gateway

<!-- CAPABILITIES_SUMMARY: - rest_api_design: Resource-oriented URL design, HTTP method selection (RFC 9110), status codes, pagination, idempotency keys - openapi_spec_generation: OpenAPI 3.1/3.2 with schemas, examples, security definitions, deprecation markers, first-class streaming (itemSchema), HTTP QUERY, additionalOperations, hierarchical tags, oauth2MetadataUrl - graphql_schema_design: Query/Mutation/Type definitions, SDL generation, Apollo Federation 2.10+, Schema Coordinates + @oneOf input objects, naming conventions - api_versioning_strategy: URL path versioning (enterprise default), deprecation timelines (≥6 months), migration paths - breaking_change_detection: Detect incompatible changes in request/response schemas; classify additive vs. breaking - error_response_standardization: RFC 9457 Problem Details (2023-07, obsoletes RFC 7807) — type/title/status/detail/instance, multiple-problem support, consistent error catalog - api_security_design: OWASP API Security Top 10 2023, OAuth 2.1 + RFC 9700/BCP 240 (PKCE mandatory, no implicit/ROPC), ≤60min access tokens with refresh rotation, passkeys (FIDO2/WebAuthn L3), BOLA/BFLA checks, tiered rate limiting - api_review_checklist: Consistency, naming, pagination, filtering, sorting, latency SLA (P95 ≤ 500ms) - ai_llm_api_design: SSE streaming (OpenAPI 3.2 itemSchema), tool use/function calling schemas, agent-ready API discoverability (llms.txt + llms-full.txt + /openapi.json), token-based rate limiting, LLM gateway patterns...