Update agent.py

agent.py

@@ -45,6 +45,24 @@ with open("prompt.txt", "r", encoding="utf-8") as f:
 sys_msg = SystemMessage(content=system_prompt)
 
 
+# build a retriever
+embeddings = HuggingFaceEmbeddings(model_name="sentence-transformers/all-MiniLM-L6-v2") #  dim=384
+supabase: Client = create_client(
+    os.environ.get("SUPABASE_URL"), 
+    os.environ.get("SUPABASE_SERVICE_KEY"))
+
+vector_store = SupabaseVectorStore(
+    client = supabase,
+    embedding = embeddings,
+    table_name = "documents",
+    query_name = "match_documents_langchain",)
+
+retriever_tool = create_retriever_tool(
+    retriever=vector_store.as_retriever(),
+    name="Question Search",
+    description="A tool to retrieve similar questions from a vector store.",)
+
+
 # Loading the assistant
 chat = ChatGoogleGenerativeAI(model="gemini-2.0-flash", temperature=0)
 
@@ -70,19 +88,31 @@ chat_with_tools = chat.bind_tools(tools)
 
 def simple_graph():
 
-    ## Defining our nodes
     def assistant(state: MessagesState):
         """Assistant node"""
-        return {"messages": [chat_with_tools.invoke([sys_msg] + state["messages"])]}
+        return {"messages": [llm_with_tools.invoke(state["messages"])]}
+    
+    def retriever(state: MessagesState):
+        """Retriever node"""
+        similar_question = vector_store.similarity_search(state["messages"][0].content)
+        example_msg = HumanMessage(
+            content=f"Here I provide a similar question and answer for reference: \n\n{similar_question[0].page_content}",
+        )
+        return {"messages": [sys_msg] + state["messages"] + [example_msg]}
     
     # Build graph / nodes
     builder = StateGraph(MessagesState)
-    builder.add_node("assistant", assistant) # Assistant
-    builder.add_node("tools", ToolNode(tools)) # Tools
+    builder.add_node("retriever", retriever)
+    builder.add_node("assistant", assistant)
+    builder.add_node("tools", ToolNode(tools))
     
     # Logic / edges
-    builder.add_edge(START, "assistant")
-    builder.add_conditional_edges("assistant", tools_condition)
+    builder.add_edge(START, "retriever")
+    builder.add_edge("retriever", "assistant")
+    builder.add_conditional_edges(
+        "assistant",
+        tools_condition,
+    )
     builder.add_edge("tools", "assistant")
     
     graph = builder.compile()