API Contract Verification

Compare an API specification (OpenAPI, GraphQL schema, protobuf) against the actual implementation, flag drift, and optionally generate fixes.

Workflow

runPipeline(
  all(parseAPISpec, analyzeImplementation)
    .then(compareContracts)
    .then(iterate().map(classifyDrift).collect())
    .then(branch({
      Breaking: iterate().map(generateFix).collect(),
      NonBreaking: drop,
    })),
);

Stages

1. Parallel extraction — parse the API spec and analyze the implementation concurrently.
2. Compare — diff the declared contract against the actual behavior. Output: list of discrepancies.
3. Classify — for each discrepancy, determine if it's a breaking change or non-breaking drift.
4. Fix breaking changes — generate patches for breaking discrepancies. Non-breaking drift is logged but not fixed.

Key points

• The spec parser is deterministic (no LLM) — it reads the OpenAPI/protobuf file and outputs structured data.
• The implementation analyzer uses an LLM to read route handlers and extract the actual request/response shapes.
• .iterate().map() processes all discrepancies concurrently.
• The fix generator sees one discrepancy at a time with focused context.