The repair paths (send-path _repair_pending_tool_calls and resume fallback)
called graph.update_state — the SYNC method — which internally invokes
AsyncPostgresSaver.get_tuple() and raises InvalidStateError ('Synchronous
calls to AsyncPostgresSaver are only allowed from a different thread').
The repair therefore always failed (surfacing as 'Event loop is closed' +
a dangling aget_tuple coroutine) and broken threads stayed broken.
Switch both repair sites to agent.aupdate_state (async checkpointer
interface) and align the mocked agent in tests. Verified live: aupdate_state
repaired the broken checkpoint of conversation 69651ca1 (pending calls → 0).