assistant-ui--assistant-ui/.github/workflows/template-metrics.yaml

name: Template Metrics

on:
  push:
    branches: [main]
    paths:
      - "templates/**"
      - "packages/ui/**"
  pull_request:
    branches: [main]
    paths:
      - "templates/**"
      - "packages/ui/**"

permissions:
  contents: read
  pull-requests: write

concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
  cancel-in-progress: true

env:
  # Templates to build for bundle-size measurement. LOC is measured for all
  # templates regardless; only these are built (next build is the expensive part).
  BUNDLE_TEMPLATES: "default minimal"
  # Per-template regression limits. A template that already exists on the main
  # baseline fails the gate if it grows past either limit.
  MAX_LOC_INCREASE: "50"
  MAX_BUNDLE_INCREASE_KB: "10"

jobs:
  metrics:
    name: LOC + Bundle Size
    runs-on: blacksmith-4vcpu-ubuntu-2404
    timeout-minutes: 20
    steps:
      - name: Checkout code repository
        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # ratchet:actions/checkout@v6
        with:
          fetch-depth: 0

      - name: Install pnpm
        uses: pnpm/action-setup@b906affcce14559ad1aafd4ab0e942779e9f58b1 # ratchet:pnpm/action-setup@v4

      - name: Setup node.js
        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # ratchet:actions/setup-node@v6
        with:
          node-version: 24
          cache: "pnpm"

      - name: Cache turbo build setup
        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # ratchet:actions/cache@v4
        with:
          path: .turbo
          key: ${{ runner.os }}-turbo-${{ github.ref }}-${{ github.sha }}
          restore-keys: |
            ${{ runner.os }}-turbo-${{ github.ref }}-
            ${{ runner.os }}-turbo-

      # Baseline is main's metrics, cached by the last run on main. PRs restore
      # the newest one via the restore-keys prefix to compute deltas against main.
      - name: Restore main baseline
        uses: actions/cache/restore@0057852bfaa89a56745cba8c7296529d2fc39830 # ratchet:actions/cache/restore@v4
        with:
          path: install-footprint/branch/main/data.json
          key: install-footprint-main-${{ github.sha }}
          restore-keys: install-footprint-main-

      - name: Install dependencies
        run: pnpm install --frozen-lockfile

      - name: Build templates (bundle subset)
        env:
          # next build needs these public vars defined; values are placeholders.
          NEXT_PUBLIC_ASSISTANT_BASE_URL: "https://example.com"
          NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY: "pk_test_placeholder"
          NEXT_TELEMETRY_DISABLED: "1"
        run: |
          filters=""
          for t in $BUNDLE_TEMPLATES; do
            filters="$filters --filter=./templates/$t"
          done
          # turbo pulls in the @assistant-ui/* workspace deps each template needs.
          pnpm turbo build $filters

      - name: Measure metrics
        run: node scripts/template-metrics.mjs measure . metrics-head.json

      - name: Build report
        run: |
          node scripts/template-metrics.mjs report install-footprint/branch/main/data.json metrics-head.json metrics-report.md metrics-gate.txt metrics-comment.txt
          cat metrics-report.md

      # continue-on-error: a fork PR's read-only token makes commenting 403; that
      # must not fail the check or skip the gate below.
      - name: Post / update PR comment
        if: github.event_name == 'pull_request'
        continue-on-error: true
        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # ratchet:actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const body = fs.readFileSync('metrics-report.md', 'utf8');
            const marker = '<!-- template-metrics -->';
            // paginate: a long PR thread can push the sticky comment past the
            // first 30, and missing it would post a duplicate on every re-run.
            const comments = await github.paginate(github.rest.issues.listComments, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
            });
            const existing = comments.find((c) => c.body?.includes(marker));
            const shouldCreate = fs.readFileSync('metrics-comment.txt', 'utf8').trim() === 'post';
            if (!existing && !shouldCreate) {
              console.log('No LOC changes; skipping template metrics comment.');
              return;
            }
            if (existing) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: existing.id,
                body,
              });
            } else {
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body,
              });
            }

      # always(): run even if the comment step failed (e.g. fork 403), so the
      # gate verdict is never lost. Only blocks PRs; pushes refresh the baseline.
      - name: Enforce regression gate
        if: always() && github.event_name == 'pull_request'
        run: |
          if [ "$(cat metrics-gate.txt 2>/dev/null)" = "fail" ]; then
            echo "::error::Template metrics regressed past the configured limits. See the PR comment."
            exit 1
          fi
          echo "Template metrics within limits."

      - name: Persist baseline (main only)
        if: github.event_name == 'push'
        run: |
          mkdir -p install-footprint/branch/main
          cp metrics-head.json install-footprint/branch/main/data.json

      - name: Save baseline cache (main only)
        if: github.event_name == 'push'
        uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # ratchet:actions/cache/save@v4
        with:
          path: install-footprint/branch/main/data.json
          key: install-footprint-main-${{ github.sha }}