## ADDED Requirements

### Requirement: API reference exists at docs/developers/api-reference.md
The system SHALL provide a human-readable API reference at `docs/developers/api-reference.md` covering all 14 endpoints across the four services: Agent Registry, OAuth 2.0 Token, Credential Management, and Audit Log.

#### Scenario: Developer finds any endpoint within 10 seconds
- **WHEN** the developer opens the API reference
- **THEN** they SHALL find a table of contents at the top linking to each of the four service sections

### Requirement: Every endpoint is documented with method, path, description, and auth requirements
For each of the 14 endpoints, the reference SHALL document: HTTP method, path, one-sentence description, and whether Bearer token auth is required.

#### Scenario: Developer knows which endpoints require authentication
- **WHEN** the developer scans the reference
- **THEN** they SHALL clearly see which endpoints require a Bearer token (all except POST /token) and which do not

### Requirement: Every endpoint includes a complete curl example
For each endpoint, the reference SHALL include at least one complete, runnable curl example with real placeholder values.

#### Scenario: Developer copies a curl example and runs it
- **WHEN** the developer copies a curl example from the reference
- **THEN** the command SHALL be complete — no ellipses, no `...`, no missing flags — requiring only substitution of their own agentId, token, and base URL

### Requirement: Every endpoint documents all request parameters and body fields
For each endpoint that accepts a request body or query parameters, the reference SHALL list every field with: name, type, required/optional, description, and validation constraints.

#### Scenario: Developer knows what fields are required for POST /agents
- **WHEN** the developer reads the POST /agents section
- **THEN** they SHALL see a table listing every field, its type, whether it is required, and any constraints (e.g. email format, max length)

### Requirement: Every endpoint documents all response codes and response body schemas
For each endpoint, the reference SHALL document every possible HTTP response code (2xx and 4xx/5xx) with a description and example response body.

#### Scenario: Developer understands a 429 response
- **WHEN** the developer reads the rate limit error documentation
- **THEN** they SHALL understand what triggered it, what the X-RateLimit-* headers mean, and when they can retry

### Requirement: API reference includes a base URL and versioning section
The reference SHALL include a section at the top explaining the base URL convention, port configuration, and that all endpoints are unversioned in Phase 1.

#### Scenario: Developer knows where to send requests
- **WHEN** the developer reads the base URL section
- **THEN** they SHALL see the default base URL (http://localhost:3000), how to change the port via environment variable, and a note that versioning will be introduced in Phase 2

### Requirement: API reference includes an errors section
The reference SHALL include a dedicated errors section listing all standard error response shapes, all custom error codes, and their HTTP status code mappings.

#### Scenario: Developer handles an AgentNotFoundError
- **WHEN** the developer reads the errors section
- **THEN** they SHALL see the exact JSON shape of the error response, the error code string, and the HTTP status (404)