fix(ci): nothing a CI job starts outlives it, even when the runner kills the job

A migration-smoke stack (PostgreSQL and SeaweedFS) ran on the shared
runner for two days. Every CI script removes its stack in an EXIT trap,
but a trap never runs when the runner kills the job container: a
cancelled job, or the runner's own time limit (Gitea 1.24 ignores
timeout-minutes). Reproduced: SIGKILL of the infrastructure smoke
mid-run leaves exactly that stack running.

Cleanup now has three layers:
- the script's own trap, unchanged;
- a final `if: always()` step in every job that starts stacks
  (infrastructure-smoke, migration-smoke, image-build, deploy-smoke)
  runs `scripts/ci-sweep.sh --job`, which removes everything that job
  started at any age;
- a first step in each of those jobs runs `scripts/ci-sweep.sh --stale`,
  which removes CI stacks older than three hours: what a killed job left
  before it could clean up.

How stacks are found is defined once, in scripts/lib/ci-project.sh:
- every CI Compose project is named `ekklesia-ci-<run>-<attempt>-<job
  key>-<kind>-<unique>`, and Compose labels its containers, networks and
  volumes with that name;
- the deploy smoke labels everything it starts outside Compose:
  browser, kiosk and driver containers, the kiosk volume, built images;
- images also record when CI built them. An image's own creation time
  can be its base's (BuildKit, metadata-only builds), and the sweep
  removed a brand-new image as "old" until it stopped trusting that.

The job key is per matrix leg, so one topology's cleanup cannot remove
the other's running stack. The sweep never touches anything outside the
ekklesia-ci- prefix, disconnects rather than removes a job container
attached to a stack's network, and refuses --job outside CI. Network
creation times are read as RFC 3339; Docker's default form was
unparseable.

scripts/test-ci-sweep.sh proves all of that against real Docker, and
CI runs it before relying on it. security.md and testing.md document
the rule, and that it complements, not replaces, a runner-side reaper.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

.github/workflows/ci.yml

@@ -63,6 +63,9 @@ jobs:
     needs: verify
     runs-on: ubuntu-latest
     timeout-minutes: 10
+    env:
+      # Names this job's stacks, so its final step removes exactly these (scripts/lib/ci-project.sh).
+      EKKLESIA_CI_JOB_KEY: infrastructure-smoke
     steps:
       - name: Check out repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -72,13 +75,29 @@ jobs:
           # in this workflow pushes, so the credential is never needed after checkout.
           persist-credentials: false
 
+      # A job the runner killed (cancelled, or past the runner's own time limit) never ran its
+      # cleanup. Anything a CI job left on this shared daemon more than three hours ago goes first.
+      - name: Sweep stale CI stacks from the runner
+        run: bash scripts/ci-sweep.sh --stale
+
+      - name: Prove the sweep removes exactly what it should, against real Docker resources
+        run: bash scripts/test-ci-sweep.sh
+
       - name: Exercise PostgreSQL and S3 infrastructure
         run: bash scripts/smoke-infrastructure.sh
 
+      # Whatever happened above, this job's own stacks do not outlive it.
+      - name: Remove this job's CI stacks
+        if: always()
+        run: bash scripts/ci-sweep.sh --job
+
   migration-smoke:
     needs: verify
     runs-on: ubuntu-latest
     timeout-minutes: 15
+    env:
+      # Names this job's stacks, so its final step removes exactly these (scripts/lib/ci-project.sh).
+      EKKLESIA_CI_JOB_KEY: migration-smoke
     steps:
       - name: Check out repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -88,6 +107,11 @@ jobs:
           # in this workflow pushes, so the credential is never needed after checkout.
           persist-credentials: false
 
+      # A job the runner killed (cancelled, or past the runner's own time limit) never ran its
+      # cleanup. Anything a CI job left on this shared daemon more than three hours ago goes first.
+      - name: Sweep stale CI stacks from the runner
+        run: bash scripts/ci-sweep.sh --stale
+
       - name: Set up Node.js
         uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
         with:
@@ -104,11 +128,18 @@ jobs:
       - name: Exercise transactional migrations against PostgreSQL
         run: pnpm test:migrations:integration
 
+      # Whatever happened above, this job's own stacks do not outlive it.
+      - name: Remove this job's CI stacks
+        if: always()
+        run: bash scripts/ci-sweep.sh --job
+
   image-build:
     needs: verify
     runs-on: ubuntu-latest
     timeout-minutes: 20
     env:
+      # Names this job's stacks, so its final step removes exactly these (scripts/lib/ci-project.sh).
+      EKKLESIA_CI_JOB_KEY: image-build
       # Cache mounts in deploy/Dockerfile need BuildKit; this selects it even where the Docker CLI
       # has no buildx plugin.
       DOCKER_BUILDKIT: "1"
@@ -121,22 +152,33 @@ jobs:
           # in this workflow pushes, so the credential is never needed after checkout.
           persist-credentials: false
 
+      # A job the runner killed (cancelled, or past the runner's own time limit) never ran its
+      # cleanup. Anything a CI job left on this shared daemon more than three hours ago goes first.
+      - name: Sweep stale CI stacks from the runner
+        run: bash scripts/ci-sweep.sh --stale
+
       # The platform-only image (ADR 0044): a checkout has no `modules/`, so this proves the image
       # builds, validates, and assembles with zero modules. Build only — no registry login, no
       # credentials, no push, no tag anywhere but this runner's local image store.
       # Tagged per run and attempt, not only per commit: a pull request and a push of the same commit
       # can build at once on one runner's Docker daemon, and neither may remove the other's image.
+      # Labeled like every CI stack, so this job's final step removes it even if the build is killed.
       - name: Build the production image without modules
-        run: >-
-          docker build
-          --file deploy/Dockerfile
-          --build-arg REVISION="$GITHUB_SHA"
-          --tag ekklesia-ci:"$GITHUB_SHA-${GITHUB_RUN_ID:-0}-${GITHUB_RUN_ATTEMPT:-1}"
-          .
+        shell: bash
+        run: |
+          source scripts/lib/ci-project.sh
+          docker build \
+            --file deploy/Dockerfile \
+            --build-arg REVISION="$GITHUB_SHA" \
+            --label "${EKKLESIA_CI_LABEL}=$(ci_project_name image)" \
+            --label "${EKKLESIA_CI_CREATED_LABEL}=$(date +%s)" \
+            --tag ekklesia-ci:"$GITHUB_SHA-${GITHUB_RUN_ID:-0}-${GITHUB_RUN_ATTEMPT:-1}" \
+            .
 
-      - name: Remove the image from the runner
+      # Whatever happened above, this job's own stacks do not outlive it.
+      - name: Remove this job's CI stacks
         if: always()
-        run: docker image rm --force ekklesia-ci:"$GITHUB_SHA-${GITHUB_RUN_ID:-0}-${GITHUB_RUN_ATTEMPT:-1}" || true
+        run: bash scripts/ci-sweep.sh --job
 
   deploy-smoke:
     needs: verify
@@ -151,6 +193,8 @@ jobs:
           - same-origin
           - split
     env:
+      # Names this job's stacks, so its final step removes exactly these (scripts/lib/ci-project.sh).
+      EKKLESIA_CI_JOB_KEY: deploy-smoke-${{ matrix.topology }}
       DOCKER_BUILDKIT: "1"
       EKKLESIA_SMOKE_TOPOLOGY: ${{ matrix.topology }}
     steps:
@@ -162,6 +206,11 @@ jobs:
           # in this workflow pushes, so the credential is never needed after checkout.
           persist-credentials: false
 
+      # A job the runner killed (cancelled, or past the runner's own time limit) never ran its
+      # cleanup. Anything a CI job left on this shared daemon more than three hours ago goes first.
+      - name: Sweep stale CI stacks from the runner
+        run: bash scripts/ci-sweep.sh --stale
+
       # The reference deployment end to end (ADR 0044): a platform-only image, base + proxy with
       # Caddy's internal CA (test-only), an explicit migration apply against this job's own fresh
       # PostgreSQL, then the API, Dashboard, storage delivery, client-address chain, and verify-full
@@ -169,3 +218,8 @@ jobs:
       # it; nothing is pushed, published, or logged in to.
       - name: Smoke-test the reference deployment (${{ matrix.topology }})
         run: bash scripts/smoke-deploy.sh
+
+      # Whatever happened above, this job's own stacks do not outlive it.
+      - name: Remove this job's CI stacks
+        if: always()
+        run: bash scripts/ci-sweep.sh --job