hermes - 💡(How to fix) Fix concurrency: _load_google_modules() TOCTOU — _google_modules_loaded set before imports complete

Bug

_load_google_modules() in plugins/platforms/google_chat/adapter.py sets _google_modules_loaded = True at line 95, before the actual import statements and before assigning the module globals.

if _google_modules_loaded:
    return GOOGLE_CHAT_AVAILABLE
_google_modules_loaded = True      # ← flag set here
try:
    import httplib2 as _httplib2   # ← imports happen here
    from google.cloud import pubsub_v1 as _pubsub_v1
    ...
GOOGLE_CHAT_AVAILABLE = True       # ← availability set last

A concurrent thread hitting the fast path after the flag write but before the imports complete:

1. Sees _google_modules_loaded=True → early returns
2. Returns GOOGLE_CHAT_AVAILABLE which is still False → Google Chat appears unavailable
3. Uses module globals (pubsub_v1, service_account, etc.) that are still their sentinel defaults (Any = Exception, None)

The Google Chat gateway is called on every concurrent incoming message.

Fix

Double-checked locking: add import threading and _google_modules_lock = threading.Lock(), compute fully inside the lock, set GOOGLE_CHAT_AVAILABLE and all module globals, then set _google_modules_loaded = True last.