Enterprise-only AI chat endpoint that accepts conversation messages and returns an assistant response via Server-Sent Events. Requires a valid Auth.js session and the aiAssistant experimental feature enabled for the tenant. The slug path segment is accepted by the catch-all route but is not used by the implementation. API-key authentication is skipped for /api/chat; tenant context comes from the session.
Content type: application/json · schema ChatStreamRequest
userassistant