fix: SelectorGroupChat livelock fallback when allow_repeated_speaker=False

patch_selector_group_chat.py

@@ -0,0 +1,30 @@
+with open("python/packages/autogen-agentchat/src/autogen_agentchat/teams/_group_chat/_selector_group_chat.py", "r") as f:
+    content = f.read()
+
+old_code = """        if self._previous_speaker is not None:
+            trace_logger.warning(f"Model failed to select a speaker after {max_attempts}, using the previous speaker.")
+            return self._previous_speaker
+        trace_logger.warning(
+            f"Model failed to select a speaker after {max_attempts} and there was no previous speaker, using the first participant."
+        )
+        return self._participant_names[0]"""
+
+new_code = """        import random
+        if not self._allow_repeated_speaker and self._previous_speaker is not None:
+            candidates = [p for p in participants if p != self._previous_speaker]
+            if candidates:
+                trace_logger.warning(f"Model failed to select a speaker after {max_attempts}, returning a random different candidate.")
+                return random.choice(candidates)
+
+        if self._previous_speaker is not None:
+            trace_logger.warning(f"Model failed to select a speaker after {max_attempts}, using the previous speaker.")
+            return self._previous_speaker
+        trace_logger.warning(
+            f"Model failed to select a speaker after {max_attempts} and there was no previous speaker, using the first participant."
+        )
+        return self._participant_names[0]"""
+
+content = content.replace(old_code, new_code)
+
+with open("python/packages/autogen-agentchat/src/autogen_agentchat/teams/_group_chat/_selector_group_chat.py", "w") as f:
+    f.write(content)