diff --git a/api/app/core/workflow/engine/graph_builder.py b/api/app/core/workflow/engine/graph_builder.py
index 0d0035ab..7b5c059c 100644
--- a/api/app/core/workflow/engine/graph_builder.py
+++ b/api/app/core/workflow/engine/graph_builder.py
@@ -7,7 +7,7 @@ import re
 import uuid
 from collections import defaultdict
 from functools import lru_cache
-from typing import Any
+from typing import Any, Iterable
 
 from langgraph.checkpoint.memory import InMemorySaver
 from langgraph.graph import START, END
@@ -81,7 +81,7 @@ class GraphBuilder:
             raise RuntimeError(f"Node not found: Id={node_id}")
 
     @staticmethod
-    def _merge_control_nodes(control_nodes: tuple[tuple[str, str]]) -> dict[str, list]:
+    def _merge_control_nodes(control_nodes: Iterable[tuple[str, str]]) -> dict[str, list]:
         result = defaultdict(list)
         for node in control_nodes:
             result[node[0]].append(node[1])
diff --git a/api/app/core/workflow/engine/result_builder.py b/api/app/core/workflow/engine/result_builder.py
index dbaf8fa6..31bccf57 100644
--- a/api/app/core/workflow/engine/result_builder.py
+++ b/api/app/core/workflow/engine/result_builder.py
@@ -5,7 +5,7 @@
 from app.core.workflow.engine.variable_pool import VariablePool
 
 
-class WorkflowResultBuiler:
+class WorkflowResultBuilder:
     def build_final_output(
             self,
             result: dict,
diff --git a/api/app/core/workflow/engine/stream_output_coordinator.py b/api/app/core/workflow/engine/stream_output_coordinator.py
index 778c6acf..5155a76f 100644
--- a/api/app/core/workflow/engine/stream_output_coordinator.py
+++ b/api/app/core/workflow/engine/stream_output_coordinator.py
@@ -263,7 +263,6 @@ class StreamOutputCoordinator:
             else:
                 # Variable segment: evaluate and transform
                 try:
-                    # Simulate evaluation (replace with actual logic)
                     chunk = variable_pool.get_literal(current_segment.literal)
                     final_chunk += chunk
                 except Exception as e:
@@ -271,7 +270,7 @@ class StreamOutputCoordinator:
                     logger.warning(f"[STREAM] Failed to evaluate segment: {current_segment.literal}, error: {e}")
 
             if final_chunk:
-                logger.warning(f"[STREAM] StreamOutput Node:{self.activate_end}, chunk:{final_chunk}")
+                logger.info(f"[STREAM] StreamOutput Node:{self.activate_end}, chunk:{final_chunk}")
                 yield {
                     "event": "message",
                     "data": {
@@ -317,7 +316,7 @@ class StreamOutputCoordinator:
             if node_info.activate
         }
 
-        if self.activate_end or self.activate_end:
+        if self.end_outputs or self.activate_end:
             while self.activate_end:
                 # Force emit all remaining chunks of the active End node
                 async for msg_event in self.emit_activate_chunk(variable_pool, force=True):
diff --git a/api/app/core/workflow/engine/variable_pool.py b/api/app/core/workflow/engine/variable_pool.py
index 55966ed6..22be08c8 100644
--- a/api/app/core/workflow/engine/variable_pool.py
+++ b/api/app/core/workflow/engine/variable_pool.py
@@ -401,10 +401,13 @@ class VariablePoolInitializer:
     ):
         user_message = input_data.get("message") or ""
         user_files = input_data.get("files") or []
+        conversations = input_data.get("conv_messages", [])
+        conversation_index = len(conversations) // 2
 
         input_variables = input_data.get("variables") or {}
         sys_vars = {
             "message": (user_message, VariableType.STRING),
+            "conversation_index": (conversation_index, VariableType.NUMBER),
             "conversation_id": (input_data.get("conversation_id"), VariableType.STRING),
             "execution_id": (context.execution_id, VariableType.STRING),
             "workspace_id": (context.workspace_id, VariableType.STRING),
diff --git a/api/app/core/workflow/executor.py b/api/app/core/workflow/executor.py
index 2ec7992b..ff48fb07 100644
--- a/api/app/core/workflow/executor.py
+++ b/api/app/core/workflow/executor.py
@@ -10,7 +10,7 @@ from langgraph.graph.state import CompiledStateGraph
 
 from app.core.workflow.engine.event_stream_handler import EventStreamHandler
 from app.core.workflow.engine.graph_builder import GraphBuilder
-from app.core.workflow.engine.result_builder import WorkflowResultBuiler
+from app.core.workflow.engine.result_builder import WorkflowResultBuilder
 from app.core.workflow.engine.runtime_schema import ExecutionContext
 from app.core.workflow.engine.state_manager import WorkflowStateManager
 from app.core.workflow.engine.stream_output_coordinator import StreamOutputCoordinator
@@ -60,7 +60,7 @@ class WorkflowExecutor:
 
         self.variable_initializer = VariablePoolInitializer(workflow_config)
         self.state_manager = WorkflowStateManager()
-        self.result_builder = WorkflowResultBuiler()
+        self.result_builder = WorkflowResultBuilder()
         self.stream_coordinator = StreamOutputCoordinator()
         self.event_handler: EventStreamHandler | None = None