🐛 Write the tool-cache completion marker into the image

setup-node still downloaded although the image carried a perfect
/opt/hostedtoolcache/node/26.8.2/x64/ tree. actions/tool-cache accepts a
cached tool only when the sibling marker <version>/<arch>.complete exists
(tc.find() tests it explicitly); a bare directory is ignored, so the probe
fell through to the download. The marker is what tc.cacheDir() writes after
installing a tool, so the baked entry must create it too.

Job-container diagnostics also confirmed the path was never in question:
RUNNER_TOOL_CACHE=/opt/hostedtoolcache, no mount over it, node -v from the
baked path prints v26.8.2.

CONTRIBUTING records both invariants — the marker, and the fact that a
Dockerfile change keeps the same tag, which forcePull=false can hide.

.gitea/workflows/ci.yml

@@ -49,15 +49,38 @@ jobs:
         needs: release-gate
         if: needs.release-gate.outputs.skip != 'true'
         runs-on: ubuntu-latest
-        # Bind-mount the shared pages tree so the coverage step below can write
+        # `image` extends the runner's default job image (catthehacker/act)
-        # into it. The runner whitelists this path via `container.valid_volumes`
+        # with Node 26 pre-planted in the tool cache layout, so setup-node's
-        # (docker-space `setup/gitea.sh`); `image` is omitted on purpose so the
+        # version probe hits and never downloads (see docker/Dockerfile). The
-        # runner keeps using its default job image.
+        # tag MUST equal the exact version pinned in `.node-version`; the bump
+        # ritual is documented in CONTRIBUTING.md § CI runner image. The volume
+        # bind-mounts the shared pages tree so the
+        # coverage step below can write into it; the runner whitelists this
+        # path via `container.valid_volumes` (docker-space `setup/gitea.sh`).
         container:
+            image: gitea.e1nsnull.de/tmu/act-ci:26.8.2
             volumes:
                 - /data/gitea-pages:/data/gitea-pages
         steps:
             - uses: actions/checkout@v4
+            # TEMPORARY (remove once understood): the image provably carries
+            # the tool-cache entry (verified with `docker run --rm <image> ls
+            # /opt/hostedtoolcache/node/26.8.2/x64/bin`), yet setup-node still
+            # downloads. Print what the job container actually sees at
+            # runtime, mounts first — a mount over /opt/hostedtoolcache would
+            # hide the baked directory from the probe.
+            - name: Tool cache diagnostics
+              run: |
+                  id
+                  grep -E 'hostedtoolcache|workspace|overlay' /proc/mounts || true
+                  ls -la /opt/hostedtoolcache || true
+                  ls -la /opt/hostedtoolcache/node || true
+                  ls -la "/opt/hostedtoolcache/node/$(tr -d '[:space:]' < .node-version)/" || true
+                  test -f "/opt/hostedtoolcache/node/$(tr -d '[:space:]' < .node-version)/x64.complete" && echo MARKER-PRESENT || echo MARKER-MISSING
+                  ls -la "/opt/hostedtoolcache/node/$(tr -d '[:space:]' < .node-version)/x64/bin" || true
+                  "/opt/hostedtoolcache/node/$(tr -d '[:space:]' < .node-version)/x64/bin/node" -v || true
+                  env | grep -iE 'RUNNER|TOOL|CACHE' || true
+                  head -2 /etc/os-release
             - uses: actions/setup-node@v4
               with:
                   node-version-file: .node-version
@@ -108,6 +131,10 @@ jobs:
         if: needs.release-gate.outputs.skip != 'true'
         runs-on: ubuntu-latest
         continue-on-error: true
+        # Same baked image as `build` — without it this job re-downloads Node
+        # per run (see docker/Dockerfile).
+        container:
+            image: gitea.e1nsnull.de/tmu/act-ci:26.8.2
         steps:
             - uses: actions/checkout@v4
             - uses: actions/setup-node@v4
@@ -121,6 +148,10 @@ jobs:
         if: startsWith(gitea.ref, 'refs/tags/')
         needs: build
         runs-on: ubuntu-latest
+        # Same baked image as `build` — setup-node still owns the registry-url
+        # `.npmrc` rewrite here; only the Node download is skipped.
+        container:
+            image: gitea.e1nsnull.de/tmu/act-ci:26.8.2
         # The release page is created with the run's automatic Gitea token
         # (`github.token`), not `NPM_TOKEN`, so it needs `contents: write`.
         permissions:
@@ -139,6 +170,10 @@ jobs:
             - uses: actions/setup-node@v4
               with:
                   node-version-file: .node-version
+                  # Same lockfile/key as `build`, and tag runs can read caches
+                  # saved on `main` — without this, every release pays a cold
+                  # `npm ci` despite the warm shared npm cache.
+                  cache: "npm"
                   registry-url: "https://registry.npmjs.org/"
             - run: npm ci
             # Consume the dist/ that `build` produced and gated, instead of

.node-version

@@ -1 +1 @@
-26
+26.8.2

CHANGELOG.md

@@ -7,9 +7,24 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.1.3] - 2026-09-14
+
+- change to custom image for CI
+
+## [0.1.2] - 2026-09-14
+
+- upgrade dependencies
+
+## [0.1.1] - 2026-09-14
+
+- upgrade dependencies
+
 ## [0.1.0] - 2026-09-14
 
 - basic setup
 
-[Unreleased]: https://gitea.e1nsnull.de/tmu/tiny-pattern-ts/compare/0.1.0...main
+[Unreleased]: https://gitea.e1nsnull.de/tmu/tiny-pattern-ts/compare/0.1.3...main
+[0.1.3]: https://gitea.e1nsnull.de/tmu/tiny-pattern-ts/compare/0.1.2...0.1.3
+[0.1.2]: https://gitea.e1nsnull.de/tmu/tiny-pattern-ts/compare/0.1.1...0.1.2
+[0.1.1]: https://gitea.e1nsnull.de/tmu/tiny-pattern-ts/compare/0.1.0...0.1.1
 [0.1.0]: https://gitea.e1nsnull.de/tmu/tiny-pattern-ts/compare/20308c5a6d8cccfb09b02ac2ebebd8055e91cd11...0.1.0

CONTRIBUTING.md

@@ -90,6 +90,23 @@ This is why every test in the suite pairs an `expectTypeOf(...)` with an `assert
 - CI runs `npm run check` + `npm run test:ci` on every push to `main` — this is the authoritative gate. The one exception: a push headed by a release commit (`:rocket: Release x.y.z`) skips the full `build`/`maintain` jobs, because `create:release` pushes the tag for that exact commit right after and the tag run is the authoritative one (see `release-gate` in [.gitea/workflows/ci.yml](./.gitea/workflows/ci.yml)).
 - **Releases are NOT triggered by pushes.** Only the maintainer triggers a release (see [Publishing workflow](#publishing-workflow)).
 
+## CI runner image
+
+The `build` / `maintain` / `publish` jobs run in `gitea.e1nsnull.de/tmu/act-ci:<version>` ([docker/Dockerfile](./docker/Dockerfile)) — the runner's default act image with the Node distribution overlaid at the exact `/opt/hostedtoolcache` layout `actions/setup-node` probes before downloading, so no job pays the ~50 MB fetch. The image tag MUST equal the exact version pinned in `.node-version`; `release-gate` uses no Node and stays on the default image. The script is deliberately NOT an `npm run` script: building requires a docker daemon and registry credentials, so it belongs to no feedback tier — per [Script prefix convention](#script-prefix-convention), no existing prefix fits and that is the signal.
+
+Bumping Node is one coordinated change, committed as a unit:
+
+1. Edit `.node-version` to the new exact `x.y.z` — floats like `26` resolve to the latest patch at runtime and silently bust the baked entry; `scripts/runner-image.sh` refuses them.
+2. `docker login gitea.e1nsnull.de` (user + package/access token), then `./scripts/runner-image.sh --push` — it reads the version from `.node-version` and builds/pushes `<IMAGE_REPO>:<version>`.
+3. Repoint the three `container.image` tags in [.gitea/workflows/ci.yml](./.gitea/workflows/ci.yml) to the same version.
+
+Skipping step 2 fails CI at image pull; skipping step 3 silently reverts to the per-job download.
+
+Two invariants the image must satisfy for the probe to hit, both easy to break:
+
+- **The `x64.complete` marker.** `actions/tool-cache` accepts a cached tool only when `<version>/<arch>.complete` exists next to the directory (`tc.find()` checks it); a plausible-looking `node/<version>/x64/` alone is ignored and the download happens anyway. See the comment in [docker/Dockerfile](./docker/Dockerfile).
+- **Tag freshness.** The tag encodes only the Node version, so a Dockerfile change (like the marker above) produces _new content under an unchanged tag_. `act_runner` skips the pull when a tag of that name already exists locally (`forcePull=false` in the job log), so the runner must either force-pull (`force_pull` under `container:` in its `config.yaml`, if the installed version has it) or have the tag removed on the runner host (`docker rmi gitea.e1nsnull.de/tmu/act-ci:<version>`) after any image change. Symptom of getting this wrong: CI keeps running the previous image while the registry shows the new digest.
+
 ## Publishing workflow
 
 Publishing is CI-only by policy. Local `npm publish` is not supported. The maintainer triggers releases from `main`:

backlog.tasks

@@ -35,7 +35,7 @@ Maintenance:
     ✔ Add a minimal dir-listing webserver to the gitea docker setup (e.g. caddy `file_server browse` reusing the existing reverse proxy, or any single-binary static server, lipanski/docker-static-website) @done (9/13/2026, 9:02:37 PM)
     ✔ drop the `actions/upload-artifact` coverage step in favour of the shared-dir layout @done (9/13/2026, 10:37:22 PM)
     ☐ Explore serving coverage for non-tag pushes (e.g. `main/coverage`, PR previews) @low
-    ☐ Manually verify the coverage was created on a real tag push (needs main) @low
+    ✔ Manually verify the coverage was created on a real tag push (needs main) @low @done (9/14/2026, 1:55:03 PM)
     → design: no deploy step in CI; the webserver just exposes the shared directory (decided over Gitea Pages / Codecov — neither confirmed available/ wanted)
 ☐ serve docs over self hosted server @low
     ☐ Add a minimal dir-listing webserver to the gitea docker setup for serving docs (reuse existing reverse proxy)
@@ -45,3 +45,7 @@ Maintenance:
     ☐ Add a minimal dir-listing webserver to the gitea docker setup for serving landing page (reuse existing reverse proxy)
     ☐ CI writes landing page to a shared volume keyed by project + tag (e.g. `/landing/tiny-pattern-ts/<tag>/`)
     ☐ Browse to `…/tiny-pattern-ts/index.html` in the browser
+☐ Stop Gitea CI re-downloading Node on every job (branch chore/fix-ci)
+    ✔ Share the warm npm cache with the publish job @done
+    ✔ Bake Node into the CI job image (docker/Dockerfile, container.image in ci.yml) @done
+    ☐ Build/push gitea.e1nsnull.de/tmu/act-ci:26.8.2 and confirm setup-node skips the download (first run on the branch = acceptance test) @high

cspell.json

@@ -27,6 +27,14 @@
         "knope",
         "runwisp",
         "glab",
+        "hostedtoolcache",
+        "nodebase",
+        "frontends",
+        "catthehacker",
+        "nsnull",
+        "dedup",
+        "dedupe",
+        "repoint",
         "postversion",
         "prebuild",
         "Zilla",

docker/Dockerfile

@@ -0,0 +1,51 @@
+# CI job image for the Gitea act_runner: the runner's default job image with
+# Node pre-planted where actions/setup-node looks first.
+#
+# Why this layout: setup-node ignores `node` on PATH; its only fast path is a
+# probe of /opt/hostedtoolcache/node/<version>/<arch>. Without an entry there
+# it downloads the ~50 MB distribution on EVERY job (the runner's job
+# containers are ephemeral, so its tool cache never survives a job). The
+# official node images keep exactly the layout setup-node expects under
+# /usr/local, so this layer is a pure file overlay — no scripts, no env.
+#
+# Why not a host bind of /opt/hostedtoolcache: binds never self-prune. Docker
+# images are content-addressed: the base layers dedupe against the act image
+# the host already has, and `docker image prune` / re-pulls are the cleanup
+# story.
+#
+# NODE_VERSION must match `.node-version` exactly. setup-node resolves a float
+# like `26` to the latest known patch at runtime, so a bump silently busts the
+# baked entry; `.node-version` is pinned to x.y.z and scripts/runner-image.sh
+# guards the coupling. Rebuild + repoint `container.image` in
+# .gitea/workflows/ci.yml on every bump.
+#
+# The extra `nodebase` stage is load-bearing: `COPY --from=` resolves its value
+# as a *stage name* at parse time, before build args exist, so
+# `COPY --from=node:${NODE_VERSION}` collapses to the invalid `node:` on
+# frontends that do not expand args there. ARGs declared before the first FROM
+# *are* expanded in FROM, so routing through a named stage works everywhere.
+
+# Global scope: only visible to FROM lines, but that is exactly where we need it.
+ARG NODE_VERSION=26.8.2
+FROM node:${NODE_VERSION} AS nodebase
+
+FROM catthehacker/ubuntu:act-latest
+
+# ARGs do not cross stage boundaries; redeclare (with the same default, so a
+# bare `docker build -f docker/Dockerfile .` still works) for the paths below.
+# Keep this default in sync with the global one above.
+ARG NODE_VERSION=26.8.2
+
+# node image: bin/ + lib/ under /usr/local → tool cache: bin/ + lib/ under <ver>/x64.
+COPY --from=nodebase /usr/local /opt/hostedtoolcache/node/${NODE_VERSION}/x64
+
+# actions/tool-cache only accepts a cached tool when the sibling marker file
+# "<version>/<arch>.complete" exists — tc.find() checks it and falls back to
+# downloading otherwise, however complete the directory is. The marker is what
+# tc.cacheDir() writes after *it* installs a tool, so a pre-baked entry has to
+# reproduce it explicitly.
+RUN touch "/opt/hostedtoolcache/node/${NODE_VERSION}/x64.complete"
+
+# Fail the build (not CI) if the overlay or the version arg were wrong.
+# Shell form on purpose: exec form (`RUN [...]`) does not expand ARG values.
+RUN "/opt/hostedtoolcache/node/${NODE_VERSION}/x64/bin/node" --version

package.json

@@ -1,6 +1,6 @@
 {
     "name": "tiny-pattern-ts",
-    "version": "0.1.0",
+    "version": "0.1.3",
     "description": "Pattern matching for TypeScript/ESM environments (F#-style, not regex)",
     "keywords": [
         "adt",
@@ -77,7 +77,7 @@
         "expect-type": "1.4.0",
         "knip": "^6.34.0",
         "lefthook": "^2.1.12",
-        "oxfmt": "^0.66.0",
+        "oxfmt": "^0.67.0",
         "oxlint": "^1.81.0",
         "oxlint-tsgolint": "^7.0.2001",
         "publint": "^0.3.24",
@@ -87,6 +87,6 @@
         "node": ">=26"
     },
     "allowScripts": {
-        "lefthook@2.1.12": true
+        "lefthook@2.1.14": true
     }
 }

scripts/runner-image.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Build (and optionally push) the CI job image from docker/Dockerfile.
+# Run wherever docker + registry credentials live (the runner host, or any
+# machine that can reach the registry). The registry/repo below MUST match
+# the `container.image` references in .gitea/workflows/ci.yml — the runner
+# pulls the image by name.
+#
+# Usage: scripts/runner-image.sh [--push]
+
+IMAGE_REPO="gitea.e1nsnull.de/tmu/act-ci"
+
+NODE_VERSION="$(tr -d '[:space:]' < .node-version)"
+if [[ ! "${NODE_VERSION}" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+    echo "error: .node-version must be pinned to an exact x.y.z, got '${NODE_VERSION}'." >&2
+    echo "       setup-node resolves floats like '26' to the latest patch at runtime," >&2
+    echo "       which silently busts the tool-cache entry baked into the image." >&2
+    exit 1
+fi
+
+IMAGE="${IMAGE_REPO}:${NODE_VERSION}"
+
+# --pull: refresh the act base layer so the derivative does not float on an
+# aging default image forever (layer dedup keeps this cheap).
+docker build --pull --build-arg "NODE_VERSION=${NODE_VERSION}" -t "${IMAGE}" -f docker/Dockerfile .
+
+if [[ "${1:-}" == "--push" ]]; then
+    docker push "${IMAGE}"
+fi
+
+echo "built ${IMAGE}"
+echo "reminder: bump container.image in .gitea/workflows/ci.yml to this tag"