Release: build on a published release, as in inlaw_outlaw

- on: release (published), not on any v* tag: only a deliberate release
  builds an image; the version is its tag without the v, plus latest.
- docker/login-action, setup-buildx and build-push-action, as the runner
  already serves them for inlaw_outlaw; the version as a build argument
  and image label.
- Comments on why the registry needs a personal token (the job token's
  empty package scope) and that packages belong to the repository owner.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

.gitea/workflows/release.yml

@@ -1,35 +1,60 @@
 name: Release
-# A tag v* publishes the agent's image to Gitea's registry (Development Plan
-# M1.5, X4): gitea.dongar.net/dongar/nisse-dev:<tag> and :latest. The token
-# is a secret (REGISTRY_TOKEN: write:package for REGISTRY_USER); the
-# account is a setting, so it's here.
+# A published release builds the agent's image and pushes it to Gitea's
+# registry (Development Plan M1.5, X4): gitea.dongar.net/dongar/nisse-dev
+# tagged with the version (the release tag without its v) and latest. Cut a
+# release in Gitea (Releases → New release, tag vX.Y.Z); a tag pushed for any
+# other reason builds nothing.
+#
+# The registry needs a personal access token with write:package
+# (REGISTRY_TOKEN), never the built-in job token: Gitea's registry resolves
+# an Actions job token to an empty package scope (go-gitea/gitea#23642 and
+# others). Packages belong to the repository's owner. Never on pull_request:
+# registry credentials stay off that trigger.
 on:
-  push:
-    tags: ["v*"]
+  release:
+    types: [published]
 
 env:
   REGISTRY: gitea.dongar.net
-  REGISTRY_USER: dongar
+  REGISTRY_USER: dongar  # the token's account
   IMAGE: gitea.dongar.net/dongar/nisse-dev
 
 jobs:
-  image:
+  build-and-push:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
     steps:
-      - uses: actions/checkout@v4
+      - name: Checkout
+        uses: actions/checkout@v4
 
-      - name: Build
-        run: |
-          docker build --target agent \
-            --label org.opencontainers.image.revision="${{ github.sha }}" \
-            --label org.opencontainers.image.version="${{ github.ref_name }}" \
-            -t "$IMAGE:${{ github.ref_name }}" -t "$IMAGE:latest" .
-
-      - name: Push
+      - name: Derive the image version from the release's tag
+        id: vars
         env:
-          REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN }}
-        run: |
-          printf '%s' "$REGISTRY_TOKEN" | docker login "$REGISTRY" -u "$REGISTRY_USER" --password-stdin
-          docker push "$IMAGE:${{ github.ref_name }}"
-          docker push "$IMAGE:latest"
-          docker logout "$REGISTRY"
+          TAG: ${{ github.event.release.tag_name }}
+        run: echo "version=${TAG#v}" >> "$GITHUB_OUTPUT"
+
+      - name: Log in to Gitea's container registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ env.REGISTRY_USER }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build and push the agent
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          target: agent
+          push: true
+          build-args: |
+            VERSION=${{ steps.vars.outputs.version }}
+          labels: |
+            org.opencontainers.image.version=${{ steps.vars.outputs.version }}
+            org.opencontainers.image.revision=${{ github.sha }}
+          tags: |
+            ${{ env.IMAGE }}:${{ steps.vars.outputs.version }}
+            ${{ env.IMAGE }}:latest