Init Tanstack Fastapi

Initialize TanStack Start + FastAPI Monorepo

Create a production-ready monorepo with a TanStack Start frontend and FastAPI backend.

For detailed configuration file contents, see [references/stack-details.md](references/stack-details.md).

Prerequisites

Verify these tools are installed before proceeding:

bun --version      # >= 1.2
uv --version       # >= 0.6
just --version     # >= 1.0
jj --version       # >= 0.25
lefthook --version # >= 1.0
docker --version   # >= 24.0 (optional, for production builds)

If any required tool is missing (bun, uv, just, jj, lefthook), stop and inform the user. Docker is optional — warn if missing but continue.

Step 1: Initialize Version Control

jj git init --colocate

Create .jj/.gitignore with content /* so git ignores jj metadata.

Step 2: Scaffold the Frontend

Run the shadcn create command to scaffold a TanStack Start project:

bunx --bun shadcn@latest create \
  --preset "https://ui.shadcn.com/init?base=base&style=mira&baseColor=neutral&theme=indigo&iconLibrary=lucide&font=geist&menuAccent=subtle&menuColor=default&radius=medium&template=start&rtl=false" \
  --template start \
  frontend

After scaffolding completes:

1. Remove the nested git repository created by shadcn (the project uses the root-level jj/git repo):

``bash rm -rf frontend/.git ``

1. Remove ESLint configuration if present (the project uses Biome instead):

• Delete eslint.config.js or .eslintrc.* if they exist
• Remove eslint, @eslint/*, and prettier packages from package.json devDependencies
• Remove any eslint/prettier scripts from package.json

1. Install Biome:

``bash cd frontend && bun add -d @biomejs/biome ``

1. Create frontend/biome.json with the configuration from stack-details.md section "Biome Configuration".

1. Auto-fix the scaffolded code to conform to Biome rules (formatting, imports):

``bash cd frontend && bunx biome check --write --unsafe . ``

1. Install hey-api and API client dependencies:

``bash cd frontend && bun add @hey-api/client-fetch zod @tanstack/react-query cd frontend && bun add -d @hey-api/openapi-ts vitest jsdom ``

1. Create frontend/openapi-ts.config.ts with the configuration from stack-details.md section "Hey-API Configuration".

1. Create frontend/vitest.config.ts and frontend/src/__tests__/smoke.test.ts from stack-details.md section "Frontend Test Configuration".

1. Merge these scripts into frontend/package.json (preserve existing scripts from scaffolding):

``json { "scripts": { "check": "biome check .", "check:fix": "biome check --write .", "typecheck": "tsc --noEmit", "test": "vitest run", "gen:api": "bunx --bun @hey-api/openapi-ts" } } ``

Step 3: Scaffold the Backend

1. Initialize a Python project with uv (pinned to Python 3.13 to match Docker images):

``bash uv init backend --app --python 3.13 ``

1. Add FastAPI and dependencies:

``bash cd backend && uv add "fastapi[standard]" ``

1. Add development dependencies:

``bash cd backend && uv add --dev ruff ty pytest httpx mkdocs mkdocs-material "mkdocstrings[python]" ``

1. Create the backend application structure:

`` backend/ ├── app/ │ ├── __init__.py │ ├── main.py │ └── routers/ │ ├── __init__.py │ └── health.py └── scripts/ └── generate_schema.py ``

1. Write backend/app/main.py with the starter code from stack-details.md section "FastAPI Main App".

1. Write backend/app/routers/health.py with the health check router from stack-details.md section "Health Router".

1. Create empty backend/app/__init__.py and backend/app/routers/__init__.py.

1. Write backend/scripts/generate_schema.py with the schema export script from stack-details.md section "Schema Generation Script".

1. Append the Ruff and ty configuration to backend/pyproject.toml from stack-details.md section "Ruff and ty Configuration" (includes pytest config).

1. Create test files from stack-details.md section "Backend Tests":

• backend/tests/__init__.py (empty)
• backend/tests/conftest.py
• backend/tests/test_health.py

1. Create backend/mkdocs.yml from stack-details.md section "MkDocs Configuration".

1. Create backend/docs/index.md from stack-details.md section "MkDocs Index Page".

1. Create backend/docs/api-reference.md from stack-details.md section "MkDocs API Reference".

1. Remove backend/hello.py if it was created by uv init (the app now lives in backend/app/).

Step 4: Create the Root Justfile

Create justfile in the project root with the content from stack-details.md section "Justfile".

Key recipes:

• set dotenv-load to read .env
• dev spawns frontend and backend in parallel
• dev-frontend / dev-backend for individual services
• check runs all linters, formatters, and type checkers
• gen-api generates OpenAPI client from static schema
• gen-api-live fetches schema from running backend server
• docs-serve / docs-build for backend API documentation

Step 5: Create Docker Configuration

1. Create frontend/Dockerfile from stack-details.md section "Frontend Dockerfile".
2. Create backend/Dockerfile from stack-details.md section "Backend Dockerfile".
3. Create docker-compose.yml in the project root from stack-details.md section "Docker Compose".
4. Create frontend/.dockerignore and backend/.dockerignore from stack-details.md section "Dockerignore Files".

Step 6: Create Root Configuration Files

1. Create .env.example from stack-details.md section "Environment Template".
2. Copy .env.example to .env:

``bash cp .env.example .env ``

1. Create .gitignore from stack-details.md section "Gitignore".
2. Create README.md from stack-details.md section "Project README".
3. Create .editorconfig from stack-details.md section "EditorConfig".
4. Create .vscode/extensions.json from stack-details.md section "VS Code Extensions".
5. Create .vscode/settings.json from stack-details.md section "VS Code Settings".
6. Create .github/workflows/ci.yml from stack-details.md section "GitHub Actions CI".

Step 7: Install Pre-commit Hooks

1. Create lefthook.yml at the project root from stack-details.md section "Lefthook Configuration".

1. Install the hooks:

``bash lefthook install ``

Step 8: Generate Initial API Client

cd backend && uv run python scripts/generate_schema.py
cd frontend && bun run gen:api

Step 9: Verify Everything Works

1. Run checks:

``bash just check ``

1. Run tests:

``bash just test ``

1. Run dev servers:

``bash just dev `` Verify:

• Frontend at http://localhost:3000
• Backend at http://localhost:8000
• API docs at http://localhost:8000/docs

1. Stop the dev servers after verification.

Final Project Structure

project/
├── frontend/
│   ├── app/                  # TanStack Start app directory
│   ├── public/
│   ├── src/
│   │   ├── __tests__/        # Frontend tests
│   │   └── client/           # Generated API client (gitignored)
│   ├── biome.json
│   ├── openapi-ts.config.ts
│   ├── vitest.config.ts
│   ├── package.json
│   ├── tsconfig.json
│   ├── Dockerfile
│   └── .dockerignore
├── backend/
│   ├── app/
│   │   ├── __init__.py
│   │   ├── main.py
│   │   └── routers/
│   │       ├── __init__.py
│   │       └── health.py
│   ├── tests/
│   │   ├── conftest.py
│   │   └── test_health.py
│   ├── scripts/
│   │   └── generate_schema.py
│   ├── docs/
│   │   ├── index.md
│   │   └── api-reference.md
│   ├── mkdocs.yml
│   ├── pyproject.toml
│   ├── uv.lock
│   ├── Dockerfile
│   └── .dockerignore
├── .github/
│   └── workflows/
│       └── ci.yml
├── .vscode/
│   ├── extensions.json
│   └── settings.json
├── justfile
├── lefthook.yml
├── docker-compose.yml
├── .editorconfig
├── .env.example
├── .env
├── .gitignore
└── README.md

Report the final status to the user, including any warnings or errors encountered during setup.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Ameyanagi
• Source: Ameyanagi/tanstack-start-fastapi
• License: MIT

Install and usage instructions live in the source repository linked above.