# CI

[.gitea/workflows/ci.yml](../.gitea/workflows/ci.yml) is the source of truth for
the job graph; this file records why it is shaped the way it is.

## Pipeline

- **`build`** (push to `main` / tag) — build + correctness + packaging.
- **`maintain`** (push to `main`, non-blocking) — `npm run maintain`; reports,
  never fails the build.
- **`publish`** (tag) — packaging checks + `publish:publint` / `publish:attw`,
  then the Gitea release page and `npm publish` (see
  [publishing.md](./publishing.md)).
- **`release-gate`** — on a `:rocket: Release x.y.z` commit it skips
  `build`/`maintain`, because `create:release` pushes the tag for the same commit
  right after and the tag run is authoritative. It uses no Node and stays on the
  default image.

## Runner image

#### Decision (2026-09)

`build` / `maintain` / `publish` run in `gitea.e1nsnull.de/tmu/act-ci:<version>`
([docker/Dockerfile](../docker/Dockerfile)): the default act image with Node
overlaid at the exact `/opt/hostedtoolcache` layout `actions/setup-node` probes.

#### Why

- No job pays the ~50 MB Node fetch, because the probe hits the baked entry.
- The tag must equal the exact [.node-version](../.node-version) pin, and the
  image is rebuilt only as part of a Node bump — there is no other trigger.
- Building needs a docker daemon and registry credentials, so it belongs to no
  feedback tier. That is why it is **not** an `npm run` script: no
  [prefix](./workflow.md#script-prefix-convention) fits, and that is the signal.

#### Rejected

- Downloading Node in every job — the ~50 MB fetch was the original problem.
- Gitea Pages / Codecov for coverage — neither was confirmed available or wanted
  (see [Coverage serving](#coverage-serving)).

## Bumping Node

Bumping Node is one coordinated change, committed as a unit:

1. Edit [.node-version](../.node-version) to the exact `x.y.z` — floats like `26`
   resolve to the latest patch at runtime and bust the baked entry, so
   [scripts/runner-image.sh](../scripts/runner-image.sh) refuses them.
2. `docker login gitea.e1nsnull.de` (user + package/access token), then
   `./scripts/runner-image.sh --push`, which reads the version and pushes
   `<IMAGE_REPO>:<version>`.
3. Repoint the three `container.image` tags in
   [.gitea/workflows/ci.yml](../.gitea/workflows/ci.yml) to that version.

Skipping step 2 fails CI at image pull; skipping step 3 silently reverts to the
per-job download.

## Image invariants

For the `setup-node` probe to hit, two things must hold — both easy to break:

### The `x64.complete` marker

#### Decision (2026-09)

Bake a `<version>/<arch>.complete` marker next to the Node directory.

#### Why

- `actions/tool-cache` accepts a cached tool only when
  `<version>/<arch>.complete` exists beside it (`tc.find()` checks). A bare
  `node/<version>/x64/` is ignored and the download happens anyway. See the
  comment in [docker/Dockerfile](../docker/Dockerfile).

### Tag freshness, with force-pull deliberately off

#### Decision (2026-09)

Leave `act_runner`'s `force_pull` disabled.

#### Why

- The tag encodes only the Node version, and the image is rebuilt only when that
  changes — so the normal flow always yields a new tag and the runner pulls it.
- Forcing a pull re-pulls the image on every job for no benefit.

#### Rejected

- Enabling `force_pull`: it is acceptable to miss a runner-side image change,
  and a `Dockerfile`-only change is not worth a per-job pull.

#### Known issue

- A `Dockerfile`-only change (like the marker above) re-pushed under an
  unchanged tag is invisible to the runner, which keeps the old image while the
  registry shows the new digest. Remove the stale tag on the runner host
  (`docker rmi gitea.e1nsnull.de/tmu/act-ci:<version>`); do not reach for
  force-pull.

## Coverage serving

#### Decision (2026-09)

Serve CI coverage from a shared directory on the runner, with no deploy step in
CI.

#### Why

- The webserver exposes the shared directory and the Gitea docker setup reuses
  the existing reverse proxy — no upload artifact, no external service.
- Coverage is written to a shared volume keyed by project and tag (for example
  `/docs/tiny-pattern-ts/<tag>/`).

#### Rejected

- Gitea Pages and Codecov: neither was confirmed available or wanted.

#### Known issue

- Coverage is served for tag pushes only; non-tag pushes (for example
  `main/coverage`) are tracked separately.

[scripts/precompress.ts](../scripts/precompress.ts) emits `.br` / `.gz` / `.zst`
sidecars next to text assets. The Gitea pages service (`static-web-server` with
`SERVER_COMPRESSION_STATIC=true`) serves the sidecar matching `Accept-Encoding`
and falls back to the original.

#### Decision (2026-09)

Precompress into sidecars rather than per request.

#### Why

- The assets are static and change only on deploy, so the work is paid once.
- Images, fonts and archives are already compressed; a sidecar would only grow
  them, so only text extensions are emitted.