TanStack Start Project Structure

Standard TanStack Start project structure I use for my projects, can be copied into a CLAUDE.md/AGENTS.md file for agents to follow.

Project Structure

• src/lib contains the project's library code, grouped by domain via this naming convention (e.g. for a todos domain):
  • todos.server.ts - server-only code, usually paired with todos.server.test.ts to unit test it.
  • todos.functions.ts - a thin wrapper exposing server functions, importing from todos.server.ts.
    • Exported server functions should be named with the Fn suffix, e.g. getTodosFn, createTodoFn, etc.
      • This makes it clearer what is a server function and what isn't
  • todos.schemas.ts - Zod schemas for data entering the domain from outside your code
    • e.g. server function inputs, form validation, third-party data at the point it's fetched
  • todo.types.ts - plain types for everything else
    • e.g. component props, internal state, and function outputs your own code already trusts
  • todos.ts - isomorphic code that can run on either the client or server (e.g. date helpers), usually paired with todos.test.ts to unit test it.