pr-title.yml

# Pull-request title check — versioning policy until the public launch.
#
# The major version is frozen until the public launch: a breaking change is
# released as a minor. So a pull request must not mark itself as breaking the
# conventional-commits way. This check fails when:
#   - the title is not a conventional commit ("type(scope): what"), or
#   - the title contains "!:" (the breaking marker), or
#   - the body, or any commit message in the pull request, has a
#     "BREAKING CHANGE:" / "BREAKING-CHANGE:" footer line.
# Commits are checked too because pull requests are merged with
# "Rebase and merge", so each commit message lands on main as it is.
# Write a breaking change as feat(...) with a "Breaking:" note in plain words.
# See "Versioning" in the README / CONTRIBUTING.

name: PR title

on:
  pull_request:
    types: [opened, edited, reopened, synchronize]

permissions:
  contents: read
  pull-requests: read

jobs:
  pr-title:
    name: pr-title
    runs-on: ubuntu-24.04
    steps:
      - name: Check title, body and commit messages
        env:
          TITLE: ${{ github.event.pull_request.title }}
          BODY: ${{ github.event.pull_request.body }}
          PR_NUMBER: ${{ github.event.pull_request.number }}
          GH_TOKEN: ${{ github.token }}
          GH_REPO: ${{ github.repository }}
        run: |
          fail=0
          types='feat|fix|perf|refactor|docs|chore|test|ci|style|build|revert'
          # A footer as the release tools read it: at the start of a line
          # (after optional spaces, "*" or ">").
          footer='^[[:space:]*>]*BREAKING[ -]CHANGE:'

          if [[ "$TITLE" == *'!:'* ]]; then
            echo "::error::Title has '!:'. The major version is frozen until launch: use feat(...) and write 'Breaking: <what>' in the body."
            fail=1
          fi
          if ! [[ "$TITLE" =~ ^($types)(\([^\)]+\))?!?:\ [^[:space:]] ]]; then
            echo "::error::Title is not a conventional commit. Use '<type>(<scope>): <what>' with type one of: ${types//|/, }."
            fail=1
          fi
          if printf '%s\n' "$BODY" | grep -Eq "$footer"; then
            echo "::error::Body has a BREAKING CHANGE footer. Write 'Breaking: <what>' instead."
            fail=1
          fi

          gh api "repos/$GH_REPO/pulls/$PR_NUMBER/commits" --paginate \
            --jq '.[] | .sha[0:8] + " " + (.commit.message | @base64)' > commits.txt
          while read -r sha msg64; do
            msg=$(printf '%s' "$msg64" | base64 -d)
            subject=${msg%%$'\n'*}
            if [[ "$subject" == *'!:'* ]]; then
              echo "::error::Commit $sha has '!:' in its subject: $subject"
              fail=1
            fi
            if printf '%s\n' "$msg" | grep -Eq "$footer"; then
              echo "::error::Commit $sha has a BREAKING CHANGE footer. Reword it to 'Breaking: <what>'."
              fail=1
            fi
          done < commits.txt

          if [ "$fail" -ne 0 ]; then exit 1; fi
          echo "Title, body and commits follow the versioning policy."