API Contract Review

Trigger Signals

• the task changes HTTP routes, request or response shapes, headers, auth semantics, examples, or client SDKs
• the repo edits OpenAPI, AsyncAPI, Protobuf, JSON Schema, or generated contract code
• a versioning, deprecation, or compatibility question exists across providers and consumers

Inspect First

• source-of-truth specs and the runtime handlers that implement them
• schema validators, generated clients, examples, docs, and error-shape helpers
• versioning and deprecation notes, auth requirements, and pagination or idempotency behavior
• consumer code, integration tests, and release notes when a public contract changed

Workflow

1. identify the canonical contract surface and compare it to the implementation
2. classify the change by protocol: HTTP, event, schema-only, or wire-level
3. evaluate backward compatibility for required fields, enums, defaults, errors, and behavior semantics
4. verify examples, validation rules, and generated artifacts stay in sync
5. emit a consumer-centered review with specific remediation or rollout guidance

Output Contract

• changed contract summary grouped by endpoint, message, or schema
• compatibility verdict with the precise breaking edges called out
• consumer impact notes covering clients, codegen, docs, and deployment sequencing
• follow-up actions for linting, versioning, deprecation, migration guides, or tests

Failure Modes

• the runtime contract diverges from the checked-in spec and the source of truth is unclear
• examples, docs, or generated clients are stale enough that contract behavior cannot be trusted
• behavior semantics changed without any schema diff to explain it

Escalation

• escalate when a breaking change lacks versioning, deprecation, or migration guidance
• escalate when error semantics, auth requirements, or event-delivery guarantees change silently
• escalate when wire compatibility for protobuf or event consumers is uncertain

References

• skills/api-contract-review/references/http-contract-checklist.md
• skills/api-contract-review/references/schema-compatibility.md
• skills/api-contract-review/references/event-and-async-contracts.md
• skills/api-contract-review/references/protobuf-and-buf.md
• skills/api-contract-review/references/style-and-linting.md
• skills/api-contract-review/references/review-template.md
• skills/api-contract-review/references/examples.md