deferredBackend
A backend whose construction needs I/O — e.g. listing MCP tools or fetching an A2A agent card — built fresh for every turn inside the turn's coroutine, so failures surface as the turn's error.
A backend whose construction needs I/O — e.g. listing MCP tools or fetching an A2A agent card — built fresh for every turn inside the turn's coroutine, so failures surface as the turn's error.