Readable job names, latest tracks main, and an AGENTS.md

Job names in the Gitea UI rendered as the raw matrix expression
("${{ fromJSON(needs.select.outputs.images) }}"). Gitea resolves a job's matrix
when it PARSES the workflow, before `needs` outputs exist, so matrix.image was
interpolated against an unresolved matrix. There is no way to win with a dynamic
matrix: jobparser.nameWithMatrix interpolates a name containing "${{ }}", and
appends "(<values>)" to one that doesn't — either way the raw expression shows.
See go-gitea/gitea#28207.

So drop the matrix. build.yaml now runs one job, "Build changed images", that
loops over the selected images and emits ::group:: markers, giving a collapsible
section per image. Also: every step has an explicit static name, because Gitea
does not interpolate expressions in names either ("Log in to ${{ env.REGISTRY }}"
rendered literally).

Tag scheme, per review: `latest` now tracks main rather than the newest release,
and `edge` is gone — it's an Alpine/Traefik convention, not a broad standard, and
`main-<sha>` already covers "a specific commit". `latest` has exactly one owner
so a release tag and a main build can't race to define it. Release tags remain
immutable `:vX.Y.Z`/`:vX.Y`/`:vX` for pinning. This also means the ToolHive
manifest's `:latest` resolves as soon as this lands on main, with no release tag
needed first.

hack/docker-tags.sh folded into hack/build-images.sh, which is now the whole
pipeline — tag, build, smoke-test, push — shared by `make build` and CI. It uses
plain `docker build` instead of buildx, dropping setup-buildx-action: it loads
into the local store so the test runs pre-publish, and emits a plain manifest
with no attestations for Gitea's registry.

Verified in a simulated runner (repo in a docker volume, socket mounted, real
runner image): select + build + group markers, all four tag modes, and the
multi-image loop with a scratch second image.

AGENTS.md records the conventions and, importantly, the three Gitea gotchas that
all look fine locally: no bind-mounting the workspace into a sibling container,
no dynamic matrix, no expressions in names.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

.gitea/workflows/build.yaml

@@ -32,61 +32,41 @@ jobs:
       images: ${{ steps.select.outputs.images }}
       any: ${{ steps.select.outputs.any }}
     steps:
-      - uses: actions/checkout@v7
+      - name: Check out repository
+        uses: actions/checkout@v7
         with:
           fetch-depth: 0 # need history to diff against the base commit
 
-      - id: select
+      - name: Work out which images changed
+        id: select
         run: ./hack/select-images.sh >> "$GITHUB_OUTPUT"
         env:
           DISPATCH_IMAGE: ${{ github.event.inputs.image }}
           BASE_SHA: ${{ github.event.pull_request.base.sha || github.event.before }}
 
+  # One job that loops, rather than a matrix job per image: Gitea resolves a matrix
+  # when it parses the workflow, before `needs` outputs exist, so a dynamic matrix
+  # produces a single job named after the raw expression. Looping keeps the job name
+  # readable and gives one collapsible log section per image.
   build:
-    name: ${{ matrix.image }}
+    name: Build changed images
     needs: select
     if: needs.select.outputs.any == 'true'
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        image: ${{ fromJSON(needs.select.outputs.images) }}
     steps:
-      - uses: actions/checkout@v7
+      - name: Check out repository
+        uses: actions/checkout@v7
 
-      - id: meta
-        run: ./hack/docker-tags.sh '${{ matrix.image }}' >> "$GITHUB_OUTPUT"
-        env:
-          PR_NUMBER: ${{ github.event.pull_request.number }}
-
-      - uses: docker/setup-buildx-action@v4
-
-      # Loaded rather than pushed, so the smoke test runs before anything is
-      # published. provenance is off because Gitea's registry rejects buildkit
-      # attestation manifests.
-      - name: Build
-        uses: docker/build-push-action@v7
-        with:
-          context: images/${{ matrix.image }}
-          load: true
-          tags: ${{ steps.meta.outputs.tags }}
-          provenance: false
-          build-args: |
-            VERSION=${{ steps.meta.outputs.version }}
-            REVISION=${{ github.sha }}
-            CREATED=${{ steps.meta.outputs.created }}
-
-      - name: Smoke test
-        run: make test IMAGE='${{ matrix.image }}' REF='${{ steps.meta.outputs.primary }}'
-
-      - name: Log in to ${{ env.REGISTRY }}
-        if: steps.meta.outputs.push == 'true'
+      # Never on a pull request, which is exactly when nothing gets published.
+      - name: Log in to the Gitea container registry
+        if: github.event_name != 'pull_request'
         uses: docker/login-action@v4
         with:
           registry: ${{ env.REGISTRY }}
           username: ${{ env.DOCKER_USER }}
           password: ${{ secrets.API_TOKEN }}
 
-      - name: Push
-        if: steps.meta.outputs.push == 'true'
-        run: printf '%s\n' '${{ steps.meta.outputs.tags }}' | xargs -r -n1 -t docker push
+      - name: Build, smoke-test and publish
+        run: ./hack/build-images.sh ${{ needs.select.outputs.images }}
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}