantKeyOne, content)
-}
-
-// TestReadOfOlderMetaFileKeepsStoredContentType checks that a read
-// which got its content type from a .meta file that StoreVariant had
-// not yet rewritten cannot replace the type the store kept in memory.
-// The test writes such a .meta file, with a different content type,
-// after the store, then runs the part of GetVariant that comes after
-// its check of memory.
-func TestReadOfOlderMetaFileKeepsStoredContentType(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<20)
-	content := []byte("webp variant bytes")
-
-	storeEvictionTestVariant(t, cache, testVariantKeyOne, content)
-
-	olderMeta, err := json.Marshal(VariantMeta{
-		ContentType: testContentTypeJPEG,
-		Size:        int64(len(content)),
-	})
-	if err != nil {
-		t.Fatalf("encoding .meta file: %v", err)
-	}
-
-	metaPath := cache.variants.keyToPath(testVariantKeyOne) + ".meta"
-
-	err = os.WriteFile(metaPath, olderMeta, StorageFilePerm)
-	if err != nil {
-		t.Fatalf("writing .meta file: %v", err)
-	}
-
-	reader, _, contentType, err := cache.loadVariantWithMeta(testVariantKeyOne)
-	if err != nil {
-		t.Fatalf("loadVariantWithMeta(%s) error = %v", testVariantKeyOne, err)
-	}
-
-	_ = reader.Close()
-
-	if contentType != testContentTypeJPEG {
-		t.Fatalf("loadVariantWithMeta(%s) content type = %q, want %q from the .meta file",
-			testVariantKeyOne, contentType, testContentTypeJPEG)
-	}
-
-	kept, _ := cache.metaCache.Get(testVariantKeyOne)
-	if kept != testContentTypeWebP {
-		t.Errorf("content type in memory = %q, want the stored %q",
-			kept, testContentTypeWebP)
-	}
-}
-
-// TestFailedReadDuringStoreKeepsStoredContentType checks that a read
-// which found no .meta file cannot leave application/octet-stream in
-// memory, even when another read has removed the content type
-// StoreVariant kept there. In this order: the store; a read that finds
-// the variant in memory but cannot open its file, and so removes it
-// from memory; a read that opened the variant file before the store
-// wrote its .meta file. Later hits must get the stored content type.
-func TestFailedReadDuringStoreKeepsStoredContentType(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<20)
-	content := []byte("webp variant bytes")
-	variantPath := cache.variants.keyToPath(testVariantKeyOne)
-	metaPath := variantPath + ".meta"
-
-	storeEvictionTestVariant(t, cache, testVariantKeyOne, content)
-
-	renameFile(t, variantPath, variantPath+".hidden")
-	assertVariantNotFound(t, cache, testVariantKeyOne)
-	renameFile(t, variantPath+".hidden", variantPath)
-
-	renameFile(t, metaPath, metaPath+".hidden")
-
-	reader, _, contentType, err := cache.GetVariant(testVariantKeyOne)
-	if err != nil {
-		t.Fatalf("GetVariant(%s) error = %v", testVariantKeyOne, err)
-	}
-
-	_ = reader.Close()
-
-	t.Logf("the read without a .meta file got content type %q", contentType)
-
-	renameFile(t, metaPath+".hidden", metaPath)
-
-	assertVariantServed(t, cache, testVariantKeyOne, content)
-}
-
-// TestEvictedVariantIsNotServed checks that a variant the evictor
-// removed is a miss and cannot be read, although it had been stored
-// and served before.
-func TestEvictedVariantIsNotServed(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1500)
-
-	oldRequest := webpRequest("/old.jpg")
-	newRequest := webpRequest("/new.jpg")
-	oldKey := CacheKey(oldRequest)
-	newKey := CacheKey(newRequest)
-	oldContent := bytes.Repeat([]byte{0x01}, 1000)
-	newContent := bytes.Repeat([]byte{0x02}, 1000)
-
-	storeEvictionTestVariant(t, cache, oldKey, oldContent)
-	storeEvictionTestVariant(t, cache, newKey, newContent)
-	assertVariantServed(t, cache, oldKey, oldContent)
-	setVariantLastAccessed(t, cache, oldKey, time.Now().Add(-time.Hour))
-
-	err := cache.EvictToLimit(t.Context())
-	if err != nil {
-		t.Fatalf("EvictToLimit() error = %v", err)
-	}
-
-	assertLookupMisses(t, cache, oldRequest)
-	assertVariantNotFound(t, cache, oldKey)
-	assertVariantServed(t, cache, newKey, newContent)
-}
-
-// TestVariantDeletedFromDiskIsNotServed checks that a variant whose
-// file was deleted by something other than the evictor cannot be read,
-// and is a miss afterwards.
-func TestVariantDeletedFromDiskIsNotServed(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<20)
-
-	request := webpRequest("/deleted.jpg")
-	key := CacheKey(request)
-	content := []byte("webp variant bytes")
-
-	storeEvictionTestVariant(t, cache, key, content)
-	assertVariantServed(t, cache, key, content)
-
-	err := os.Remove(cache.variants.keyToPath(key))
-	if err != nil {
-		t.Fatalf("removing variant file: %v", err)
-	}
-
-	assertVariantNotFound(t, cache, key)
-	assertLookupMisses(t, cache, request)
-}
-
-// TestConcurrentVariantStoreReadAndEvict stores, reads and evicts
-// variants from several goroutines at once, for the race detector.
-func TestConcurrentVariantStoreReadAndEvict(t *testing.T) {
-	t.Parallel()
-
-	cache, _ := newEvictionTestCache(t, 1<<20)
-	ctx := t.Context()
-
-	var wg sync.WaitGroup
-
-	for goroutine := range 8 {
-		wg.Go(func() {
-			key := VariantKey(fmt.Sprintf("aabbccdd01%02d", goroutine))
-			content := []byte(key)
-
-			for range 20 {
-				err := cache.StoreVariant(
-					ctx, key, bytes.NewReader(content), testContentTypeWebP)
-				if err != nil {
-					t.Errorf("StoreVariant(%s) error = %v", key, err)
-
-					return
-				}
-
-				reader, _, contentType, err := cache.GetVariant(key)
-				if err != nil {
-					t.Errorf("GetVariant(%s) error = %v", key, err)
-
-					return
-				}
-
-				_ = reader.Close()
-
-				if contentType != testContentTypeWebP {
-					t.Errorf("GetVariant(%s) content type = %q, want %q",
-						key, contentType, testContentTypeWebP)
-				}
-
-				err = cache.evictVariant(ctx, key)
-				if err != nil {
-					t.Errorf("evictVariant(%s) error = %v", key, err)
-
-					return
-				}
-
-				assertVariantNotFound(t, cache, key)
-			}
-		})
-	}
-
-	wg.Wait()
-}