Nitro

Owns the static-build contract that emits apps/<app>/dist/client/ for upload to GitHub Pages. There is no apps/<app>/nitro.config.ts file in dean-stack — Nitro v3 is driven internally by TanStack Start's Vite plugin via tanstackStart({ spa: …, prerender: … }). This skill owns the GH-Pages-specific concerns layered on top.

When to invoke

• Touching .github/workflows/deploy.yml, apps/<app>/package.json's build script, or apps/<app>/vite.config.ts's base resolution.
• Adding or fixing the BASE_PATH env contract for project pages / user-org pages / custom domains.
• Diagnosing a missing 404.html, missing .nojekyll, or 404'd asset paths in the deployed site.
• Deciding which app in the monorepo gets published.

Owns

• The BASE_PATH env contract — the single channel that drives Vite's base and therefore every emitted asset URL. Set canonically by actions/configure-pages@v5's base_path output in CI.
• The post-Vite-build steps that turn dist/client/ into a GH-Pages-compliant payload: cp dist/client/index.html dist/client/404.html for the SPA fallback, touch dist/client/.nojekyll for the Jekyll opt-out marker.
• The deploy workflow's APP selector — inputs.app (workflow_dispatch) → vars.PAGES_APP (repo var fallback) → web (default), feeding both the Turbo filter and the upload path.
• The prerender.failOnError: true invariant — a missing prerender route fails CI (Pillar 4).

Defers to

• tanstack-start-spa-prerender (Wave 3, forward) — for the application-level SPA + prerender switch (tanstackStart({ spa: { enabled: true, prerender: { outputPath: "/index" } }, prerender: { enabled: true, crawlLinks: true } })).
• tanstack-router-pwa-deep-links (Wave 3, forward) — for the Workbox navigation-fallback contract that resolves deep links offline against the prerendered shell.
• vite — for vite.config.ts's resolveBase() helper that consumes BASE_PATH.
• turborepo — for turbo run build --filter=@dean-stack/<app> task ordering and the build cache.
• bun-runtime — for invoking bun run build and bun install --frozen-lockfile in CI.

Dean-stack rules

• There is no apps/<app>/nitro.config.ts. TanStack Start's Vite plugin owns Nitro configuration. Don't introduce a standalone Nitro config — it duplicates and races with the framework-level config.
• The static artifact lives at apps/<app>/dist/client/, NOT .output/public/. Vite writes there directly via TanStack Start's SPA + prerender pipeline. The apps/<app>/package.json build script is vite build && cp dist/client/index.html dist/client/404.html && touch dist/client/.nojekyll — that's the entire post-build contract.
• Pillar 4 (CLI-gate-first): the build is part of bun run build and any prerender error MUST fail the gate (tanstackStart({ prerender: { failOnError: true } })).
• The deploy workflow MUST drive BASE_PATH from actions/configure-pages@v5's base_path output — never hardcode /dean-stack/ or any repo name. The output is /<repo> for project pages and / (or empty) for user-org pages and custom domains. vite.config.ts's resolveBase() normalizes the trailing slash.
• The package is nitro (v3), not nitropack (v2). Imports come from nitro / nitro/vite / nitro/storage if you ever need them — but you generally won't, because TanStack Start mediates.
• The deploy workflow publishes ONE app per run. The selector is inputs.app (workflow_dispatch) → vars.PAGES_APP → 'web'. To publish a different app, either trigger workflow_dispatch with app: <name> or set the PAGES_APP repo variable.

Patterns

apps/<app>/vite.config.ts — base-path resolver

function resolveBase(): string {
  const raw = process.env.BASE_PATH;
  if (!raw || raw === "/") return "/";
  return raw.endsWith("/") ? raw : `${raw}/`;
}

export default defineConfig(async ({ mode }) => {
  Object.assign(process.env, loadEnv(mode, process.cwd(), ""));
  await import("./app/env");
  return {
    base: resolveBase(),
    plugins: [
      tanstackStart({
        srcDirectory: "app",
        spa: { enabled: true, prerender: { outputPath: "/index" } },
        prerender: {
          enabled: true,
          crawlLinks: true,
          autoSubfolderIndex: true,
          failOnError: true,
        },
      }),
      // ... VitePWA, Tailwind, etc.
    ],
  };
});

Local dev: BASE_PATH unset → /. CI: BASE_PATH=/dean-stack (project pages) → /dean-stack/. Custom domain: BASE_PATH=/ (or unset) → /.

apps/<app>/package.json — build script

"build": "vite build && cp dist/client/index.html dist/client/404.html && touch dist/client/.nojekyll"

The cp provides the SPA fallback GH Pages serves on any 404. The touch .nojekyll opts out of Jekyll's underscore-folder stripping (Vite emits _metadata.json and similar). Both are load-bearing.

.github/workflows/deploy.yml — selector + base path + upload

on:
  push: { branches: [main] }
  workflow_dispatch:
    inputs:
      app:
        description: "App to publish (folder name under apps/)"
        required: false
        default: web
        type: string

env:
  APP: ${{ github.event.inputs.app || vars.PAGES_APP || 'web' }}

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with: { node-version-file: ".nvmrc" }
      - uses: oven-sh/setup-bun@v2
        with: { bun-version-file: "package.json" }

      - id: pages
        uses: actions/configure-pages@v5

      - run: bun install --frozen-lockfile
      - run: bunx playwright install --with-deps chromium

      # Pillar 4 — gate runs BEFORE the prod build, so we never deploy
      # code that fails lint/types/unit/e2e. This is the only CI surface
      # that runs on push to main; check.yml is PR-only.
      - run: bun run check

      - name: Build ${{ env.APP }}
        env:
          BASE_PATH: ${{ steps.pages.outputs.base_path }}
        run: bun run build --filter=@dean-stack/${{ env.APP }}

      - name: Verify SSG output
        run: |
          set -euo pipefail
          dir="apps/${APP}/dist/client"
          test -f "$dir/index.html" && test -f "$dir/404.html" && test -f "$dir/.nojekyll"

      - uses: actions/upload-pages-artifact@v3
        with:
          path: apps/${{ env.APP }}/dist/client

The actions/configure-pages@v5 step runs before the build so BASE_PATH is in scope. Its base_path output is GitHub's canonical answer — handles project pages, user-org pages, and custom domains without local logic. Use upload-pages-artifact@v3 and deploy-pages@v4 — older revs no longer pass the deploy gate.

Add a route to the prerender list

Crawled links from the home page are picked up automatically (crawlLinks: true). For routes the crawler can't reach (islands, dynamic links), pass them explicitly via TanStack Start's prerender.routes:

tanstackStart({
  prerender: {
    enabled: true,
    crawlLinks: true,
    failOnError: true,
    routes: ["/games/maze", "/games/maze/level-1"],
  },
});

Custom domain (no project base path)

Set the custom domain in repo settings → Pages. actions/configure-pages@v5 will then return an empty base_path, BASE_PATH is unset/empty in the build env, and resolveBase() returns /. No code change required.

Anti-patterns

• Don't create apps/<app>/nitro.config.ts — TanStack Start drives Nitro; a standalone config duplicates and races with framework-level config.
• Don't reference .output/public — that's the upstream Nitro doc default, but TanStack Start's SPA mode writes to dist/client/ instead. The deploy workflow uploads from apps/<app>/dist/client/, not .output/public/.
• Don't import from nitropack — that's v2; v3 is nitro / nitro/vite / nitro/storage.
• Don't hardcode /dean-stack/ (or any repo name) in vite.config.ts's base. The base must come from BASE_PATH so the workflow is portable across forks, renames, custom domains, and user-org pages.
• Don't omit the cp index.html → 404.html step — without it, GH Pages serves its own ugly 404 on deep links instead of the SPA shell.
• Don't omit touch .nojekyll — without it, Jekyll on Pages strips folders that start with _ (Vite emits these) and the deploy silently breaks.
• Don't introduce serverHandlers, routeRules.cache, routeRules.swr, routeRules.proxy, or useStorage — there is no server on GH Pages; these silently no-op or break the build.
• Don't set prerender.failOnError: false to make a build pass — the missing route is the bug, fix the route.
• Don't trust upstream Nitro doc YAML verbatim — its actions/upload-pages-artifact@v1 and actions/deploy-pages@v1 revs are stale and fail the deploy gate. Use @v3 / @v4.

Triggers on

nitro, github_pages, BASE_PATH, baseURL, prerender, SPA fallback 404, .nojekyll, GH Pages deploy, dist/client, configure-pages, deploy-pages, upload-pages-artifact