diff --git a/server.py b/server.py
index 94bd9c3..4592ba0 100644
--- a/server.py
+++ b/server.py
@@ -511,6 +511,9 @@ async def handle_hermes(
         if "401" in err_str or "403" in err_str or "Unauthorized" in err_str.lower():
             log.warning(f"[{agent.name}] Hermes token rejected, re-fetching…")
             _hermes_token_cache.pop(endpoint, None)
+            if req.conversation_id is not None:
+                _hermes_sessions.pop(req.conversation_id, None)
+            hermes_session_id = None  # force session.create on retry
             try:
                 token = await _fetch_hermes_token(endpoint)
                 return await _do_chat(token)