linear.yml

name: Linear History

on:
  pull_request:
    branches: ["modules"]
  workflow_dispatch:

jobs:
  check-linear-history:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v6
        with:
          ref: ${{ github.event.pull_request.head.sha || github.sha }}
          fetch-depth: 0

      - name: Check for merge commits
        run: |
          BASE_REF=${{ github.base_ref || 'modules' }}
          echo "Comparing against base: $BASE_REF"
          git fetch origin $BASE_REF:$BASE_REF
          MERGE_COMMITS=$(git rev-list --merges $BASE_REF..HEAD)
          if [ -n "$MERGE_COMMITS" ]; then
            echo "Error: Merge commits detected. libfork requires a linear history."
            echo "Please rebase your branch onto $BASE_REF to remove merge commits."
            echo ""
            echo "Merge commits found:"
            git log --merges --oneline $BASE_REF..HEAD
            exit 1
          else
            echo "No merge commits detected. Linear history check passed."
          fi