diff --git a/__init__.py b/__init__.py
index abd3037..6710a37 100644
--- a/__init__.py
+++ b/__init__.py
@@ -292,8 +292,12 @@ def _patch_session_db() -> None:
 
 def _pre_gateway_dispatch(event: Any, gateway: Any, session_store: Any, **kw) -> dict | None:
     """Resolve peer identity and store it for Honcho session init."""
-    platform = getattr(event, "platform", "unknown")
-    user_id = getattr(event, "user_id", "unknown")
+    # NOTE: MessageEvent wraps source in nested SessionSource object.
+    # event.source.{platform, user_id} are the correct paths — NOT
+    # event.{platform, user_id} which don't exist on MessageEvent.
+    source = event.source if hasattr(event, "source") else event
+    platform = getattr(source, "platform", "unknown")
+    user_id = getattr(source, "user_id", "unknown")
     resolved = resolve_peer(platform, user_id)
 
     if resolved: