hermes - 💡(How to fix) Fix concurrency: agent/transports _discovered flag set before imports complete (TOCTOU) [1 pull requests]

Bug

agent/transports/__init__.py::_discover_transports() sets _discovered = True on line 52 before any of the four import agent.transports.* calls complete.

def _discover_transports() -> None:
    global _discovered
    _discovered = True          # ← flag set HERE (line 52)
    try:
        import agent.transports.anthropic   # ← imports happen AFTER
    ...

Race window: Thread A sets _discovered = True, then Thread B enters get_transport(), sees _discovered = True, and skips _discover_transports(). Thread B reads _REGISTRY.get(api_mode) → None (Thread A has not yet registered the transport). Thread B falls to the miss-retry path and calls _discover_transports() again — this works because Python caches modules in sys.modules, so re-imports are fast and idempotent.

Current behaviour: The miss-retry path in get_transport() masks the bug. However, under non-GIL Python (3.13+ free-threaded), the window is wider and the retry path is hit more often. The flag-before-work pattern is a reliability anti-pattern that should be corrected.

Fix: Move _discovered = True to after all imports complete, protected by double-checked locking (threading.Lock()).

Affected file

• agent/transports/__init__.py — _discover_transports(), get_transport()