fullstack-starter/AGENTS.md

AGENTS.md - AI Coding Agent Guidelines

This document provides comprehensive guidelines for AI coding agents working in this TanStack Start fullstack starter codebase.

Project Overview

• Framework: TanStack Start (React SSR framework with file-based routing)
• Runtime: Bun
• Language: TypeScript (strict mode, ESNext)
• Styling: Tailwind CSS v4
• Database: PostgreSQL with Drizzle ORM
• State Management: TanStack Query
• Routing: TanStack Router (file-based)
• Build Tool: Vite
• Linter/Formatter: Biome

Build, Lint, and Test Commands

Development

bun dev                    # Start development server
bun db:studio              # Open Drizzle Studio for database management

Building

bun build                  # Build for production (outputs to .output/)
bun compile                # Compile to standalone executable (out/server)
bun serve                  # Preview production build

Code Quality

bun typecheck              # Run TypeScript compiler (tsc -b)
bun fix                    # Run Biome linter and formatter (auto-fix issues)
biome check .              # Check without auto-fix
biome format --write .     # Format code only

Database

bun db:generate            # Generate migration files from schema
bun db:migrate             # Run migrations
bun db:push                # Push schema changes directly (dev only)

Testing

Note: No test framework is currently configured. When adding tests:

• Use Vitest or Bun's built-in test runner
• Run single test file: bun test path/to/test.ts
• Run specific test: bun test -t "test name pattern"

Code Style Guidelines

Formatting (Biome)

Indentation: 2 spaces (not tabs) Line Endings: LF (Unix-style) Quotes: Single quotes for strings Semicolons: As needed (ASI - automatic semicolon insertion) Arrow Parens: Always use parentheses (x) => x

Example:

const myFunc = (value: string) => {
  return value.toUpperCase()
}

Import Organization

Imports are auto-organized by Biome. Order:

1. External dependencies
2. Internal imports using @/* alias
3. Type imports (use type keyword when importing only types)

Example:

import { createFileRoute } from '@tanstack/react-router'
import { createServerFn } from '@tanstack/react-start'
import { db } from '@/db'
import type { ReactNode } from 'react'

TypeScript

Strict Mode: Enabled with additional strictness flags

• strict: true
• noUncheckedIndexedAccess: true - Array/object indexing returns T | undefined
• noImplicitOverride: true
• noFallthroughCasesInSwitch: true

Module Resolution: bundler mode with verbatimModuleSyntax

• Always use .ts/.tsx extensions in imports
• Use @/* path alias for src/*

Type Annotations:

• Always annotate function parameters and return types for public APIs
• Prefer explicit types over any
• Use type for object shapes, interface for extendable contracts
• Use Readonly<T> for immutable props

Example:

function getTodos(): Promise<Todo[]> {
  return db.query.todoTable.findMany()
}

type Props = Readonly<{
  children: ReactNode
}>

Naming Conventions

• Files: kebab-case for utilities, PascalCase for components
  • utils.ts, todo.tsx, NotFound.tsx
• Routes: Use TanStack Router conventions
  • routes/index.tsx → /
  • routes/todo.tsx → /todo
  • routes/__root.tsx → Root layout
• Components: PascalCase function declarations
• Functions: camelCase
• Constants: UPPER_SNAKE_CASE for true constants, camelCase for config objects
• Types/Interfaces: PascalCase

React Patterns

Components: Use arrow functions (enforced by Biome rule useArrowFunction)

const MyComponent = ({ title }: { title: string }) => {
  return <div>{title}</div>
}

Server Functions: Use TanStack Start's createServerFn

const getTodos = createServerFn({ method: 'GET' }).handler(async () => {
  const todos = await db.query.todoTable.findMany()
  return todos
})

Routing: Use createFileRoute for route definitions

export const Route = createFileRoute('/todo')({
  component: Todo,
})

Data Fetching: Use TanStack Query hooks

• useSuspenseQuery for guaranteed data
• useQuery when data might be optional

Props: No direct prop mutations (enforced by noReactPropAssignments)

Database Schema (Drizzle)

• Define schemas in src/db/schema/*.ts
• Export from src/db/schema/index.ts
• Use PostgreSQL types from drizzle-orm/pg-core
• Use uuidv7() for primary keys (requires PostgreSQL extension)
• Always include createdAt and updatedAt timestamps

Example:

import { pgTable, text, timestamp, uuid } from 'drizzle-orm/pg-core'
import { sql } from 'drizzle-orm'

export const myTable = pgTable('my_table', {
  id: uuid('id').primaryKey().default(sql`uuidv7()`),
  name: text('name').notNull(),
  createdAt: timestamp('created_at', { withTimezone: true })
    .notNull()
    .defaultNow(),
  updatedAt: timestamp('updated_at', { withTimezone: true })
    .notNull()
    .defaultNow()
    .$onUpdateFn(() => new Date()),
})

Environment Variables

• Use @t3-oss/env-core for type-safe env validation
• Define schema in src/env.ts
• Server vars: No prefix
• Client vars: Must have VITE_ prefix
• Always validate with Zod schemas

Error Handling

• Use try-catch for async operations
• Throw errors with descriptive messages
• Prefer Result types or error boundaries for user-facing errors
• Log errors appropriately (avoid logging sensitive data)

Styling (Tailwind CSS)

• Use Tailwind v4 utility classes
• Import styles via @/styles.css?url
• Prefer composition over custom CSS
• Use responsive modifiers: sm:, md:, lg:
• Use Chinese text for UI when appropriate (as seen in codebase)

File Structure

src/
├── components/         # Reusable React components
├── db/
│   ├── schema/        # Drizzle schema definitions
│   └── index.ts       # Database instance
├── lib/               # Utility functions
├── routes/            # TanStack Router file-based routes
│   ├── __root.tsx     # Root layout
│   └── index.tsx      # Home page
├── env.ts             # Environment variable validation
├── index.ts           # Application entry point
├── router.tsx         # Router configuration
├── routeTree.gen.ts   # Auto-generated (DO NOT EDIT)
└── styles.css         # Global styles

Important Notes

• DO NOT edit src/routeTree.gen.ts - it's auto-generated
• DO NOT commit .env files - use .env.example for templates
• DO run bun fix before committing to ensure code quality
• DO use the @/* path alias instead of relative imports
• DO leverage React Compiler (babel-plugin-react-compiler) - avoid manual memoization

Git Workflow

1. Make changes following the style guidelines above
2. Run bun fix to auto-format and lint
3. Run bun typecheck to ensure type safety
4. Test changes locally with bun dev
5. Commit with clear, descriptive messages

Common Patterns

Adding a New Route

1. Create src/routes/my-route.tsx
2. Export route with createFileRoute
3. Route tree auto-updates on save

Adding Database Table

1. Create schema in src/db/schema/my-table.ts
2. Export from src/db/schema/index.ts
3. Run bun db:generate to create migration
4. Run bun db:migrate to apply migration

Creating Server Function

const myServerFn = createServerFn({ method: 'POST' })
  .validator((data) => mySchema.parse(data))
  .handler(async ({ data }) => {
    // Server-side logic here
    return result
  })

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Last Updated: 2026-01-17 Project Version: Based on package.json dependencies