Model-release watch: don't register unofferable models + CI-opened PRs

.github/workflows/open-model-release-pr.yml

@@ -0,0 +1,59 @@
+name: Open model-release PR
+
+# The daily model-release watch runs in a scheduled Claude session, which can
+# push a branch but cannot open a pull request: the GitHub API access an
+# interactive session has is not passed through to a scheduled one, and the
+# container's git credentials are scoped to git transport only. So the branch
+# arrives here with nothing behind it and this workflow opens the PR.
+#
+# The pushing session has no way to set a title and body either, so it puts
+# them in the commit message — subject becomes the PR title, body becomes the
+# PR body. Keep that contract in step with the routine's prompt.
+
+on:
+  push:
+    branches:
+      - "claude/model-release-**"
+
+permissions:
+  contents: read
+  pull-requests: write
+
+concurrency:
+  group: open-model-release-pr-${{ github.ref }}
+  cancel-in-progress: false
+
+jobs:
+  open-draft-pr:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Open a draft PR if the branch has none
+        env:
+          GH_TOKEN: ${{ github.token }}
+          BRANCH: ${{ github.ref_name }}
+          BASE: ${{ github.event.repository.default_branch }}
+        run: |
+          set -euo pipefail
+
+          if [ "$(gh pr list --head "$BRANCH" --state open --json number --jq 'length')" != "0" ]; then
+            echo "An open PR already exists for $BRANCH — leaving it alone."
+            exit 0
+          fi
+
+          title=$(git log -1 --pretty=%s)
+
+          # Commit trailers are bookkeeping, not PR prose.
+          {
+            git log -1 --pretty=%b | sed -E '/^(Co-Authored-By|Claude-Session):/d'
+            printf '\n---\n\nOpened automatically from `%s` by the daily model-release watch.\n' "$BRANCH"
+            printf 'The companion change is on the same branch name in the other repository.\n'
+          } > /tmp/pr-body.md
+
+          gh pr create \
+            --draft \
+            --base "$BASE" \
+            --head "$BRANCH" \
+            --title "$title" \
+            --body-file /tmp/pr-body.md