What it does
API Contract and SDK Agent exists for a specific failure: your documentation drifted away from your code, and the people consuming your API found out by breaking. You supply the last-known-good contract and the current one as endpoint specs, and it diffs them, tells you exactly what changed and who it hurts, and hands back fresh client SDKs. Every delta is classified against explicit rules rather than judgement. Breaking: an endpoint removed, a required parameter added or removed, a response field removed. Non-breaking: an endpoint added, an optional parameter added or removed, a response field added. From that classification it computes the semver impact and the concrete next version, so the bump follows from the diff instead of from a guess. Findings name the consequence, not just the change: "a new required parameter shippingAddress was added to POST /orders, existing callers that omit it will fail". The changelog comes back worst-first with breaking entries tagged, and alongside it a fresh OpenAPI 3.0 document and TypeScript and PHP client SDK stubs with one method per endpoint. Each step is callable alone. `classify_semver` answers "what version does this make it" without generating anything. `build_changelog` gives you release notes from the diff. `generate_sdks` regenerates clients from the current contract. `run_full` does all of it. One limitation the agent states rather than hides: schema inference in dynamically typed languages can be incomplete, so a static extraction should be verified against real runtime traffic before you rely on it alone. The diff, the classification, the semver decision and the SDK generation are all deterministic. The language model only narrates the root cause and the migration step for each finding; it never invents an endpoint, a parameter or a version number. No connectors and no credentials — it never fetches from a repository or introspects a running service. You give it the two contracts. Built for backend and platform engineers who own an API other teams depend on.
Example prompts
- Diff these two contracts and tell me what breaks for consumers
- What semver bump does this API change require?
- Generate TypeScript and PHP client SDKs from the current contract
