Problem

When the gateway is running and a Weixin user sends a message, the agent responds via send_weixin_direct() which tries to reuse the live adapter's aiohttp.ClientSession (bound to the gateway's event loop). However, send_message tool calls are dispatched via _run_async() which may run on a worker thread using loop.run_until_complete().

run_until_complete() does not create a task, so asyncio.current_task() returns None. This causes aiohttp.ClientTimeout.__enter__ to raise:

RuntimeError: Timeout context manager should be used inside a task

This breaks all Weixin send operations (text + media) from the send_message tool and cron delivery when the gateway is running.

Introduced by commit 5ca52bae (split poll/send sessions, reuse live adapter).

Fix

1. gateway/platforms/weixin.py — send_weixin_direct() always creates its own aiohttp.ClientSession instead of reusing the live adapter's session (which is bound to the gateway's event loop and may be on a different thread).

2. model_tools.py — _run_async() uses asyncio.run() instead of run_until_complete() for both worker-thread and main-thread fallback paths. asyncio.run() creates a proper task context, which aiohttp >= 3.9 requires for ClientTimeout.

Trade-off

Using asyncio.run() instead of a persistent loop means each call creates/destroys an event loop. The original persistent loop was introduced to prevent "Event loop is closed" errors with cached httpx/AsyncOpenAI clients (commit 7a427d7b). If this becomes an issue again, an alternative fix would be to wrap the coroutine in loop.create_task() before run_until_complete(), e.g.:

worker_loop = _get_worker_loop()
return worker_loop.run_until_complete(worker_loop.create_task(coro))

This preserves the persistent loop while still providing a task context.

Verification

• Reproduced: all send_message calls to Weixin fail with timeout error when gateway is running
• Fixed: send_weixin_direct() creates its own session, asyncio.run() provides task context
• No impact on gateway's own send path (which runs on the gateway loop directly)