fix(api): resolve error in agent‑strategy prompt generator (#26278)

api/core/llm_generator/llm_generator.py

 from core.ops.utils import measure_time
 from core.prompt.utils.prompt_template_parser import PromptTemplateParser
 from core.workflow.entities.workflow_node_execution import WorkflowNodeExecutionMetadataKey
-from core.workflow.node_events import AgentLogEvent
 from extensions.ext_database import db
 from extensions.ext_storage import storage
 from models import App, Message, WorkflowNodeExecutionModel
             )
 
         def agent_log_of(node_execution: WorkflowNodeExecutionModel) -> Sequence:
-            raw_agent_log = node_execution.execution_metadata_dict.get(WorkflowNodeExecutionMetadataKey.AGENT_LOG)
+            raw_agent_log = node_execution.execution_metadata_dict.get(WorkflowNodeExecutionMetadataKey.AGENT_LOG, [])
             if not raw_agent_log:
                 return []
-            parsed: Sequence[AgentLogEvent] = json.loads(raw_agent_log)
 
-            def dict_of_event(event: AgentLogEvent):
-                return {
-                    "status": event.status,
-                    "error": event.error,
-                    "data": event.data,
+            return [
+                {
+                    "status": event["status"],
+                    "error": event["error"],
+                    "data": event["data"],
                 }
-
-            return [dict_of_event(event) for event in parsed]
+                for event in raw_agent_log
+            ]
 
         inputs = last_run.load_full_inputs(session, storage)
         last_run_dict = {