Problem

Sending files via the tool to WeChat fails with:

This happens in → .

Root Cause

The function tries to reuse the cached
session (line 1983-2008 before this fix). That session was created in the
gateway's main event loop, but tool calls it from a worker
thread via → , which creates a separate
event loop. aiohttp session operations are tied to the loop they were created
on, causing the error when called from a mismatched loop.

Fix

Skip the session reuse path entirely and always create a fresh
for each call. This ensures loop
compatibility regardless of the caller's async context.

Testing

• Text messages (no media): continue to work via the text chunk path in the same function
• File/image attachments: now use a freshly created session with correct loop affinity
• No functional changes to the gateway's own WeixinAdapter lifecycle (still uses its own session)

Fixes: WeChat file/document sending via tool