Send Task

Receive an A2A task, store it as 'submitted', and return the task envelope.

Request body (A2A spec TaskSendParams): { "id": "<caller-supplied task id, optional>", "message": { "role": "user", "parts": [...] }, "metadata": {...} # optional }

Response (202 Accepted) follows the A2A Task schema: { "task_id": "<uuid>", "agent_id": "<agent_id>", "status": { "state": "submitted" }, "artifacts": [], "metadata": {...}, "created_at": "...", "updated_at": "..." }