From bbb308259b033e0f5509c9f4453d01706f62b6ce Mon Sep 17 00:00:00 2001
From: Quanzheng Long <long@langchain.dev>
Date: Thu, 12 Mar 2026 12:31:46 -0700
Subject: [PATCH] poc

---
 .../tests/advanced-graph/test_sub_agents.py   | 124 ++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 libs/langgraph/tests/advanced-graph/test_sub_agents.py

diff --git a/libs/langgraph/tests/advanced-graph/test_sub_agents.py b/libs/langgraph/tests/advanced-graph/test_sub_agents.py
new file mode 100644
index 000000000..583f648af
--- /dev/null
+++ b/libs/langgraph/tests/advanced-graph/test_sub_agents.py
@@ -0,0 +1,124 @@
+from typing import Annotated
+
+class MainAgentState(TypedDict):
+    input: str
+    output: list[str]
+
+advanced_flow = AdvancedStateGraph(MainAgentState)
+advanced_flow.add_async_channel("inbox", str) # default to infinite buffer like Rust channel
+
+prompt = "based on current state, decide to use tool, or kick off subagent, or complete"
+main_llm = new_mock_llm(prompt, [email_tool, slack_tool])
+
+async def llm_node(state: MainAgentState):
+    decisions = await main_llm.ainvoke(state)
+    sends = []
+    for decision in decisions:
+        if decision.type == "end":
+            return Command(goto=Send("end", decision.complete)) # NOTE: we can simplify to just Complete(decision.complete)
+        elif decision.type == "sub_agent":
+            sends.append(Send("sub_agent", decision.sub_agent)) # NOTE: we can simplify to just sends.apppend(subagent, decision.sub_agent)
+        elif decision.type == "tool":
+            sends.append(Send("tool", decision.tool))
+    sends.append(Send("wait_node"))
+    return Command(goto=sends)        
+
+async def wait_node(state: MainAgentState):
+    # wait for at least one message on the inbox channel
+    # this is a "lightweight" interrupt, that does not block the entire graph
+    msgs = wait_for("inbox") 
+
+    output = state.output
+    if msg.type == "tool":
+        output.append("tool: " + msg.payload)
+    elif msg.type == "sub_agent":
+        output.append("sub_agent: " + msg.payload)
+    elif msg.type == "user_input":
+        output.append("user_input: " + msg.payload)
+    
+    # loop back to llm node with new output
+    return Command(goto=Send("llm_node", output))
+
+
+async def tool_node(tool_input: str):
+    await asyncio.sleep(5)
+    output = "tool completed for: " + tool_input
+    publish_to_channel("inbox", {"type": "tool", "payload": output})
+    # just complete without going to next node
+
+async def order_food_node(state: str):
+    return "order_food_node completed for: " + state
+
+# sub agent uses regular/simple state graph 
+sub_agent = StateGraph(str)
+async def research_node (state: str):
+    await asyncio.sleep(10)
+    return "research sub agent completed for: " + state
+sub_agent.add_node("research_node", research_node)
+sub_agent.add_edge(START, "research_node")
+sub_agent.add_edge("research_node", END)
+
+async def sub_agent_node(sub_agent_input: str):
+    sub_agent_output = sub_agent.invoke({"input": sub_agent_input})
+    publish_to_channel("inbox", {"type": "sub_agent", "payload": sub_agent_output})
+    # just complete without going to next node
+
+advanced_flow.add_node("llm_node", llm_node) 
+advanced_flow.add_node("wait_node", wait_node) 
+advanced_flow.add_node("tool_node", tool_node)
+advanced_flow.add_node("sub_agent_node", sub_agent_node)
+advanced_flow.add_node("order_food_node", order_food_node)
+advanced_flow.set_entry_point("llm_node")
+advanced_flow.set_finish_point("order_food_node")
+
+## NOTE: above can be simplified to:
+# advanced_flow.add_entry_node(llm_node)
+# advanced_flow.node(wait_node)
+# advanced_flow.node(tool_node)
+# advanced_flow.node(sub_agent_node)
+# advanced_flow.add_finish_node(order_food_node)
+
+main_agent = advanced_flow.compile()
+
+async def test_async_sub_graph():
+    main_llm.mock_response = [
+        # first llm invoke
+        [
+            {
+                "type": "sub_agent",
+                "sub_agent": "research_node"
+            },
+                        {
+                "type": "tool",
+                "tool": "slack_tool"
+            }
+        ],
+        # 2nd llm invoke, after additional user input
+        [
+            {
+                "type": "sub_agent",
+            }
+        ],
+        # 3rd llm invoke, after tool node completes
+        [], 
+        # 4th llm invoke, after 1st sub agent node completes
+        [],
+        # 5th llm invoke, after 2nd sub agent node completes
+        [
+            {
+                "type": "end"
+            }
+        ],
+    ]
+
+    started = main_agent.ainvoke({"input": "help me get something for lunch"})
+    # provide more info after 2 seconds
+    await asyncio.sleep(2)
+    main_agent.apublish_to_channel("inbox", {"type": "user_input", "payload": "No spicy food please"})
+    result = await started
+    assert result == {
+        "input": "help me get something for lunch",
+        "output":[
+
+        ]
+    }
\ No newline at end of file