Allow a team without leader

metagpt/environment/mgx/mgx_env.py

@@ -27,10 +27,17 @@ def publish_message(self, message: Message, user_defined_recipient: str = "", pu
 
         tl = self.get_role(TEAMLEADER_NAME)  # TeamLeader's name is Mike
 
+        # If there is no TeamLeader in the environment, fall back to the regular publishing flow
+        if tl is None:
+            self._publish_message(message)
+            self.history.add(message)
+            return True
+
         if user_defined_recipient:
             # human user's direct chat message to a certain role
             for role_name in message.send_to:
-                if self.get_role(role_name).is_idle:
+                role_obj = self.get_role(role_name)
+                if role_obj and role_obj.is_idle:
                     # User starts a new direct chat with a certain role, expecting a direct chat response from the role; Other roles including TL should not be involved.
                     # If the role is not idle, it means the user helps the role with its current work, in this case, we handle the role's response message as usual.
                     self.direct_chat_roles.add(role_name)

tests/metagpt/environment/test_mgx_env.py

@@ -0,0 +1,61 @@
+import pytest
+
+from metagpt.environment.mgx.mgx_env import MGXEnv
+from metagpt.schema import Message
+
+
+def test_publish_message_without_team_leader_falls_back_and_records_history():
+    env = MGXEnv()
+    before_count = env.history.count()
+
+    msg = Message(content="hi", role="user")
+
+    # Should not raise and should return True
+    assert env.publish_message(msg) is True
+
+    # History should increase (once in base env, and once in MGXEnv)
+    assert env.history.count() >= before_count + 1
+
+    # The transformed message (from _publish_message) should be present in history
+    # It includes the sender/receiver info moved into content
+    assert any(
+        "[Message] from" in m.content and "to" in m.content for m in env.history.storage
+    )
+
+
+def test_user_defined_recipient_with_missing_role_is_safe_and_no_direct_chat_added():
+    env = MGXEnv()
+    before_count = env.history.count()
+
+    # Direct chat to a non-existent role should not crash and should not add to direct_chat_roles
+    msg = Message(content="ping", role="user")
+    msg.send_to = {"NonExistentRole"}
+
+    assert env.publish_message(msg, user_defined_recipient="NonExistentRole") is True
+
+    # No direct chat role should be recorded for a missing role
+    assert "NonExistentRole" not in env.direct_chat_roles
+
+    # Still publishes and records in history
+    assert env.history.count() >= before_count + 1
+
+
+def test_user_defined_recipient_with_existing_role_does_not_error():
+    env = MGXEnv()
+
+    # Define a minimal role by name and add to env
+    from metagpt.roles import Role
+
+    class DummyRole(Role):
+        name: str = "Alice"
+        profile: str = "DummyRole"
+
+    env.add_roles([DummyRole()])
+
+    msg = Message(content="hello", role="user")
+    msg.send_to = {"Alice"}
+
+    # Should not raise and should return True
+    assert env.publish_message(msg, user_defined_recipient="Alice") is True
+
+