FastAPI Architecture Rules

This skill is the definitive source for FastAPI architecture rules. Any agent (architect, dev, or otherwise) should load this skill for authoritative rules on routes, services, models, utils, and monorepo layout.

Step 0: Detect Layout

Before auditing or implementing, determine which layout the project uses:

Monorepo — if any of these are true:

• Root pyproject.toml contains [tool.uv.workspace]
• An apps/ directory and a packages/ directory both exist at the root

Standalone — otherwise (single src/{project}/ layout)

State the detected layout at the top of your report.