name: release

# Publishes an immutable, version-tagged image on ghcr.io (spec 10.1).
# Ordinary commits do not publish anything — only a pushed tag matching
# vX.Y.Z does. That tag is the single source the version comes from: it goes
# into both the image tag and the panel binary's -ldflags version, so the two
# can never drift apart (the invariant restore's version check in spec 7.5.A
# depends on).
on:
  push:
    tags:
      - "v[0-9]+.[0-9]+.[0-9]+"

permissions:
  contents: read
  packages: write

jobs:
  build-and-push:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Derive version from tag
        id: version
        run: echo "version=${GITHUB_REF_NAME#v}" >> "$GITHUB_OUTPUT"

      - uses: docker/setup-qemu-action@v3
      - uses: docker/setup-buildx-action@v3

      - name: Log in to ghcr.io
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          context: .
          file: build/Dockerfile
          platforms: linux/amd64,linux/arm64
          build-args: |
            VERSION=${{ steps.version.outputs.version }}
          push: true
          provenance: false
          tags: ghcr.io/${{ github.repository }}:${{ steps.version.outputs.version }}