The module-global `_loop` / `_loop_thread` pair is shared across every
`HindsightMemoryProvider` instance in the process — the plugin loader
creates one provider per `AIAgent`, and the gateway creates one `AIAgent`
per concurrent chat session (Telegram/Discord/Slack/CLI).
`HindsightMemoryProvider.shutdown()` stopped the shared loop when any one
session ended. That stranded the aiohttp `ClientSession` and `TCPConnector`
owned by every sibling provider on a now-dead loop — they were never
reachable for close and surfaced as the `Unclosed client session` /
`Unclosed connector` warnings reported in #11923.
Fix: stop stopping the shared loop in `shutdown()`. Per-provider cleanup
still closes that provider's own client via `self._client.aclose()`. The
loop runs on a daemon thread and is reclaimed on process exit; keeping
it alive between provider shutdowns means sibling providers can drain
their own sessions cleanly.
Regression tests in `tests/plugins/memory/test_hindsight_provider.py`
(`TestSharedEventLoopLifecycle`):
- `test_shutdown_does_not_stop_shared_event_loop` — two providers share
the loop; shutting down one leaves the loop live for the other. This
test reproduces the #11923 leak on `main` and passes with the fix.
- `test_client_aclose_called_on_cloud_mode_shutdown` — each provider's
own aiohttp session is still closed via `aclose()`.
Fixes#11923.
93a74f74bf