agentic-jumpstart-starter-kit

Enforce the layered architecture in this TanStack Start app — routes/components/hooks/queries call server functions in `src/fn/`, which call use cases or data access; only `src/data-access/` touches Drizzle/the database. Use when adding or modifying any feature that crosses the client→server→DB boundary, creating files in `src/routes/`, `src/components/`, `src/hooks/`, `src/queries/`, `src/fn/`, `src/use-cases/`, or `src/data-access/`, or when reviewing where a new function belongs. Trigger phrases: "add a feature", "create endpoint", "new server function", "fetch data", "save to database", "where does this go".