fix: preserve empty dict allow_from handling

Keep dict-backed channel configs compatible with both allow_from and allowFrom without losing empty-list semantics, and add focused regression coverage for the allow-list boundary.

Made-with: Cursor

nanobot/channels/base.py

@@ -117,7 +117,10 @@ class BaseChannel(ABC):
     def is_allowed(self, sender_id: str) -> bool:
         """Check if *sender_id* is permitted.  Empty list → deny all; ``"*"`` → allow all."""
         if isinstance(self.config, dict):
-            allow_list = self.config.get("allow_from") or self.config.get("allowFrom") or []
+            if "allow_from" in self.config:
+                allow_list = self.config.get("allow_from")
+            else:
+                allow_list = self.config.get("allowFrom", [])
         else:
             allow_list = getattr(self.config, "allow_from", [])
         if not allow_list:

nanobot/channels/manager.py

@@ -77,7 +77,10 @@ class ChannelManager:
         for name, ch in self.channels.items():
             cfg = ch.config
             if isinstance(cfg, dict):
-                allow = cfg.get("allow_from") or cfg.get("allowFrom")
+                if "allow_from" in cfg:
+                    allow = cfg.get("allow_from")
+                else:
+                    allow = cfg.get("allowFrom")
             else:
                 allow = getattr(cfg, "allow_from", None)
             if allow == []: