ci: replace per-commit conventional commits check with pr title check

bdraco · bdraco · commit 0aceb6388328 · 2026-05-19T15:53:09.000-05:00
diff --git a/.claude/skills/pr-workflow/SKILL.md b/.claude/skills/pr-workflow/SKILL.md
@@ -49,28 +49,29 @@ behaviour change that affects packet contents or timing —
 reviewers shouldn't have to reverse-engineer why a constant moved
 or a probe interval changed.
 
-## 3. Commit message conventions
-
-Commit messages are linted by `commitlint` with
-`@commitlint/config-conventional`, _and_ by `commitizen` in
-pre-commit (`stages: [commit-msg]`). Both must pass.
-
-- **Conventional Commits prefix is required.** Pick from:
-  `feat`, `fix`, `perf`, `refactor`, `docs`, `test`, `build`,
-  `ci`, `chore`, `style`, `revert`. The `feat`/`fix`/`perf`
-  prefixes show up in the release-notes; `chore*` and `ci*` are
-  excluded by semantic-release (`exclude_commit_patterns` in
-  `pyproject.toml`), so use those for housekeeping.
+## 3. PR title conventions
+
+PRs are squash-merged, so the PR title becomes the commit on
+`master`. Only the PR title is linted (by the `pr-title` CI job
+running `amannn/action-semantic-pull-request`); per-commit
+messages on the PR branch are not checked.
+
+- **Conventional Commits prefix is required on the PR title.**
+  Pick from: `feat`, `fix`, `perf`, `refactor`, `docs`, `test`,
+  `build`, `ci`, `chore`, `style`, `revert`. The
+  `feat`/`fix`/`perf` prefixes show up in the release-notes;
+  `chore*` and `ci*` are excluded by semantic-release
+  (`exclude_commit_patterns` in `pyproject.toml`), so use those
+  for housekeeping.
 - **Imperative-mood subject.** "fix: handle empty answer", not
   "fix: handled empty answer".
-- **No header length cap.** The commitlint config sets
-  `header-max-length: [0, "always", Infinity]`, so a slightly
-  longer subject is fine if it earns the space; don't pad.
+- **Lowercase first character after the prefix** (enforced by
+  `subjectPattern: ^(?![A-Z]).+$`).
 - **No `Co-Authored-By` trailers from automated agents.**
-- **One logical change per commit.** Let pre-commit run (ruff
+- **One logical change per PR.** Let pre-commit run (ruff
   lint + format, mypy, flake8, codespell, cython-lint,
   pyupgrade). If a hook auto-fixes something, re-stage and
-  re-commit; the commit-msg hook re-runs on the new commit.
+  re-commit.
 
 ## 4. Cython / `.pxd` discipline
 
@@ -101,22 +102,23 @@ Always pass the body via `--body-file`, never `--body "..."` with
 shell-escaping — Markdown backticks, asterisks, and angle
 brackets must pass through verbatim.
 
-The PR title should match the commit subject (same Conventional
-Commits prefix). If the PR ends up squash-merged, the title
-becomes the merged commit message, so it has to satisfy
-commitlint on its own.
+The PR title is what gets enforced — it becomes the squash-merge
+commit subject on `master`, so it has to parse as a Conventional
+Commit on its own. Per-commit messages on the branch are not
+linted.
 
 ## 6. After the PR is open
 
 CI runs three jobs:
 
 - `lint` — `pre-commit/action`. If pre-commit passed locally
   this passes too.
-- `commitlint` — `wagoid/commitlint-github-action`. Validates
-  every commit on the PR; if you amended after pushing, force-
-  push the branch so the rewritten commits get linted.
-- `test` — the full pytest matrix across CPython 3.9–3.14,
-  3.14t (free-threaded), and PyPy 3.9 / 3.10, on Linux + macOS +
+- `pr-title` — `amannn/action-semantic-pull-request`. Validates
+  the PR title against Conventional Commits. If it fails, fix
+  the title in the GitHub UI or with `gh pr edit --title "..."`;
+  the workflow re-runs on the edit, no push needed.
+- `test` — the full pytest matrix across CPython 3.10–3.14,
+  3.14t (free-threaded), and PyPy 3.10, on Linux + macOS +
   Windows. The free-threaded entry is the canary for unguarded
   shared-state bugs; failures there are often genuine even when
   the GIL-enabled rows pass.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -24,20 +24,10 @@ jobs:
           python-version: "3.12"
       - uses: pre-commit/action@2c7b3805fd2a0fd8c1884dcaebf91fc102a13ecd # v3.0.1
 
-  # Make sure commit messages follow the conventional commits convention:
+  # Make sure the PR title follows the conventional commits convention:
   # https://www.conventionalcommits.org
-  commitlint:
-    name: Lint Commit Messages
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v4
-        with:
-          fetch-depth: 0
-      - uses: wagoid/commitlint-github-action@b948419dd99f3fd78a6548d48f94e3df7f6bf3ed # v6
-
-  # PRs are squash-merged, so the PR title becomes the commit subject on
-  # master. Validate it against Conventional Commits so the squashed commit
-  # stays release-tool-friendly even when individual commits don't.
+  # PRs are squash-merged, so the PR title becomes the commit on master and
+  # drives python-semantic-release's version bump.
   pr-title:
     name: Lint PR Title
     runs-on: ubuntu-latest
@@ -48,6 +38,12 @@ jobs:
       - uses: amannn/action-semantic-pull-request@48f256284bd46cdaab1048c3721360e808335d50 # v6.1.1
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          subjectPattern: ^(?![A-Z]).+$
+          subjectPatternError: |
+            The subject "{subject}" found in the pull request title "{title}"
+            didn't match the configured pattern. Please ensure that the subject
+            starts with a lowercase character.
 
   test:
     strategy:
@@ -155,7 +151,6 @@ jobs:
     needs:
       - test
       - lint
-      - commitlint
     if: ${{ github.repository_owner }} == "python-zeroconf"
 
     runs-on: ubuntu-latest
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
@@ -8,11 +8,6 @@ ci:
   autoupdate_commit_msg: "chore(pre-commit.ci): pre-commit autoupdate"
 
 repos:
-  - repo: https://github.com/commitizen-tools/commitizen
-    rev: v4.16.2
-    hooks:
-      - id: commitizen
-        stages: [commit-msg]
   - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v6.0.0
     hooks:
diff --git a/CLAUDE.md b/CLAUDE.md
@@ -85,13 +85,17 @@ path. The authoritative list of cythonized modules lives in
 
 ## Commit / PR conventions
 
-- **Conventional Commits are enforced.** CI runs commitlint with
-  `@commitlint/config-conventional`, and pre-commit runs
-  commitizen on the commit message. The header has no length cap
-  (`header-max-length = [0, "always", Infinity]`), but the
-  _type_ prefix is required: `feat:`, `fix:`, `chore:`, `ci:`,
-  `docs:`, `refactor:`, `test:`, `perf:`, `build:`, etc.
-  `semantic-release` excludes `chore*` and `ci*` from the
+- **Conventional Commits PR title, lowercase subject.** PRs are
+  squash-merged, so the **PR title** becomes the commit on
+  `master` and is the only string that has to parse as a
+  Conventional Commit. The repo enforces this via the `pr-title`
+  CI job in `ci.yml` using `amannn/action-semantic-pull-request`.
+  Accepted types: `feat`, `fix`, `chore`, `ci`, `docs`,
+  `refactor`, `test`, `perf`, `build`, etc. The subject (text
+  after `type(scope):`) must start lowercase (enforced by
+  `subjectPattern: ^(?![A-Z]).+$`). Per-commit messages on the
+  PR branch are **not** linted; they get collapsed at squash-
+  merge. `semantic-release` excludes `chore*` and `ci*` from the
   changelog, so use those prefixes for housekeeping and reserve
   `feat`/`fix`/`perf` for user-visible changes.
 - **No `Co-Authored-By` trailers from automated agents.** Project
@@ -267,8 +271,8 @@ or commit that names the bug class and the affected code path.
   the resulting wheel will crash at import time.
 - **Don't add `Co-Authored-By` trailers from automated agents
   to commits** in this repo.
-- **Don't introduce a commit message that violates Conventional
-  Commits.** The commitlint job will fail the PR.
+- **Don't introduce a PR title that violates Conventional
+  Commits.** The `pr-title` job will fail the PR.
 - **Don't tighten timings or constants in `const.py` without an
   RFC citation in the commit message.** mDNS interop with
   Avahi / Bonjour / Windows hinges on those numbers.
diff --git a/commitlint.config.mjs b/commitlint.config.mjs
