api-design

When this skill is invoked:

1. Read the target API spec or route files in full.

For API design in an existing domain, SHOULD also inspect docs/technical/API.md, related design/specs/, related design/contracts/ if present, and recent relevant ledger entries via /trace-history. This is advisory unless the change is an ADR, coordination-rule change, high-risk retry, or protocol removal.

1. Identify the API type (REST, GraphQL, WebSocket) and apply appropriate standards.

1. Evaluate REST design quality (if REST):
2. [ ] Resources use nouns, not verbs (/users, not /getUsers)
3. [ ] Correct HTTP methods (GET=read, POST=create, PUT/PATCH=update, DELETE=remove)
4. [ ] Consistent plural resource naming (/users, /orders)
5. [ ] Nested resources have max 2-3 levels of depth
6. [ ] Query parameters used for filtering, sorting, pagination (not in path)

1. Evaluate request/response schemas:
2. [ ] All inputs are validated and typed
3. [ ] Responses are consistent in structure (envelope format if used)
4. [ ] Pagination is consistent (cursor or page-based, not mixed)
5. [ ] Timestamps in ISO 8601 (UTC)
6. [ ] Money values in smallest currency unit (cents), not floats

1. Evaluate authentication & authorization:
2. [ ] Every endpoint has explicit auth requirement documented
3. [ ] Authorization is checked server-side, not just on the client
4. [ ] Sensitive data not leaked in error messages

1. Evaluate error responses:
2. [ ] Consistent error format (RFC 7807 Problem Details recommended)
3. [ ] HTTP status codes used correctly (400 for client errors, 500 for server)
4. [ ] Error messages are user-safe (no stack traces, SQL errors)

1. Evaluate versioning & backward compatibility:
2. [ ] Breaking changes require a version bump
3. [ ] Deprecation policy documented
4. [ ] Clients can negotiate API version

1. Output the review:

## API Design Review: [API/Endpoint Name]

### REST Design: [CLEAN / ISSUES FOUND]
[List specific issues with examples]

### Schema Quality: [CLEAN / ISSUES FOUND]
[List schema inconsistencies or problems]

### Auth & Security: [SECURE / ISSUES FOUND]
[List authentication and authorization issues]

### Error Handling: [CONSISTENT / ISSUES FOUND]
[List error response problems]

### Versioning: [HANDLED / UNADDRESSED]
[Notes on breaking change risk]

### Positive Observations
[What is well-designed]

### Required Changes
[Must-fix items before shipping]

### Suggestions
[Nice-to-have improvements]

### Verdict: [APPROVED / APPROVED WITH SUGGESTIONS / CHANGES REQUIRED]

Protocol

• Question: Auto-starts from argument (path to API spec or route files); no clarification needed
• Options: Skip — single review path
• Decision: Skip — verdict is advisory
• Draft: Full review report shown in conversation only
• Approval: Skip — read-only; no files written

Output

Deliver exactly:

• Endpoint compliance score (X/Y checks passing across naming, methods, validation, errors)
• Security issues with severity — CRITICAL / HIGH / MEDIUM (or "None")
• Required changes — must fix before shipping (or "None")
• Verdict: APPROVED / APPROVED WITH SUGGESTIONS / CHANGES REQUIRED