upstream_sync.yml

name: Upstream Sync

on:
  schedule:
    - cron: '0 */4 * * *' # Run every 4 hours
  workflow_dispatch: # Allow manual triggering

jobs:
  check-and-create-pr:
    name: Check Upstream and Create PR
    runs-on: ubuntu-latest
    permissions:
      contents: write
      pull-requests: write

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0 # Required to fetch all history for commit comparison
          token: ${{ secrets.SWIFTLM_PR_TOKEN || secrets.GITHUB_TOKEN }}

      - name: Check for upstream changes and set up branch
        id: check_upstream
        run: |
          # Add the upstream repository
          git remote add upstream https://github.com/ml-explore/mlx-swift.git
          git fetch upstream main
          
          # Check how many commits upstream is ahead of our local main
          AHEAD=$(git rev-list --count HEAD..upstream/main)
          echo "Upstream is $AHEAD commits ahead."
          
          if [ "$AHEAD" -gt 0 ]; then
            echo "has_changes=true" >> $GITHUB_OUTPUT
            BRANCH_NAME="sync/upstream-latest"
            echo "branch_name=$BRANCH_NAME" >> $GITHUB_OUTPUT
            
            # Checkout upstream main into the static sync branch (force reset if it exists)
            git checkout -B $BRANCH_NAME upstream/main
            git push --force origin $BRANCH_NAME
          else
            echo "has_changes=false" >> $GITHUB_OUTPUT
            echo "No new commits to sync."
          fi

      - name: Create or Update Pull Request
        if: steps.check_upstream.outputs.has_changes == 'true'
        run: |
          # Check if a PR already exists for this branch
          PR_EXISTS=$(gh pr list HEAD --head ${{ steps.check_upstream.outputs.branch_name }} --json number --jq 'length')
          
          if [ "$PR_EXISTS" -eq "0" ]; then
            gh pr create \
              --title "🔄 Auto-Sync: Upstream changes from ml-explore/mlx-swift" \
              --body "Automated PR to sync the latest changes from upstream \`ml-explore/mlx-swift\`'s \`main\` branch.
              
            ### Merge Warnings
            * **Do NOT blind merge!** This repo contains custom SharpAI out-of-core SSD features.
            * Refer to the \`UPSTREAM_MERGE_PLAN.md\` file locally to check standard SharpAI metal optimization discrepancies.
            * Do **not** overwrite the submodule branch pointers under \`Package.swift\` without consultation." \
              --base main \
              --head ${{ steps.check_upstream.outputs.branch_name }}
          else
            echo "PR already exists. Force pushing to the branch updated the PR automatically."
          fi
        env:
          GH_TOKEN: ${{ secrets.SWIFTLM_PR_TOKEN || secrets.GITHUB_TOKEN }}