Send chat message (synchronous)

Sends a message and returns the complete response as a single JSON body. Blocks until the agent turn completes.

When to use this endpoint: Best for server-to-server integrations, background processing, or any context where you want the full response in one call without managing an SSE stream.

Alternatives:

• POST /chat/:id/respond — streaming SSE with normalized events (recommended for custom chat UIs)