cross-file-type-mismatch
Cross-file type mismatch between API endpoint and client call site.
Applies to: Project-level
Why this matters
When API endpoints and their clients define types independently, the types drift apart over time. A field added on the backend but not the frontend (or vice versa) causes runtime errors. Use shared type definitions or code generation to keep both sides in sync.
Catch it before it ships
pip install stablestack # or: npx stablestackstablestack # scans your project, API006 includedstablestack explain API006API006 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: API006
More API Contracts checks
unhandled-api-error
API calls without error handling will crash on network failures
API002inconsistent-api-naming
Mixed naming conventions (snake_case/camelCase) in API code cause bugs
API003missing-content-type
POST/PUT requests without Content-Type may fail or be misinterpreted
API004hardcoded-api-url
Hardcoded API URLs make it hard to switch between environments
API005api-type-alignment
Backend endpoints should have response_model; frontend should use generated types.
API007untyped-api-response
API endpoint has no typed response — consumers can't rely on the response shape.