API INTEROPERABILITY SPECIFICATION

Version: 1.0 Date: 2025-11-15 Classification: Public/Technical

1. OBJECTIVE To ensure consistent, secure, and standardized communication between the Covenant's internal microservices and external partner systems.  
2. COMMUNICATION STANDARD All API traffic must use RESTful JSON over TLS 1.3. Non-TLS communication is strictly prohibited.  
3. AUTHENTICATION External API access must utilize the OAuth 2.0 Client Credentials Flow, with client IDs and secrets managed via the Phoenix Access Pillar's Identity Vetting Protocol (IVP-1.1).  
4. ERROR HANDLING All API responses must include a standard JSON error object on failure, including a specific HTTP status code, an internal error code, and a human-readable message.

| HTTP Code | Internal Code Range | | 400-499 | 1000-1999 (Client Errors) | | 500-599 | 2000-2999 (Server Errors) |

