pr-context.yml

name: Suggest relevant context for PRs

on:
  pull_request:
    types: [opened]

permissions:
  pull-requests: write

jobs:
  suggest-context:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - uses: astral-sh/setup-uv@v7

      - name: Install cognitive-cache
        run: uv tool install cognitive-cache

      - name: Get changed files
        id: diff
        env:
          BASE_REF: ${{ github.base_ref }}
        run: |
          echo "files<<EOF" >> "$GITHUB_OUTPUT"
          git diff --name-only "origin/${BASE_REF}...HEAD" >> "$GITHUB_OUTPUT"
          echo "EOF" >> "$GITHUB_OUTPUT"

      - name: Select relevant context
        id: select
        env:
          PR_TITLE: ${{ github.event.pull_request.title }}
          PR_BODY: ${{ github.event.pull_request.body }}
          CHANGED_FILES: ${{ steps.diff.outputs.files }}
        run: |
          TASK="PR: ${PR_TITLE}. ${PR_BODY}. Changed files: ${CHANGED_FILES}"
          cognitive-cache select \
            --repo . \
            --task "${TASK}" \
            --budget 16000 \
            --json > /tmp/cc-result.json

      - name: Comment on PR
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const result = JSON.parse(fs.readFileSync('/tmp/cc-result.json', 'utf8'));

            if (!result.files || result.files.length === 0) {
              core.info('No relevant context files found, skipping comment.');
              return;
            }

            const changedFiles = process.env.CHANGED_FILES?.split('\n').filter(Boolean) || [];
            const contextFiles = result.files.filter(f => !changedFiles.includes(f.path));

            if (contextFiles.length === 0) {
              core.info('All relevant files are already in the diff, skipping comment.');
              return;
            }

            const rows = contextFiles.slice(0, 15).map(f =>
              `| \`${f.path}\` | ${f.score.toFixed(3)} | ${f.token_count} |`
            ).join('\n');

            const body = [
              '### Context for reviewers',
              '',
              'Files not in this diff but likely needed to understand the change:',
              '',
              '| File | Relevance | Tokens |',
              '|------|-----------|--------|',
              rows,
              '',
              `<sub>${contextFiles.length} context files selected via symbol analysis, dependency graphs, and git history. No LLM calls.</sub>`,
            ].join('\n');

            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
              body,
            });
        env:
          CHANGED_FILES: ${{ steps.diff.outputs.files }}