Release workflow revision

.gitea/workflows/build-image.yml

@@ -1,5 +1,6 @@
-# Build the Crucible image. PR-first (D7): PRs build only; push to main also
-# publishes registry.westgate.pw/deployment/crucible:<git-sha>. Never a mutable tag.
+# Publish the immutable crucible:<sha> image on version tags.
+# PR/main test builds live in test-image.yml and never publish, so registry
+# packages are only generated for releases we intend to use (not on every merge).
 #
 # Daemonless: the host-mode runner has no container runtime, so the image is
 # built by Nix (`nix build .#image`, see flake.nix) and pushed with skopeo
@@ -8,15 +9,14 @@ name: build-image
 
 on:
   push:
-    branches: [main]
-  pull_request:
+    tags: ["v*"]
 
 env:
   REGISTRY: registry.westgate.pw
   IMAGE: deployment/crucible
 
 jobs:
-  build-image:
+  publish:
     runs-on: nix-docker
     steps:
       - uses: actions/checkout@v4
@@ -29,9 +29,7 @@ jobs:
       - name: Build OCI image (daemonless)
         run: nix build .#image
 
-      # Publish only on main (post-merge). PRs verify the build but never push.
       - name: Publish image
-        if: github.event_name == 'push' && github.ref == 'refs/heads/main'
         env:
           REGISTRY_USER: ${{ secrets.REGISTRY_USER }}
           REGISTRY_PASSWORD: ${{ secrets.REGISTRY_PASSWORD }}