AI coding assistants still reach for FastAPI patterns from a few years ago: .dict() , orm_mode , session.query() , HTTPException raised deep inside service code, SQLite in tests. The code runs, but it isn't the code you'd write today. Cursor's project rules fix most of this. A rule is a small .mdc file in .cursor/rules/ with a glob, so it loads only when you edit matching files: --- description : " FastAPI routers, dependencies and Pydantic v2 s...