refactor(workflow): optimize workflow history queries and migrate ORM to SQLAlchemy 2.0

- Migrate historical workflow queries from legacy ORM Query API to SQLAlchemy 2.0 select() + execute()
- Limit query fields and use pagination to reduce returned data, improving performance
- Preserve original ordering and filtering logic

api/app/repositories/workflow_repository.py

@@ -3,9 +3,9 @@
 """
 
 import uuid
-from typing import Any, Annotated
+from typing import Any, Annotated, Literal
 from sqlalchemy.orm import Session
-from sqlalchemy import desc
+from sqlalchemy import desc, select
 from fastapi import Depends
 
 from app.models.workflow_model import (
@@ -128,29 +128,36 @@ class WorkflowExecutionRepository:
         Returns:
             执行记录列表
         """
-        return self.db.query(WorkflowExecution).filter(
+        stmt = select(WorkflowExecution).filter(
             WorkflowExecution.app_id == app_id
         ).order_by(
             desc(WorkflowExecution.started_at)
-        ).limit(limit).offset(offset).all()
+        ).limit(limit).offset(offset)
+        return list(self.db.execute(stmt).scalars())
     
     def get_by_conversation_id(
         self,
-        conversation_id: uuid.UUID
+        conversation_id: uuid.UUID,
+        status: Literal["running", "completed", "failed"] = None,
+        limit_count: int = 50
     ) -> list[WorkflowExecution]:
         """根据会话 ID 获取执行记录列表
         
         Args:
+            limit_count:
             conversation_id: 会话 ID
+            status: 状态（可选）
         
         Returns:
             执行记录列表
         """
-        return self.db.query(WorkflowExecution).filter(
+        stmt = select(WorkflowExecution).filter(
             WorkflowExecution.conversation_id == conversation_id
-        ).order_by(
-            desc(WorkflowExecution.started_at)
-        ).all()
+        )
+        if status:
+            stmt = stmt.filter(WorkflowExecution.status == status)
+        stmt = stmt.order_by(desc(WorkflowExecution.started_at)).limit(limit_count)
+        return list(self.db.execute(stmt).scalars())
     
     def count_by_app_id(self, app_id: uuid.UUID) -> int:
         """统计应用的执行次数
@@ -199,11 +206,12 @@ class WorkflowNodeExecutionRepository:
         Returns:
             节点执行记录列表（按执行顺序排序）
         """
-        return self.db.query(WorkflowNodeExecution).filter(
+        stmt = select(WorkflowNodeExecution).filter(
             WorkflowNodeExecution.execution_id == execution_id
         ).order_by(
             WorkflowNodeExecution.execution_order
-        ).all()
+        )
+        return list(self.db.execute(stmt).scalars())
     
     def get_by_node_id(
         self,
@@ -219,12 +227,13 @@ class WorkflowNodeExecutionRepository:
         Returns:
             节点执行记录列表
         """
-        return self.db.query(WorkflowNodeExecution).filter(
+        stmt = select(WorkflowNodeExecution).filter(
             WorkflowNodeExecution.execution_id == execution_id,
             WorkflowNodeExecution.node_id == node_id
         ).order_by(
             WorkflowNodeExecution.retry_count
-        ).all()
+        )
+        return list(self.db.execute(stmt).scalars())
 
 
 # ==================== 依赖注入函数 ====================

api/app/services/workflow_service.py

@@ -561,6 +561,24 @@ class WorkflowService:
                 storage_type = 'neo4j'
         return storage_type, user_rag_memory_id
 
+    def _get_history_info(self, conversation_id: uuid.UUID) -> tuple[dict, list] | None:
+        executions = self.execution_repo.get_by_conversation_id(
+            conversation_id=conversation_id,
+            status="completed",
+            limit_count=1
+        )
+
+        if executions:
+            last_state = executions[0].output_data
+            if isinstance(last_state, dict):
+                variables = last_state.get("variables", {})
+                conv_vars = variables.get("conv", {})
+                # input_data["conv"] = conv_vars
+                # input_data["conv_messages"] = last_state.get("messages") or []
+                conv_messages = last_state.get("messages") or []
+                return conv_vars, conv_messages
+        return None
+
     # ==================== 工作流执行 ====================
 
     async def run(
@@ -634,18 +652,11 @@ class WorkflowService:
             # 更新状态为运行中
             self.update_execution_status(execution.execution_id, "running")
 
-            executions = self.execution_repo.get_by_conversation_id(conversation_id=conversation_id_uuid)
-
-            for exec_res in executions:
-                if exec_res.status == "completed":
-                    last_state = exec_res.output_data
-                    if isinstance(last_state, dict):
-                        variables = last_state.get("variables", {})
-                        conv_vars = variables.get("conv", {})
-                        input_data["conv"] = conv_vars
-                        input_data["conv_messages"] = last_state.get("messages") or []
-                        break
-
+            history = self._get_history_info(conversation_id_uuid)
+            if history:
+                conv_vars, conv_messages = history
+                input_data["conv"] = conv_vars
+                input_data["conv_messages"] = conv_messages
             init_message_length = len(input_data.get("conv_messages", []))
 
             result = await execute_workflow(
@@ -807,17 +818,11 @@ class WorkflowService:
             storage_type, user_rag_memory_id = self._get_memory_store_info(workspace_id)
             input_data["files"] = files
             self.update_execution_status(execution.execution_id, "running")
-            executions = self.execution_repo.get_by_conversation_id(conversation_id=conversation_id_uuid)
-
-            for exec_res in executions:
-                if exec_res.status == "completed":
-                    last_state = exec_res.output_data
-                    if isinstance(last_state, dict):
-                        variables = last_state.get("variables", {})
-                        conv_vars = variables.get("conv", {})
-                        input_data["conv"] = conv_vars
-                        input_data["conv_messages"] = last_state.get("messages") or []
-                        break
+            history = self._get_history_info(conversation_id_uuid)
+            if history:
+                conv_vars, conv_messages = history
+                input_data["conv"] = conv_vars
+                input_data["conv_messages"] = conv_messages
             init_message_length = len(input_data.get("conv_messages", []))
             message_id = uuid.uuid4()
             async for event in execute_workflow_stream(