github_release_on_release_branch_merge.yml

# When a release/* PR merges into main, create a GitHub release (tag vX.Y.Z).
# Events from GITHUB_TOKEN do not start other workflows; publish.yml is triggered via
# workflow_run when this workflow completes (see publish.yml).

name: Release on merge

on:
  pull_request:
    types: [closed]
    branches:
      - main

concurrency:
  group: release-on-merge-${{ github.event.pull_request.number }}
  cancel-in-progress: false

permissions:
  contents: write

jobs:
  github-release:
    if: >-
      github.event.pull_request.merged == true &&
      startsWith(github.head_ref, 'release/') &&
      github.event.pull_request.head.repo.full_name == github.repository
    runs-on: ubuntu-latest
    steps:
      - name: Checkout merge commit
        uses: actions/checkout@v6
        with:
          ref: ${{ github.event.pull_request.merge_commit_sha }}

      - name: Set up Python
        uses: actions/setup-python@v6
        with:
          python-version: "3.12"

      - name: Read version from pyproject.toml
        id: meta
        run: |
          python3 <<'PY'
          import os
          import tomllib

          with open("pyproject.toml", "rb") as f:
              data = tomllib.load(f)
          version = data["project"]["version"]
          with open(os.environ["GITHUB_OUTPUT"], "a", encoding="utf-8") as out:
              out.write(f"version={version}\n")
          PY

      - name: Create GitHub Release
        env:
          GH_TOKEN: ${{ github.token }}
        run: |
          set -euo pipefail
          VERSION="${{ steps.meta.outputs.version }}"
          TAG="v${VERSION}"
          MERGE_SHA="${{ github.event.pull_request.merge_commit_sha }}"
          if gh release view "${TAG}" --repo "${{ github.repository }}" >/dev/null 2>&1; then
            echo "Release ${TAG} already exists; skipping."
            exit 0
          fi
          gh release create "${TAG}" \
            --repo "${{ github.repository }}" \
            --target "${MERGE_SHA}" \
            --title "${TAG}" \
            --generate-notes