fix: populate stop_reason [LET-6040] (#5955)

fix: populate stop_reason

letta/agents/letta_agent_v2.py

@@ -308,6 +308,10 @@ class LettaAgentV2(BaseAgentV2):
 
                 input_messages_to_persist = []
 
+            if self.stop_reason is None:
+                # terminated due to hitting max_steps
+                self.stop_reason = LettaStopReason(stop_reason=StopReasonType.max_steps.value)
+
             if not self.agent_state.message_buffer_autoclear:
                 await self.summarize_conversation_history(
                     in_context_messages=in_context_messages,
@@ -327,6 +331,8 @@ class LettaAgentV2(BaseAgentV2):
                 use_assistant_message=use_assistant_message,
                 reverse=False,
             )
+            if not self.stop_reason:
+                self.stop_reason = LettaStopReason(stop_reason=StopReasonType.end_turn.value)
             result = LettaResponse(messages=letta_messages, stop_reason=self.stop_reason, usage=self.usage)
             if self.job_update_metadata is None:
                 self.job_update_metadata = {}

letta/agents/letta_agent_v3.py

@@ -288,6 +288,9 @@ class LettaAgentV3(LettaAgentV2):
 
                 input_messages_to_persist = []
 
+            if self.stop_reason is None:
+                self.stop_reason = LettaStopReason(stop_reason=StopReasonType.max_steps.value)
+
             if not self.agent_state.message_buffer_autoclear:
                 if self.last_step_usage:
                     await self.summarize_conversation_history(