API005warningPro

api-type-alignment

Backend endpoints should have response_model; frontend should use generated types.

Applies to: Python, TypeScript

Why this matters

When backend endpoints lack response_model, the OpenAPI spec can't generate TypeScript types. This forces frontend to define inline types that drift from the actual API response shape, causing runtime errors. Use response_model on all endpoints and import generated types in frontend.

Catch it before it ships

pip install stablestack # or: npx stablestackstablestack # scans your project, API005 includedstablestack explain API005

API005 is part of the Pro rule set. See pricing — the free tier ships 24 checks with no signup.

False positive in your codebase? Suppress a single line with # noqa: API005

More API Contracts checks

unhandled-api-error

API calls without error handling will crash on network failures

inconsistent-api-naming

Mixed naming conventions (snake_case/camelCase) in API code cause bugs

missing-content-type

POST/PUT requests without Content-Type may fail or be misinterpreted

hardcoded-api-url

Hardcoded API URLs make it hard to switch between environments

cross-file-type-mismatch

Cross-file type mismatch between API endpoint and client call site.

untyped-api-response

API endpoint has no typed response — consumers can't rely on the response shape.