diff --git a/lang_agent/pipeline.py b/lang_agent/pipeline.py
index 36c5686..8ab9783 100644
--- a/lang_agent/pipeline.py
+++ b/lang_agent/pipeline.py
@@ -82,6 +82,7 @@ class PipelineConfig(KeyConfig):
 class Pipeline:
     def __init__(self, config:PipelineConfig):
         self.config = config
+        self.thread_id_cache = {}
 
         self.populate_module()
     
@@ -149,11 +150,15 @@ class Pipeline:
         as_raw (bool): return full dialoge of List[SystemMessage, HumanMessage, ToolMessage]
         """
 
+        rm_id = self.get_remove_id(thread_id)
+        if rm_id:
+            self.graph.clear_memory(rm_id)
+
         device_id = "0"
         spl_ls = thread_id.split("_")
         assert len(spl_ls) <= 2, "something wrong!"
         if len(spl_ls) == 2:
-            thread_id, device_id = spl_ls
+            _, device_id = spl_ls
 
         inp = {"messages":[HumanMessage(inp)]}, {"configurable": {"thread_id": thread_id,
                                                                   "device_id":device_id}}
@@ -165,6 +170,31 @@ class Pipeline:
             return self._stream_res(out, thread_id)
         else:
             return out
+    
+    def get_remove_id(self, thread_id:str) -> bool:
+        """
+        returns a id to remove if a new conversation has starte
+        """
+        parts = thread_id.split("_")
+        if len(parts) < 2:
+            return None
+
+        assert len(parts) == 2, "should have exactly two parts"
+
+        thread_id, device_id = parts
+        c_th_id = self.thread_id_cache.get(device_id)
+        
+        if c_th_id is None:
+            self.thread_id_cache[device_id] = thread_id
+            return None
+        elif c_th_id == thread_id:
+            return None
+        elif c_th_id != thread_id:
+            self.thread_id_cache[device_id] = thread_id
+            return f"{c_th_id}_{device_id}"
+        else:
+            assert 0, "BUG SHOULD NOT BE HERE"
+
 
     async def ainvoke(self, *nargs, **kwargs):
         """Async version of invoke using LangGraph's native async support."""
@@ -196,6 +226,10 @@ class Pipeline:
         as_stream (bool): if true, enable the thing to be streamable
         as_raw (bool): return full dialoge of List[SystemMessage, HumanMessage, ToolMessage]
         """
+        rm_id = self.get_remove_id(thread_id)
+        if rm_id:
+            await self.graph.aclear_memory(rm_id)
+
         # NOTE: this prompt will be overwritten by 'configs/route_sys_prompts/chat_prompt.txt' for route graph
         u = DEFAULT_PROMPT
 
@@ -203,7 +237,7 @@ class Pipeline:
         spl_ls = thread_id.split("_")
         assert len(spl_ls) <= 2, "something wrong!"
         if len(spl_ls) == 2:
-            thread_id, device_id = spl_ls
+            _, device_id = spl_ls
             print(f"\033[32m====================DEVICE ID: {device_id}=============================\033[0m")
 
         inp_data = {"messages":[SystemMessage(u),