api
Use when designing, reviewing, or changing an HTTP, REST, or GraphQL API — endpoints, resource naming, error responses, pagination, versioning, idempotency, or API contracts between services.
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- Repository
- xoai/sage
- Last source activity
- October 26, 2026 at 08:51
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- English
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- 31
- Forks
- 5
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Source instructions · Read-only preview- name
- api
- description
- Use when designing, reviewing, or changing an HTTP, REST, or GraphQL API — endpoints, resource naming, error responses, pagination, versioning, idempotency, or API contracts between services.
- version
- 2.0.0
- type
- knowledge
- layer
- domain
- requires
- {"sage":">=1.0.0"}
- activates-when
- {"detected":["express","fastify","koa","hono","django","flask","rails","spring","gin","echo","actix-web","axum"]}
- tags
- ["express","fastify","koa","hono","django"]
# api
**Layer 1 — Domain Foundation (v2.0)**
Corrects the 13 most common API design mistakes agents make, grounded in
5 authoritative sources:
- **Geewax** (API Design Patterns) — cursor pagination, error structure, idempotency, request deduplication
- **Amundsen** (RESTful Web API Cookbook) — PUT for idempotent creates, HTTP method semantics
- **Ousterhout** (Philosophy of Software Design) — information hiding, define errors out of existence, different layer/different abstraction
- **Kleppmann** (Designing Data-Intensive Applications) — network failures are normal, batch processing, data integrity
- **Gough/Bryant** (Mastering API Architecture) — schema validation, API lifecycle, backward compatibility, deprecation
## What's Included
| Type | Count | Coverage |
|------|-------|----------|
| Patterns | 13 | Error envelope, input validation, cursor pagination, batch queries, auth-first, URL conventions, rate limiting, idempotent writes, separate representation, versioning, HTTP status codes, structured logging, health endpoints |
| Anti-patterns | 9 | Inconsistent errors, trusting input, returning all records, N+1 loops, bolt-on auth, non-idempotent creates, leaking DB internals, 200-with-error-body, no versioning plan |
| Constitution | 11 | principles |
Every pattern includes code examples showing wrong vs right approaches.
Every anti-pattern includes root cause explaining WHY agents default to the wrong behavior.
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