ci-emitter-diff-python.yml

name: "python / emitter diff"

# Diffs generated code between this PR's emitter and the merge-base baseline.
# Informational only: reports a sticky PR comment + HTML artifact, and fails the
# job only on a tool/build error (never on a diff). See eng/emitter-diff.
#
# The tool runs `npm run regenerate` verbatim in each tree. It auto-prepares the
# baseline tree it fetches from GitHub (via the preset's --setup: install +
# build + venv), so this workflow only builds the head (PR) emitter itself.

on:
  pull_request:
    branches: [main, release/*]
    paths:
      - "packages/http-client-python/**"
      - "eng/emitter-diff/**"
      - ".github/workflows/ci-emitter-diff-python.yml"
  workflow_dispatch:
    inputs:
      baseline:
        description: "Baseline emitter ref (local path or github ref). Defaults to the PR merge-base. A gh:/github: ref is fetched and auto-prepared (install + build) by the tool; a local: path is used as-is."
        required: false
        default: ""

permissions:
  contents: read
  pull-requests: write

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  emitter-diff:
    name: "Generate & Diff"
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6
        with:
          fetch-depth: 0
      - uses: ./.github/actions/setup
      - uses: actions/setup-python@v5
        with:
          python-version: "3.12"

      - name: Install repo dependencies
        run: pnpm install

      - name: Determine baseline
        id: baseline
        # Dispatch input is untrusted: pass via env, reference only as "$VAR".
        env:
          BASELINE_INPUT: ${{ github.event.inputs.baseline || '' }}
          BASE_REF: ${{ github.event.pull_request.base.ref || github.event.repository.default_branch }}
        run: |
          input="$BASELINE_INPUT"
          if [ -n "$input" ]; then
            echo "ref=$input" >> "$GITHUB_OUTPUT"
            echo "Baseline (explicit): $input"
          else
            # merge-base = a real commit on the base branch; survives squash/rebase.
            git fetch --no-tags origin "$BASE_REF"
            base_sha="$(git merge-base FETCH_HEAD HEAD)"
            [ -n "$base_sha" ] || { echo "::error::No merge-base with $BASE_REF."; exit 1; }
            # gh:<sha> = this repo at the merge-base. The tool fetches that tree
            # and auto-preps it (install + build + venv) via the preset's --setup.
            echo "ref=gh:$base_sha" >> "$GITHUB_OUTPUT"
            echo "Baseline (merge-base): gh:$base_sha"
          fi

      - name: Prepare head emitter (build + venv)
        working-directory: packages/http-client-python
        # http-client-python is excluded from the pnpm workspace (standalone,
        # registry-versioned deps), so the repo-level `pnpm install` above does
        # NOT provision its node_modules. Install them first (scripts skipped),
        # then `npm run setup` (build + venv). Mirrors the baseline tree prep the
        # tool does via the python preset's --setup.
        run: |
          npm install --ignore-scripts
          npm run setup

      - name: Run emitter diff
        id: diff
        working-directory: packages/http-client-python
        env:
          BASELINE_REF: ${{ steps.baseline.outputs.ref }}
          RUNNER_TEMP: ${{ runner.temp }}
        run: |
          set +e
          # No --fail-on-diff (informational); tool/build errors still exit non-zero
          # (checked in "Fail on tool error").
          npm run diff-spector-tests -- \
            --ci \
            --baseline "$BASELINE_REF" \
            --html "$RUNNER_TEMP/emitter-diff.html" \
            | tee "$RUNNER_TEMP/emitter-diff.log"
          echo "status=${PIPESTATUS[0]}" >> "$GITHUB_OUTPUT"
          # Reuse the tool's own summary line (strip ANSI) instead of re-parsing.
          summary="$(sed -r 's/\x1b\[[0-9;]*m//g' "$RUNNER_TEMP/emitter-diff.log" \
            | grep -oE 'Diff summary: [0-9]+ file\(s\), \+[0-9]+ / -[0-9]+' | head -1)"
          echo "summary=${summary:-No changes to generated output.}" >> "$GITHUB_OUTPUT"

      - name: Upload HTML diff
        if: always()
        uses: actions/upload-artifact@v7
        with:
          name: emitter-diff-html
          path: ${{ runner.temp }}/emitter-diff.html
          if-no-files-found: ignore
          retention-days: 7

      - name: Comment on PR
        if: always() && github.event_name == 'pull_request'
        continue-on-error: true
        uses: actions/github-script@v7
        env:
          BASELINE: ${{ steps.baseline.outputs.sha || steps.baseline.outputs.ref }}
          STATUS: ${{ steps.diff.outputs.status }}
          SUMMARY: ${{ steps.diff.outputs.summary }}
        with:
          script: |
            const marker = "<!-- emitter-diff-python -->";
            const runUrl = `${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions/runs/${context.runId}`;
            const { STATUS, SUMMARY, BASELINE } = process.env;
            let body = `${marker}\n### Python emitter diff\nBaseline \`${BASELINE}\` vs this PR.\n\n`;
            body += STATUS !== "0"
              ? `⚠️ **emitter-diff failed** (exit \`${STATUS}\`) — tool/build error, not a diff. See the [run](${runUrl}).\n`
              : `${SUMMARY}\n\nFull rendered diff: **emitter-diff-html** artifact on the [run](${runUrl}).\n`;
            body += `\n_Informational check (eng/emitter-diff); does not block the PR._`;
            const { owner, repo } = context.repo, issue_number = context.issue.number;
            const { data } = await github.rest.issues.listComments({ owner, repo, issue_number });
            const hit = data.find((c) => c.body && c.body.includes(marker));
            if (hit) await github.rest.issues.updateComment({ owner, repo, comment_id: hit.id, body });
            else await github.rest.issues.createComment({ owner, repo, issue_number, body });

      - name: Fail on tool error
        if: always()
        env:
          STATUS: ${{ steps.diff.outputs.status }}
        run: '[ "$STATUS" = "0" ] || { echo "::error::emitter-diff failed (exit $STATUS)."; exit 1; }'