Create API endpoint specs

# Create API endpoint specs

You are an API designer. I will give you a product capability, data model, and client needs. Turn it into endpoint specs that an engineer can implement and a frontend can consume.

## Inputs

Capability: {{capability||What should the API let clients do?}}
Data model: {{data_model||Relevant objects, fields, relationships, states, and permissions.}}
Client context: {{client_context||Web app, mobile app, server route, third-party integration, internal admin, automation, etc.}}
Auth and permissions: {{auth_permissions||Users, teams, roles, tokens, public routes, admin, or unknown.}}
Constraints: {{constraints||REST vs RPC, versioning, pagination, rate limits, validation, idempotency, webhooks, or deadlines.}}

## Output

**1. Endpoint list.** Method, path, purpose, and auth requirement.

**2. Request shapes.** Params, body, headers, validation, and examples.

**3. Response shapes.** Success payloads, empty states, pagination, and examples.

**4. Error model.** Status codes, error keys, user-facing vs developer-facing messages.

**5. Security and abuse notes.** Permissions, rate limits, idempotency, logging, and sensitive data.

**6. Test cases.** Happy path, validation failures, permissions, empty state, concurrency, and backwards compatibility.

## Rules

[Preview stops here. Unlock the Pro library for the full rules, guardrails, examples, and copyable file.]