API Documentation Generator

Scans the codebase for API endpoints and generates structured documentation.

When to Use

• After Sprint Phase 3 [3c] when new endpoints are implemented
• Before Release Phase 5 as part of documentation checklist
• When user explicitly requests API documentation
• When onboarding new developers who need endpoint reference

Capabilities

1. Endpoint Detection

Automatically detect API routes from common patterns:

Framework	Detection Pattern
Express	app.get/post/put/delete(), router.get/post/put/delete()
Next.js App Router	app/api/**/route.ts — export GET/POST/PUT/DELETE
Next.js Pages Router	pages/api/**/*.ts
FastAPI	@app.get/post/put/delete() decorators
Django REST	urlpatterns, ViewSet classes
Flask	@app.route() decorators
Hono	app.get/post/put/delete()
tRPC	router.query/mutation()

2. Schema Extraction

For each endpoint, extract:

• Request parameters (path, query, body)
• Request body schema (from TypeScript types, Zod schemas, Pydantic models)
• Response schema (from return types)
• Authentication requirements
• Error responses

3. Output Formats

Markdown (default)

## POST /api/invoices

Create a new invoice.

**Authentication:** Bearer token required

**Request Body:**
| Field | Type | Required | Description |
|-------|------|----------|-------------|
| clientId | string | Yes | Client UUID |
| items | InvoiceItem[] | Yes | Line items |

**Response (201):**
| Field | Type | Description |
|-------|------|-------------|
| id | string | Invoice UUID |
| total | number | Calculated total |

**Error Responses:**
| Status | Code | Description |
|--------|------|-------------|
| 400 | VALIDATION_ERROR | Missing required fields |
| 401 | UNAUTHORIZED | Invalid or missing token |

OpenAPI 3.0

Generate docs/api/openapi.yaml — machine-readable spec for Swagger UI, Postman, etc.

How It Works

Step 0: Load Project-Level API Contract

Check if .kickstart/artifacts/API.md exists. If it does:

• Read it as the baseline contract — this defines intended endpoints, conventions, auth patterns
• Compare discovered endpoints against API.md to flag: implemented, missing, or undocumented extras
• Use API.md conventions (error format, pagination, status codes) as the documentation standard

If API.md does not exist, proceed with codebase-only detection.

Step 1: Detect Framework

# Check for framework signals
ls package.json pyproject.toml requirements.txt go.mod Cargo.toml 2>/dev/null

Read package.json or equivalent to identify the API framework.

Step 2: Scan for Endpoints

Use Glob + Grep to find all route definitions:

Glob: app/api/**/route.{ts,js}     # Next.js App Router
Glob: pages/api/**/*.{ts,js}        # Next.js Pages Router
Grep: "router\.(get|post|put|delete)" # Express
Grep: "@app\.(get|post|put|delete)"   # FastAPI/Flask

Step 3: Extract Schema Info

For each endpoint file:

1. Read the file
2. Parse request types (TypeScript interfaces, Zod schemas, Pydantic models)
3. Parse response types
4. Identify auth middleware
5. Extract JSDoc/docstring comments

Step 4: Generate Documentation

Write to docs/api/:

• README.md — API overview with authentication guide
• endpoints/ — One file per resource group
• openapi.yaml — OpenAPI 3.0 spec (if requested)

Step 5: Validate

• Check all endpoints are documented
• Verify schema completeness
• Flag undocumented endpoints

Integration with Lifecycle

Post-Sprint Hook

After Sprint Phase 3 completes, check if new API endpoints were added:

# Check if any api/ route files were modified
git diff --name-only HEAD~1 | grep -E "(api/|routes/|endpoints/)"

If yes → suggest running API docs generation.

Pre-Release Gate

In Release Phase 5, verify:

• All endpoints documented
• Documentation matches current code
• No stale docs for removed endpoints

Commands

/cks:api-docs              # Generate docs for all endpoints
/cks:api-docs --openapi    # Generate OpenAPI 3.0 spec
/cks:api-docs --diff       # Only document new/changed endpoints

Output

docs/api/
├── README.md              — API overview, auth guide, base URL
├── endpoints/
│   ├── auth.md            — Authentication endpoints
│   ├── invoices.md        — Invoice CRUD
│   └── users.md           — User management
└── openapi.yaml           — OpenAPI 3.0 spec (optional)

Customization

This skill ships with opinionated defaults. Review and adapt to your needs:

• Output format: OpenAPI YAML vs markdown (default markdown) — edit SKILL.md or use --openapi flag
• OpenAPI template: Skeleton spec structure — edit references/openapi-template.md
• Endpoint grouping: How endpoints are grouped into doc files — edit SKILL.md
• Auth documentation level: How much auth detail to include — edit SKILL.md
• allowed-tools: Currently Read, Grep, Glob, Write, Bash. Add tools if needed.
• model: Currently sonnet. Remove to use your default model.