Bug Description

The _WEIXIN_TARGET_RE regex on line 30 of tools/send_message_tool.py only matches session IDs with the @chatroom suffix, rejecting all personal user (DM) IDs ending in @im.wechat. When the send_message target is a personal user (e.g., weixin:[email protected]), _parse_target_ref() returns (None, None, False) → is_explicit=False → falls through to channel name resolution → resolution fails → fallback to home channel → home channel lacks a valid context_token → iLink returns ret=-2.

Group chat messages (@chatroom) work fine because an inbound message in the same session carries a valid context_token.

Steps to Reproduce

1. Configure the Weixin gateway (iLink clawbot mode)
2. Use send_message(action='list') to obtain a personal user ID (ending in @im.wechat)
3. Call send_message(action='send', target='weixin:[email protected]', message='test')
4. Receive ret=-2 error

Root Cause

WeChat internally uses two session ID suffixes to distinguish session types:

Current regex:

_WEIXIN_TARGET_RE = re.compile(r"^\s*((?:wxid|gh|v\d+|wm|wb)_[A-Za-z0-9_-]+|[A-Za-z0-9._-]+@chatroom|filehelper)\s*$")

@chatroom only matches group chats; DM IDs with @im.wechat are rejected at the format validation stage.

Fix

Change @chatroom to @(?:chatroom|im\.wechat) to allow both group chats and personal DMs:

-_WEIXIN_TARGET_RE = re.compile(r"^\s*((?:wxid|gh|v\d+|wm|wb)_[A-Za-z0-9_-]+|[A-Za-z0-9._-]+@chatroom|filehelper)\s*$")
+_WEIXIN_TARGET_RE = re.compile(r"^\s*((?:wxid|gh|v\d+|wm|wb)_[A-Za-z0-9_-]+|[A-Za-z0-9._-]+@(?:chatroom|im\.wechat)|filehelper)\s*$")

Impact

• The tool is named send_message but can only send to group chats — functionality doesn't match the API name
• Affects all Weixin scenarios requiring direct messages (DM) to personal users
• Fix is backward-compatible: existing @chatroom matching is unaffected

Environment

• Hermes Agent main branch
• Weixin platform (iLink clawbot)