netwatch/TODO.md

# Workflow

- branch from `next`
- 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)
- push the branch and open a PR against `next`

# Status

pre-1.0. Release candidates are tagged on `next`, the first being `v1.0.0-rc1`;
`git tag --merged origin/next` lists them. `main` is the stable branch and
`next` the development branch, which every PR targets. The frontend and the Go
backend ship as one Docker image. The Gitea workflow
`.gitea/workflows/check.yml` runs `script/cibuild` on every push, and cancels
the older run on the same branch. Working toward 1.0.0.

# Next Step

Run `make frontend-viewport-test` in CI as its own step; it is not part of
`make check`, as it needs Docker and takes minutes.

# Completed Steps

- 2026-10-26: `README.md`, `TODO.md` and `test/viewport/README.md` are rewritten
  sentence by sentence ([#189](https://git.eeqj.de/sneak/netwatch/issues/189)).
  Each sentence reads on the first pass: one idea, under about 30 words, the
  verb early. Every statement matches the code on `next`.
- 2026-10-26: a target whose home page answers with a redirect is checked at
  `/robots.txt` on the same host, which answers without one
  ([#194](https://git.eeqj.de/sneak/netwatch/issues/194)). These are the AWS
  Console, Akamai, B2 and the 8 S3 regions. The browser followed each redirect,
  so their figures also timed the page it led to. The Google Cloud Console is
  checked at `/robots.txt` too, as its home page redirects `curl`'s requests.
  The S3 regions are checked with a HEAD request, as Chrome closes their
  connection after most GET requests. `README.md` says what a figure includes.
- 2026-10-26: the six Hetzner targets answer wherever the page is served from
  ([#191](https://git.eeqj.de/sneak/netwatch/issues/191)). They close the
  connection without an answer when the request has a `Referer` header. The
  browser sent one unless the page came with the image's
  `Referrer-Policy: no-referrer` header, which a static host and `make dev` do
  not send. Each check now sets `referrerPolicy: 'no-referrer'`.
- 2026-10-19: the server's `OnStart` hook in `internal/server/server.go` starts
  `listenAndServe` in an anonymous function, as the Go style guide asks
  ([#162](https://git.eeqj.de/sneak/netwatch/issues/162)). It was
  `go s.listenAndServe()`. Nothing the server does changed.
- 2026-10-19: `.gitignore`, `.editorconfig` and `.golangci.yml` are the
  sneak/prompts copies at `0653579`
  ([#174](https://git.eeqj.de/sneak/netwatch/issues/174)). `.gitignore` is the
  standard file followed by this repository's own entries. `.editorconfig` is
  the standard file alone, which carries the `[*.go]` section. `.golangci.yml`
  disables `canonicalheader`, as the canonical copy does: golangci-lint v2.14.0
  misses its findings at random.
- 2026-10-19: `package.json` has no `version` field and is marked
  `"private": true` ([#158](https://git.eeqj.de/sneak/netwatch/issues/158)). It
  said `1.0.0`, a release that has not been made, and nothing read it. The git
  tag is the one version; the image and `make build` take it from
  `git describe --tags`. The package is never published.
- 2026-10-19: Status names `v1.0.0-rc1`, the first release candidate, and says
  release candidates are tagged on `next`
  ([#157](https://git.eeqj.de/sneak/netwatch/issues/157)). It said there were no
  git tags.
- 2026-10-19: `netwatch-server` starts the server only when given no arguments
  ([#179](https://git.eeqj.de/sneak/netwatch/issues/179)). `check-cidr CIDR` and
  `prepare-data-dir DATA_DIR` behave as before. Any other arguments print a
  one-line usage message naming both forms to stderr and exit 2; they used to
  start the server. Unit tests cover each case.
- 2026-10-19: `main()` in `cmd/netwatch-server/main.go` is one call into the new
  package `internal/cli`, as the Go style guide asks
  ([#160](https://git.eeqj.de/sneak/netwatch/issues/160)). `internal/cli` runs
  the `check-cidr` and `prepare-data-dir` subcommands, with the same arguments,
  messages and exit codes, and otherwise the server with the `fx` wiring.
  `Appname` and `Version` stay in `main`, where the build sets `Version`. `main`
  gives `cli.Main` stderr and the function that runs the server; the tests
  replace both. Unit tests give each subcommand input it takes and input it
  refuses.
- 2026-10-19: when `VERSION` is unset or empty, `script/build` stamps the
  version from `git describe --tags --always --dirty`, as `script/docker` does
  ([#156](https://git.eeqj.de/sneak/netwatch/issues/156)). Without `--tags` it
  skipped lightweight tags, so `make run` could report a commit where the image
  built from the same tree reported the tag.
- 2026-10-19: `.dockerignore` keeps Go test binaries and coverage output at the
  root out of the build context, with `/*.test` and `/*.out` in the repository's
  own section ([#155](https://git.eeqj.de/sneak/netwatch/issues/155)). Such
  files were copied into the lint, test and build stages. The entries match only
  at the root, so the same files in a subdirectory still reach the image.
- 2026-10-19: `.gitea/workflows/check.yml` is the sneak/prompts copy at
  `0653579` ([#153](https://git.eeqj.de/sneak/netwatch/issues/153)). Its
  checkout step sets `fetch-depth: 0`, so CI clones all history and tags. The
  image built from a tagged commit then gets the tag as its version; it got the
  short commit. The step also sets `persist-credentials: false`, so the job's
  token is not left in `.git/config`. A new push cancels the older run on the
  same branch, and a run stops after 20 minutes.
- 2026-10-19: `script/bootstrap` keeps the `yarn` on `PATH` only when
  `yarn --version` is exactly `YARN_VERSION`; otherwise it installs that version
  ([#154](https://git.eeqj.de/sneak/netwatch/issues/154)). Any yarn used to be
  kept. It uses the `node` on `PATH` only when that node has the major version
  of `NODE_VERSION` and is at least `NODE_MIN_VERSION`; a node 24 was kept
  before. After installing node or yarn it looks the tool up through `PATH`
  again and stops if that one fails the same check, as it does for Go. It prints
  the node and yarn versions it uses. Every script that runs yarn on the host,
  except `script/bootstrap`, runs it through the new `script/yarn`. That script
  puts `~/.local/bin` first on `PATH`. It uses the first `node` there when it
  passes the same test, and otherwise runs yarn under the pinned node in nvm.
  `make build` ran yarn under whatever node was first on `PATH`.
- 2026-10-19: `bin/entrypoint.sh` has each step in a function, and a `main` at
  the end calls them in order, as the code style guide's shell section asks
  ([#163](https://git.eeqj.de/sneak/netwatch/issues/163)). It is still POSIX sh
  with no `set -e`, and does what it did, with the same messages and exit codes.
- 2026-10-19: while report files cannot be written, the health check answers 503
  with `"status":"error"` and the same fields, so the image's `HEALTHCHECK`
  reports the container `unhealthy`
  ([#142](https://git.eeqj.de/sneak/netwatch/issues/142)). It answered 200
  whatever happened, so the platform saw a healthy container while every report
  was refused with 500. It answers 200 at start, before any write has failed,
  and again from the first write that succeeds.
- 2026-10-19: report file writes no longer overlap
  ([#150](https://git.eeqj.de/sneak/netwatch/issues/150)), so the reports of
  failed writes are written in the order they arrived. Two writes that failed at
  the same time put their reports back in the wrong order when the older failed
  first. One write runs at a time. Each takes the waiting reports only when it
  starts, after a failed write has put its own back. The write that `Append`
  starts at 10 MiB waits for any write under way, and `Append` starts no other
  while it waits. Files written since the start are deleted to make room in the
  order they were written, after those found at start.
- 2026-10-19: `DEBUG` unset or empty leaves debug logging off, and any other
  value, `false` and `0` included, turns it on, as the code style guide says
  ([#159](https://git.eeqj.de/sneak/netwatch/issues/159)). No value of it stops
  the start any more. Before, only `1`, `t`, `T`, `TRUE`, `true`, `True`, `0`,
  `f`, `F`, `FALSE`, `false` and `False` were accepted. `README.md` no longer
  gives `false` as its default.
- 2026-10-19: check builds keep Go's modules and compiled packages between runs
  ([#118](https://git.eeqj.de/sneak/netwatch/issues/118)), on sneak's rulings in
  [prompts#113](https://git.eeqj.de/sneak/prompts/issues/113) and
  [prompts#130](https://git.eeqj.de/sneak/prompts/issues/130).
  `REPO_POLICIES.md`, `script/test`, `script/lint`, `script/docker` and
  `script/cibuild` are the sneak/prompts copies at `0653579`. The scripts pass a
  new `CACHEBUST` value where they passed `--no-cache`, and the lint and test
  builds write no image. In each stage of `Dockerfile`, `ARG CACHEBUST` comes
  after the system packages and the Go module download. Every step that lints,
  tests or compiles comes after it, as does the node stages' `yarn install`.
  Go's build cache and golangci-lint's are cache mounts, and both `go test` runs
  carry `-count=1`. The test phase's Go caches used to be in memory, empty on
  every build.
- 2026-10-19: the three unit tests of a discarded check also check that the
  host's history is still empty, its status still `pending`, and the console
  untouched ([#151](https://git.eeqj.de/sneak/netwatch/issues/151)). The
  discarded cases are a round given up, a pause, and the first round. The tests
  checked only the row. So a change that recorded the result and skipped only
  the row would have kept them passing.
- 2026-10-18: run on its own, the backend stops at start when `DATA_DIR` cannot
  be created or read, or when no file can be created in it
  ([#148](https://git.eeqj.de/sneak/netwatch/issues/148)). The error names
  `DATA_DIR` and its value. The first two cases named only the path, and the
  third was found only at the first write of a report file. At start the server
  creates a file in `DATA_DIR` and removes it. The report file number is an
  `atomic.Int64`, as the Go style guide asks for int types
  ([#161](https://git.eeqj.de/sneak/netwatch/issues/161)); file names are
  unchanged.
- 2026-10-18: the image's nginx sends the page with `Cache-Control: no-cache`
  ([#141](https://git.eeqj.de/sneak/netwatch/issues/141)), so a browser that
  keeps a copy checks with the server that it is current before using it again.
  The page went out with no `Cache-Control`. So a browser could keep it after a
  deploy, ask for files under `/assets/` that the new build no longer has, and
  show an empty page. A path that `location /` answers with the page through its
  `try_files` fallback gets the same header. `location /` includes the security
  headers again, as `/assets/` does, since its own `add_header` drops the
  server's. `/assets/` keeps its immutable caching.
  `make frontend-viewport-test` fails unless `/` and a path that falls back to
  the page carry `Cache-Control: no-cache` and `Content-Security-Policy`.
- 2026-10-18: `README.md` says what the page loses while reports are refused or
  the page is paused ([#145](https://git.eeqj.de/sneak/netwatch/issues/145)). It
  says how fast one address can replace the stored reports
  ([#146](https://git.eeqj.de/sneak/netwatch/issues/146)). It says that in the
  image nginx answers a body over 1 MiB itself
  ([#147](https://git.eeqj.de/sneak/netwatch/issues/147)). nginx's
  `client_max_body_size` is 1 MiB by default, so in the image it answers a
  larger body with 413 and its own HTML page, and the backend never sees it. The
  reporter, the body limit and nginx are unchanged.
- 2026-10-18: a browser that cannot format the header's clocks still probes
  ([#149](https://git.eeqj.de/sneak/netwatch/issues/149)). The clocks name the
  local time zone through `Intl.DateTimeFormat`'s `shortGeneric` option, which
  Chrome before 95, Firefox before 91 and Safari before 15.4 reject with an
  error. It came before the first round started, so such a browser never checked
  a target. The clocks now start last, after the rounds, and an error formatting
  them leaves both blank. The footer's color legend reads `>=500ms` for red,
  where it read `>500ms`
  ([#152](https://git.eeqj.de/sneak/netwatch/issues/152)).
- 2026-10-18: `netwatch-server prepare-data-dir` no longer changes the owner of
  a file outside `/data` through a hard link in the volume
  ([#143](https://git.eeqj.de/sneak/netwatch/issues/143)). A file with a second
  name (hard link) keeps its owner, and the start logs its path. Owners are set
  on the opened directory, file or link, never by name, so a hard link swapped
  in after the check is caught too. A symbolic link is opened without following
  it, and the link itself is given to the netwatch user. So the server can still
  follow one in a sticky directory that anyone can write to. Devices, named
  pipes and sockets keep their owner. Setting the owner on an open file that is
  not a directory is built only for Linux. `prepare-data-dir` runs only in the
  Linux image, and macOS has neither `O_PATH` nor `AT_EMPTY_PATH`. On any other
  system the package still builds, and `prepare-data-dir` fails at the first
  file that is not a directory.
- 2026-10-18: from a trusted proxy, the backend takes the client address from
  the right-most `X-Forwarded-For` entry that is not in `TRUSTED_PROXIES`
  ([#144](https://git.eeqj.de/sneak/netwatch/issues/144)). It took the left-most
  entry, which the client writes itself behind a proxy that appends to the
  header. So a client could choose the address the rate limit counts and the
  request log records. An entry written as an address with a port is read as
  that address. The direct peer is used when the header holds only trusted
  addresses, or when the search meets an entry that is not an address at all,
  such as `unknown`. `X-Real-IP` is read only without `X-Forwarded-For`, and
  every `X-Forwarded-For` header line is read, not only the first. The image's
  nginx, and the `TRUSTED_PROXIES=127.0.0.1/32` it starts the backend with, are
  unchanged.
- 2026-10-18: after an interval change, the summary's Reachable slot reads
  `--/--` in white, as at page load, until the second round since the change
  ends ([#140](https://git.eeqj.de/sneak/netwatch/issues/140)). It read 0/26 in
  red from the change on, as no WAN host had a check recorded, for up to two
  intervals with the network fine.
- 2026-10-14: stopping the server waits for a report file write already under
  way, then runs the final flush
  ([#122](https://git.eeqj.de/sneak/netwatch/issues/122)). Such a write is the
  periodic flush's, or the one `Append` starts when 10 MiB are waiting. It used
  to return at once, and the process exiting cut the write off, losing its
  reports. A write under way that fails puts its reports back in memory, so the
  final flush writes them. The stop fails, and the process exits non-zero, only
  if that flush fails too.
- 2026-10-14: `make test` no longer runs the frontend's production build, which
  the tests do not need ([#118](https://git.eeqj.de/sneak/netwatch/issues/118)).
  `yarn build` moved out of the stage that runs the frontend's unit tests, now
  named `frontend-test`, into a new `frontend-build` stage. That stage starts
  from `frontend-test` and, like the `builder` stage, waits on the lint and test
  phases, so the image still cannot be built unless they pass. The runtime stage
  copies `dist/` from it, and the `git` that `vite.config.js` reads the commit
  with is installed there. No build cache was added.
- 2026-10-14: opening the debug log no longer raises the measured latencies
  ([#131](https://git.eeqj.de/sneak/netwatch/issues/131)). With the panel open,
  each line written drew the panel again with every line before it, up to 1000.
  A check that ends while the page draws is timed only when the drawing is done.
  Each line is now added at the end of the open panel, and its first line is
  dropped once it holds more than 1000. It scrolls to its newest line once a
  frame rather than once a line. The whole panel is drawn only when it is
  opened.
- 2026-10-14: unset, the backend's own `TRUSTED_PROXIES` trusts `10.0.0.0/8`,
  `172.16.0.0/12` and `192.168.0.0/16`, and no longer loopback
  ([#129](https://git.eeqj.de/sneak/netwatch/issues/129)). A list replaces that.
  Set and empty, it trusts no proxy; it used to get the default, as viper reads
  an empty environment variable as unset. A value it cannot parse still stops
  the start, and the image still starts the backend with
  `TRUSTED_PROXIES=127.0.0.1/32`.
- 2026-10-14: while report files cannot be written, `POST /api/v1/reports`
  answers 500, and storing recovers once writing works again, with no restart
  ([#123](https://git.eeqj.de/sneak/netwatch/issues/123)). A failed write puts
  its reports back in the report buffer, still counted against
  `DATA_DIR_MAX_BYTES`, where they used to be lost. The next flush, within a
  minute, tries them again. Until a write succeeds, every report is refused and
  nothing of it is kept, so the buffer does not grow while writes fail.
- 2026-10-14: a request whose handler panics is logged with status 500 and
  counted with `code` 500 in the metrics, not 200
  ([#125](https://git.eeqj.de/sneak/netwatch/issues/125)). `Recoverer` is still
  the first middleware. `Write500OnPanic` sits after the request log and after
  the metrics. It writes the 500 as the panic passes and lets the panic go on to
  Sentry and `Recoverer`. `Recoverer` now writes a 500 only when no status was
  written.
- 2026-10-14: with `TRUSTED_PROXIES` unset, the container's nginx trusts the
  three private ranges of RFC 1918, `10.0.0.0/8`, `172.16.0.0/12` and
  `192.168.0.0/16` ([#119](https://git.eeqj.de/sneak/netwatch/issues/119)), as
  sneak ruled on 2026-09-22 for every app. It trusted no proxy before. A list
  replaces them, and set and empty it trusts none. The backend inside the
  container still trusts only `127.0.0.1/32`.
- 2026-10-14: `POST /api/v1/reports` takes only a report sent with
  `Content-Type: application/json`, parameters such as `charset` allowed
  ([#126](https://git.eeqj.de/sneak/netwatch/issues/126)). It refuses any other
  with 415 and the usual error body, storing nothing. A page on another origin
  can send a `text/plain` POST without a CORS preflight, so any site could make
  its visitors' browsers store reports. A JSON POST waits for the preflight,
  which only an origin in `CORS_ALLOWED_ORIGINS` passes. The page already sent
  `application/json`.
- 2026-10-14: changing the interval no longer drops the samples not yet reported
  to the backend ([#124](https://git.eeqj.de/sneak/netwatch/issues/124)). The
  interval menu resets each host with the new `HostState.reset`, which moves the
  history's entries to `clearedHistory`, keeping the last 100 of all it has
  cleared. `buildReport` reads both, so the next report has the samples recorded
  before the change that no report has delivered. Until its next check, such a
  host is sent with the status of its last check, not `pending`. The page's
  history still starts over. `web/src/main.js` exports `Reporter` for the tests.
- 2026-10-14: the repo has the layout `REPO_POLICIES.md` gives
  ([#30](https://git.eeqj.de/sneak/netwatch/issues/30)). The Go module is at the
  root (`go.mod`, `go.sum`, `.golangci.yml`, `cmd/netwatch-server/`,
  `internal/`), so its path `sneak.berlin/go/netwatch` names the repository.
  `go.mod` ignores `node_modules/`, where npm packages can ship `.go` files that
  `make tidy` would otherwise read as this module's packages. The page's source
  is in `web/` (`index.html`, `src/`), which `vite.config.js` makes Vite's root;
  the build still goes to `dist/`. `nginx.conf` and `security-headers.conf` are
  in `configs/`. `backend/` is gone. Its `LICENSE` and `.dockerignore` are
  deleted, its `.gitignore` entries are in the root one, and its `README.md` is
  folded into the root `README.md`. Its scripts are in the root `script/`:
  `script/build` builds the server binary after the frontend, and `script/run`
  and `script/clean` came from `backend/script/`. `make test`, `make lint`,
  `make fmt` and `make fmt-check` do what its `test`, `lint`, `fmt` and
  `fmt-check` did. `script/bootstrap` no longer installs gcc, which only the
  host Go tests needed. The image and the page are unchanged.
- 2026-10-07: the files shared from `sneak/prompts` were its copies at commit
  `dd4027b` ([#113](https://git.eeqj.de/sneak/netwatch/issues/113)), with this
  repository's own entries after the shared content in `.gitignore`,
  `.dockerignore` and `.editorconfig`. `make lint` and `make test` each built
  one phase of `Dockerfile` without the cache. `lint` ran golangci-lint v2.14.0
  over `backend/` and, through the `frontend-lint` stage, eslint. `test` ran the
  Go tests on the Debian Go image and, through the `frontend` stage, the
  frontend's unit tests and build. The builder stage waits on both. Without a
  `VERSION` build argument it takes the version from `git describe` on the
  `.git` in the build context. Neither linter nor the tests run on the host for
  `make check`. `backend/.golangci.yml` was no longer checked against a sha256.
  prettier formats only the JavaScript, CSS, HTML and Markdown, so the shared
  `.golangci.yml` stays as fetched. `script/fmt` and `script/fmt-check` put
  `~/.local/bin` on `PATH`. `script/frontend-lint` and `script/frontend-check`
  are gone.
- 2026-10-07: the six Hetzner targets answer again, and failed checks are
  written to the browser console
  ([#114](https://git.eeqj.de/sneak/netwatch/issues/114)). The Hetzner
  speed-test servers close the connection without an answer when the URL has a
  query string, and every check added `?_cb=` and the time. Checks now fetch
  each target's URL as written, with `cache: 'no-store'` as before. Each
  recorded check that fails writes one `console.error` line, and the same line
  to the debug log. The line gives the target's name and URL, the time, what
  failed and how long the request took. A target that answers after failed
  checks writes one `console.info` line. Checks the page does not record write
  none, so the debug log no longer lists failures in the first round or in the
  recovery probe.
- 2026-10-04: the page's footer no longer says "IPv4 only"
  ([#111](https://git.eeqj.de/sneak/netwatch/issues/111)). Each check is a
  `fetch`, the browser picks IPv4 or IPv6 for each WAN host, and the local
  targets are IPv4 addresses.
- 2026-10-04: `README.md`, `TODO.md` and `test/viewport/README.md` say what the
  tree does ([#24](https://git.eeqj.de/sneak/netwatch/issues/24)). The README's
  Getting Started leads with `make` targets. A new Backend section says what
  `netwatch-server` stores, its routes and how the image builds and runs it; it
  pointed to `backend/README.md` for its settings. The checks are GET requests.
  The 26 WAN hosts, the four health states, the summary's figures and the
  features the list lacked are described as the page has them. The README's TODO
  section points here. This file's Workflow branches from `next` and opens the
  PR against `next`. Status says where the repo stands, and Next Step and Future
  Steps hold only open work, linked to its issue where one exists. The viewport
  test's README names Node's test runner, not `vitest`.
- 2026-10-04: in `src/main.js`, a target's min, max, median and average latency
  come from one list of its answers
  ([#102](https://git.eeqj.de/sneak/netwatch/issues/102)). The summary's figures
  use the same function, so the median is written once. The latency color limits
  are one table in `CONFIG`, read by both the figure's and the sparkline's
  color. The health thresholds, the debug log's length and the gateway check's
  timeout are `CONFIG` entries too. So are the recovery probe's host count and
  interval, how often the rows are sorted, and the delay before the first
  sparkline resize. Nothing the page does or shows changed; the footer's color
  legend still writes the limits out as text.
- 2026-10-04: password guesses at `/metrics` are rate limited
  ([#104](https://git.eeqj.de/sneak/netwatch/issues/104)). Each client address,
  resolved through `TRUSTED_PROXIES` as for reports, may make 60 requests to
  `/metrics` a minute, counted by `go-chi/httprate` apart from its reports. Past
  that it gets 429 and its basic auth credentials are not checked. The limit is
  a constant in `internal/server/routes.go`.
- 2026-10-04: the backend reports errors to Sentry
  ([#95](https://git.eeqj.de/sneak/netwatch/issues/95)). With `SENTRY_DSN` set,
  it sets up `sentry-go` with the release `netwatch-server-` and its version. It
  reports each panic in a handler through `sentryhttp`, the last middleware
  every request goes through. `sentryhttp` panics again, so the request still
  gets the 500 from the panic recovery. On shutdown it waits up to 2 seconds for
  Sentry to finish sending. A DSN Sentry refuses stops the start with an error
  naming `SENTRY_DSN`. With it empty, Sentry is not set up and nothing is sent
  to it.
- 2026-10-04: a target's name and URL and a debug log message show as the
  characters they are and are never read as HTML
  ([#29](https://git.eeqj.de/sneak/netwatch/issues/29)). A host row escapes the
  name and URL it writes into its markup, and the debug log sets each line as
  text. `README.md` no longer calls `CONFIG` frozen: the interval menu sets its
  `updateInterval`, and the values computed from it follow. `AppState` declares
  the recovery probe's two properties. The sparkline axis functions lose the
  parameters they did not use, and the comment on a target's history names both
  kinds of entry it holds.
- 2026-10-04: a dependency can be added without running yarn or go by hand
  ([#45](https://git.eeqj.de/sneak/netwatch/issues/45)).
  `make add-dependency PACKAGE=<name>@<version>` shims to the new
  `script/add-dependency`, which runs `yarn add --dev`, so `package.json` and
  `yarn.lock` change together, then `yarn install --frozen-lockfile`. The same
  command moves a package to another version. `make tidy` shims to the new
  `script/tidy`, which runs `go mod tidy`. A Go module is added by importing it,
  or moved by editing its `require` line, then `make tidy`. `script/bootstrap`
  still installs with `--frozen-lockfile`.
- 2026-10-04: the backend serves Prometheus metrics
  ([#94](https://git.eeqj.de/sneak/netwatch/issues/94)). With `METRICS_USERNAME`
  and `METRICS_PASSWORD` both set, it records request duration and response size
  through `go-http-metrics`. It serves them, with Go's runtime and process
  metrics, at `GET /metrics` behind basic auth with those credentials. nginx
  passes `/metrics` to it as it does `/api/`. With neither set there are no
  metrics and `/metrics` is 404. One without the other stops the start with an
  error naming both, and so does a `METRICS_USERNAME` containing `:`. Only
  requests that reach the health check or `POST /api/v1/reports` are recorded,
  not `/metrics` itself and not every request as `GO_HTTP_SERVER_CONVENTIONS.md`
  shows. The labels are the request's path and method, which clients can make up
  without end. For that, `POST /api/v1/reports` is registered by its full path
  instead of inside a `/api/v1` route group.
- 2026-10-04: `script/` and `Makefile` follow the org models
  ([#28](https://git.eeqj.de/sneak/netwatch/issues/28)). `make dev` shims to the
  new `script/dev`, the Vite dev server, and the new `make build` to
  `script/build`, the frontend production build. `.prettierignore` no longer
  left out `backend/`, so `make fmt` and `make fmt-check` covered
  `backend/README.md`; it left out `backend/.golangci.yml` by name.
  `script/install-precommit` and the date on `script/bootstrap`'s pins are the
  org model again. `script/bootstrap`, `script/fmt` and `script/fmt-check` each
  say in a comment why they differ from it.
- 2026-10-04: a frontend build on Node 26 or newer no longer prints Node's
  warning that `module.register()` is deprecated
  ([#32](https://git.eeqj.de/sneak/netwatch/issues/32)). The build in
  `Dockerfile` runs on Node 22, which never printed it. The call was in
  `@tailwindcss/node`, which `@tailwindcss/vite` brings in at its own exact
  version. tailwind 4.3.1 calls `module.registerHooks()` instead where Node has
  it. `yarn.lock` has `@tailwindcss/vite` and `tailwindcss` at 4.3.3, inside the
  ranges `package.json` already allowed, and tailwind's own dependencies moved
  with them. The built CSS changed only in how it is written out, in tailwind's
  Firefox focus-ring rule, and in tailwind's default sans-serif font list, which
  the page does not use.
- 2026-10-03: the frontend's unit tests cover what the page computes
  ([#21](https://git.eeqj.de/sneak/netwatch/issues/21)). They cover
  `humanDuration`, and the latency colours of a figure and of a sparkline either
  side of each boundary. They cover a target's min, max, average and median
  latency, and each of the four health states either side of its thresholds.
  `package.json` has a `test` script, so `yarn run test` and `npm run test` run
  them, and `script/frontend-test` runs it. `src/main.js` exports
  `humanDuration`, `HostState`, `latencyClass` and `latencyHex` for the tests;
  nothing it does changed.
- 2026-10-03: the backend's logs are one stream
  ([#27](https://git.eeqj.de/sneak/netwatch/issues/27)). fx logs its own steps
  of starting and stopping through the backend's logger. So off a terminal,
  every line the backend and fx write is JSON; fx used to write plain text to
  stderr. A config file that is found but cannot be read stops the start with
  its error, logged as JSON like a bad setting. It used to end in a Go panic.
  The backend logs its name, version and architecture once at start. The health
  check's uptime keys are `uptime_seconds` and `uptime_human`; its path, content
  type, `"status":"ok"` and 200 are unchanged. `SENTRY_DSN`, `METRICS_USERNAME`
  and `METRICS_PASSWORD` were still read and unused until
  [#94](https://git.eeqj.de/sneak/netwatch/issues/94) and
  [#95](https://git.eeqj.de/sneak/netwatch/issues/95) wired them up.
- 2026-10-03: the frontend has a real linter
  ([#47](https://git.eeqj.de/sneak/netwatch/issues/47), and item 2 of
  [#28](https://git.eeqj.de/sneak/netwatch/issues/28)): `eslint` with its
  recommended rules, set in `eslint.config.js`, runs in a new `frontend-lint`
  stage of `Dockerfile`. `script/lint` builds the lint stages and runs no linter
  on the host. `script/bootstrap` wants node 22.13.0 or newer, as eslint 10
  does.
- 2026-10-03: the tap-target check in `make frontend-viewport-test` expects one
  visible pin button per WAN host row
  ([#46](https://git.eeqj.de/sneak/netwatch/issues/46)), where it expected at
  least 10 of the 26. Pin buttons missing from only some rows now fail it. The
  host row count the test gathers, which the `app-rendered` check also reads,
  counts only the WAN host rows: the local host rows have no pin button.
- 2026-10-03: each target's row shows its result as soon as its check ends
  ([#91](https://git.eeqj.de/sneak/netwatch/issues/91)). Every row waited for
  the round's slowest check, up to 24 seconds at a 30-second interval. Every row
  is still redrawn, and sorting, the summary, the health box and offline
  detection still run, once, when the round's last check ends. So no row reads
  "paused" after a pause and resume during the round. A check that ends after
  the user pauses or after its round is given up shows nothing. The first round
  is still discarded as a whole.
- 2026-10-03: root no longer acts outside `/data` when it prepares `DATA_DIR`
  ([#80](https://git.eeqj.de/sneak/netwatch/issues/80)). `bin/entrypoint.sh`
  runs `netwatch-server prepare-data-dir`, which refuses a `DATA_DIR` that is
  not `/data` or a path below it written in full. Then it creates `DATA_DIR`,
  gives `/data` and everything in it to `netwatch` and sets the modes, all
  through a Go `os.Root` opened on `/data`. That refuses any path leading out of
  `/data`. So no symbolic link, already there or swapped in by a host process
  during the start, can make root create or change anything elsewhere.
  `DATA_DIR=/etc` no longer gives `/etc` to `netwatch`. The `README.md` section
  "Running under upaas" says which values are accepted.
- 2026-10-03: `DATA_DIR_MAX_BYTES` is how much of the report files is kept
  ([#54](https://git.eeqj.de/sneak/netwatch/issues/54)). When a report would
  take them past it, the oldest report files are deleted to make room, each
  deletion logged. At start, files already past it are deleted the same way. A
  file still being written is never deleted. A report is refused with 507 only
  when the reports waiting to be written fill the cap on their own, and then no
  file is deleted. A file that cannot be deleted still counts until the next
  start; one already deleted by hand counts as freed.
- 2026-10-03: `backend/script/lint` said what went wrong with its
  `.golangci.yml` check ([#34](https://git.eeqj.de/sneak/netwatch/issues/34)).
  On a hash mismatch it said to compare the file with the org standard. If they
  differed, restore the org standard. If they were the same, the org standard
  had changed, so update `GOLANGCI_CONFIG_SHA256` in that script. It used to say
  only to restore the file, which loops once the org standard itself has moved.
  A missing `.golangci.yml`, and a `sha256sum` that is missing or prints no
  hash, each got their own message instead of being reported as a mismatch.
- 2026-10-03: the Go tests run with the race detector and coverage
  ([#88](https://git.eeqj.de/sneak/netwatch/issues/88)):
  `go test -timeout 30s -race -cover ./...` and, if that fails, the same again
  with `-v`, then a failing exit. Go's `-timeout` bounds the tests, not their
  compile. The race detector needs a C compiler; the binary is still built with
  `CGO_ENABLED=0`. New tests cover the health check's answer, a valid report's
  answer, a report file's exact contents, and the flush when the buffer reaches
  10 MiB.
- 2026-10-03: each target check times out after 80% of the refresh interval
  ([#78](https://git.eeqj.de/sneak/netwatch/issues/78)), 24 seconds at 30
  seconds, where it was capped at 3 seconds. A round started early gives up the
  last round's checks if they are still waiting, so rounds never overlap. A
  round starts early after an interval change, or when the recovery probe finds
  a target answering. The recovery probe gives up its own checks after half a
  second. The frontend has its first unit tests, run by `script/frontend-test`
  with Node's built-in test runner. For them, `index.html` links
  `src/styles.css`, which `src/main.js` used to import.
- 2026-09-29: the container sets up its own data directory
  ([#75](https://git.eeqj.de/sneak/netwatch/issues/75)). `bin/entrypoint.sh`,
  still as root, created `DATA_DIR` if missing and gave it and `/data` to the
  `netwatch` user with mode 750 before starting the backend as that user. So an
  empty host directory owned by root, or one holding files from another uid,
  works with no step on the host. It stopped the start when a symbolic link was
  on the path to `DATA_DIR`, since root would change whatever the link points
  to. The `README.md` first-run step that created and chowned the host directory
  is gone, and the image no longer sets that ownership at build time.
- 2026-09-29: CI can no longer pass on checks that did not run
  ([#37](https://git.eeqj.de/sneak/netwatch/issues/37)). `script/cibuild` became
  the org model, byte for byte. It runs `script/bootstrap` and `script/check`,
  then builds the image with the version from `git describe` as the `VERSION`
  build argument. It used to be a plain `docker build .` whose check steps could
  come from the build cache. The workflow put `~/.local/bin`, where bootstrap
  links what it installs, on the step's `PATH`. bootstrap installs its pinned
  node when the installed one is older than the frontend's dependencies need.
- 2026-09-29: `backend/.golangci.yml` was re-vendored from `sneak/prompts`
  ([#41](https://git.eeqj.de/sneak/netwatch/issues/41)). `gomodguard`,
  deprecated in golangci-lint v2.12.0, is disabled and its successor
  `gomodguard_v2` enabled with the org block list, so lint runs print no
  deprecation warning. The file also turns `depguard` on with its `test-support`
  rule, which keeps `net/http/httptest` out of non-test code; netwatch adds no
  entries of its own to that rule.
- 2026-09-29: nginx sends the security headers `REPO_POLICIES.md` requires on
  every response ([#18](https://git.eeqj.de/sneak/netwatch/issues/18)), errors
  and `/assets/` included. On what it passes on from the backend, it drops the
  backend's own copies, so each header goes out once. They live in
  `security-headers.conf`, which `nginx.conf` includes. The content security
  policy allows no inline script or style, so the status dot's grey in
  `src/main.js` is a class. `connect-src` is `*` because probed hosts redirect
  to others, and the browser checks each redirect against it.
- 2026-09-29: the request log is bounded
  ([#60](https://git.eeqj.de/sneak/netwatch/issues/60)). Each field it writes
  from the request is cut to 128 bytes, the bound the report handler already
  used. The fields are the method, URL, protocol, `User-Agent`, `Referer`,
  request ID and client address. chi takes the request ID from the client's
  `X-Request-Id` header. One request could put about 1 MiB per field into a log
  line. That bound and its helper live in the `logger` package, shared by both.
- 2026-09-29: nginx takes the client address from `X-Forwarded-For` only on
  requests from the reverse proxies named in the container's `TRUSTED_PROXIES`
  ([#64](https://git.eeqj.de/sneak/netwatch/issues/64)), and at the time by
  default from none. It trusted every RFC1918 address before, so a client could
  write a new address on each request and escape the rate limit.
  `bin/entrypoint.sh` writes one `set_real_ip_from` line per entry into
  `/etc/nginx/trusted-proxies.conf`, which `nginx.conf` includes. It refuses an
  entry that is not an IP address or CIDR, as `netwatch-server check-cidr`
  finds. It starts the backend with `TRUSTED_PROXIES=127.0.0.1/32`, since nginx
  is its only client.
- 2026-09-29: report file names can no longer collide
  ([#61](https://git.eeqj.de/sneak/netwatch/issues/61)). Each is
  `reports-<timestamp>-<number>.jsonl.zst`, where the number goes up by one for
  each file the server starts to write. So two flushes in the same millisecond
  each get a file of their own; the second one used to fail. A flush for size
  and the final flush at shutdown can fall in the same millisecond. A failed
  write uses up its number.
- 2026-09-29: ready to run under upaas
  ([#59](https://git.eeqj.de/sneak/netwatch/issues/59)). The image has a
  `HEALTHCHECK` that requests `/.well-known/healthcheck` through nginx on the
  port from `PORT`. The backend no longer reads a bad `PORT` as 0 or a bad
  `DEBUG` as false. Those, and a `BIND_ADDRESS` that is not an IP address, stop
  it from starting with an error naming the variable. The limits,
  `CORS_ALLOWED_ORIGINS` and, now by name, `TRUSTED_PROXIES` already did.
  `bin/entrypoint.sh` also refuses a `PORT` outside 1 to 65535, and `8081`,
  where the backend listens inside the container, naming `PORT`. `README.md` got
  a "Running under upaas" section.
- 2026-09-29: nginx listens on `PORT`
  ([#26](https://git.eeqj.de/sneak/netwatch/issues/26)), 8080 when unset or
  empty. The nginx image renders `nginx.conf` as a template at container start,
  filling in `PORT` and no other variable. `bin/entrypoint.sh` refuses to start
  when `PORT` is not digits only. `server_tokens off` keeps the nginx version
  out of responses. `script/frontend-viewport-test` renders the template the
  same way. Gzip and a `50x.html` error page are not added.
- 2026-09-29: the report endpoint is bounded
  ([#20](https://git.eeqj.de/sneak/netwatch/issues/20)). `POST /api/v1/reports`
  still needs no credentials. Each client address, as resolved through
  `TRUSTED_PROXIES`, may send `REPORTS_PER_MINUTE` (default 60) reports a
  minute, counted by `go-chi/httprate`, and past that gets 429 with
  `Retry-After`. The report files in `DATA_DIR`, counted from start with those
  already there, may total at most `DATA_DIR_MAX_BYTES` (default 1 GiB); past
  that, reports got 507. The wildcard CORS is gone: no CORS headers unless
  `CORS_ALLOWED_ORIGINS` lists origins. An entry that is not a plain
  `scheme://host[:port]` origin, `*` included, stops the server from starting.
  Deleting report files freed room only at the next start, until
  [#54](https://git.eeqj.de/sneak/netwatch/issues/54).
- 2026-09-28: one container image
  ([#52](https://git.eeqj.de/sneak/netwatch/issues/52)). The root `Dockerfile`
  builds the only image, and `Dockerfile.backend` is gone. nginx serves the
  frontend on port 8080 and proxies `/api/` and `/.well-known/healthcheck` to
  the backend, which listens on `127.0.0.1:8081` in the same container. The new
  `BIND_ADDRESS` setting sets its listen address. `bin/entrypoint.sh` starts
  both, passes TERM and INT on to both, and exits non-zero when either exits on
  its own. The backend runs as user `netwatch` and stores reports on the `/data`
  volume. `script/docker` is the org model again.
- 2026-09-28: one gate ([#16](https://git.eeqj.de/sneak/netwatch/issues/16)).
  The root `make check` covers the Go backend as well as the frontend, and the
  pre-commit hook with it. The backend moved onto scripts-to-rule-them-all:
  `backend/script/*`, `backend/Makefile` as shims, its duplicate hook installer
  removed. `script/cibuild` built both images and was the workflow's only build
  step. The root `make lint` ran golangci-lint only in Docker, by building the
  lint stage of `Dockerfile.backend` without the cache. `script/bootstrap`
  installed the pinned Go unless the installed one was at least what
  `backend/go.mod` asked for. It links what it installs into `~/.local/bin`
  without replacing anything it did not create, and installs no linter. When
  `VERSION` is unset or empty, the backend binary's version falls back to
  `git describe` inside a git checkout, then to `dev`.
- 2026-09-28: frontend reporting client
  ([#53](https://git.eeqj.de/sneak/netwatch/issues/53)). A `Reporter` class
  posts collected samples to `/api/v1/reports` every `reportInterval` (default
  60s) as a per-host delta. The report-building step is a pure exported function
  of host state. A per-host mark advances only on a delivered POST. At most one
  report POST is pending at a time, and it is abandoned after half the interval.
  So a slow POST never overlaps the next report, and a mark never moves
  backwards. The samples of an abandoned POST are sent again at the next
  interval, so a backend that stored them but answered late receives them twice.
  The per-browser client id works in insecure (plain-HTTP) contexts.
  `vite.config.js` proxies `/api` to the local backend for `yarn dev`.
- 2026-09-28: report ingest correctness
  ([#23](https://git.eeqj.de/sneak/netwatch/issues/23)). A storage failure
  returns 500 instead of a false `ok`. An oversize body returns 413, apart from
  malformed JSON, which stays 400. A `MaxBodyBytes` middleware caps every route,
  not just the report route. The raw attacker-controlled `geo` blob is no longer
  logged, only its length, and `client_id`, `timestamp` and decode error text
  are length-bounded before logging. A `decodeJSON` handler helper was added.
  Panic recovery routes the stack through slog instead of chi's plain-text
  stderr. Writing a report file returns its error, so a failed final flush on
  shutdown makes the process exit non-zero instead of losing the buffered
  reports silently.
- 2026-09-21: shutdown lifecycle correctness. The process shuts down through fx
  instead of `os.Exit`, so every component's `OnStop` runs and buffered reports
  are flushed to disk on `SIGTERM`. Before, a full flush window of telemetry was
  lost on every restart. The `http.Server` is built before its serving goroutine
  starts, so shutdown can no longer race or nil-deref it. A listen failure exits
  non-zero via `fx.Shutdowner`. `reportbuf`'s `OnStop` is idempotent.
  `writeTimeout` exceeds the chi per-request budget, so that budget is
  reachable. Dead `startupTime`, `exitCode` and `cancelFunc` fields were
  removed.
- 2026-09-21: backend HTTP hardening
  ([#19](https://git.eeqj.de/sneak/netwatch/issues/19)): `ReadHeaderTimeout` and
  `IdleTimeout` on the server, and a `SecurityHeaders` middleware (HSTS, tight
  CSP, frame, sniff, referrer and permissions headers) registered before CORS.
  `X-Forwarded-For` and `X-Real-IP` are honoured only from a `TRUSTED_PROXIES`
  allowlist, at the time loopback plus RFC1918 by default.
- 2026-08-10: adopted the org-standard `backend/.golangci.yml` verbatim and
  moved the pinned golangci-lint from v2.7.2 to v2.12.2; the `lint` stage of
  `Dockerfile.backend` pinned the `golangci/golangci-lint:v2.12.2` image by
  digest. The previous config declared `version: "2"` but used v1 schema keys,
  so every threshold in it was inert and its green result meant nothing.
  `backend/Makefile`'s `lint` target asserted the config's sha256 against the
  canonical file first, so drift from the org standard failed the build instead
  of silently degrading to defaults.
- 2026-08-10: every interactive control meets the 44x44 CSS px minimum tap
  target: `.pin-btn`, `#interval-select`, the debug-log label and, on narrow
  viewports, `#pause-btn`. The pin button's hit area grows via matching negative
  margins, so its layout footprint and row density are unchanged.
- 2026-08-10: the per-host status line wraps below the 768px breakpoint instead
  of forcing horizontal page scroll at 320px.
- 2026-08-09: `Dockerfile.backend` was reworked to the Go multistage lint-stage
  pattern. It got a separate `lint` stage on the hash-pinned
  `golangci/golangci-lint` image, and a `COPY --from=lint` stage dependency. The
  build became a `CGO_ENABLED=0` static build driven by `ARG VERSION`, with no
  more `COPY .git`.
- 2026-08-09: dotfile compliance. `backend/.editorconfig` moved to the repo root
  so `root = true` covers the frontend too. `.gitignore` became the org model
  (OS, editor, node, and environment/secrets sections) plus this repo's `dist/`
  and `*.log`. `.env`, `.env.*`, `*.pem` and `*.key` are ignored repo-wide, not
  just under `backend/`. Excluding `.git` from `.dockerignore` stayed deferred:
  both images read git metadata at build time.
- 2026-08-09: automated responsive-layout test (`make frontend-viewport-test`):
  a digest-pinned headless Chrome driven over CDP against the built `dist/`, at
  viewport widths derived from the breakpoints in `src/styles.css`
  ([#13](https://git.eeqj.de/sneak/netwatch/issues/13)). The tap-target and
  host-row checks each fail when they measured nothing. The overflow,
  viewport-edge and clipped-text checks have no such guard of their own and rely
  on the `app-rendered` check, which fails the run when the app did not render.
  It found two real layout defects, filed as
  [#42](https://git.eeqj.de/sneak/netwatch/issues/42) and
  [#43](https://git.eeqj.de/sneak/netwatch/issues/43).
- 2026-07-07: adopted scripts-to-rule-them-all: `script/` entrypoints, Makefile
  shims, README Entrypoints section.
- 2026-02-27: backend with buffered zstd-compressed report storage; CI workflow
  and backend repo standard files; backend Dockerfile fixed (Go 1.25,
  golangci-lint) and moved to repo root (`feat/reportbuf-storage`).
- 2026-02-26: host row layout redesigned with CSS grid; overflow and spacing
  fixes; nginx config extracted; port hardcoded to 8080.
- 2026-02-26: debug log panel, median stats, recovery probe, Docker build fix,
  S3 Singapore endpoint added.
- 2026-02-23: summary box redesign, host pinning, local and UTC clocks, checks
  counter.
- 2026-02-23: hosts sorted by latency; GET instead of HEAD for latency; timeout
  derived from interval; Hetzner regional endpoints; 3s interval.
- 2026-01-29: initial NetWatch network latency monitor.

# Future Steps

- A backend test that posts a report to `POST /api/v1/reports` and checks the
  compressed file it is written to
- A backend route that decompresses the stored reports and answers queries on
  them
- Prometheus metrics for the backend's in-memory buffer: its size, the number of
  flushes and the number of reports
- A configurable host list (an environment variable or a config file)
- Export of the latency history (CSV or JSON)
- A notification when the health status changes to DEGRADED