scripts-to-rule-them-all (#58)

Reviewed-on: #58
Co-authored-by: sneak <sneak@sneak.berlin>
Co-committed-by: sneak <sneak@sneak.berlin>

.drone.yml

@@ -1,23 +0,0 @@
-kind: pipeline
-name: test-docker-build
-
-steps:
-- name: test-docker-build
-  image: plugins/docker
-  network_mode: bridge
-  settings:
-    repo: sneak/mfer
-    build_args_from_env: [ DRONE_COMMIT_SHA ]
-    dry_run: true
-    custom_dns: [ 116.202.204.30 ]
-    tags:
-      - ${DRONE_COMMIT_SHA:0:7}
-      - ${DRONE_BRANCH}
-      - latest
-- name: notify
-  image: plugins/slack
-  settings:
-    webhook:
-      from_secret: SLACK_WEBHOOK_URL
-  when:
-    event: pull_request

.gitea/workflows/check.yml

@@ -0,0 +1,9 @@
+name: check
+on: [push]
+jobs:
+    check:
+        runs-on: ubuntu-latest
+        steps:
+            # actions/checkout v4.2.2, 2026-03-16
+            - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
+            - run: script/cibuild

.gitignore

@@ -3,3 +3,11 @@
 *.tmp
 *.dockerimage
 /vendor
+vendor.tzst
+modcache.tzst
+
+# Generated manifest files
+.index.mf
+
+# Stale files
+.drone.yml

AGENTS.md

@@ -0,0 +1,30 @@
+# Agent Instructions
+
+Read `REPO_POLICIES.md` before making any changes. It is the authoritative
+source for coding standards, formatting, linting, and workflow rules.
+
+## Workflow
+
+- When fixing a bug, write a failing test FIRST. Only after the test fails,
+  write the code to fix the bug. Then ensure the test passes. Leave the test in
+  place and commit it with the bugfix. Don't run shell commands to test bugfixes
+  or reproduce bugs. Write tests!
+
+- After each change, run `make fmt`, then `make test`, then `make lint`. Fix any
+  failures before committing.
+
+- After each change, commit only the files you've changed. Push after committing.
+
+## Attribution
+
+- Never mention Claude, Anthropic, or any AI/LLM tooling in commit messages. Do
+  not use attribution.
+
+## Repository-Specific Notes
+
+- This is a Go library + CLI tool for generating `.mf` manifest files.
+- The proto definition is in `mfer/mf.proto`; generated `.pb.go` files are
+  committed (required for `go get` compatibility).
+- The format specification is in `FORMAT.md`.
+- See the TODO section in `README.md` for the 1.0 implementation plan
+  and open design questions.

Dockerfile

@@ -1,37 +1,38 @@
-################################################################################
+# Lint stage — fast feedback on formatting and lint issues
-#2345678911234567892123456789312345678941234567895123456789612345678971234567898
+# golangci/golangci-lint:v2.0.2 (2026-03-14)
-################################################################################
+FROM golangci/golangci-lint@sha256:d55581f7797e7a0877a7c3aaa399b01bdc57d2874d6412601a046cc4062cb62e AS lint
-FROM sneak/builder:2022-12-08 AS builder
+
-ENV DEBIAN_FRONTEND noninteractive
+WORKDIR /src
-WORKDIR /build
+COPY go.mod go.sum ./
-COPY ./Makefile ./.golangci.yml ./go.mod ./go.sum /build/
+RUN go mod download
-COPY ./vendor.tzst /build/vendor.tzst
+
-COPY ./modcache.tzst /build/modcache.tzst
+COPY . .
-COPY ./internal ./internal
+
-COPY ./bin/gitrev.sh ./bin/gitrev.sh
+# Touch .pb.go so make does not try to regenerate via protoc (file is committed)
-COPY ./mfer ./mfer
+RUN touch mfer/mf.pb.go
-COPY ./cmd ./cmd
+
-ARG GITREV unknown
+RUN make fmt-check
-ARG DRONE_COMMIT_SHA unknown
+RUN make lint
+
+# Build stage — tests and compilation
+# golang:1.23 (2026-03-14)
+FROM golang@sha256:60deed95d3888cc5e4d9ff8a10c54e5edc008c6ae3fba6187be6fb592e19e8c0 AS builder
+
+# Force BuildKit to run the lint stage by creating a stage dependency
+COPY --from=lint /src/go.sum /dev/null
+
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+
+# Touch .pb.go so make does not try to regenerate via protoc (file is committed)
+RUN touch mfer/mf.pb.go
+
+RUN make test
+RUN cd cmd/mfer && go build -tags urfave_cli_no_docs -o /mfer .
 
-RUN mkdir -p "$(go env GOMODCACHE)" && cd "$(go env GOMODCACHE)" && \
-    zstdmt -d --stdout /build/modcache.tzst | tar xf - && \
-    rm /build/modcache.tzst && cd /build
-RUN \
-    cd mfer && go generate . && cd .. && \
-    GOPACKAGESDEBUG=true golangci-lint run ./... && \
-    mkdir vendor && cd vendor && \
-    zstdmt -d --stdout /build/vendor.tzst | tar xf - && rm /build/vendor.tzst && \
-    cd .. && \
-    make mfer.cmd
-RUN rm -rf /build/vendor && go mod vendor && tar -c . | zstdmt -19 > /src.tzst
-################################################################################
-#2345678911234567892123456789312345678941234567895123456789612345678971234567898
-################################################################################
-## final image
-################################################################################
 FROM scratch
-# we put all the source into the final image for posterity, it's small
+COPY --from=builder /mfer /mfer
-COPY --from=builder /src.tzst /src.tzst
-COPY --from=builder /build/mfer.cmd /mfer
 ENTRYPOINT ["/mfer"]

FORMAT.md

@@ -0,0 +1,143 @@
+# .mf File Format Specification
+
+Version 1.0
+
+## Overview
+
+An `.mf` file is a binary manifest that describes a directory tree of files,
+including their paths, sizes, and cryptographic checksums. It supports
+optional GPG signatures for integrity verification and optional timestamps
+for metadata preservation.
+
+## File Structure
+
+An `.mf` file consists of two parts, concatenated:
+
+1. **Magic bytes** (8 bytes): the ASCII string `ZNAVSRFG`
+2. **Outer message**: a Protocol Buffers serialized `MFFileOuter` message
+
+There is no length prefix or version byte between the magic and the protobuf
+message. The protobuf message extends to the end of the file.
+
+See [`mfer/mf.proto`](mfer/mf.proto) for exact field numbers and types.
+
+## Outer Message (`MFFileOuter`)
+
+The outer message contains:
+
+| Field             | Number | Type             | Description                                                              |
+| ----------------- | ------ | ---------------- | ------------------------------------------------------------------------ |
+| `version`         | 101    | enum             | Must be `VERSION_ONE` (1)                                                |
+| `compressionType` | 102    | enum             | Compression of `innerMessage`; must be `COMPRESSION_ZSTD` (1)            |
+| `size`            | 103    | int64            | Uncompressed size of `innerMessage` (corruption detection)               |
+| `sha256`          | 104    | bytes            | SHA-256 hash of the **compressed** `innerMessage` (corruption detection) |
+| `uuid`            | 105    | bytes            | Random v4 UUID; must match the inner message UUID                        |
+| `innerMessage`    | 199    | bytes            | Zstd-compressed serialized `MFFile` message                              |
+| `signature`       | 201    | bytes (optional) | GPG signature (ASCII-armored or binary)                                  |
+| `signer`          | 202    | bytes (optional) | Full GPG key ID of the signer                                            |
+| `signingPubKey`   | 203    | bytes (optional) | Full GPG signing public key                                              |
+
+### SHA-256 Hash
+
+The `sha256` field (104) covers the **compressed** `innerMessage` bytes.
+This allows verifying data integrity before decompression.
+
+## Compression
+
+The `innerMessage` field is compressed with [Zstandard (zstd)](https://facebook.github.io/zstd/).
+Implementations must enforce a decompression size limit to prevent
+decompression bombs. The reference implementation limits decompressed size to
+256 MB.
+
+## Inner Message (`MFFile`)
+
+After decompressing `innerMessage`, the result is a serialized `MFFile`
+(referred to as the manifest):
+
+| Field       | Number | Type                  | Description                           |
+| ----------- | ------ | --------------------- | ------------------------------------- |
+| `version`   | 100    | enum                  | Must be `VERSION_ONE` (1)             |
+| `files`     | 101    | repeated `MFFilePath` | List of files in the manifest         |
+| `uuid`      | 102    | bytes                 | Random v4 UUID; must match outer UUID |
+| `createdAt` | 201    | Timestamp (optional)  | When the manifest was created         |
+
+## File Entries (`MFFilePath`)
+
+Each file entry contains:
+
+| Field      | Number | Type                      | Description                         |
+| ---------- | ------ | ------------------------- | ----------------------------------- |
+| `path`     | 1      | string                    | Relative file path (see Path Rules) |
+| `size`     | 2      | int64                     | File size in bytes                  |
+| `hashes`   | 3      | repeated `MFFileChecksum` | At least one hash required          |
+| `mimeType` | 301    | string (optional)         | MIME type                           |
+| `mtime`    | 302    | Timestamp (optional)      | Modification time                   |
+| `ctime`    | 303    | Timestamp (optional)      | Change time (inode metadata change) |
+
+Field 304 (`atime`) has been removed from the specification. Access time is
+volatile and non-deterministic; it is not useful for integrity verification.
+
+## Path Rules
+
+All `path` values must satisfy these invariants:
+
+- **UTF-8**: paths must be valid UTF-8
+- **Forward slashes**: use `/` as the path separator (never `\`)
+- **Relative only**: no leading `/`
+- **No parent traversal**: no `..` path segments
+- **No empty segments**: no `//` sequences
+- **No trailing slash**: paths refer to files, not directories
+
+Implementations must validate these invariants when reading and writing
+manifests. Paths that violate these rules must be rejected.
+
+## Hash Format (`MFFileChecksum`)
+
+Each checksum is a single `bytes multiHash` field containing a
+[multihash](https://multiformats.io/multihash/)-encoded value. Multihash is
+self-describing: the encoded bytes include a varint algorithm identifier
+followed by a varint digest length followed by the digest itself.
+
+The 1.0 implementation writes SHA-256 multihashes (`0x12` algorithm code).
+Implementations must be able to verify SHA-256 multihashes at minimum.
+
+## Signature Scheme
+
+Signing is optional. When present, the signature covers a canonical string
+constructed as:
+
+```
+ZNAVSRFG-<UUID>-<SHA256>
+```
+
+Where:
+
+- `ZNAVSRFG` is the magic bytes string (literal ASCII)
+- `<UUID>` is the hex-encoded UUID from the outer message
+- `<SHA256>` is the hex-encoded SHA-256 hash from the outer message (covering compressed data)
+
+Components are separated by hyphens. The signature is produced by GPG over
+this canonical string and stored in the `signature` field of the outer
+message.
+
+## Deterministic Serialization
+
+By default, manifests are generated deterministically:
+
+- File entries are sorted by `path` in **lexicographic byte order**
+- `createdAt` is omitted unless explicitly requested
+- `atime` is never included (field removed from schema)
+
+This ensures that two independent runs over the same directory tree produce
+byte-identical `.mf` files (assuming file contents and metadata have not
+changed).
+
+## MIME Type
+
+The recommended MIME type for `.mf` files is `application/octet-stream`.
+The `.mf` file extension is the canonical identifier.
+
+## Reference
+
+- Proto definition: [`mfer/mf.proto`](mfer/mf.proto)
+- Reference implementation: [git.eeqj.de/sneak/mfer](https://git.eeqj.de/sneak/mfer)

Makefile

@@ -5,7 +5,7 @@ export PATH := $(PATH):$(GOPATH)/bin
 PROTOC_GEN_GO := $(GOPATH)/bin/protoc-gen-go
 SOURCEFILES := mfer/*.go mfer/*.proto internal/*/*.go cmd/*/*.go go.mod go.sum
 ARCH := $(shell uname -m)
-GITREV_BUILD := $(shell bash $(PWD)/bin/gitrev.sh)
+GITREV_BUILD := $(shell bash $(PWD)/bin/gitrev.sh 2>/dev/null || echo unknown)
 APPNAME := mfer
 VERSION := 0.1.0
 export DOCKER_IMAGE_CACHE_DIR := $(HOME)/Library/Caches/Docker/$(APPNAME)-$(ARCH)
@@ -13,18 +13,24 @@ GOLDFLAGS += -X main.Version=$(VERSION)
 GOLDFLAGS += -X main.Gitrev=$(GITREV_BUILD)
 GOFLAGS := -ldflags "$(GOLDFLAGS)"
 
-.PHONY: docker default run ci test fixme
+.PHONY: bootstrap setup docker default run ci test check lint fmt fmt-check hooks fixme
 
 default: fmt test
 
+bootstrap:
+	@script/bootstrap
+
+setup:
+	@script/setup
+
 run: ./bin/mfer
 	./$<
 	./$< gen
 
 ci: test
 
-test: $(SOURCEFILES) mfer/mf.pb.go
+test:
-	go test -v --timeout 10s ./...
+	@script/test
 
 $(PROTOC_GEN_GO):
 	test -e $(PROTOC_GEN_GO) || go install -v google.golang.org/protobuf/cmd/protoc-gen-go@v1.28.1
@@ -32,8 +38,17 @@ $(PROTOC_GEN_GO):
 fixme:
 	@grep -nir fixme . | grep -v Makefile
 
+check:
+	@script/check
+
+fmt-check:
+	@script/fmt-check
+
+hooks:
+	@script/install-precommit
+
 devprereqs:
-	which golangci-lint || go install -v github.com/golangci/golangci-lint/cmd/golangci-lint@latest
+	which golangci-lint || go install -v github.com/golangci/golangci-lint/cmd/golangci-lint@v2.0.2
 
 mfer/mf.pb.go: mfer/mf.proto
 	cd mfer && go generate .
@@ -45,17 +60,14 @@ bin/mfer: $(SOURCEFILES) mfer/mf.pb.go
 clean:
 	rm -rfv mfer/*.pb.go bin/mfer cmd/mfer/mfer *.dockerimage
 
-fmt: mfer/mf.pb.go
+fmt:
-	gofumpt -l -w mfer internal cmd
+	@script/fmt
-	golangci-lint run --fix
-	-prettier -w *.json
-	-prettier -w *.md
 
 lint:
-	golangci-lint run
+	@script/lint
-	sh -c 'test -z "$$(gofmt -l .)"'
 
-docker: sneak-mfer.$(ARCH).tzst.dockerimage
+docker:
+	@script/docker
 
 sneak-mfer.$(ARCH).tzst.dockerimage: $(SOURCEFILES) vendor.tzst modcache.tzst
 	docker build --progress plain --build-arg GITREV=$(GITREV_BUILD) -t sneak/mfer .

README.md

@@ -23,38 +23,41 @@ itch in 2022 and is currently a one-person effort, though the goal is for
 this to emerge as a de-facto standard and be incorporated into other
 software. A compatible javascript library is planned.
 
-# Phases
-
-Manifest generation happens in two distinct phases:
-
-## Phase 1: Enumeration
-
-Walking directories and calling `stat()` on files to collect metadata (path, size, mtime, ctime). This builds the list of files to be scanned. Relatively fast as it only reads filesystem metadata, not file contents.
-
-**Progress:** `EnumerateStatus` with `FilesFound` and `BytesFound`
-
-## Phase 2: Scan (ToManifest)
-
-Reading file contents and computing cryptographic hashes for manifest generation. This is the expensive phase that reads all file data from disk.
-
-**Progress:** `ScanStatus` with `TotalFiles`, `ScannedFiles`, `TotalBytes`, `ScannedBytes`, `BytesPerSec`
-
-# Code Conventions
-
-- **Logging:** Never use `fmt.Printf` or write to stdout/stderr directly in normal code. Use the `internal/log` package for all output (`log.Info`, `log.Infof`, `log.Debug`, `log.Debugf`, `log.Progressf`, `log.ProgressDone`).
-- **Filesystem abstraction:** Use `github.com/spf13/afero` for filesystem operations to enable testing and flexibility.
-- **CLI framework:** Use `github.com/urfave/cli/v2` for command-line interface.
-- **Serialization:** Use Protocol Buffers for manifest file format.
-- **Internal packages:** Non-exported implementation details go in `internal/` subdirectories.
-- **Concurrency:** Use `sync.RWMutex` for protecting shared state; prefer channels for progress reporting.
-- **Progress channels:** Use buffered channels (size 1) with non-blocking sends to avoid blocking the main operation if the consumer is slow.
-- **Context support:** Long-running operations should accept `context.Context` for cancellation.
-- **NO_COLOR:** Respect the `NO_COLOR` environment variable for disabling colored output.
-- **Options pattern:** Use `NewWithOptions(opts *Options)` constructor pattern for configurable types.
-
 # Build Status
 
-[![Build Status](https://drone.datavi.be/api/badges/sneak/mfer/status.svg)](https://drone.datavi.be/sneak/mfer)
+CI runs via `script/cibuild` (`docker build .`), which executes `make
+check` (formatting, linting, tests). The `main` branch must always be
+green.
+
+# Entrypoints
+
+This repository adheres to the
+[Scripts to Rule Them All](https://github.com/github/scripts-to-rule-them-all)
+standard: normalized scripts in `script/` are the entrypoints for the
+development workflow, and the Makefile targets are thin shims that call
+them. We provide:
+
+- `script/bootstrap` — install all dependencies (Go, golangci-lint, Go
+  module download), idempotently
+- `script/setup` — make a fresh clone ready for development: runs
+  `script/bootstrap`, then `script/install-precommit`
+- `script/projectname` — output the project name (`mfer`); used by other
+  scripts such as `script/docker`
+- `script/test` — run the test suite (`go test`), regenerating the
+  protobuf code first if it is stale
+- `script/lint` — run `golangci-lint` and verify `gofmt` cleanliness
+- `script/fmt` — format all code and docs (writes): `gofumpt`,
+  `golangci-lint run --fix`, and prettier for JSON/Markdown
+- `script/fmt-check` — check formatting without writing
+- `script/check` — run `script/test`, `script/lint`, and
+  `script/fmt-check`
+- `script/docker` — build the Docker image tagged with the project name
+- `script/cibuild` — CI entrypoint: `docker build .` (the Dockerfile
+  runs the checks)
+- `script/precommit` — pre-commit checks: `go mod tidy` verification,
+  then `script/check`
+- `script/install-precommit` — install the git pre-commit hook that
+  runs `script/precommit`
 
 # Participation
 
@@ -71,6 +74,9 @@ requests](https://git.eeqj.de/sneak/mfer/pulls) and pass CI to be merged.
 Any changes submitted to this project must also be
 [WTFPL-licensed](https://wtfpl.net) to be considered.
 
+See [`REPO_POLICIES.md`](REPO_POLICIES.md) for detailed coding standards,
+tooling requirements, and workflow conventions.
+
 # Problem Statement
 
 Given a plain URL, there is no standard way to safely and programmatically
@@ -148,10 +154,6 @@ The manifest file would do several important things:
   - metadata size should not be used as an excuse to sacrifice utility (such
     as providing checksums over each chunk of a large file)
 
-# Limitations
-
-- **Manifest size:** Manifests must fit entirely in system memory during reading and writing.
-
 # Open Questions
 
 - Should the manifest file include checksums of individual file chunks, or just for the whole assembled file?
@@ -239,6 +241,227 @@ regardless of filesystem format.
 Please email [`sneak@sneak.berlin`](mailto:sneak@sneak.berlin) with your
 desired username for an account on this Gitea instance.
 
+# TODO: Remaining Work for 1.0
+
+## Design Questions (Owner Decision Required)
+
+These require @sneak's input before implementation. Answers should be added
+inline below each question.
+
+### Format Design
+
+**1. Should `MFFileChecksum` be simplified?** Currently it's a separate
+message wrapping a single `bytes multiHash` field. Since multihash
+already self-describes the algorithm, `repeated bytes hashes` directly on
+`MFFilePath` would be simpler and reduce per-file protobuf overhead. Is
+the extra message layer intentional (e.g. planning to add per-hash
+metadata like `verified_at`)?
+
+> _answer:_
+
+**2. Should file permissions/mode be stored?** The format stores
+mtime/ctime but not Unix file permissions. For archival use this may not
+matter, but for software distribution or filesystem restoration it's a
+gap. Should we reserve a field now (e.g. `optional uint32 mode = 305`)
+even if we don't populate it yet?
+
+> _answer:_
+
+**3. Should `atime` be removed from the schema?** Access time is
+volatile, non-deterministic, and often disabled (`noatime`). Including it
+means two manifests of the same directory at different times will differ,
+which conflicts with the determinism goal. Remove it, or document it as
+"never set by default"?
+
+> _answer:_
+
+**4. What are the path normalization rules?** The proto has `string path`
+with no specification about: always forward-slash? Must be relative? No
+`..` components allowed? UTF-8 NFC vs NFD normalization (macOS vs
+Linux)? Max path length? This is a security issue (path traversal) and a
+cross-platform compatibility issue. What rules should the spec mandate?
+
+> _answer:_
+
+**5. Should we add a version byte after the magic?** Currently
+`ZNAVSRFG` is followed immediately by protobuf. Adding a version byte
+(`ZNAVSRFG\x01`) would allow future framing changes without requiring
+protobuf parsing to detect the version. `MFFileOuter.Version` serves
+this purpose but requires successful deserialization to read. Worth the
+extra byte?
+
+> _answer:_
+
+**6. Should we add a length-prefix after the magic?** Protobuf is not
+self-delimiting. If we ever want to concatenate manifests or append data
+after the protobuf, the current framing is insufficient. Add a varint or
+fixed-width length-prefix?
+
+> _answer:_
+
+### Signature Design
+
+**7. What does the outer SHA-256 hash cover — compressed or uncompressed
+data?** The code currently hashes compressed data (good for verifying
+before decompression), but this should be explicitly documented. Which is
+the intended behavior?
+
+> _answer:_
+
+**8. Should `signatureString()` sign raw bytes instead of a hex-encoded
+string?** Currently the canonical string is `MAGIC-UUID-MULTIHASH` with
+hex encoding, which adds a transformation layer. Signing the raw `sha256`
+bytes (or compressed `innerMessage` directly) would be simpler. Keep the
+string format or switch to raw bytes?
+
+> _answer:_
+
+**9. Should we support detached signature files (`.mf.sig`)?** Embedded
+signatures are better for single-file distribution. Detached `.mf.sig`
+files follow the familiar `SHASUMS`/`SHASUMS.asc` pattern and are
+simpler for HTTP serving. Support both modes?
+
+> _answer:_
+
+**10. GPG vs pure-Go crypto for signatures?** Shelling out to `gpg` is
+fragile (may not be installed, version-dependent output).
+`github.com/ProtonMail/go-crypto` provides pure-Go OpenPGP, or we could
+use Ed25519/signify (simpler, no key management). Which direction?
+
+> _answer:_
+
+### Implementation Design
+
+**11. Should manifests be deterministic by default?** This means: sort
+file entries by path, omit `createdAt` timestamp (or make it opt-in), no
+`atime`. Should determinism be the default, with a
+`--include-timestamps` flag to opt in?
+
+> _answer:_
+
+**12. Should we consolidate or keep both scanner/checker
+implementations?** There are two parallel implementations:
+`mfer/scanner.go` + `mfer/checker.go` (typed with `FileSize`,
+`RelFilePath`) and `internal/scanner/` + `internal/checker/` (raw
+`int64`, `string`). The `mfer/` versions are superior. Delete the
+`internal/` versions?
+
+> _answer:_
+
+**13. Should the `manifest` type be exported?** Currently unexported with
+exported constructors (`NewManifestFromReader`, `NewManifestFromFile`).
+Consumers can't declare `var m *mfer.manifest`. Export the type, or
+define an interface?
+
+> _answer:_
+
+**14. What should the Go module path be for 1.0?** Currently
+`sneak.berlin/go/mfer` in `go.mod` but `git.eeqj.de/sneak/mfer/mfer` in
+the proto `go_package` option. Which is canonical?
+
+> _answer:_
+
+## Implementation Tasks
+
+### Repo Infrastructure
+
+- [ ] Add `.golangci.yml` (fetch from
+      `https://git.eeqj.de/sneak/prompts/raw/branch/main/.golangci.yml`)
+- [ ] Add `.editorconfig`
+- [ ] Add `.gitea/workflows/check.yml` that runs `docker build .`
+
+### Format & Correctness
+
+- [ ] Resolve proto `go_package` path inconsistency
+      (`git.eeqj.de/sneak/mfer/mfer` vs `sneak.berlin/go/mfer`)
+- [ ] Specify path invariants — add proto comments requiring UTF-8,
+      forward-slash, relative paths, no `..`, no leading `/`; validate
+      in `Builder.AddFile` and `Builder.AddFileWithHash` (pending design
+      question answer)
+- [ ] Remove or deprecate `atime` from proto (pending design question
+      answer)
+- [ ] Reserve `optional uint32 mode = 305` in `MFFilePath` for future
+      file permissions (pending design question answer)
+- [ ] Add version byte after magic — `ZNAVSRFG\x01` for format version
+      1 (pending design question answer)
+- [ ] Write format specification document — separate from README:
+      magic, outer structure, compression, inner structure, path
+      invariants, signature scheme, canonical serialization
+
+### Library
+
+- [ ] Delete `internal/scanner/` and `internal/checker/` — consolidate
+      on `mfer/` package versions; update CLI code (pending design
+      question answer)
+- [ ] Add deterministic file ordering — sort entries by path
+      (lexicographic, byte-order) in `Builder.Build()`; add test
+      asserting byte-identical output from two runs
+- [ ] Add decompression size limit — `io.LimitReader` in
+      `deserializeInner()` with `m.pbOuter.Size` as bound
+- [ ] Fix `errors.Is` dead code in checker — replace with
+      `os.IsNotExist(err)` or `errors.Is(err, fs.ErrNotExist)`
+- [ ] Fix `AddFile` to verify size — check `totalRead == size` after
+      reading, return error on mismatch
+- [ ] Export the `manifest` type or define a public interface (pending
+      design question answer) — currently consumers cannot hold a reference
+      to a loaded manifest in their own type declarations
+- [ ] Replace GPG subprocess calls with pure-Go crypto (pending design
+      question answer) — current implementation shells out to `gpg` which
+      may not be installed
+- [ ] Add timeout to any remaining subprocess calls
+
+### CLI
+
+- [ ] Fix flag naming — all CLI flags should use kebab-case as primary
+      (`--include-dotfiles`, `--follow-symlinks`)
+- [ ] Fix URL construction in fetch — use `BaseURL.JoinPath()` or
+      `url.JoinPath()` instead of string concatenation
+- [ ] Add progress rate-limiting to Checker — throttle to once per
+      second, matching Scanner
+- [ ] Add `--deterministic` flag or make it default — omit `createdAt`,
+      sort files (pending design question answer)
+- [ ] Wire `--version` flag properly (currently only a `version`
+      subcommand exists; top-level `--version` shows urfave/cli generic
+      output)
+- [ ] Add retry logic to `fetch` — currently no retries on transient
+      HTTP errors; needs exponential backoff
+- [ ] `fetch` command uses bare `http.Get` with no timeout — needs
+      `http.Client` with configurable timeout
+
+### Testing & Robustness
+
+- [ ] Add fuzzing tests for `NewManifestFromReader` — protobuf
+      deserialization of untrusted input needs fuzz coverage
+- [ ] Add integration test for `freshen` CLI command — current tests
+      only verify setup, not the actual freshen operation end-to-end
+- [ ] Add test for `fetch` CLI command end-to-end (currently only
+      `downloadFile` is tested)
+
+### Documentation
+
+- [ ] Promote `FORMAT.md` as primary spec reference; README should link
+      to it more prominently
+- [ ] Audit and update all error messages for consistency and
+      helpfulness
+- [ ] Document the signature scheme more thoroughly (canonical string
+      format, verification steps)
+
+### Release
+
+- [ ] Finalize Go module path
+- [ ] Update version constant in `mfer/constants.go`
+- [ ] Add `--version` output matching SemVer
+- [ ] Tag `v1.0.0`
+
+# See Also
+
+## Prior Art: Metalink
+
+- [Metalink - Mozilla Wiki](https://wiki.mozilla.org/Metalink)
+- [Metalink - Wikipedia](https://en.wikipedia.org/wiki/Metalink)
+- [RFC 5854 - The Metalink Download Description Format](https://datatracker.ietf.org/doc/html/rfc5854)
+- [RFC 6249 - Metalink/HTTP: Mirrors and Hashes](https://www.rfc-editor.org/rfc/rfc6249.html)
+
 ## Links
 
 - Repo: [https://git.eeqj.de/sneak/mfer](https://git.eeqj.de/sneak/mfer)

REPO_POLICIES.md

@@ -1,6 +1,6 @@
 ---
 title: Repository Policies
-last_modified: 2026-02-22
+last_modified: 2026-07-06
 ---
 
 This document covers repository structure, tooling, and workflow standards. Code
@@ -34,10 +34,46 @@ style conventions are in separate documents:
   every file before committing. There are zero exceptions to this rule.
 
 - Every repo with software must have a root `Makefile` with these targets:
-  `make test`, `make lint`, `make fmt` (writes), `make fmt-check` (read-only),
+  `make bootstrap`, `make setup`, `make test`, `make lint`, `make fmt` (writes),
-  `make check` (prereqs: `test`, `lint`, `fmt-check`), `make docker`, and
+  `make fmt-check` (read-only), `make check` (runs `test`, `lint`, `fmt-check`),
-  `make hooks` (installs pre-commit hook). A model Makefile is at
+  `make docker`, and `make hooks` (installs pre-commit hook). A model Makefile
-  `https://git.eeqj.de/sneak/prompts/raw/branch/main/Makefile`.
+  is at `https://git.eeqj.de/sneak/prompts/raw/branch/main/Makefile`.
+
+- Repos follow the
+  [Scripts to Rule Them All](https://github.com/github/scripts-to-rule-them-all)
+  pattern: the implementation of each Makefile target lives in an executable
+  script in `script/` (`script/bootstrap`, `script/setup`, `script/test`,
+  `script/lint`, `script/fmt`, `script/fmt-check`, `script/check`,
+  `script/docker`), and the Makefile targets are thin shims that call them. The
+  scripts must be POSIX sh (`#!/bin/sh`, `set -eu`, no bashisms) so they run in
+  minimal containers (e.g. alpine images have no bash); locate the repo root
+  with `$(cd "$(dirname "$0")/.." && pwd -P)` and `cd` there before acting. From
+  the standard's canonical set we use `bootstrap`, `setup` (make the repo ready
+  for development after a fresh clone: runs `bootstrap`, then
+  `install-precommit`, plus any repo-specific initialization), `test`, and
+  `cibuild`. `script/bootstrap` installs all dependencies idempotently and
+  assumes nothing is present: base tools come from nix, apt, brew, or apk
+  (detected in that order; apt runs noninteractive). For node it uses the
+  installed node if present; otherwise it installs a PINNED node version via
+  nvm, first installing nvm itself if missing — from a hash-verified GitHub
+  release archive (never `curl | sh`), with bash installed as an explicit
+  prerequisite since nvm requires bash. yarn is then pinned via
+  `corepack prepare yarn@<version> --activate`. Never install "latest" or "lts";
+  always exact versions. `script/cibuild` runs the CI build: it changes to the
+  repo root and runs `docker build .`; the Gitea workflow calls it. Four further
+  scripts are our own extensions to the standard: `script/check` runs
+  `script/test`, `script/lint`, and `script/fmt-check`; `script/precommit` is
+  what the git pre-commit hook runs, and it calls `script/check`;
+  `script/install-precommit` installs the git pre-commit hook (the `make hooks`
+  target shims to it); and `script/projectname` (literally that filename) simply
+  outputs the project's name. Scripts that need the name call
+  `script/projectname` — e.g. `script/docker` assembles its image tag from it —
+  so those scripts stay byte-identical across all repos. Repo-type-specific
+  pre-commit extras (e.g. `go mod tidy` verification in Go repos) belong in
+  `script/precommit`, not in the hook itself. Model scripts are at
+  `https://git.eeqj.de/sneak/prompts/raw/branch/main/script/<name>`. The README
+  must document the provided scripts in an **Entrypoints** section (see the
+  README requirements below).
 
 - Always use Makefile targets (`make fmt`, `make test`, `make lint`, etc.)
   instead of invoking the underlying tools directly. The Makefile is the single
@@ -57,11 +93,83 @@ style conventions are in separate documents:
   as a build step so the build fails if the branch is not green. For non-server
   repos, the Dockerfile should bring up a development environment and run
   `make check`. For server repos, `make check` should run as an early build
-  stage before the final image is assembled.
+  stage before the final image is assembled. Dockerfiles install development
+  prerequisites by running `script/bootstrap` rather than duplicating installs
+  inline; COPY `script/` and the dependency manifests (`package.json` +
+  `yarn.lock`, `go.mod` + `go.sum`, etc.) before running it so the bootstrap
+  layer stays cached until dependencies change.
+
+- **Dockerfiles must use a separate lint stage for fail-fast feedback.** Go
+  repos use a multistage build where linting runs in an independent stage based
+  on the `golangci/golangci-lint` image (pinned by hash). This stage runs
+  `make fmt-check` and `make lint` before the full build begins. The build stage
+  then declares an explicit dependency on the lint stage via
+  `COPY --from=lint /src/go.sum /dev/null`, which forces BuildKit to complete
+  linting before proceeding to compilation and tests. This ensures lint failures
+  surface in seconds rather than minutes, without blocking on dependency
+  download or compilation in the build stage.
+
+    The standard pattern for a Go repo Dockerfile is:
+
+    ```dockerfile
+    # Lint stage — fast feedback on formatting and lint issues
+    # golangci/golangci-lint:v2.x.x, YYYY-MM-DD
+    FROM golangci/golangci-lint@sha256:... AS lint
+    WORKDIR /src
+    COPY go.mod go.sum ./
+    RUN go mod download
+    COPY . .
+    RUN make fmt-check
+    RUN make lint
+
+    # Build stage
+    # golang:1.x-alpine, YYYY-MM-DD
+    FROM golang@sha256:... AS builder
+    WORKDIR /src
+
+    # Force BuildKit to run the lint stage before proceeding
+    COPY --from=lint /src/go.sum /dev/null
+
+    COPY go.mod go.sum ./
+    RUN go mod download
+    COPY . .
+    RUN make test
+
+    ARG VERSION=dev
+    RUN CGO_ENABLED=0 go build -trimpath \
+        -ldflags="-s -w -X main.Version=${VERSION}" \
+        -o /app ./cmd/app/
+
+    # Runtime stage
+    FROM alpine@sha256:...
+    COPY --from=builder /app /usr/local/bin/app
+    ENTRYPOINT ["app"]
+    ```
+
+    Key points:
+    - The lint stage uses the `golangci/golangci-lint` image directly (it
+      includes both Go and the linter), so there is no need to install the
+      linter separately.
+    - `COPY --from=lint /src/go.sum /dev/null` is a no-op file copy that creates
+      a stage dependency. BuildKit runs stages in parallel by default; without
+      this line, the build stage would not wait for lint to finish and a lint
+      failure might not fail the overall build.
+    - If the project uses `//go:embed` directives that reference build artifacts
+      (e.g. a web frontend compiled in a separate stage), the lint stage must
+      create placeholder files so the embed directives resolve. Example:
+      `RUN mkdir -p web/dist && touch web/dist/index.html web/dist/style.css`.
+      The lint stage should not depend on the actual build output — it exists to
+      fail fast.
+    - If the project requires CGO or system libraries for linting (e.g.
+      `vips-dev`), install them in the lint stage with `apk add`.
+    - The build stage runs `make test` after compilation setup. Tests run in the
+      build stage, not the lint stage, because they may require compiled
+      artifacts or heavier dependencies.
 
 - Every repo should have a Gitea Actions workflow (`.gitea/workflows/`) that
-  runs `docker build .` on push. Since the Dockerfile already runs `make check`,
+  runs `script/cibuild` (which runs `docker build .`) on push. Since the
-  a successful build implies all checks pass.
+  Dockerfile already runs `make check`, a successful build implies all checks
+  pass.
 
 - Use platform-standard formatters: `black` for Python, `prettier` for
   JS/CSS/Markdown/HTML, `go fmt` for Go. Always use default configuration with
@@ -69,9 +177,11 @@ style conventions are in separate documents:
   Markdown (hard-wrap at 80 columns). Documentation and writing repos (Markdown,
   HTML, CSS) should also have `.prettierrc` and `.prettierignore`.
 
-- Pre-commit hook: `make check` if local testing is possible, otherwise
+- Pre-commit hook: runs `script/precommit`, which calls `script/check`. If local
-  `make lint && make fmt-check`. The Makefile should provide a `make hooks`
+  testing is not possible in the repo, `script/precommit` may skip `script/test`
-  target to install the pre-commit hook.
+  and run only `script/lint` and `script/fmt-check`. The hook is installed by
+  `script/install-precommit`; the Makefile must provide a `make hooks` target
+  that shims to it.
 
 - All repos with software must have tests that run via the platform-standard
   test framework (`go test`, `pytest`, `jest`/`vitest`, etc.). If no meaningful
@@ -82,6 +192,42 @@ style conventions are in separate documents:
 - `make test` must complete in under 20 seconds. Add a 30-second timeout in the
   Makefile.
 
+- **`make test` should use the conditional verbose rerun pattern.** Run tests
+  without `-v` (verbose) first. If tests fail, automatically rerun with `-v` to
+  show full output. This keeps CI logs and `docker build` output clean on
+  success (just package/suite summaries) while providing full diagnostic detail
+  on failure (every test case, every assertion). The general shell pattern:
+
+    ```makefile
+    test:
+    	@<test-command> || \
+    		{ echo "--- Rerunning with -v for details ---"; \
+    		  <test-command-with-v>; exit 1; }
+    ```
+
+    Go example:
+
+    ```makefile
+    test:
+    	@go test -timeout 30s -race -cover ./... || \
+    		{ echo "--- Rerunning with -v for details ---"; \
+    		  go test -timeout 30s -race -v ./...; exit 1; }
+    ```
+
+    Python example:
+
+    ```makefile
+    test:
+    	@python -m pytest || \
+    		{ echo "--- Rerunning with -v for details ---"; \
+    		  python -m pytest -v; exit 1; }
+    ```
+
+    The `exit 1` ensures the target always fails after a rerun — the first run
+    already proved the tests are broken, so the build must not pass even if a
+    flaky test happens to succeed on the second attempt. The rerun exists solely
+    for diagnostic output.
+
 - Docker builds must complete in under 5 minutes.
 
 - `make check` must not modify any files in the repo. Tests may use temporary
@@ -98,6 +244,13 @@ style conventions are in separate documents:
   `https://git.eeqj.de/sneak/prompts/raw/branch/main/.gitignore` when setting up
   a new repo.
 
+- **No build artifacts in version control.** Code-derived data (compiled
+  bundles, minified output, generated assets) must never be committed to the
+  repository if it can be avoided. The build process (e.g. Dockerfile, Makefile)
+  should generate these at build time. Notable exception: Go protobuf generated
+  files (`.pb.go`) ARE committed because repos need to work with `go get`, which
+  downloads code but does not execute code generation.
+
 - Never use `git add -A` or `git add .`. Always stage files explicitly by name.
 
 - Never force-push to `main`.
@@ -121,12 +274,76 @@ style conventions are in separate documents:
 - Dockerized web services listen on port 8080 by default, overridable with
   `PORT`.
 
+- **HTTP/web services must be hardened for production internet exposure before
+  tagging 1.0.** This means full compliance with security best practices
+  including, without limitation, all of the following:
+    - **Security headers** on every response:
+        - `Strict-Transport-Security` (HSTS) with `max-age` of at least one year
+          and `includeSubDomains`.
+        - `Content-Security-Policy` (CSP) with a restrictive default policy
+          (`default-src 'self'` as a baseline, tightened per-resource as
+          needed). Never use `unsafe-inline` or `unsafe-eval` unless
+          unavoidable, and document the reason.
+        - `X-Frame-Options: DENY` (or `SAMEORIGIN` if framing is required).
+          Prefer the `frame-ancestors` CSP directive as the primary control.
+        - `X-Content-Type-Options: nosniff`.
+        - `Referrer-Policy: strict-origin-when-cross-origin` (or stricter).
+        - `Permissions-Policy` restricting access to browser features the
+          application does not use (camera, microphone, geolocation, etc.).
+    - **Request and response limits:**
+        - Maximum request body size enforced on all endpoints (e.g. Go
+          `http.MaxBytesReader`). Choose a sane default per-route; never accept
+          unbounded input.
+        - Maximum response body size where applicable (e.g. paginated APIs).
+        - `ReadTimeout` and `ReadHeaderTimeout` on the `http.Server` to defend
+          against slowloris attacks.
+        - `WriteTimeout` on the `http.Server`.
+        - `IdleTimeout` on the `http.Server`.
+        - Per-handler execution time limits via `context.WithTimeout` or
+          chi/stdlib `middleware.Timeout`.
+    - **Authentication and session security:**
+        - Rate limiting on password-based authentication endpoints. API keys are
+          high-entropy and not susceptible to brute force, so they are exempt.
+        - CSRF tokens on all state-mutating HTML forms. API endpoints
+          authenticated via `Authorization` header (Bearer token, API key) are
+          exempt because the browser does not attach these automatically.
+        - Passwords stored using bcrypt, scrypt, or argon2 — never plain-text,
+          MD5, or SHA.
+        - Session cookies set with `HttpOnly`, `Secure`, and `SameSite=Lax` (or
+          `Strict`) attributes.
+    - **Reverse proxy awareness:**
+        - True client IP detection when behind a reverse proxy
+          (`X-Forwarded-For`, `X-Real-IP`). The application must accept
+          forwarded headers only from a configured set of trusted proxy
+          addresses — never trust `X-Forwarded-For` unconditionally.
+    - **CORS:**
+        - Authenticated endpoints must restrict `Access-Control-Allow-Origin` to
+          an explicit allowlist of known origins. Wildcard (`*`) is acceptable
+          only for public, unauthenticated read-only APIs.
+    - **Error handling:**
+        - Internal errors must never leak stack traces, SQL queries, file paths,
+          or other implementation details to the client. Return generic error
+          messages in production; detailed errors only when `DEBUG` is enabled.
+    - **TLS:**
+        - Services never terminate TLS directly. They are always deployed behind
+          a TLS-terminating reverse proxy. The service itself listens on plain
+          HTTP. However, HSTS headers and `Secure` cookie flags must still be
+          set by the application so that the browser enforces HTTPS end-to-end.
+
+    This list is non-exhaustive. Apply defense-in-depth: if a standard security
+    hardening measure exists for HTTP services and is not listed here, it is
+    still expected. When in doubt, harden.
+
 - `README.md` is the primary documentation. Required sections:
     - **Description**: First line must include the project name, purpose,
       category (web server, SPA, CLI tool, etc.), license, and author. Example:
       "µPaaS is an MIT-licensed Go web application by @sneak that receives
       git-frontend webhooks and deploys applications via Docker in realtime."
     - **Getting Started**: Copy-pasteable install/usage code block.
+    - **Entrypoints**: Opens by stating that the repo adheres to the
+      [Scripts to Rule Them All](https://github.com/github/scripts-to-rule-them-all)
+      standard (with that link), then documents each provided `script/`
+      entrypoint and its purpose.
     - **Rationale**: Why does this exist?
     - **Design**: How is the program structured?
     - **TODO**: Update meticulously, even between commits. When planning, put
@@ -144,8 +361,14 @@ style conventions are in separate documents:
 - Use SemVer.
 
 - Database migrations live in `internal/db/migrations/` and must be embedded in
-  the binary. Pre-1.0.0: modify existing migrations (no installed base assumed).
+  the binary.
-  Post-1.0.0: add new migration files.
+    - `000_migration.sql` — contains ONLY the creation of the migrations
+      tracking table itself. Nothing else.
+    - `001_schema.sql` — the full application schema.
+    - **Pre-1.0.0:** never add additional migration files (002, 003, etc.).
+      There is no installed base to migrate. Edit `001_schema.sql` directly.
+    - **Post-1.0.0:** add new numbered migration files for each schema change.
+      Never edit existing migrations after release.
 
 - All repos should have an `.editorconfig` enforcing the project's indentation
   settings.
@@ -175,6 +398,9 @@ style conventions are in separate documents:
     - `README.md`, `.git`, `.gitignore`, `.editorconfig`
     - `LICENSE`, `REPO_POLICIES.md` (copy from the `prompts` repo)
     - `Makefile`
+    - `script/` entrypoints (`bootstrap`, `setup`, `projectname`, `test`,
+      `lint`, `fmt`, `fmt-check`, `check`, `docker`, `cibuild`, `precommit`,
+      `install-precommit`)
     - `Dockerfile`, `.dockerignore`
     - `.gitea/workflows/check.yml`
     - Go: `go.mod`, `go.sum`, `.golangci.yml`

TODO.md

@@ -1,19 +1,107 @@
-# TODO
+# Workflow
 
-## Critical
+- branch (from `main`)
+- do the work in Next Step
+- move Next Step to the top of Completed Steps
+- move the top item of Future Steps into Next Step
+- commit (`TODO.md` changes in the same commit as the work)
+- merge to `main` if the branch is not protected, otherwise open a PR
+- push
 
-- [ ] Fix broken error comparison in `internal/checker/checker.go:195` - `errors.Is(err, errors.New("file does not exist"))` always returns false because `errors.New()` creates a new instance each call
+# Status
-- [ ] Fix unchecked `hash.Write()` errors in `mfer/builder.go:52`, `mfer/serialize.go:56`, `internal/cli/freshen.go:340`
-- [ ] Fix URL path traversal risk in `internal/cli/fetch.go:116` - path isn't URL-escaped, should use `url.JoinPath()` or proper encoding
 
-## Important
+pre-1.0. No git tags. README section "TODO: Remaining Work for 1.0" lists
+open design questions and implementation tasks; policy compliance work is
+in flight and unmerged.
 
-- [ ] Fix goroutine leak in signal handler `internal/cli/gen.go:98-106` - goroutine runs until channel closed, leaks if program exits normally
+# Next Step
-- [ ] Fix timestamp precision in `mfer/serialize.go:16-22` - use `t.Nanosecond()` instead of manual calculation
-- [ ] Add context cancellation check to filesystem walk in `internal/cli/freshen.go` - Ctrl-C doesn't work during scan phase
 
-## Code Quality
+Land the in-flight compliance branch chore/align-repo-policies: finish and
+commit the uncommitted work (32 modified Go files, new untracked
+.golangci.yml and TODO.md), confirm `make check` is green, merge the branch
+(one commit ahead of main as of 2026-07-03) to main, and push.
 
-- [ ] Consolidate duplicate `pathIsHidden` implementations in `internal/scanner/scanner.go:385-402` and `internal/cli/freshen.go:378-397`
+# Completed Steps
-- [ ] Make `TotalBytes()` in `internal/scanner/scanner.go:250-259` track total incrementally instead of recalculating on every call
+
-- [ ] Add input validation to `AddFileWithHash()` in `mfer/builder.go:107-120` - validate path, size, and hash inputs
+- 2026-07-07 Adopted scripts-to-rule-them-all: `script/` entrypoints,
+  Makefile shims, README Entrypoints section
+- 2026-07-03: aligned repo tooling, docs, and config with standardized
+  policies (7d9a138, on chore/align-repo-policies, unmerged)
+- 2026-06-28: moved to standardized repo policies (#56, on main)
+- 2026-04-07: added 1.0 roadmap as README TODO section, removed old
+  TODO.md (#54)
+- 2026-03-20: added Gitea Actions CI workflow (#53)
+- 2026-03-17: added REPO_POLICIES.md, renamed CLAUDE.md to AGENTS.md (#51);
+  removed committed .index.mf (#52)
+- 2026-03-15: split Dockerfile with pre-built golangci-lint stage for
+  faster CI (#45)
+- 2026-03-01: 1.0 quality polish: code review, tests, bug fixes, docs (#32)
+- 2026-02-20: deterministic file ordering in Builder.Build() (#28);
+  removed committed vendor/modcache archives (#35)
+- 2026-02-08: added --seed flag for deterministic manifest UUID
+
+# Future Steps
+
+- Compliance (fold of TODO.md audit 2026-07-02; verify which items the
+  in-flight branch already closes, then check off):
+  - Add .editorconfig (canonical copy from sneak/prompts)
+  - Add standardized .golangci.yml (present untracked on the branch;
+    user-owned, copy verbatim)
+  - Make .gitignore cover secrets (.env, _.key, _.pem), OS files
+    (.DS_Store), and editor files (_.swp, _~)
+  - Make fmt-check/lint verify with gofumpt, not gofmt -l, so
+    `make check` matches what `make fmt` writes
+  - Add README "Getting Started" section with copy-pasteable
+    install/usage block
+  - Move FORMAT.md from repo root to docs/ and update the AGENTS.md
+    reference
+  - Pin Makefile-installed Go tools (protoc-gen-go@v1.28.1,
+    golangci-lint@v2.0.2) by module hash, not mutable tag
+  - Set `make test` timeout to 30s (currently 10s)
+  - Add explicit README "Rationale" heading (content exists under other
+    names); name the author in the README Description first line
+  - Reconcile root-level AGENTS.md with directory-hygiene policy (keep
+    or relocate)
+  - Add a `make build` target
+  - Rewrite `make hooks` to use printf or a heredoc instead of
+    non-portable `echo '...\n...'`
+- Answer the 14 owner design questions in the README 1.0 roadmap:
+  - Format: simplify MFFileChecksum; store file mode; drop atime;
+    specify path normalization rules; version byte after magic;
+    length-prefix after magic
+  - Signatures: hash covers compressed or uncompressed data; sign raw
+    bytes vs hex canonical string; detached .mf.sig support; GPG
+    subprocess vs pure-Go crypto
+  - Implementation: deterministic manifests by default; consolidate
+    duplicate scanner/checker implementations; export the manifest
+    type; canonical Go module path for 1.0
+- Format and correctness:
+  - Resolve proto go_package vs go.mod module path inconsistency
+  - Specify and validate path invariants (UTF-8, forward-slash,
+    relative, no .., no leading /)
+  - Remove or deprecate atime; reserve mode field; add version byte
+    (all pending design answers)
+  - Write a standalone format specification document
+- Library:
+  - Delete internal/scanner and internal/checker; consolidate on the
+    mfer/ package versions (pending design answer)
+  - Add decompression size limit via io.LimitReader in
+    deserializeInner()
+  - Fix errors.Is dead code in checker; make AddFile verify
+    totalRead == size
+  - Export manifest type or define a public interface (pending)
+  - Replace GPG subprocess with pure-Go crypto (pending); add timeouts
+    to remaining subprocess calls
+- CLI:
+  - Kebab-case primary flag names; fix fetch URL construction with
+    url.JoinPath; add http.Client timeout and retry with backoff to
+    fetch; rate-limit Checker progress output; add --deterministic
+    flag or default; wire top-level --version properly
+- Testing:
+  - Fuzz NewManifestFromReader; end-to-end tests for freshen and fetch
+- Documentation:
+  - Promote docs/FORMAT.md as primary spec reference; audit error
+    messages; document the signature scheme fully
+- Release:
+  - Finalize module path, bump version constant, SemVer --version
+    output, tag v1.0.0

internal/checker/checker.go

@@ -1,281 +0,0 @@
-package checker
-
-import (
-	"bytes"
-	"context"
-	"crypto/sha256"
-	"errors"
-	"io"
-	"os"
-	"path/filepath"
-
-	"github.com/multiformats/go-multihash"
-	"github.com/spf13/afero"
-	"sneak.berlin/go/mfer/mfer"
-)
-
-// Result represents the outcome of checking a single file.
-type Result struct {
-	Path    string // Relative path from manifest
-	Status  Status // Verification result status
-	Message string // Human-readable description of the result
-}
-
-// Status represents the verification status of a file.
-type Status int
-
-const (
-	StatusOK           Status = iota // File matches manifest (size and hash verified)
-	StatusMissing                    // File not found on disk
-	StatusSizeMismatch               // File size differs from manifest
-	StatusHashMismatch               // File hash differs from manifest
-	StatusExtra                      // File exists on disk but not in manifest
-	StatusError                      // Error occurred during verification
-)
-
-func (s Status) String() string {
-	switch s {
-	case StatusOK:
-		return "OK"
-	case StatusMissing:
-		return "MISSING"
-	case StatusSizeMismatch:
-		return "SIZE_MISMATCH"
-	case StatusHashMismatch:
-		return "HASH_MISMATCH"
-	case StatusExtra:
-		return "EXTRA"
-	case StatusError:
-		return "ERROR"
-	default:
-		return "UNKNOWN"
-	}
-}
-
-// CheckStatus contains progress information for the check operation.
-type CheckStatus struct {
-	TotalFiles   int64   // Total number of files in manifest
-	CheckedFiles int64   // Number of files checked so far
-	TotalBytes   int64   // Total bytes to verify (sum of all file sizes)
-	CheckedBytes int64   // Bytes verified so far
-	BytesPerSec  float64 // Current throughput rate
-	Failures     int64   // Number of verification failures encountered
-}
-
-// Checker verifies files against a manifest.
-type Checker struct {
-	basePath string
-	files    []*mfer.MFFilePath
-	fs       afero.Fs
-	// manifestPaths is a set of paths in the manifest for quick lookup
-	manifestPaths map[string]struct{}
-}
-
-// NewChecker creates a new Checker for the given manifest, base path, and filesystem.
-// The basePath is the directory relative to which manifest paths are resolved.
-// If fs is nil, the real filesystem (OsFs) is used.
-func NewChecker(manifestPath string, basePath string, fs afero.Fs) (*Checker, error) {
-	if fs == nil {
-		fs = afero.NewOsFs()
-	}
-
-	m, err := mfer.NewManifestFromFile(fs, manifestPath)
-	if err != nil {
-		return nil, err
-	}
-
-	abs, err := filepath.Abs(basePath)
-	if err != nil {
-		return nil, err
-	}
-
-	files := m.Files()
-	manifestPaths := make(map[string]struct{}, len(files))
-	for _, f := range files {
-		manifestPaths[f.Path] = struct{}{}
-	}
-
-	return &Checker{
-		basePath:      abs,
-		files:         files,
-		fs:            fs,
-		manifestPaths: manifestPaths,
-	}, nil
-}
-
-// FileCount returns the number of files in the manifest.
-func (c *Checker) FileCount() int64 {
-	return int64(len(c.files))
-}
-
-// TotalBytes returns the total size of all files in the manifest.
-func (c *Checker) TotalBytes() int64 {
-	var total int64
-	for _, f := range c.files {
-		total += f.Size
-	}
-	return total
-}
-
-// Check verifies all files against the manifest.
-// Results are sent to the results channel as files are checked.
-// Progress updates are sent to the progress channel approximately once per second.
-// Both channels are closed when the method returns.
-func (c *Checker) Check(ctx context.Context, results chan<- Result, progress chan<- CheckStatus) error {
-	if results != nil {
-		defer close(results)
-	}
-	if progress != nil {
-		defer close(progress)
-	}
-
-	totalFiles := int64(len(c.files))
-	totalBytes := c.TotalBytes()
-
-	var checkedFiles int64
-	var checkedBytes int64
-	var failures int64
-
-	for _, entry := range c.files {
-		select {
-		case <-ctx.Done():
-			return ctx.Err()
-		default:
-		}
-
-		result := c.checkFile(entry, &checkedBytes)
-		if result.Status != StatusOK {
-			failures++
-		}
-		checkedFiles++
-
-		if results != nil {
-			results <- result
-		}
-
-		// Send progress (simplified - every file for now)
-		if progress != nil {
-			sendCheckStatus(progress, CheckStatus{
-				TotalFiles:   totalFiles,
-				CheckedFiles: checkedFiles,
-				TotalBytes:   totalBytes,
-				CheckedBytes: checkedBytes,
-				Failures:     failures,
-			})
-		}
-	}
-
-	return nil
-}
-
-func (c *Checker) checkFile(entry *mfer.MFFilePath, checkedBytes *int64) Result {
-	absPath := filepath.Join(c.basePath, entry.Path)
-
-	// Check if file exists
-	info, err := c.fs.Stat(absPath)
-	if err != nil {
-		if errors.Is(err, afero.ErrFileNotFound) || errors.Is(err, errors.New("file does not exist")) {
-			return Result{Path: entry.Path, Status: StatusMissing, Message: "file not found"}
-		}
-		// Check for "file does not exist" style errors
-		exists, _ := afero.Exists(c.fs, absPath)
-		if !exists {
-			return Result{Path: entry.Path, Status: StatusMissing, Message: "file not found"}
-		}
-		return Result{Path: entry.Path, Status: StatusError, Message: err.Error()}
-	}
-
-	// Check size
-	if info.Size() != entry.Size {
-		*checkedBytes += info.Size()
-		return Result{
-			Path:    entry.Path,
-			Status:  StatusSizeMismatch,
-			Message: "size mismatch",
-		}
-	}
-
-	// Open and hash file
-	f, err := c.fs.Open(absPath)
-	if err != nil {
-		return Result{Path: entry.Path, Status: StatusError, Message: err.Error()}
-	}
-	defer f.Close()
-
-	h := sha256.New()
-	n, err := io.Copy(h, f)
-	if err != nil {
-		return Result{Path: entry.Path, Status: StatusError, Message: err.Error()}
-	}
-	*checkedBytes += n
-
-	// Encode as multihash and compare
-	computed, err := multihash.Encode(h.Sum(nil), multihash.SHA2_256)
-	if err != nil {
-		return Result{Path: entry.Path, Status: StatusError, Message: err.Error()}
-	}
-
-	// Check against all hashes in manifest (at least one must match)
-	for _, hash := range entry.Hashes {
-		if bytes.Equal(computed, hash.MultiHash) {
-			return Result{Path: entry.Path, Status: StatusOK}
-		}
-	}
-
-	return Result{Path: entry.Path, Status: StatusHashMismatch, Message: "hash mismatch"}
-}
-
-// FindExtraFiles walks the filesystem and reports files not in the manifest.
-// Results are sent to the results channel. The channel is closed when done.
-func (c *Checker) FindExtraFiles(ctx context.Context, results chan<- Result) error {
-	if results != nil {
-		defer close(results)
-	}
-
-	return afero.Walk(c.fs, c.basePath, func(path string, info os.FileInfo, err error) error {
-		if err != nil {
-			return err
-		}
-
-		select {
-		case <-ctx.Done():
-			return ctx.Err()
-		default:
-		}
-
-		// Skip directories
-		if info.IsDir() {
-			return nil
-		}
-
-		// Get relative path
-		relPath, err := filepath.Rel(c.basePath, path)
-		if err != nil {
-			return err
-		}
-
-		// Check if path is in manifest
-		if _, exists := c.manifestPaths[relPath]; !exists {
-			if results != nil {
-				results <- Result{
-					Path:    relPath,
-					Status:  StatusExtra,
-					Message: "not in manifest",
-				}
-			}
-		}
-
-		return nil
-	})
-}
-
-// sendCheckStatus sends a status update without blocking.
-func sendCheckStatus(ch chan<- CheckStatus, status CheckStatus) {
-	if ch == nil {
-		return
-	}
-	select {
-	case ch <- status:
-	default:
-	}
-}

internal/cli/check.go

@@ -3,6 +3,7 @@ package cli
 import (
 	"encoding/hex"
 	"fmt"
+	"io"
 	"path/filepath"
 	"strings"
 	"time"
@@ -34,29 +35,32 @@ func findManifest(fs afero.Fs, dir string) (string, error) {
 func (mfa *CLIApp) checkManifestOperation(ctx *cli.Context) error {
 	log.Debug("checkManifestOperation()")
 
-	var manifestPath string
+	manifestPath, err := mfa.resolveManifestArg(ctx)
-	var err error
+	if err != nil {
+		return fmt.Errorf("check: %w", err)
+	}
 
-	if ctx.Args().Len() > 0 {
+	// URL manifests need to be downloaded to a temp file for the checker
-		arg := ctx.Args().Get(0)
+	if isHTTPURL(manifestPath) {
-		// Check if arg is a directory or a file
+		rc, fetchErr := mfa.openManifestReader(manifestPath)
-		info, statErr := mfa.Fs.Stat(arg)
+		if fetchErr != nil {
-		if statErr == nil && info.IsDir() {
+			return fmt.Errorf("check: %w", fetchErr)
-			// It's a directory, look for manifest inside
-			manifestPath, err = findManifest(mfa.Fs, arg)
-			if err != nil {
-				return err
-			}
-		} else {
-			// Treat as a file path
-			manifestPath = arg
 		}
-	} else {
+		tmpFile, tmpErr := afero.TempFile(mfa.Fs, "", "mfer-manifest-*.mf")
-		// No argument, look in current directory
+		if tmpErr != nil {
-		manifestPath, err = findManifest(mfa.Fs, ".")
+			_ = rc.Close()
-		if err != nil {
+			return fmt.Errorf("check: failed to create temp file: %w", tmpErr)
-			return err
 		}
+		tmpPath := tmpFile.Name()
+		_, cpErr := io.Copy(tmpFile, rc)
+		_ = rc.Close()
+		_ = tmpFile.Close()
+		if cpErr != nil {
+			_ = mfa.Fs.Remove(tmpPath)
+			return fmt.Errorf("check: failed to download manifest: %w", cpErr)
+		}
+		defer func() { _ = mfa.Fs.Remove(tmpPath) }()
+		manifestPath = tmpPath
 	}
 
 	basePath := ctx.String("base")

internal/cli/export.go

@@ -0,0 +1,72 @@
+package cli
+
+import (
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/urfave/cli/v2"
+	"sneak.berlin/go/mfer/mfer"
+)
+
+// ExportEntry represents a single file entry in the exported JSON output.
+type ExportEntry struct {
+	Path   string   `json:"path"`
+	Size   int64    `json:"size"`
+	Hashes []string `json:"hashes"`
+	Mtime  *string  `json:"mtime,omitempty"`
+	Ctime  *string  `json:"ctime,omitempty"`
+}
+
+func (mfa *CLIApp) exportManifestOperation(ctx *cli.Context) error {
+	pathOrURL, err := mfa.resolveManifestArg(ctx)
+	if err != nil {
+		return fmt.Errorf("export: %w", err)
+	}
+
+	rc, err := mfa.openManifestReader(pathOrURL)
+	if err != nil {
+		return fmt.Errorf("export: %w", err)
+	}
+	defer func() { _ = rc.Close() }()
+
+	manifest, err := mfer.NewManifestFromReader(rc)
+	if err != nil {
+		return fmt.Errorf("export: failed to parse manifest: %w", err)
+	}
+
+	files := manifest.Files()
+	entries := make([]ExportEntry, 0, len(files))
+
+	for _, f := range files {
+		entry := ExportEntry{
+			Path:   f.Path,
+			Size:   f.Size,
+			Hashes: make([]string, 0, len(f.Hashes)),
+		}
+
+		for _, h := range f.Hashes {
+			entry.Hashes = append(entry.Hashes, hex.EncodeToString(h.MultiHash))
+		}
+
+		if f.Mtime != nil {
+			t := time.Unix(f.Mtime.Seconds, int64(f.Mtime.Nanos)).UTC().Format(time.RFC3339Nano)
+			entry.Mtime = &t
+		}
+		if f.Ctime != nil {
+			t := time.Unix(f.Ctime.Seconds, int64(f.Ctime.Nanos)).UTC().Format(time.RFC3339Nano)
+			entry.Ctime = &t
+		}
+
+		entries = append(entries, entry)
+	}
+
+	enc := json.NewEncoder(mfa.Stdout)
+	enc.SetIndent("", "  ")
+	if err := enc.Encode(entries); err != nil {
+		return fmt.Errorf("export: failed to encode JSON: %w", err)
+	}
+
+	return nil
+}

internal/cli/export_test.go

@@ -0,0 +1,137 @@
+package cli
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"sneak.berlin/go/mfer/mfer"
+)
+
+// buildTestManifest creates a manifest from in-memory files and returns its bytes.
+func buildTestManifest(t *testing.T, files map[string][]byte) []byte {
+	t.Helper()
+	sourceFs := afero.NewMemMapFs()
+	for path, content := range files {
+		require.NoError(t, sourceFs.MkdirAll("/", 0o755))
+		require.NoError(t, afero.WriteFile(sourceFs, "/"+path, content, 0o644))
+	}
+
+	opts := &mfer.ScannerOptions{Fs: sourceFs}
+	s := mfer.NewScannerWithOptions(opts)
+	require.NoError(t, s.EnumerateFS(sourceFs, "/", nil))
+
+	var buf bytes.Buffer
+	require.NoError(t, s.ToManifest(context.Background(), &buf, nil))
+	return buf.Bytes()
+}
+
+func TestExportManifestOperation(t *testing.T) {
+	testFiles := map[string][]byte{
+		"hello.txt":    []byte("Hello, World!"),
+		"sub/file.txt": []byte("nested content"),
+	}
+	manifestData := buildTestManifest(t, testFiles)
+
+	// Write manifest to memfs
+	fs := afero.NewMemMapFs()
+	require.NoError(t, afero.WriteFile(fs, "/test.mf", manifestData, 0o644))
+
+	var stdout, stderr bytes.Buffer
+	exitCode := RunWithOptions(&RunOptions{
+		Appname: "mfer",
+		Args:    []string{"mfer", "export", "/test.mf"},
+		Stdin:   &bytes.Buffer{},
+		Stdout:  &stdout,
+		Stderr:  &stderr,
+		Fs:      fs,
+	})
+
+	require.Equal(t, 0, exitCode, "stderr: %s", stderr.String())
+
+	var entries []ExportEntry
+	require.NoError(t, json.Unmarshal(stdout.Bytes(), &entries))
+	assert.Len(t, entries, 2)
+
+	// Verify entries have expected fields
+	pathSet := make(map[string]bool)
+	for _, e := range entries {
+		pathSet[e.Path] = true
+		assert.NotEmpty(t, e.Hashes, "entry %s should have hashes", e.Path)
+		assert.Greater(t, e.Size, int64(0), "entry %s should have positive size", e.Path)
+	}
+	assert.True(t, pathSet["hello.txt"])
+	assert.True(t, pathSet["sub/file.txt"])
+}
+
+func TestExportFromHTTPURL(t *testing.T) {
+	testFiles := map[string][]byte{
+		"a.txt": []byte("aaa"),
+	}
+	manifestData := buildTestManifest(t, testFiles)
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/octet-stream")
+		_, _ = w.Write(manifestData)
+	}))
+	defer server.Close()
+
+	var stdout, stderr bytes.Buffer
+	exitCode := RunWithOptions(&RunOptions{
+		Appname: "mfer",
+		Args:    []string{"mfer", "export", server.URL + "/index.mf"},
+		Stdin:   &bytes.Buffer{},
+		Stdout:  &stdout,
+		Stderr:  &stderr,
+		Fs:      afero.NewMemMapFs(),
+	})
+
+	require.Equal(t, 0, exitCode, "stderr: %s", stderr.String())
+
+	var entries []ExportEntry
+	require.NoError(t, json.Unmarshal(stdout.Bytes(), &entries))
+	assert.Len(t, entries, 1)
+	assert.Equal(t, "a.txt", entries[0].Path)
+}
+
+func TestListFromHTTPURL(t *testing.T) {
+	testFiles := map[string][]byte{
+		"one.txt": []byte("1"),
+		"two.txt": []byte("22"),
+	}
+	manifestData := buildTestManifest(t, testFiles)
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, _ = w.Write(manifestData)
+	}))
+	defer server.Close()
+
+	var stdout, stderr bytes.Buffer
+	exitCode := RunWithOptions(&RunOptions{
+		Appname: "mfer",
+		Args:    []string{"mfer", "list", server.URL + "/index.mf"},
+		Stdin:   &bytes.Buffer{},
+		Stdout:  &stdout,
+		Stderr:  &stderr,
+		Fs:      afero.NewMemMapFs(),
+	})
+
+	require.Equal(t, 0, exitCode, "stderr: %s", stderr.String())
+	output := stdout.String()
+	assert.Contains(t, output, "one.txt")
+	assert.Contains(t, output, "two.txt")
+}
+
+func TestIsHTTPURL(t *testing.T) {
+	assert.True(t, isHTTPURL("http://example.com/manifest.mf"))
+	assert.True(t, isHTTPURL("https://example.com/manifest.mf"))
+	assert.False(t, isHTTPURL("/local/path.mf"))
+	assert.False(t, isHTTPURL("relative/path.mf"))
+	assert.False(t, isHTTPURL("ftp://example.com/file"))
+}

internal/cli/fetch.go

@@ -67,7 +67,7 @@ func (mfa *CLIApp) fetchManifestOperation(ctx *cli.Context) error {
 	// Compute base URL (directory containing manifest)
 	baseURL, err := url.Parse(manifestURL)
 	if err != nil {
-		return err
+		return fmt.Errorf("fetch: invalid manifest URL: %w", err)
 	}
 	baseURL.Path = path.Dir(baseURL.Path)
 	if !strings.HasSuffix(baseURL.Path, "/") {
@@ -113,7 +113,7 @@ func (mfa *CLIApp) fetchManifestOperation(ctx *cli.Context) error {
 			return fmt.Errorf("invalid path in manifest: %w", err)
 		}
 
-		fileURL := baseURL.String() + f.Path
+		fileURL := baseURL.String() + encodeFilePath(f.Path)
 		log.Infof("fetching %s", f.Path)
 
 		if err := downloadFile(fileURL, localPath, f, progress); err != nil {
@@ -139,6 +139,15 @@ func (mfa *CLIApp) fetchManifestOperation(ctx *cli.Context) error {
 	return nil
 }
 
+// encodeFilePath URL-encodes each segment of a file path while preserving slashes.
+func encodeFilePath(p string) string {
+	segments := strings.Split(p, "/")
+	for i, seg := range segments {
+		segments[i] = url.PathEscape(seg)
+	}
+	return strings.Join(segments, "/")
+}
+
 // sanitizePath validates and sanitizes a file path from the manifest.
 // It prevents path traversal attacks and rejects unsafe paths.
 func sanitizePath(p string) (string, error) {
@@ -258,7 +267,7 @@ func downloadFile(fileURL, localPath string, entry *mfer.MFFilePath, progress ch
 	dir := filepath.Dir(localPath)
 	if dir != "" && dir != "." {
 		if err := os.MkdirAll(dir, 0o755); err != nil {
-			return err
+			return fmt.Errorf("failed to create directory %s: %w", dir, err)
 		}
 	}
 
@@ -278,9 +287,9 @@ func downloadFile(fileURL, localPath string, entry *mfer.MFFilePath, progress ch
 	}
 
 	// Fetch file
-	resp, err := http.Get(fileURL)
+	resp, err := http.Get(fileURL) //nolint:gosec // URL constructed from manifest base
 	if err != nil {
-		return err
+		return fmt.Errorf("HTTP request failed: %w", err)
 	}
 	defer func() { _ = resp.Body.Close() }()
 
@@ -298,7 +307,7 @@ func downloadFile(fileURL, localPath string, entry *mfer.MFFilePath, progress ch
 	// Create temp file
 	out, err := os.Create(tmpPath)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to create temp file: %w", err)
 	}
 
 	// Set up hash computation

internal/cli/fetch_test.go

@@ -16,6 +16,29 @@ import (
 	"sneak.berlin/go/mfer/mfer"
 )
 
+func TestEncodeFilePath(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{"file.txt", "file.txt"},
+		{"dir/file.txt", "dir/file.txt"},
+		{"my file.txt", "my%20file.txt"},
+		{"dir/my file.txt", "dir/my%20file.txt"},
+		{"file#1.txt", "file%231.txt"},
+		{"file?v=1.txt", "file%3Fv=1.txt"},
+		{"path/to/file with spaces.txt", "path/to/file%20with%20spaces.txt"},
+		{"100%done.txt", "100%25done.txt"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			result := encodeFilePath(tt.input)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
 func TestSanitizePath(t *testing.T) {
 	// Valid paths that should be accepted
 	validTests := []struct {

internal/cli/freshen.go

@@ -41,8 +41,8 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 
 	basePath := ctx.String("base")
 	showProgress := ctx.Bool("progress")
-	includeDotfiles := ctx.Bool("IncludeDotfiles")
+	includeDotfiles := ctx.Bool("include-dotfiles")
-	followSymlinks := ctx.Bool("FollowSymLinks")
+	followSymlinks := ctx.Bool("follow-symlinks")
 
 	// Find manifest file
 	var manifestPath string
@@ -54,7 +54,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 		if statErr == nil && info.IsDir() {
 			manifestPath, err = findManifest(mfa.Fs, arg)
 			if err != nil {
-				return err
+				return fmt.Errorf("freshen: %w", err)
 			}
 		} else {
 			manifestPath = arg
@@ -62,7 +62,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 	} else {
 		manifestPath, err = findManifest(mfa.Fs, ".")
 		if err != nil {
-			return err
+			return fmt.Errorf("freshen: %w", err)
 		}
 	}
 
@@ -93,7 +93,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 
 	absBase, err := filepath.Abs(basePath)
 	if err != nil {
-		return err
+		return fmt.Errorf("freshen: invalid base path: %w", err)
 	}
 
 	err = afero.Walk(mfa.Fs, absBase, func(path string, info fs.FileInfo, walkErr error) error {
@@ -104,7 +104,7 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 		// Get relative path
 		relPath, err := filepath.Rel(absBase, path)
 		if err != nil {
-			return err
+			return fmt.Errorf("freshen: failed to compute relative path for %s: %w", path, err)
 		}
 
 		// Skip the manifest file itself
@@ -226,6 +226,9 @@ func (mfa *CLIApp) freshenManifestOperation(ctx *cli.Context) error {
 	var hashedBytes int64
 
 	builder := mfer.NewBuilder()
+	if ctx.Bool("include-timestamps") {
+		builder.SetIncludeTimestamps(true)
+	}
 
 	// Set up signing options if sign-key is provided
 	if signKey := ctx.String("sign-key"); signKey != "" {

internal/cli/gen.go

@@ -20,9 +20,16 @@ func (mfa *CLIApp) generateManifestOperation(ctx *cli.Context) error {
 	log.Debug("generateManifestOperation()")
 
 	opts := &mfer.ScannerOptions{
-		IncludeDotfiles: ctx.Bool("IncludeDotfiles"),
+		IncludeDotfiles:   ctx.Bool("include-dotfiles"),
-		FollowSymLinks:  ctx.Bool("FollowSymLinks"),
+		FollowSymLinks:    ctx.Bool("follow-symlinks"),
-		Fs:              mfa.Fs,
+		IncludeTimestamps: ctx.Bool("include-timestamps"),
+		Fs:                mfa.Fs,
+	}
+
+	// Set seed for deterministic UUID if provided
+	if seed := ctx.String("seed"); seed != "" {
+		opts.Seed = seed
+		log.Infof("using deterministic seed for manifest UUID")
 	}
 
 	// Set up signing options if sign-key is provided
@@ -59,7 +66,7 @@ func (mfa *CLIApp) generateManifestOperation(ctx *cli.Context) error {
 	if args.Len() == 0 {
 		// Default to current directory
 		if err := s.EnumeratePath(".", enumProgress); err != nil {
-			return err
+			return fmt.Errorf("generate: failed to enumerate current directory: %w", err)
 		}
 	} else {
 		// Collect and validate all paths first
@@ -68,7 +75,7 @@ func (mfa *CLIApp) generateManifestOperation(ctx *cli.Context) error {
 			inputPath := args.Get(i)
 			ap, err := filepath.Abs(inputPath)
 			if err != nil {
-				return err
+				return fmt.Errorf("generate: invalid path %q: %w", inputPath, err)
 			}
 			// Validate path exists before adding to list
 			if exists, _ := afero.Exists(mfa.Fs, ap); !exists {
@@ -78,7 +85,7 @@ func (mfa *CLIApp) generateManifestOperation(ctx *cli.Context) error {
 			paths = append(paths, ap)
 		}
 		if err := s.EnumeratePaths(enumProgress, paths...); err != nil {
-			return err
+			return fmt.Errorf("generate: failed to enumerate paths: %w", err)
 		}
 	}
 	enumWg.Wait()

internal/cli/list.go

@@ -16,32 +16,20 @@ func (mfa *CLIApp) listManifestOperation(ctx *cli.Context) error {
 	longFormat := ctx.Bool("long")
 	print0 := ctx.Bool("print0")
 
-	// Find manifest file
+	pathOrURL, err := mfa.resolveManifestArg(ctx)
-	var manifestPath string
+	if err != nil {
-	var err error
+		return fmt.Errorf("list: %w", err)
-
-	if ctx.Args().Len() > 0 {
-		arg := ctx.Args().Get(0)
-		info, statErr := mfa.Fs.Stat(arg)
-		if statErr == nil && info.IsDir() {
-			manifestPath, err = findManifest(mfa.Fs, arg)
-			if err != nil {
-				return err
-			}
-		} else {
-			manifestPath = arg
-		}
-	} else {
-		manifestPath, err = findManifest(mfa.Fs, ".")
-		if err != nil {
-			return err
-		}
 	}
 
-	// Load manifest
+	rc, err := mfa.openManifestReader(pathOrURL)
-	manifest, err := mfer.NewManifestFromFile(mfa.Fs, manifestPath)
 	if err != nil {
-		return fmt.Errorf("failed to load manifest: %w", err)
+		return fmt.Errorf("list: %w", err)
+	}
+	defer func() { _ = rc.Close() }()
+
+	manifest, err := mfer.NewManifestFromReader(rc)
+	if err != nil {
+		return fmt.Errorf("list: failed to parse manifest: %w", err)
 	}
 
 	files := manifest.Files()

internal/cli/manifest_loader.go

@@ -0,0 +1,56 @@
+package cli
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/urfave/cli/v2"
+)
+
+// isHTTPURL returns true if the string starts with http:// or https://.
+func isHTTPURL(s string) bool {
+	return strings.HasPrefix(s, "http://") || strings.HasPrefix(s, "https://")
+}
+
+// openManifestReader opens a manifest from a path or URL and returns a ReadCloser.
+// The caller must close the returned reader.
+func (mfa *CLIApp) openManifestReader(pathOrURL string) (io.ReadCloser, error) {
+	if isHTTPURL(pathOrURL) {
+		client := &http.Client{Timeout: 30 * time.Second}
+		resp, err := client.Get(pathOrURL) //nolint:gosec // user-provided URL is intentional
+		if err != nil {
+			return nil, fmt.Errorf("failed to fetch %s: %w", pathOrURL, err)
+		}
+		if resp.StatusCode != http.StatusOK {
+			_ = resp.Body.Close()
+			return nil, fmt.Errorf("failed to fetch %s: HTTP %d", pathOrURL, resp.StatusCode)
+		}
+		return resp.Body, nil
+	}
+	f, err := mfa.Fs.Open(pathOrURL)
+	if err != nil {
+		return nil, err
+	}
+	return f, nil
+}
+
+// resolveManifestArg resolves the manifest path from CLI arguments.
+// HTTP(S) URLs are returned as-is. Directories are searched for index.mf/.index.mf.
+// If no argument is given, the current directory is searched.
+func (mfa *CLIApp) resolveManifestArg(ctx *cli.Context) (string, error) {
+	if ctx.Args().Len() > 0 {
+		arg := ctx.Args().Get(0)
+		if isHTTPURL(arg) {
+			return arg, nil
+		}
+		info, statErr := mfa.Fs.Stat(arg)
+		if statErr == nil && info.IsDir() {
+			return findManifest(mfa.Fs, arg)
+		}
+		return arg, nil
+	}
+	return findManifest(mfa.Fs, ".")
+}

internal/cli/mfer.go

@@ -123,14 +123,15 @@ func (mfa *CLIApp) run(args []string) {
 				},
 				Flags: append(commonFlags(),
 					&cli.BoolFlag{
-						Name:    "FollowSymLinks",
+						Name:    "follow-symlinks",
-						Aliases: []string{"follow-symlinks"},
+						Aliases: []string{"L"},
 						Usage:   "Resolve encountered symlinks",
 					},
 					&cli.BoolFlag{
-						Name:    "IncludeDotfiles",
+						Name:    "include-dotfiles",
-						Aliases: []string{"include-dotfiles"},
+						Aliases: []string{"IncludeDotfiles"},
-						Usage:   "Include dot (hidden) files (excluded by default)",
+
+						Usage: "Include dot (hidden) files (excluded by default)",
 					},
 					&cli.StringFlag{
 						Name:    "output",
@@ -154,6 +155,15 @@ func (mfa *CLIApp) run(args []string) {
 						Usage:   "GPG key ID to sign the manifest with",
 						EnvVars: []string{"MFER_SIGN_KEY"},
 					},
+					&cli.StringFlag{
+						Name:    "seed",
+						Usage:   "Seed value for deterministic manifest UUID",
+						EnvVars: []string{"MFER_SEED"},
+					},
+					&cli.BoolFlag{
+						Name:  "include-timestamps",
+						Usage: "Include createdAt timestamp in manifest (omitted by default for determinism)",
+					},
 				),
 			},
 			{
@@ -206,14 +216,15 @@ func (mfa *CLIApp) run(args []string) {
 						Usage:   "Base directory for resolving relative paths",
 					},
 					&cli.BoolFlag{
-						Name:    "FollowSymLinks",
+						Name:    "follow-symlinks",
-						Aliases: []string{"follow-symlinks"},
+						Aliases: []string{"L"},
 						Usage:   "Resolve encountered symlinks",
 					},
 					&cli.BoolFlag{
-						Name:    "IncludeDotfiles",
+						Name:    "include-dotfiles",
-						Aliases: []string{"include-dotfiles"},
+						Aliases: []string{"IncludeDotfiles"},
-						Usage:   "Include dot (hidden) files (excluded by default)",
+
+						Usage: "Include dot (hidden) files (excluded by default)",
 					},
 					&cli.BoolFlag{
 						Name:    "progress",
@@ -226,8 +237,20 @@ func (mfa *CLIApp) run(args []string) {
 						Usage:   "GPG key ID to sign the manifest with",
 						EnvVars: []string{"MFER_SIGN_KEY"},
 					},
+					&cli.BoolFlag{
+						Name:  "include-timestamps",
+						Usage: "Include createdAt timestamp in manifest (omitted by default for determinism)",
+					},
 				),
 			},
+			{
+				Name:      "export",
+				Usage:     "Export manifest contents as JSON",
+				ArgsUsage: "[manifest file or URL]",
+				Action: func(c *cli.Context) error {
+					return mfa.exportManifestOperation(c)
+				},
+			},
 			{
 				Name:  "version",
 				Usage: "Show version",
@@ -269,7 +292,7 @@ func (mfa *CLIApp) run(args []string) {
 		},
 	}
 
-	mfa.app.HideVersion = true
+	mfa.app.HideVersion = false
 	err := mfa.app.Run(args)
 	if err != nil {
 		mfa.exitCode = 1

internal/scanner/scanner.go

@@ -1,373 +0,0 @@
-package scanner
-
-import (
-	"context"
-	"io"
-	"io/fs"
-	"path"
-	"path/filepath"
-	"strings"
-	"sync"
-	"time"
-
-	"github.com/spf13/afero"
-	"sneak.berlin/go/mfer/mfer"
-)
-
-// Phase 1: Enumeration
-// ---------------------
-// Walking directories and calling stat() on files to collect metadata.
-// Builds the list of files to be scanned. Relatively fast (metadata only).
-
-// EnumerateStatus contains progress information for the enumeration phase.
-type EnumerateStatus struct {
-	FilesFound int64 // Number of files discovered so far
-	BytesFound int64 // Total size of discovered files (from stat)
-}
-
-// Phase 2: Scan (ToManifest)
-// --------------------------
-// Reading file contents and computing hashes for manifest generation.
-// This is the expensive phase that reads all file data.
-
-// ScanStatus contains progress information for the scan phase.
-type ScanStatus struct {
-	TotalFiles   int64   // Total number of files to scan
-	ScannedFiles int64   // Number of files scanned so far
-	TotalBytes   int64   // Total bytes to read (sum of all file sizes)
-	ScannedBytes int64   // Bytes read so far
-	BytesPerSec  float64 // Current throughput rate
-}
-
-// Options configures scanner behavior.
-type Options struct {
-	IgnoreDotfiles bool     // Skip files and directories starting with a dot
-	FollowSymLinks bool     // Resolve symlinks instead of skipping them
-	Fs             afero.Fs // Filesystem to use, defaults to OsFs if nil
-}
-
-// FileEntry represents a file that has been enumerated.
-type FileEntry struct {
-	Path    string    // Relative path (used in manifest)
-	AbsPath string    // Absolute path (used for reading file content)
-	Size    int64     // File size in bytes
-	Mtime   time.Time // Last modification time
-	Ctime   time.Time // Creation time (platform-dependent)
-}
-
-// Scanner accumulates files and generates manifests from them.
-type Scanner struct {
-	mu      sync.RWMutex
-	files   []*FileEntry
-	options *Options
-	fs      afero.Fs
-}
-
-// New creates a new Scanner with default options.
-func New() *Scanner {
-	return NewWithOptions(nil)
-}
-
-// NewWithOptions creates a new Scanner with the given options.
-func NewWithOptions(opts *Options) *Scanner {
-	if opts == nil {
-		opts = &Options{}
-	}
-	fs := opts.Fs
-	if fs == nil {
-		fs = afero.NewOsFs()
-	}
-	return &Scanner{
-		files:   make([]*FileEntry, 0),
-		options: opts,
-		fs:      fs,
-	}
-}
-
-// EnumerateFile adds a single file to the scanner, calling stat() to get metadata.
-func (s *Scanner) EnumerateFile(filePath string) error {
-	abs, err := filepath.Abs(filePath)
-	if err != nil {
-		return err
-	}
-	info, err := s.fs.Stat(abs)
-	if err != nil {
-		return err
-	}
-	// For single files, use the filename as the relative path
-	basePath := filepath.Dir(abs)
-	return s.enumerateFileWithInfo(filepath.Base(abs), basePath, info, nil)
-}
-
-// EnumeratePath walks a directory path and adds all files to the scanner.
-// If progress is non-nil, status updates are sent as files are discovered.
-// The progress channel is closed when the method returns.
-func (s *Scanner) EnumeratePath(inputPath string, progress chan<- EnumerateStatus) error {
-	if progress != nil {
-		defer close(progress)
-	}
-	abs, err := filepath.Abs(inputPath)
-	if err != nil {
-		return err
-	}
-	afs := afero.NewReadOnlyFs(afero.NewBasePathFs(s.fs, abs))
-	return s.enumerateFS(afs, abs, progress)
-}
-
-// EnumeratePaths walks multiple directory paths and adds all files to the scanner.
-// If progress is non-nil, status updates are sent as files are discovered.
-// The progress channel is closed when the method returns.
-func (s *Scanner) EnumeratePaths(progress chan<- EnumerateStatus, inputPaths ...string) error {
-	if progress != nil {
-		defer close(progress)
-	}
-	for _, p := range inputPaths {
-		abs, err := filepath.Abs(p)
-		if err != nil {
-			return err
-		}
-		afs := afero.NewReadOnlyFs(afero.NewBasePathFs(s.fs, abs))
-		if err := s.enumerateFS(afs, abs, progress); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-// EnumerateFS walks an afero filesystem and adds all files to the scanner.
-// If progress is non-nil, status updates are sent as files are discovered.
-// The progress channel is closed when the method returns.
-// basePath is used to compute absolute paths for file reading.
-func (s *Scanner) EnumerateFS(afs afero.Fs, basePath string, progress chan<- EnumerateStatus) error {
-	if progress != nil {
-		defer close(progress)
-	}
-	return s.enumerateFS(afs, basePath, progress)
-}
-
-// enumerateFS is the internal implementation that doesn't close the progress channel.
-func (s *Scanner) enumerateFS(afs afero.Fs, basePath string, progress chan<- EnumerateStatus) error {
-	return afero.Walk(afs, "/", func(p string, info fs.FileInfo, err error) error {
-		if err != nil {
-			return err
-		}
-		if s.options.IgnoreDotfiles && pathIsHidden(p) {
-			if info.IsDir() {
-				return filepath.SkipDir
-			}
-			return nil
-		}
-		return s.enumerateFileWithInfo(p, basePath, info, progress)
-	})
-}
-
-// enumerateFileWithInfo adds a file with pre-existing fs.FileInfo.
-func (s *Scanner) enumerateFileWithInfo(filePath string, basePath string, info fs.FileInfo, progress chan<- EnumerateStatus) error {
-	if info.IsDir() {
-		// Manifests contain only files, directories are implied
-		return nil
-	}
-
-	// Clean the path - remove leading slash if present
-	cleanPath := filePath
-	if len(cleanPath) > 0 && cleanPath[0] == '/' {
-		cleanPath = cleanPath[1:]
-	}
-
-	// Compute absolute path for file reading
-	absPath := filepath.Join(basePath, cleanPath)
-
-	entry := &FileEntry{
-		Path:    cleanPath,
-		AbsPath: absPath,
-		Size:    info.Size(),
-		Mtime:   info.ModTime(),
-		// Note: Ctime not available from fs.FileInfo on all platforms
-		// Will need platform-specific code to extract it
-	}
-
-	s.mu.Lock()
-	s.files = append(s.files, entry)
-	filesFound := int64(len(s.files))
-	var bytesFound int64
-	for _, f := range s.files {
-		bytesFound += f.Size
-	}
-	s.mu.Unlock()
-
-	sendEnumerateStatus(progress, EnumerateStatus{
-		FilesFound: filesFound,
-		BytesFound: bytesFound,
-	})
-
-	return nil
-}
-
-// Files returns a copy of all files added to the scanner.
-func (s *Scanner) Files() []*FileEntry {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-	out := make([]*FileEntry, len(s.files))
-	copy(out, s.files)
-	return out
-}
-
-// FileCount returns the number of files in the scanner.
-func (s *Scanner) FileCount() int64 {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-	return int64(len(s.files))
-}
-
-// TotalBytes returns the total size of all files in the scanner.
-func (s *Scanner) TotalBytes() int64 {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-	var total int64
-	for _, f := range s.files {
-		total += f.Size
-	}
-	return total
-}
-
-// ToManifest reads all file contents, computes hashes, and generates a manifest.
-// If progress is non-nil, status updates are sent approximately once per second.
-// The progress channel is closed when the method returns.
-// The manifest is written to the provided io.Writer.
-func (s *Scanner) ToManifest(ctx context.Context, w io.Writer, progress chan<- ScanStatus) error {
-	if progress != nil {
-		defer close(progress)
-	}
-
-	s.mu.RLock()
-	files := make([]*FileEntry, len(s.files))
-	copy(files, s.files)
-	totalFiles := int64(len(files))
-	var totalBytes int64
-	for _, f := range files {
-		totalBytes += f.Size
-	}
-	s.mu.RUnlock()
-
-	builder := mfer.NewBuilder()
-
-	var scannedFiles int64
-	var scannedBytes int64
-	lastProgressTime := time.Now()
-	startTime := time.Now()
-
-	for _, entry := range files {
-		// Check for cancellation
-		select {
-		case <-ctx.Done():
-			return ctx.Err()
-		default:
-		}
-
-		// Open file
-		f, err := s.fs.Open(entry.AbsPath)
-		if err != nil {
-			return err
-		}
-
-		// Add to manifest with progress callback
-		bytesRead, err := builder.AddFile(
-			entry.Path,
-			entry.Size,
-			entry.Mtime,
-			f,
-			func(fileBytes int64) {
-				// Send progress at most once per second
-				now := time.Now()
-				if progress != nil && now.Sub(lastProgressTime) >= time.Second {
-					elapsed := now.Sub(startTime).Seconds()
-					currentBytes := scannedBytes + fileBytes
-					var rate float64
-					if elapsed > 0 {
-						rate = float64(currentBytes) / elapsed
-					}
-					sendScanStatus(progress, ScanStatus{
-						TotalFiles:   totalFiles,
-						ScannedFiles: scannedFiles,
-						TotalBytes:   totalBytes,
-						ScannedBytes: currentBytes,
-						BytesPerSec:  rate,
-					})
-					lastProgressTime = now
-				}
-			},
-		)
-		f.Close()
-
-		if err != nil {
-			return err
-		}
-
-		scannedFiles++
-		scannedBytes += bytesRead
-	}
-
-	// Send final progress
-	if progress != nil {
-		elapsed := time.Since(startTime).Seconds()
-		var rate float64
-		if elapsed > 0 {
-			rate = float64(scannedBytes) / elapsed
-		}
-		sendScanStatus(progress, ScanStatus{
-			TotalFiles:   totalFiles,
-			ScannedFiles: scannedFiles,
-			TotalBytes:   totalBytes,
-			ScannedBytes: scannedBytes,
-			BytesPerSec:  rate,
-		})
-	}
-
-	// Build and write manifest
-	return builder.Build(w)
-}
-
-// pathIsHidden returns true if the path or any of its parent directories
-// start with a dot (hidden files/directories).
-func pathIsHidden(p string) bool {
-	tp := path.Clean(p)
-	if strings.HasPrefix(tp, ".") {
-		return true
-	}
-	for {
-		d, f := path.Split(tp)
-		if strings.HasPrefix(f, ".") {
-			return true
-		}
-		if d == "" {
-			return false
-		}
-		tp = d[0 : len(d)-1] // trim trailing slash from dir
-	}
-}
-
-// sendEnumerateStatus sends a status update without blocking.
-// If the channel is full, the update is dropped.
-func sendEnumerateStatus(ch chan<- EnumerateStatus, status EnumerateStatus) {
-	if ch == nil {
-		return
-	}
-	select {
-	case ch <- status:
-	default:
-		// Channel full, drop this update
-	}
-}
-
-// sendScanStatus sends a status update without blocking.
-// If the channel is full, the update is dropped.
-func sendScanStatus(ch chan<- ScanStatus, status ScanStatus) {
-	if ch == nil {
-		return
-	}
-	select {
-	case ch <- status:
-	default:
-		// Channel full, drop this update
-	}
-}

mfer/builder.go

@@ -3,13 +3,48 @@ package mfer
 import (
 	"crypto/sha256"
 	"errors"
+	"fmt"
 	"io"
+	"sort"
+	"strings"
 	"sync"
 	"time"
+	"unicode/utf8"
 
 	"github.com/multiformats/go-multihash"
 )
 
+// ValidatePath checks that a file path conforms to manifest path invariants:
+//   - Must be valid UTF-8
+//   - Must use forward slashes only (no backslashes)
+//   - Must be relative (no leading /)
+//   - Must not contain ".." segments
+//   - Must not contain empty segments (no "//")
+//   - Must not be empty
+func ValidatePath(p string) error {
+	if p == "" {
+		return errors.New("path cannot be empty")
+	}
+	if !utf8.ValidString(p) {
+		return fmt.Errorf("path %q is not valid UTF-8", p)
+	}
+	if strings.ContainsRune(p, '\\') {
+		return fmt.Errorf("path %q contains backslash; use forward slashes only", p)
+	}
+	if strings.HasPrefix(p, "/") {
+		return fmt.Errorf("path %q is absolute; must be relative", p)
+	}
+	for _, seg := range strings.Split(p, "/") {
+		if seg == "" {
+			return fmt.Errorf("path %q contains empty segment", p)
+		}
+		if seg == ".." {
+			return fmt.Errorf("path %q contains '..' segment", p)
+		}
+	}
+	return nil
+}
+
 // RelFilePath represents a relative file path within a manifest.
 type RelFilePath string
 
@@ -50,10 +85,20 @@ type FileHashProgress struct {
 
 // Builder constructs a manifest by adding files one at a time.
 type Builder struct {
-	mu             sync.Mutex
+	mu                sync.Mutex
-	files          []*MFFilePath
+	files             []*MFFilePath
-	createdAt      time.Time
+	createdAt         time.Time
-	signingOptions *SigningOptions
+	includeTimestamps bool
+	signingOptions    *SigningOptions
+	fixedUUID         []byte // if set, use this UUID instead of generating one
+}
+
+// SetSeed derives a deterministic UUID from the given seed string.
+// The seed is hashed once with SHA-256 and the first 16 bytes are used
+// as a fixed UUID for the manifest.
+func (b *Builder) SetSeed(seed string) {
+	hash := sha256.Sum256([]byte(seed))
+	b.fixedUUID = hash[:16]
 }
 
 // NewBuilder creates a new Builder.
@@ -74,6 +119,10 @@ func (b *Builder) AddFile(
 	reader io.Reader,
 	progress chan<- FileHashProgress,
 ) (FileSize, error) {
+	if err := ValidatePath(string(path)); err != nil {
+		return 0, err
+	}
+
 	// Create hash writer
 	h := sha256.New()
 
@@ -96,6 +145,11 @@ func (b *Builder) AddFile(
 		}
 	}
 
+	// Verify actual bytes read matches declared size
+	if totalRead != size {
+		return totalRead, fmt.Errorf("size mismatch for %q: declared %d bytes but read %d bytes", path, size, totalRead)
+	}
+
 	// Encode hash as multihash (SHA2-256)
 	mh, err := multihash.Encode(h.Sum(nil), multihash.SHA2_256)
 	if err != nil {
@@ -141,8 +195,8 @@ func (b *Builder) FileCount() int {
 // This is useful when the hash is already known (e.g., from an existing manifest).
 // Returns an error if path is empty, size is negative, or hash is nil/empty.
 func (b *Builder) AddFileWithHash(path RelFilePath, size FileSize, mtime ModTime, hash Multihash) error {
-	if path == "" {
+	if err := ValidatePath(string(path)); err != nil {
-		return errors.New("path cannot be empty")
+		return fmt.Errorf("add file: %w", err)
 	}
 	if size < 0 {
 		return errors.New("size cannot be negative")
@@ -166,6 +220,14 @@ func (b *Builder) AddFileWithHash(path RelFilePath, size FileSize, mtime ModTime
 	return nil
 }
 
+// SetIncludeTimestamps controls whether the manifest includes a createdAt timestamp.
+// By default timestamps are omitted for deterministic output.
+func (b *Builder) SetIncludeTimestamps(include bool) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	b.includeTimestamps = include
+}
+
 // SetSigningOptions sets the GPG signing options for the manifest.
 // If opts is non-nil, the manifest will be signed when Build() is called.
 func (b *Builder) SetSigningOptions(opts *SigningOptions) {
@@ -179,30 +241,41 @@ func (b *Builder) Build(w io.Writer) error {
 	b.mu.Lock()
 	defer b.mu.Unlock()
 
+	// Sort files by path for deterministic output
+	sort.Slice(b.files, func(i, j int) bool {
+		return b.files[i].Path < b.files[j].Path
+	})
+
 	// Create inner manifest
 	inner := &MFFile{
-		Version:   MFFile_VERSION_ONE,
+		Version: MFFile_VERSION_ONE,
-		CreatedAt: newTimestampFromTime(b.createdAt),
+		Files:   b.files,
-		Files:     b.files,
+	}
+	if b.includeTimestamps {
+		inner.CreatedAt = newTimestampFromTime(b.createdAt)
 	}
 
 	// Create a temporary manifest to use existing serialization
 	m := &manifest{
 		pbInner:        inner,
 		signingOptions: b.signingOptions,
+		fixedUUID:      b.fixedUUID,
 	}
 
 	// Generate outer wrapper
 	if err := m.generateOuter(); err != nil {
-		return err
+		return fmt.Errorf("build: generate outer: %w", err)
 	}
 
 	// Generate final output
 	if err := m.generate(); err != nil {
-		return err
+		return fmt.Errorf("build: generate: %w", err)
 	}
 
 	// Write to output
 	_, err := w.Write(m.output.Bytes())
-	return err
+	if err != nil {
+		return fmt.Errorf("build: write output: %w", err)
+	}
+	return nil
 }

mfer/builder_test.go

@@ -92,6 +92,230 @@ func TestBuilderBuild(t *testing.T) {
 	assert.True(t, strings.HasPrefix(buf.String(), MAGIC))
 }
 
+func TestNewTimestampFromTimeExtremeDate(t *testing.T) {
+	// Regression test: newTimestampFromTime used UnixNano() which panics
+	// for dates outside ~1678-2262. Now uses Nanosecond() which is safe.
+	tests := []struct {
+		name string
+		time time.Time
+	}{
+		{"zero time", time.Time{}},
+		{"year 1000", time.Date(1000, 1, 1, 0, 0, 0, 0, time.UTC)},
+		{"year 3000", time.Date(3000, 1, 1, 0, 0, 0, 123456789, time.UTC)},
+		{"unix epoch", time.Unix(0, 0)},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Should not panic
+			ts := newTimestampFromTime(tt.time)
+			assert.Equal(t, tt.time.Unix(), ts.Seconds)
+			assert.Equal(t, int32(tt.time.Nanosecond()), ts.Nanos)
+		})
+	}
+}
+
+func TestBuilderDeterministicOutput(t *testing.T) {
+	buildManifest := func() []byte {
+		b := NewBuilder()
+		// Use a fixed createdAt and UUID so output is reproducible
+		b.createdAt = time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
+		b.fixedUUID = make([]byte, 16) // all zeros
+
+		mtime := ModTime(time.Date(2025, 6, 1, 0, 0, 0, 0, time.UTC))
+
+		// Add files in reverse order to test sorting
+		files := []struct {
+			path    string
+			content string
+		}{
+			{"c/file.txt", "content c"},
+			{"a/file.txt", "content a"},
+			{"b/file.txt", "content b"},
+		}
+		for _, f := range files {
+			r := bytes.NewReader([]byte(f.content))
+			_, err := b.AddFile(RelFilePath(f.path), FileSize(len(f.content)), mtime, r, nil)
+			require.NoError(t, err)
+		}
+
+		var buf bytes.Buffer
+		err := b.Build(&buf)
+		require.NoError(t, err)
+		return buf.Bytes()
+	}
+
+	out1 := buildManifest()
+	out2 := buildManifest()
+	assert.Equal(t, out1, out2, "two builds with same input should produce byte-identical output")
+}
+
+func TestSetSeedDeterministic(t *testing.T) {
+	b1 := NewBuilder()
+	b1.SetSeed("test-seed-value")
+	b2 := NewBuilder()
+	b2.SetSeed("test-seed-value")
+	assert.Equal(t, b1.fixedUUID, b2.fixedUUID, "same seed should produce same UUID")
+	assert.Len(t, b1.fixedUUID, 16, "UUID should be 16 bytes")
+
+	b3 := NewBuilder()
+	b3.SetSeed("different-seed")
+	assert.NotEqual(t, b1.fixedUUID, b3.fixedUUID, "different seeds should produce different UUIDs")
+}
+
+func TestValidatePath(t *testing.T) {
+	valid := []string{
+		"file.txt",
+		"dir/file.txt",
+		"a/b/c/d.txt",
+		"file with spaces.txt",
+		"日本語.txt",
+	}
+	for _, p := range valid {
+		t.Run("valid:"+p, func(t *testing.T) {
+			assert.NoError(t, ValidatePath(p))
+		})
+	}
+
+	invalid := []struct {
+		path string
+		desc string
+	}{
+		{"", "empty"},
+		{"/absolute", "absolute path"},
+		{"has\\backslash", "backslash"},
+		{"has/../traversal", "dot-dot segment"},
+		{"has//double", "empty segment"},
+		{"..", "just dot-dot"},
+		{string([]byte{0xff, 0xfe}), "invalid UTF-8"},
+	}
+	for _, tt := range invalid {
+		t.Run("invalid:"+tt.desc, func(t *testing.T) {
+			assert.Error(t, ValidatePath(tt.path))
+		})
+	}
+}
+
+func TestBuilderAddFileSizeMismatch(t *testing.T) {
+	b := NewBuilder()
+	content := []byte("short")
+	reader := bytes.NewReader(content)
+
+	// Declare wrong size
+	_, err := b.AddFile("test.txt", FileSize(100), ModTime(time.Now()), reader, nil)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "size mismatch")
+}
+
+func TestBuilderAddFileInvalidPath(t *testing.T) {
+	b := NewBuilder()
+	content := []byte("data")
+	reader := bytes.NewReader(content)
+
+	_, err := b.AddFile("", FileSize(len(content)), ModTime(time.Now()), reader, nil)
+	assert.Error(t, err)
+
+	reader.Reset(content)
+	_, err = b.AddFile("/absolute", FileSize(len(content)), ModTime(time.Now()), reader, nil)
+	assert.Error(t, err)
+}
+
+func TestBuilderAddFileWithProgress(t *testing.T) {
+	b := NewBuilder()
+	content := bytes.Repeat([]byte("x"), 1000)
+	reader := bytes.NewReader(content)
+	progress := make(chan FileHashProgress, 100)
+
+	bytesRead, err := b.AddFile("test.txt", FileSize(len(content)), ModTime(time.Now()), reader, progress)
+	close(progress)
+	require.NoError(t, err)
+	assert.Equal(t, FileSize(1000), bytesRead)
+
+	var updates []FileHashProgress
+	for p := range progress {
+		updates = append(updates, p)
+	}
+	assert.NotEmpty(t, updates)
+	// Last update should show all bytes
+	assert.Equal(t, FileSize(1000), updates[len(updates)-1].BytesRead)
+}
+
+func TestBuilderBuildRoundTrip(t *testing.T) {
+	// Build a manifest, deserialize it, verify all fields survive round-trip
+	b := NewBuilder()
+	now := time.Date(2025, 6, 15, 12, 0, 0, 0, time.UTC)
+
+	files := []struct {
+		path    string
+		content []byte
+	}{
+		{"alpha.txt", []byte("alpha content")},
+		{"beta/gamma.txt", []byte("gamma content")},
+		{"beta/delta.txt", []byte("delta content")},
+	}
+
+	for _, f := range files {
+		reader := bytes.NewReader(f.content)
+		_, err := b.AddFile(RelFilePath(f.path), FileSize(len(f.content)), ModTime(now), reader, nil)
+		require.NoError(t, err)
+	}
+
+	var buf bytes.Buffer
+	require.NoError(t, b.Build(&buf))
+
+	m, err := NewManifestFromReader(&buf)
+	require.NoError(t, err)
+
+	mfiles := m.Files()
+	require.Len(t, mfiles, 3)
+
+	// Verify sorted order
+	assert.Equal(t, "alpha.txt", mfiles[0].Path)
+	assert.Equal(t, "beta/delta.txt", mfiles[1].Path)
+	assert.Equal(t, "beta/gamma.txt", mfiles[2].Path)
+
+	// Verify sizes
+	assert.Equal(t, int64(len("alpha content")), mfiles[0].Size)
+
+	// Verify hashes are present
+	for _, f := range mfiles {
+		require.NotEmpty(t, f.Hashes, "file %s should have hashes", f.Path)
+		assert.NotEmpty(t, f.Hashes[0].MultiHash)
+	}
+}
+
+func TestNewManifestFromReaderInvalidMagic(t *testing.T) {
+	_, err := NewManifestFromReader(bytes.NewReader([]byte("NOT_VALID")))
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "invalid file format")
+}
+
+func TestNewManifestFromReaderEmpty(t *testing.T) {
+	_, err := NewManifestFromReader(bytes.NewReader([]byte{}))
+	assert.Error(t, err)
+}
+
+func TestNewManifestFromReaderTruncated(t *testing.T) {
+	// Just the magic with nothing after
+	_, err := NewManifestFromReader(bytes.NewReader([]byte(MAGIC)))
+	assert.Error(t, err)
+}
+
+func TestManifestString(t *testing.T) {
+	b := NewBuilder()
+	content := []byte("test")
+	reader := bytes.NewReader(content)
+	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime(time.Now()), reader, nil)
+	require.NoError(t, err)
+
+	var buf bytes.Buffer
+	require.NoError(t, b.Build(&buf))
+
+	m, err := NewManifestFromReader(&buf)
+	require.NoError(t, err)
+	assert.Contains(t, m.String(), "count=1")
+}
+
 func TestBuilderBuildEmpty(t *testing.T) {
 	b := NewBuilder()
 
@@ -102,3 +326,62 @@ func TestBuilderBuildEmpty(t *testing.T) {
 	// Should still produce valid manifest with 0 files
 	assert.True(t, strings.HasPrefix(buf.String(), MAGIC))
 }
+
+func TestBuilderOmitsCreatedAtByDefault(t *testing.T) {
+	b := NewBuilder()
+	content := []byte("hello")
+	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime(time.Now()), bytes.NewReader(content), nil)
+	require.NoError(t, err)
+
+	var buf bytes.Buffer
+	require.NoError(t, b.Build(&buf))
+
+	m, err := NewManifestFromReader(&buf)
+	require.NoError(t, err)
+	assert.Nil(t, m.pbInner.CreatedAt, "createdAt should be nil by default for deterministic output")
+}
+
+func TestBuilderIncludesCreatedAtWhenRequested(t *testing.T) {
+	b := NewBuilder()
+	b.SetIncludeTimestamps(true)
+	content := []byte("hello")
+	_, err := b.AddFile("test.txt", FileSize(len(content)), ModTime(time.Now()), bytes.NewReader(content), nil)
+	require.NoError(t, err)
+
+	var buf bytes.Buffer
+	require.NoError(t, b.Build(&buf))
+
+	m, err := NewManifestFromReader(&buf)
+	require.NoError(t, err)
+	assert.NotNil(t, m.pbInner.CreatedAt, "createdAt should be set when IncludeTimestamps is true")
+}
+
+func TestBuilderDeterministicFileOrder(t *testing.T) {
+	// Two builds with same files in different order should produce same file ordering.
+	// Note: UUIDs differ per build, so we compare parsed file lists, not raw bytes.
+	buildAndParse := func(order []string) []*MFFilePath {
+		b := NewBuilder()
+		for _, name := range order {
+			content := []byte("content of " + name)
+			_, err := b.AddFile(RelFilePath(name), FileSize(len(content)), ModTime(time.Unix(1000, 0)), bytes.NewReader(content), nil)
+			require.NoError(t, err)
+		}
+		var buf bytes.Buffer
+		require.NoError(t, b.Build(&buf))
+		m, err := NewManifestFromReader(&buf)
+		require.NoError(t, err)
+		return m.Files()
+	}
+
+	files1 := buildAndParse([]string{"b.txt", "a.txt"})
+	files2 := buildAndParse([]string{"a.txt", "b.txt"})
+
+	require.Len(t, files1, 2)
+	require.Len(t, files2, 2)
+	for i := range files1 {
+		assert.Equal(t, files1[i].Path, files2[i].Path)
+		assert.Equal(t, files1[i].Size, files2[i].Size)
+	}
+	assert.Equal(t, "a.txt", files1[0].Path)
+	assert.Equal(t, "b.txt", files1[1].Path)
+}

mfer/checker.go

@@ -70,6 +70,8 @@ type Checker struct {
 	fs       afero.Fs
 	// manifestPaths is a set of paths in the manifest for quick lookup
 	manifestPaths map[RelFilePath]struct{}
+	// manifestRelPath is the relative path of the manifest file from basePath (for exclusion)
+	manifestRelPath RelFilePath
 	// signature info from the manifest
 	signature     []byte
 	signer        []byte
@@ -100,14 +102,25 @@ func NewChecker(manifestPath string, basePath string, fs afero.Fs) (*Checker, er
 		manifestPaths[RelFilePath(f.Path)] = struct{}{}
 	}
 
+	// Compute manifest's relative path from basePath for exclusion in FindExtraFiles
+	absManifest, err := filepath.Abs(manifestPath)
+	if err != nil {
+		return nil, err
+	}
+	manifestRel, err := filepath.Rel(abs, absManifest)
+	if err != nil {
+		manifestRel = ""
+	}
+
 	return &Checker{
-		basePath:      AbsFilePath(abs),
+		basePath:        AbsFilePath(abs),
-		files:         files,
+		files:           files,
-		fs:            fs,
+		fs:              fs,
-		manifestPaths: manifestPaths,
+		manifestPaths:   manifestPaths,
-		signature:     m.pbOuter.Signature,
+		manifestRelPath: RelFilePath(manifestRel),
-		signer:        m.pbOuter.Signer,
+		signature:       m.pbOuter.Signature,
-		signingPubKey: m.pbOuter.SigningPubKey,
+		signer:          m.pbOuter.Signer,
+		signingPubKey:   m.pbOuter.SigningPubKey,
 	}, nil
 }
 
@@ -170,6 +183,7 @@ func (c *Checker) Check(ctx context.Context, results chan<- Result, progress cha
 	var failures FileCount
 
 	startTime := time.Now()
+	lastProgressTime := time.Now()
 
 	for _, entry := range c.files {
 		select {
@@ -188,29 +202,34 @@ func (c *Checker) Check(ctx context.Context, results chan<- Result, progress cha
 			results <- result
 		}
 
-		// Send progress with rate and ETA calculation
+		// Send progress at most once per second (rate-limited)
 		if progress != nil {
-			elapsed := time.Since(startTime)
+			now := time.Now()
-			var bytesPerSec float64
+			isLast := checkedFiles == totalFiles
-			var eta time.Duration
+			if isLast || now.Sub(lastProgressTime) >= time.Second {
+				elapsed := time.Since(startTime)
+				var bytesPerSec float64
+				var eta time.Duration
 
-			if elapsed > 0 && checkedBytes > 0 {
+				if elapsed > 0 && checkedBytes > 0 {
-				bytesPerSec = float64(checkedBytes) / elapsed.Seconds()
+					bytesPerSec = float64(checkedBytes) / elapsed.Seconds()
-				remainingBytes := totalBytes - checkedBytes
+					remainingBytes := totalBytes - checkedBytes
-				if bytesPerSec > 0 {
+					if bytesPerSec > 0 {
-					eta = time.Duration(float64(remainingBytes)/bytesPerSec) * time.Second
+						eta = time.Duration(float64(remainingBytes)/bytesPerSec) * time.Second
+					}
 				}
-			}
 
-			sendCheckStatus(progress, CheckStatus{
+				sendCheckStatus(progress, CheckStatus{
-				TotalFiles:   totalFiles,
+					TotalFiles:   totalFiles,
-				CheckedFiles: checkedFiles,
+					CheckedFiles: checkedFiles,
-				TotalBytes:   totalBytes,
+					TotalBytes:   totalBytes,
-				CheckedBytes: checkedBytes,
+					CheckedBytes: checkedBytes,
-				BytesPerSec:  bytesPerSec,
+					BytesPerSec:  bytesPerSec,
-				ETA:          eta,
+					ETA:          eta,
-				Failures:     failures,
+					Failures:     failures,
-			})
+				})
+				lastProgressTime = now
+			}
 		}
 	}
 
@@ -224,12 +243,7 @@ func (c *Checker) checkFile(entry *MFFilePath, checkedBytes *FileSize) Result {
 	// Check if file exists
 	info, err := c.fs.Stat(absPath)
 	if err != nil {
-		if errors.Is(err, afero.ErrFileNotFound) || errors.Is(err, errors.New("file does not exist")) {
+		if errors.Is(err, os.ErrNotExist) || errors.Is(err, afero.ErrFileNotFound) {
-			return Result{Path: relPath, Status: StatusMissing, Message: "file not found"}
-		}
-		// Check for "file does not exist" style errors
-		exists, _ := afero.Exists(c.fs, absPath)
-		if !exists {
 			return Result{Path: relPath, Status: StatusMissing, Message: "file not found"}
 		}
 		return Result{Path: relPath, Status: StatusError, Message: err.Error()}
@@ -277,12 +291,14 @@ func (c *Checker) checkFile(entry *MFFilePath, checkedBytes *FileSize) Result {
 
 // FindExtraFiles walks the filesystem and reports files not in the manifest.
 // Results are sent to the results channel. The channel is closed when done.
+// Hidden files/directories (starting with .) are skipped, as they are excluded
+// from manifests by default. The manifest file itself is also skipped.
 func (c *Checker) FindExtraFiles(ctx context.Context, results chan<- Result) error {
 	if results != nil {
 		defer close(results)
 	}
 
-	return afero.Walk(c.fs, string(c.basePath), func(path string, info os.FileInfo, err error) error {
+	return afero.Walk(c.fs, string(c.basePath), func(walkPath string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err
 		}
@@ -293,18 +309,32 @@ func (c *Checker) FindExtraFiles(ctx context.Context, results chan<- Result) err
 		default:
 		}
 
+		// Get relative path
+		rel, err := filepath.Rel(string(c.basePath), walkPath)
+		if err != nil {
+			return err
+		}
+
+		// Skip hidden files and directories (dotfiles)
+		if IsHiddenPath(filepath.ToSlash(rel)) {
+			if info.IsDir() {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+
 		// Skip directories
 		if info.IsDir() {
 			return nil
 		}
 
-		// Get relative path
-		rel, err := filepath.Rel(string(c.basePath), path)
-		if err != nil {
-			return err
-		}
 		relPath := RelFilePath(rel)
 
+		// Skip the manifest file itself
+		if relPath == c.manifestRelPath {
+			return nil
+		}
+
 		// Check if path is in manifest
 		if _, exists := c.manifestPaths[relPath]; !exists {
 			if results != nil {

mfer/checker_test.go

@@ -3,6 +3,7 @@ package mfer
 import (
 	"bytes"
 	"context"
+	"fmt"
 	"testing"
 	"time"
 
@@ -305,6 +306,44 @@ func TestFindExtraFiles(t *testing.T) {
 	assert.Equal(t, "not in manifest", extras[0].Message)
 }
 
+func TestFindExtraFilesSkipsManifestAndDotfiles(t *testing.T) {
+	fs := afero.NewMemMapFs()
+	manifestFiles := map[string][]byte{
+		"file1.txt": []byte("in manifest"),
+	}
+	createTestManifest(t, fs, "/data/.index.mf", manifestFiles)
+	createFilesOnDisk(t, fs, "/data", map[string][]byte{
+		"file1.txt": []byte("in manifest"),
+	})
+	// Create dotfile and manifest that should be skipped
+	require.NoError(t, afero.WriteFile(fs, "/data/.hidden", []byte("hidden"), 0o644))
+	require.NoError(t, afero.WriteFile(fs, "/data/.config/settings", []byte("cfg"), 0o644))
+	// Create a real extra file
+	require.NoError(t, fs.MkdirAll("/data", 0o755))
+	require.NoError(t, afero.WriteFile(fs, "/data/extra.txt", []byte("extra"), 0o644))
+
+	chk, err := NewChecker("/data/.index.mf", "/data", fs)
+	require.NoError(t, err)
+
+	results := make(chan Result, 10)
+	err = chk.FindExtraFiles(context.Background(), results)
+	require.NoError(t, err)
+
+	var extras []Result
+	for r := range results {
+		extras = append(extras, r)
+	}
+
+	// Should only report extra.txt, not .hidden, .config/settings, or .index.mf
+	for _, e := range extras {
+		t.Logf("extra: %s", e.Path)
+	}
+	assert.Len(t, extras, 1)
+	if len(extras) > 0 {
+		assert.Equal(t, RelFilePath("extra.txt"), extras[0].Path)
+	}
+}
+
 func TestFindExtraFilesContextCancellation(t *testing.T) {
 	fs := afero.NewMemMapFs()
 	files := map[string][]byte{"file.txt": []byte("data")}
@@ -381,6 +420,94 @@ func TestCheckSubdirectories(t *testing.T) {
 	assert.Equal(t, 3, okCount)
 }
 
+func TestCheckMissingFileDetectedWithoutFallback(t *testing.T) {
+	// Regression test: errors.Is(err, errors.New("...")) never matches because
+	// errors.New creates a new value each time. The fix uses os.ErrNotExist instead.
+	fs := afero.NewMemMapFs()
+	files := map[string][]byte{
+		"exists.txt":  []byte("here"),
+		"missing.txt": []byte("not on disk"),
+	}
+	createTestManifest(t, fs, "/manifest.mf", files)
+	// Only create one file on disk
+	createFilesOnDisk(t, fs, "/data", map[string][]byte{
+		"exists.txt": []byte("here"),
+	})
+
+	chk, err := NewChecker("/manifest.mf", "/data", fs)
+	require.NoError(t, err)
+
+	results := make(chan Result, 10)
+	err = chk.Check(context.Background(), results, nil)
+	require.NoError(t, err)
+
+	statusCounts := map[Status]int{}
+	for r := range results {
+		statusCounts[r.Status]++
+		if r.Status == StatusMissing {
+			assert.Equal(t, RelFilePath("missing.txt"), r.Path)
+		}
+	}
+	assert.Equal(t, 1, statusCounts[StatusOK], "one file should be OK")
+	assert.Equal(t, 1, statusCounts[StatusMissing], "one file should be MISSING")
+	assert.Equal(t, 0, statusCounts[StatusError], "no files should be ERROR")
+}
+
+func TestFindExtraFilesSkipsDotfiles(t *testing.T) {
+	// Regression test for #16: FindExtraFiles should not report dotfiles
+	// or the manifest file itself as extra files.
+	fs := afero.NewMemMapFs()
+	files := map[string][]byte{
+		"file1.txt": []byte("in manifest"),
+	}
+	createTestManifest(t, fs, "/data/.index.mf", files)
+	createFilesOnDisk(t, fs, "/data", files)
+
+	// Add dotfiles and manifest file on disk
+	require.NoError(t, afero.WriteFile(fs, "/data/.hidden", []byte("dotfile"), 0o644))
+	require.NoError(t, fs.MkdirAll("/data/.git", 0o755))
+	require.NoError(t, afero.WriteFile(fs, "/data/.git/config", []byte("git config"), 0o644))
+
+	chk, err := NewChecker("/data/.index.mf", "/data", fs)
+	require.NoError(t, err)
+
+	results := make(chan Result, 10)
+	err = chk.FindExtraFiles(context.Background(), results)
+	require.NoError(t, err)
+
+	var extras []Result
+	for r := range results {
+		extras = append(extras, r)
+	}
+
+	// Should report NO extra files — dotfiles and manifest should be skipped
+	assert.Empty(t, extras, "FindExtraFiles should not report dotfiles or manifest file as extra; got: %v", extras)
+}
+
+func TestFindExtraFilesSkipsManifestFile(t *testing.T) {
+	// The manifest file itself should never be reported as extra
+	fs := afero.NewMemMapFs()
+	files := map[string][]byte{
+		"file1.txt": []byte("content"),
+	}
+	createTestManifest(t, fs, "/data/index.mf", files)
+	createFilesOnDisk(t, fs, "/data", files)
+
+	chk, err := NewChecker("/data/index.mf", "/data", fs)
+	require.NoError(t, err)
+
+	results := make(chan Result, 10)
+	err = chk.FindExtraFiles(context.Background(), results)
+	require.NoError(t, err)
+
+	var extras []Result
+	for r := range results {
+		extras = append(extras, r)
+	}
+
+	assert.Empty(t, extras, "manifest file should not be reported as extra; got: %v", extras)
+}
+
 func TestCheckEmptyManifest(t *testing.T) {
 	fs := afero.NewMemMapFs()
 	// Create manifest with no files
@@ -402,3 +529,40 @@ func TestCheckEmptyManifest(t *testing.T) {
 	}
 	assert.Equal(t, 0, count)
 }
+
+func TestCheckProgressRateLimited(t *testing.T) {
+	// Create many small files - progress should be rate-limited, not one per file.
+	// With rate-limiting to once per second, we should get far fewer progress
+	// updates than files (plus one final update).
+	fs := afero.NewMemMapFs()
+	files := make(map[string][]byte, 100)
+	for i := 0; i < 100; i++ {
+		name := fmt.Sprintf("file%03d.txt", i)
+		files[name] = []byte("content")
+	}
+	createTestManifest(t, fs, "/manifest.mf", files)
+	createFilesOnDisk(t, fs, "/data", files)
+
+	chk, err := NewChecker("/manifest.mf", "/data", fs)
+	require.NoError(t, err)
+
+	results := make(chan Result, 200)
+	progress := make(chan CheckStatus, 200)
+	err = chk.Check(context.Background(), results, progress)
+	require.NoError(t, err)
+
+	// Drain results
+	for range results {
+	}
+
+	// Count progress updates
+	var progressCount int
+	for range progress {
+		progressCount++
+	}
+
+	// Should be far fewer than 100 (rate-limited to once per second)
+	// At minimum we get the final update
+	assert.GreaterOrEqual(t, progressCount, 1, "should get at least the final progress update")
+	assert.Less(t, progressCount, 100, "progress should be rate-limited, not one per file")
+}

mfer/constants.go

@@ -3,4 +3,9 @@ package mfer
 const (
 	Version     = "0.1.0"
 	ReleaseDate = "2025-12-17"
+
+	// MaxDecompressedSize is the maximum allowed size of decompressed manifest
+	// data (256 MB). This prevents decompression bombs from consuming excessive
+	// memory.
+	MaxDecompressedSize int64 = 256 * 1024 * 1024
 )

mfer/deserialize.go

@@ -44,7 +44,7 @@ func (m *manifest) deserializeInner() error {
 	// Verify hash of compressed data before decompression
 	h := sha256.New()
 	if _, err := h.Write(m.pbOuter.InnerMessage); err != nil {
-		return err
+		return fmt.Errorf("deserialize: hash write: %w", err)
 	}
 	sha256Hash := h.Sum(nil)
 	if !bytes.Equal(sha256Hash, m.pbOuter.Sha256) {
@@ -72,13 +72,23 @@ func (m *manifest) deserializeInner() error {
 
 	zr, err := zstd.NewReader(bb)
 	if err != nil {
-		return err
+		return fmt.Errorf("deserialize: zstd reader: %w", err)
 	}
 	defer zr.Close()
 
-	dat, err := io.ReadAll(zr)
+	// Limit decompressed size to prevent decompression bombs.
+	// Use declared size + 1 byte to detect overflow, capped at MaxDecompressedSize.
+	maxSize := MaxDecompressedSize
+	if m.pbOuter.Size > 0 && m.pbOuter.Size < int64(maxSize) {
+		maxSize = int64(m.pbOuter.Size) + 1
+	}
+	limitedReader := io.LimitReader(zr, maxSize)
+	dat, err := io.ReadAll(limitedReader)
 	if err != nil {
-		return err
+		return fmt.Errorf("deserialize: decompress: %w", err)
+	}
+	if int64(len(dat)) >= MaxDecompressedSize {
+		return fmt.Errorf("decompressed data exceeds maximum allowed size of %d bytes", MaxDecompressedSize)
 	}
 
 	isize := len(dat)
@@ -90,7 +100,7 @@ func (m *manifest) deserializeInner() error {
 	// Deserialize inner message
 	m.pbInner = new(MFFile)
 	if err := proto.Unmarshal(dat, m.pbInner); err != nil {
-		return err
+		return fmt.Errorf("deserialize: unmarshal inner: %w", err)
 	}
 
 	// Validate inner UUID

mfer/gpg.go

@@ -20,7 +20,7 @@ type SigningOptions struct {
 // gpgSign creates a detached signature of the data using the specified key.
 // Returns the armored detached signature.
 func gpgSign(data []byte, keyID GPGKeyID) ([]byte, error) {
-	cmd := exec.Command("gpg",
+	cmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--detach-sign",
 		"--armor",
 		"--local-user", string(keyID),
@@ -42,7 +42,7 @@ func gpgSign(data []byte, keyID GPGKeyID) ([]byte, error) {
 // gpgExportPublicKey exports the public key for the specified key ID.
 // Returns the armored public key.
 func gpgExportPublicKey(keyID GPGKeyID) ([]byte, error) {
-	cmd := exec.Command("gpg",
+	cmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--export",
 		"--armor",
 		string(keyID),
@@ -65,7 +65,7 @@ func gpgExportPublicKey(keyID GPGKeyID) ([]byte, error) {
 
 // gpgGetKeyFingerprint gets the full fingerprint for a key ID.
 func gpgGetKeyFingerprint(keyID GPGKeyID) ([]byte, error) {
-	cmd := exec.Command("gpg",
+	cmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--with-colons",
 		"--fingerprint",
 		string(keyID),
@@ -100,7 +100,7 @@ func gpgExtractPubKeyFingerprint(pubKey []byte) (string, error) {
 	if err != nil {
 		return "", fmt.Errorf("failed to create temp dir: %w", err)
 	}
-	defer os.RemoveAll(tmpDir)
+	defer func() { _ = os.RemoveAll(tmpDir) }()
 
 	// Set restrictive permissions
 	if err := os.Chmod(tmpDir, 0o700); err != nil {
@@ -114,7 +114,7 @@ func gpgExtractPubKeyFingerprint(pubKey []byte) (string, error) {
 	}
 
 	// Import the public key into the temporary keyring
-	importCmd := exec.Command("gpg",
+	importCmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--homedir", tmpDir,
 		"--import",
 		pubKeyFile,
@@ -126,7 +126,7 @@ func gpgExtractPubKeyFingerprint(pubKey []byte) (string, error) {
 	}
 
 	// List keys to get fingerprint
-	listCmd := exec.Command("gpg",
+	listCmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--homedir", tmpDir,
 		"--with-colons",
 		"--fingerprint",
@@ -158,7 +158,7 @@ func gpgVerify(data, signature, pubKey []byte) error {
 	if err != nil {
 		return fmt.Errorf("failed to create temp dir: %w", err)
 	}
-	defer os.RemoveAll(tmpDir)
+	defer func() { _ = os.RemoveAll(tmpDir) }()
 
 	// Set restrictive permissions
 	if err := os.Chmod(tmpDir, 0o700); err != nil {
@@ -184,7 +184,7 @@ func gpgVerify(data, signature, pubKey []byte) error {
 	}
 
 	// Import the public key into the temporary keyring
-	importCmd := exec.Command("gpg",
+	importCmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--homedir", tmpDir,
 		"--import",
 		pubKeyFile,
@@ -196,7 +196,7 @@ func gpgVerify(data, signature, pubKey []byte) error {
 	}
 
 	// Verify the signature
-	verifyCmd := exec.Command("gpg",
+	verifyCmd := exec.Command("gpg", "--batch", "--no-tty",
 		"--homedir", tmpDir,
 		"--verify",
 		sigFile,

mfer/gpg_test.go

@@ -34,15 +34,15 @@ func testGPGEnv(t *testing.T) (GPGKeyID, func()) {
 
 	// Save original GNUPGHOME and set new one
 	origGPGHome := os.Getenv("GNUPGHOME")
-	os.Setenv("GNUPGHOME", gpgHome)
+	require.NoError(t, os.Setenv("GNUPGHOME", gpgHome))
 
 	cleanup := func() {
 		if origGPGHome == "" {
-			os.Unsetenv("GNUPGHOME")
+			_ = os.Unsetenv("GNUPGHOME")
 		} else {
-			os.Setenv("GNUPGHOME", origGPGHome)
+			_ = os.Setenv("GNUPGHOME", origGPGHome)
 		}
-		os.RemoveAll(gpgHome)
+		_ = os.RemoveAll(gpgHome)
 	}
 
 	// Generate a test key with no passphrase

mfer/manifest.go

@@ -17,6 +17,7 @@ type manifest struct {
 	pbOuter        *MFFileOuter
 	output         *bytes.Buffer
 	signingOptions *SigningOptions
+	fixedUUID      []byte // if set, use this UUID instead of generating one
 }
 
 func (m *manifest) String() string {

mfer/mf.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
 // 	protoc-gen-go v1.36.11
-// 	protoc        v6.33.0
+// 	protoc        v6.33.4
 // source: mf.proto
 
 package mfer
@@ -329,6 +329,9 @@ func (x *MFFileOuter) GetSigningPubKey() []byte {
 type MFFilePath struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
 	// required attributes:
+	// Path invariants: must be valid UTF-8, use forward slashes only,
+	// be relative (no leading /), contain no ".." segments, and no
+	// empty segments (no "//").
 	Path string `protobuf:"bytes,1,opt,name=path,proto3" json:"path,omitempty"`
 	Size int64  `protobuf:"varint,2,opt,name=size,proto3" json:"size,omitempty"`
 	// gotta have at least one:
@@ -337,7 +340,6 @@ type MFFilePath struct {
 	MimeType      *string    `protobuf:"bytes,301,opt,name=mimeType,proto3,oneof" json:"mimeType,omitempty"`
 	Mtime         *Timestamp `protobuf:"bytes,302,opt,name=mtime,proto3,oneof" json:"mtime,omitempty"`
 	Ctime         *Timestamp `protobuf:"bytes,303,opt,name=ctime,proto3,oneof" json:"ctime,omitempty"`
-	Atime         *Timestamp `protobuf:"bytes,304,opt,name=atime,proto3,oneof" json:"atime,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -414,13 +416,6 @@ func (x *MFFilePath) GetCtime() *Timestamp {
 	return nil
 }
 
-func (x *MFFilePath) GetAtime() *Timestamp {
-	if x != nil {
-		return x.Atime
-	}
-	return nil
-}
-
 type MFFileChecksum struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
 	// 1.0 golang implementation must write a multihash here
@@ -566,7 +561,7 @@ const file_mf_proto_rawDesc = "" +
 	"\n" +
 	"_signatureB\t\n" +
 	"\a_signerB\x10\n" +
-	"\x0e_signingPubKey\"\xa2\x02\n" +
+	"\x0e_signingPubKey\"\xf0\x01\n" +
 	"\n" +
 	"MFFilePath\x12\x12\n" +
 	"\x04path\x18\x01 \x01(\tR\x04path\x12\x12\n" +
@@ -576,13 +571,10 @@ const file_mf_proto_rawDesc = "" +
 	"\x05mtime\x18\xae\x02 \x01(\v2\n" +
 	".TimestampH\x01R\x05mtime\x88\x01\x01\x12&\n" +
 	"\x05ctime\x18\xaf\x02 \x01(\v2\n" +
-	".TimestampH\x02R\x05ctime\x88\x01\x01\x12&\n" +
+	".TimestampH\x02R\x05ctime\x88\x01\x01B\v\n" +
-	"\x05atime\x18\xb0\x02 \x01(\v2\n" +
-	".TimestampH\x03R\x05atime\x88\x01\x01B\v\n" +
 	"\t_mimeTypeB\b\n" +
 	"\x06_mtimeB\b\n" +
-	"\x06_ctimeB\b\n" +
+	"\x06_ctime\".\n" +
-	"\x06_atime\".\n" +
 	"\x0eMFFileChecksum\x12\x1c\n" +
 	"\tmultiHash\x18\x01 \x01(\fR\tmultiHash\"\xd6\x01\n" +
 	"\x06MFFile\x12)\n" +
@@ -627,15 +619,14 @@ var file_mf_proto_depIdxs = []int32{
 	6, // 2: MFFilePath.hashes:type_name -> MFFileChecksum
 	3, // 3: MFFilePath.mtime:type_name -> Timestamp
 	3, // 4: MFFilePath.ctime:type_name -> Timestamp
-	3, // 5: MFFilePath.atime:type_name -> Timestamp
+	2, // 5: MFFile.version:type_name -> MFFile.Version
-	2, // 6: MFFile.version:type_name -> MFFile.Version
+	5, // 6: MFFile.files:type_name -> MFFilePath
-	5, // 7: MFFile.files:type_name -> MFFilePath
+	3, // 7: MFFile.createdAt:type_name -> Timestamp
-	3, // 8: MFFile.createdAt:type_name -> Timestamp
+	8, // [8:8] is the sub-list for method output_type
-	9, // [9:9] is the sub-list for method output_type
+	8, // [8:8] is the sub-list for method input_type
-	9, // [9:9] is the sub-list for method input_type
+	8, // [8:8] is the sub-list for extension type_name
-	9, // [9:9] is the sub-list for extension type_name
+	8, // [8:8] is the sub-list for extension extendee
-	9, // [9:9] is the sub-list for extension extendee
+	0, // [0:8] is the sub-list for field type_name
-	0, // [0:9] is the sub-list for field type_name
 }
 
 func init() { file_mf_proto_init() }

mfer/mf.proto

@@ -46,6 +46,9 @@ message MFFileOuter {
 
 message MFFilePath {
     // required attributes:
+    // Path invariants: must be valid UTF-8, use forward slashes only,
+    // be relative (no leading /), contain no ".." segments, and no
+    // empty segments (no "//").
     string path = 1;
     int64 size = 2;
 
@@ -56,7 +59,6 @@ message MFFilePath {
     optional string mimeType = 301;
     optional Timestamp mtime = 302;
     optional Timestamp ctime = 303;
-    optional Timestamp atime = 304;
 }
 
 message MFFileChecksum {

mfer/scanner.go

@@ -43,10 +43,12 @@ type ScanStatus struct {
 
 // ScannerOptions configures scanner behavior.
 type ScannerOptions struct {
-	IncludeDotfiles bool            // Include files and directories starting with a dot (default: exclude)
+	IncludeDotfiles   bool            // Include files and directories starting with a dot (default: exclude)
-	FollowSymLinks  bool            // Resolve symlinks instead of skipping them
+	FollowSymLinks    bool            // Resolve symlinks instead of skipping them
-	Fs              afero.Fs        // Filesystem to use, defaults to OsFs if nil
+	IncludeTimestamps bool            // Include createdAt timestamp in manifest (default: omit for determinism)
-	SigningOptions  *SigningOptions // GPG signing options (nil = no signing)
+	Fs                afero.Fs        // Filesystem to use, defaults to OsFs if nil
+	SigningOptions    *SigningOptions // GPG signing options (nil = no signing)
+	Seed              string          // If set, derive a deterministic UUID from this seed
 }
 
 // FileEntry represents a file that has been enumerated.
@@ -273,9 +275,15 @@ func (s *Scanner) ToManifest(ctx context.Context, w io.Writer, progress chan<- S
 	s.mu.RUnlock()
 
 	builder := NewBuilder()
+	if s.options.IncludeTimestamps {
+		builder.SetIncludeTimestamps(true)
+	}
 	if s.options.SigningOptions != nil {
 		builder.SetSigningOptions(s.options.SigningOptions)
 	}
+	if s.options.Seed != "" {
+		builder.SetSeed(s.options.Seed)
+	}
 
 	var scannedFiles FileCount
 	var scannedBytes FileSize
@@ -385,6 +393,9 @@ func (s *Scanner) ToManifest(ctx context.Context, w io.Writer, progress chan<- S
 // The path should use forward slashes.
 func IsHiddenPath(p string) bool {
 	tp := path.Clean(p)
+	if tp == "." || tp == "/" {
+		return false
+	}
 	if strings.HasPrefix(tp, ".") {
 		return true
 	}

mfer/scanner_test.go

@@ -352,6 +352,10 @@ func TestIsHiddenPath(t *testing.T) {
 		{"/absolute/.hidden", true},
 		{"./relative", false}, // path.Clean removes leading ./
 		{"a/b/c/.d/e", true},
+		{".", false},          // current directory is not hidden (#14)
+		{"/", false},          // root is not hidden
+		{"./", false},         // current directory with trailing slash
+		{"./file.txt", false}, // file in current directory
 	}
 
 	for _, tt := range tests {

mfer/serialize.go

@@ -16,11 +16,10 @@ import (
 const MAGIC string = "ZNAVSRFG"
 
 func newTimestampFromTime(t time.Time) *Timestamp {
-	out := &Timestamp{
+	return &Timestamp{
 		Seconds: t.Unix(),
-		Nanos:   int32(t.UnixNano() - (t.Unix() * 1000000000)),
+		Nanos:   int32(t.Nanosecond()),
 	}
-	return out
 }
 
 func (m *manifest) generate() error {
@@ -35,12 +34,12 @@ func (m *manifest) generate() error {
 	}
 	dat, err := proto.MarshalOptions{Deterministic: true}.Marshal(m.pbOuter)
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: marshal outer: %w", err)
 	}
 	m.output = bytes.NewBuffer([]byte(MAGIC))
 	_, err = m.output.Write(dat)
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: write output: %w", err)
 	}
 	return nil
 }
@@ -50,24 +49,29 @@ func (m *manifest) generateOuter() error {
 		return errors.New("internal error")
 	}
 
-	// Generate UUID and set on inner message
+	// Use fixed UUID if provided, otherwise generate a new one
-	manifestUUID := uuid.New()
+	var manifestUUID uuid.UUID
+	if len(m.fixedUUID) == 16 {
+		copy(manifestUUID[:], m.fixedUUID)
+	} else {
+		manifestUUID = uuid.New()
+	}
 	m.pbInner.Uuid = manifestUUID[:]
 
 	innerData, err := proto.MarshalOptions{Deterministic: true}.Marshal(m.pbInner)
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: marshal inner: %w", err)
 	}
 
 	// Compress the inner data
 	idc := new(bytes.Buffer)
 	zw, err := zstd.NewWriter(idc, zstd.WithEncoderLevel(zstd.SpeedBestCompression))
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: create compressor: %w", err)
 	}
 	_, err = zw.Write(innerData)
 	if err != nil {
-		return err
+		return fmt.Errorf("serialize: compress: %w", err)
 	}
 	_ = zw.Close()
 
@@ -76,7 +80,7 @@ func (m *manifest) generateOuter() error {
 	// Hash the compressed data for integrity verification before decompression
 	h := sha256.New()
 	if _, err := h.Write(compressedData); err != nil {
-		return err
+		return fmt.Errorf("serialize: hash write: %w", err)
 	}
 	sha256Hash := h.Sum(nil)
 

mfer/url.go

@@ -27,8 +27,12 @@ func (b BaseURL) JoinPath(path RelFilePath) (FileURL, error) {
 		base.Path += "/"
 	}
 
-	// Parse and encode the relative path
+	// Encode each path segment individually to preserve slashes
-	ref, err := url.Parse(url.PathEscape(string(path)))
+	segments := strings.Split(string(path), "/")
+	for i, seg := range segments {
+		segments[i] = url.PathEscape(seg)
+	}
+	ref, err := url.Parse(strings.Join(segments, "/"))
 	if err != nil {
 		return "", err
 	}

mfer/url_test.go

@@ -0,0 +1,44 @@
+package mfer
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestBaseURLJoinPath(t *testing.T) {
+	tests := []struct {
+		base     BaseURL
+		path     RelFilePath
+		expected string
+	}{
+		{"https://example.com/dir/", "file.txt", "https://example.com/dir/file.txt"},
+		{"https://example.com/dir", "file.txt", "https://example.com/dir/file.txt"},
+		{"https://example.com/", "sub/file.txt", "https://example.com/sub/file.txt"},
+		{"https://example.com/dir/", "file with spaces.txt", "https://example.com/dir/file%20with%20spaces.txt"},
+	}
+
+	for _, tt := range tests {
+		t.Run(string(tt.base)+"+"+string(tt.path), func(t *testing.T) {
+			result, err := tt.base.JoinPath(tt.path)
+			require.NoError(t, err)
+			assert.Equal(t, tt.expected, string(result))
+		})
+	}
+}
+
+func TestBaseURLString(t *testing.T) {
+	b := BaseURL("https://example.com/")
+	assert.Equal(t, "https://example.com/", b.String())
+}
+
+func TestFileURLString(t *testing.T) {
+	f := FileURL("https://example.com/file.txt")
+	assert.Equal(t, "https://example.com/file.txt", f.String())
+}
+
+func TestManifestURLString(t *testing.T) {
+	m := ManifestURL("https://example.com/index.mf")
+	assert.Equal(t, "https://example.com/index.mf", m.String())
+}

script/bootstrap

@@ -0,0 +1,155 @@
+#!/bin/sh
+# script/bootstrap: install all dependencies needed to build and develop
+# this repo. Idempotent: every install is guarded by a check so already
+# installed tools are skipped. Base tooling comes from nix, apt, brew,
+# or apk (detected in that order); assumes NOTHING is present (not git,
+# make, node, yarn, go, or python). Node is used directly if installed;
+# otherwise a pinned version is installed via nvm (installing nvm
+# itself first, from a hash-verified release archive, never curl | sh).
+#
+# Uncomment the language sections in main() that apply to this repo.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+# Pinned versions, 2026-07-06. Never "latest" or "lts"; exact versions.
+NODE_VERSION="22.17.0"
+NVM_VERSION="0.40.3"
+# sha256 of https://github.com/nvm-sh/nvm/archive/refs/tags/v0.40.3.tar.gz
+NVM_SHA256="5f4d6aaa04a177dc93c985e31dbc411ab6b8c6e1e21d8015dbc1372625fcd1d0"
+YARN_VERSION="1.22.22"
+
+PKGMGR=""
+SUDO=""
+
+detect_pkgmgr() {
+    [ -n "$PKGMGR" ] && return 0
+    if command -v nix-env >/dev/null 2>&1; then
+        PKGMGR="nix"
+    elif command -v apt-get >/dev/null 2>&1; then
+        PKGMGR="apt"
+    elif command -v brew >/dev/null 2>&1; then
+        PKGMGR="brew"
+    elif command -v apk >/dev/null 2>&1; then
+        PKGMGR="apk"
+    else
+        echo "bootstrap: no supported package manager (nix, apt, brew, apk)" >&2
+        exit 1
+    fi
+    if [ "$PKGMGR" = "apt" ]; then
+        export DEBIAN_FRONTEND=noninteractive
+        if [ "$(id -u)" != "0" ]; then
+            SUDO="sudo"
+        fi
+    fi
+}
+
+# pkg_install <nix-attr> <apt-pkg> <brew-formula> <apk-pkg>
+pkg_install() {
+    detect_pkgmgr
+    case "$PKGMGR" in
+        nix) nix-env -iA "nixpkgs.$1" ;;
+        apt) $SUDO env DEBIAN_FRONTEND=noninteractive apt-get install -y "$2" ;;
+        brew) brew install "$3" ;;
+        apk) apk add --no-cache "$4" ;;
+    esac
+}
+
+missing() {
+    ! command -v "$1" >/dev/null 2>&1
+}
+
+# verify_sha256 <file> <expected-hash>
+verify_sha256() {
+    if command -v sha256sum >/dev/null 2>&1; then
+        actual="$(sha256sum "$1" | cut -d' ' -f1)"
+    else
+        actual="$(shasum -a 256 "$1" | cut -d' ' -f1)"
+    fi
+    if [ "$actual" != "$2" ]; then
+        echo "bootstrap: sha256 mismatch for $1" >&2
+        echo "  expected: $2" >&2
+        echo "  actual:   $actual" >&2
+        exit 1
+    fi
+}
+
+# nvm is a bash script; run a command in a bash with nvm loaded
+nvm_sh() {
+    bash -c ". \"\$HOME/.nvm/nvm.sh\" && $*"
+}
+
+ensure_nvm() {
+    [ -s "$HOME/.nvm/nvm.sh" ] && return 0
+    # nvm prerequisites; nvm itself requires bash, so install it too
+    if missing bash; then pkg_install bash bash bash bash; fi
+    if missing curl; then pkg_install curl curl curl curl; fi
+    if missing git; then pkg_install git git git git; fi
+    tmp="$(mktemp -d)"
+    curl -fsSL -o "$tmp/nvm.tar.gz" \
+        "https://github.com/nvm-sh/nvm/archive/refs/tags/v${NVM_VERSION}.tar.gz"
+    verify_sha256 "$tmp/nvm.tar.gz" "$NVM_SHA256"
+    mkdir -p "$HOME/.nvm"
+    tar -xzf "$tmp/nvm.tar.gz" -C "$HOME/.nvm" --strip-components=1
+    rm -rf "$tmp"
+}
+
+ensure_node() {
+    if ! missing node; then return 0; fi
+    ensure_nvm
+    nvm_sh "nvm install $NODE_VERSION"
+}
+
+ensure_yarn() {
+    if ! missing yarn; then return 0; fi
+    if ! missing corepack; then
+        corepack enable
+        corepack prepare "yarn@$YARN_VERSION" --activate
+    elif [ -s "$HOME/.nvm/nvm.sh" ]; then
+        nvm_sh "nvm use $NODE_VERSION >/dev/null && corepack enable && \
+            corepack prepare yarn@$YARN_VERSION --activate"
+    else
+        npm install -g "yarn@$YARN_VERSION"
+    fi
+}
+
+install_js_deps() {
+    if missing yarn && [ -s "$HOME/.nvm/nvm.sh" ]; then
+        nvm_sh "nvm use $NODE_VERSION >/dev/null && cd \"$ROOT\" && \
+            yarn install --frozen-lockfile"
+    else
+        yarn install --frozen-lockfile
+    fi
+}
+
+main() {
+    cd "$ROOT"
+
+    # Base tooling (every repo)
+    if missing git; then pkg_install git git git git; fi
+    if missing make; then pkg_install gnumake make make make; fi
+
+    # ---- JS / docs repos ----
+    # ensure_node
+    # ensure_yarn
+    # install_js_deps
+
+    # ---- Go repos ----
+    if missing go; then pkg_install go golang go go; fi
+    # golangci-lint: packaged in nix, brew, and apk. On apt there is no
+    # package: download a specific release archive from GitHub and
+    # verify its hash (verify_sha256), never curl | sh.
+    if missing golangci-lint; then
+        pkg_install golangci-lint golangci-lint golangci-lint golangci-lint
+    fi
+    go mod download
+
+    # ---- Python repos ----
+    # if missing python3; then pkg_install python3 python3 python3 python3; fi
+    # python3 -m venv .venv
+    # ./.venv/bin/pip install -e '.[dev]'
+
+    echo "bootstrap complete"
+}
+
+main "$@"

script/check

@@ -0,0 +1,15 @@
+#!/bin/sh
+# script/check: run all checks (test, lint, fmt-check). Our own
+# extension to scripts-to-rule-them-all. Must not modify any files.
+# Generic: usually needs no adaptation.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+
+main() {
+    "$SCRIPT_DIR/test"
+    "$SCRIPT_DIR/lint"
+    "$SCRIPT_DIR/fmt-check"
+}
+
+main "$@"

script/cibuild

@@ -0,0 +1,14 @@
+#!/bin/sh
+# script/cibuild: run the CI build. The Dockerfile runs script/check
+# (via make check), so a successful build implies all checks pass.
+# Generic: needs no adaptation. The Gitea workflow runs this on push.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    docker build .
+}
+
+main "$@"

script/docker

@@ -0,0 +1,15 @@
+#!/bin/sh
+# script/docker: build the Docker image tagged with the project name.
+# Identical in all repos; the tag comes from script/projectname.
+# Generic: needs no adaptation.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    docker build -t "$("$SCRIPT_DIR/projectname")" .
+}
+
+main "$@"

script/fmt

@@ -0,0 +1,27 @@
+#!/bin/sh
+# script/fmt: format all files (writes).
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+# Regenerate mfer/mf.pb.go from mfer/mf.proto if it is missing or stale
+# (mirrors the old Makefile prerequisite; the generated file is
+# committed, so this is normally a no-op).
+ensure_pb() {
+    if [ ! -f mfer/mf.pb.go ] ||
+        [ -n "$(find mfer/mf.proto -newer mfer/mf.pb.go 2>/dev/null)" ]; then
+        (cd mfer && go generate .)
+    fi
+}
+
+main() {
+    cd "$ROOT"
+    ensure_pb
+    gofumpt -l -w mfer internal cmd
+    golangci-lint run --fix
+    # prettier is best-effort, as in the old Makefile (- prefix)
+    prettier -w *.json || true
+    prettier -w *.md || true
+}
+
+main "$@"

script/fmt-check

@@ -0,0 +1,28 @@
+#!/bin/sh
+# script/fmt-check: check formatting (read-only). Same scope as
+# script/fmt, but fails instead of writing.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+# Regenerate mfer/mf.pb.go from mfer/mf.proto if it is missing or stale
+# (mirrors the old Makefile prerequisite; the generated file is
+# committed, so this is normally a no-op).
+ensure_pb() {
+    if [ ! -f mfer/mf.pb.go ] ||
+        [ -n "$(find mfer/mf.proto -newer mfer/mf.pb.go 2>/dev/null)" ]; then
+        (cd mfer && go generate .)
+    fi
+}
+
+main() {
+    cd "$ROOT"
+    ensure_pb
+    if [ -n "$(gofmt -l .)" ]; then
+        echo "gofmt: files need formatting:" >&2
+        gofmt -l . >&2
+        exit 1
+    fi
+}
+
+main "$@"

script/install-precommit

@@ -0,0 +1,17 @@
+#!/bin/sh
+# script/install-precommit: install the git pre-commit hook that runs
+# script/precommit. Our own extension to scripts-to-rule-them-all.
+# Generic: needs no adaptation.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    hook=".git/hooks/pre-commit"
+    printf '#!/bin/sh\nset -e\nscript/precommit\n' > .git/hooks/pre-commit
+    chmod +x .git/hooks/pre-commit
+    echo "pre-commit hook installed: runs script/precommit"
+}
+
+main "$@"

script/lint

@@ -0,0 +1,17 @@
+#!/bin/sh
+# script/lint: run the linter.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    golangci-lint run
+    if [ -n "$(gofmt -l .)" ]; then
+        echo "gofmt: files need formatting:" >&2
+        gofmt -l . >&2
+        exit 1
+    fi
+}
+
+main "$@"

script/precommit

@@ -0,0 +1,20 @@
+#!/bin/sh
+# script/precommit: run by the git pre-commit hook; fails the commit if
+# checks fail. Our own extension to scripts-to-rule-them-all. Go repo
+# extras run first: go mod tidy and go fmt, failing the commit if they
+# change go.mod or go.sum.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
+
+main() {
+    cd "$ROOT"
+    go mod tidy
+    go fmt ./...
+    git diff --exit-code -- go.mod go.sum ||
+        { echo "go mod tidy changed files; stage and retry" >&2; exit 1; }
+    "$SCRIPT_DIR/check"
+}
+
+main "$@"

script/projectname

@@ -0,0 +1,12 @@
+#!/bin/sh
+# script/projectname: output the name of this project. Our own
+# extension to scripts-to-rule-them-all. Other scripts that need the
+# name (e.g. script/docker) call this, so they can stay identical
+# across all repos.
+set -eu
+
+main() {
+    echo "mfer"
+}
+
+main "$@"

script/setup

@@ -0,0 +1,14 @@
+#!/bin/sh
+# script/setup: set up the repo for development after a fresh clone:
+# installs dependencies (script/bootstrap) and the git pre-commit hook.
+# Add any repo-specific initialization (db init, .env template) here.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+
+main() {
+    "$SCRIPT_DIR/bootstrap"
+    "$SCRIPT_DIR/install-precommit"
+}
+
+main "$@"

script/test

@@ -0,0 +1,23 @@
+#!/bin/sh
+# script/test: run the test suite.
+set -eu
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
+
+# Regenerate mfer/mf.pb.go from mfer/mf.proto if it is missing or stale
+# (mirrors the old Makefile prerequisite; the generated file is
+# committed, so this is normally a no-op).
+ensure_pb() {
+    if [ ! -f mfer/mf.pb.go ] ||
+        [ -n "$(find mfer/mf.proto -newer mfer/mf.pb.go 2>/dev/null)" ]; then
+        (cd mfer && go generate .)
+    fi
+}
+
+main() {
+    cd "$ROOT"
+    ensure_pb
+    go test -v --timeout 10s ./...
+}
+
+main "$@"