# Brain-aware pull requests — copy this file to .github/workflows/brain-pr.yml
# in any repo whose brain.klypix is committed.
#
# On every PR it posts (and keeps updated) ONE sticky comment with:
#   1. the brain decisions/corrections that reference the files the PR touches
#      (evidence tags: #file-<name> inside cards), and
#   2. a readable card-level diff of the brain itself, when the PR changes it.
#
# Nothing here talks to any KLYPIX service — the brain is read from the
# checkout, exactly as your agents read it. Requires only the default
# GITHUB_TOKEN with pull-requests: write.

name: brain-pr
on:
  pull_request:
    types: [opened, synchronize, reopened]

permissions:
  contents: read
  pull-requests: write

jobs:
  brain-context:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0            # pr-brief and diff need the base ref

      - uses: actions/setup-node@v4
        with:
          node-version: 20

      - name: Build the comment
        id: brain
        env:
          BASE: ${{ github.event.pull_request.base.sha }}
        run: |
          {
            npx --yes klypix-mcp pr-brief "$BASE" || true
            echo ""
            # Only show the brain diff when the PR actually changes the brain.
            if git diff --name-only "$BASE"...HEAD | grep -q '\.klypix$'; then
              npx --yes klypix-mcp diff "$BASE" || true
            fi
          } > brain-comment.md
          # Skip the comment entirely when there is nothing to say.
          if ! grep -qE '🧠' brain-comment.md; then
            echo "post=false" >> "$GITHUB_OUTPUT"
          else
            echo "post=true" >> "$GITHUB_OUTPUT"
          fi

      - name: Post / update the sticky comment
        if: steps.brain.outputs.post == 'true'
        env:
          GH_TOKEN: ${{ github.token }}
          PR: ${{ github.event.pull_request.number }}
        run: |
          MARKER="<!-- klypix-brain-pr -->"
          printf '%s\n\n' "$MARKER" | cat - brain-comment.md > body.md
          EXISTING=$(gh api "repos/${GITHUB_REPOSITORY}/issues/${PR}/comments" \
            --jq ".[] | select(.body | startswith(\"$MARKER\")) | .id" | head -1)
          if [ -n "$EXISTING" ]; then
            gh api -X PATCH "repos/${GITHUB_REPOSITORY}/issues/comments/${EXISTING}" -F body=@body.md > /dev/null
          else
            gh pr comment "$PR" --body-file body.md > /dev/null
          fi