revert: feat(langchain): ls_agent_type tag on create_agent calls (#37249)

libs/langchain_v1/langchain/agents/factory.py

@@ -1647,12 +1647,7 @@ def create_agent(
 
     # Set recursion limit to 9_999
     # https://github.com/langchain-ai/langgraph/issues/7313
-    config: RunnableConfig = {
-        "recursion_limit": 9_999,
-        "configurable": {
-            "ls_agent_type": "root",
-        },
-    }
+    config: RunnableConfig = {"recursion_limit": 9_999}
     config["metadata"] = {"ls_integration": "langchain_create_agent"}
     if name:
         config["metadata"]["lc_agent_name"] = name

libs/langchain_v1/tests/unit_tests/agents/test_injected_runtime_create_agent.py

@@ -16,17 +16,12 @@ configurations.
 
 from __future__ import annotations
 
-import json
 from typing import TYPE_CHECKING, Annotated, Any
-from unittest.mock import MagicMock
 
-from langchain_core.callbacks import BaseCallbackHandler
 from langchain_core.messages import HumanMessage, ToolMessage
 from langchain_core.tools import tool
 from langgraph.prebuilt import InjectedStore
 from langgraph.store.memory import InMemoryStore
-from langsmith import Client
-from langsmith.run_helpers import tracing_context
 
 from langchain.agents import create_agent
 from langchain.agents.middleware.types import AgentMiddleware, AgentState
@@ -847,109 +842,3 @@ async def test_combined_injected_state_runtime_store_async() -> None:
     # Verify store was injected and writable
     assert injected_data["store"] is not None
     assert injected_data["store_write_success"] is True
-
-
-def test_ls_agent_type_is_trace_only_metadata() -> None:
-    """Test that ls_agent_type is added to metadata on tracing only, not in streamed chunks."""
-    # Capture metadata from regular callback handler (simulates streamed metadata)
-    captured_callback_metadata: list[dict[str, Any]] = []
-
-    class CaptureHandler(BaseCallbackHandler):
-        def on_chain_start(
-            self,
-            serialized: dict[str, Any],
-            inputs: dict[str, Any],
-            *,
-            run_id: str,
-            parent_run_id: str | None = None,
-            tags: list[str] | None = None,
-            metadata: dict[str, Any] | None = None,
-            **kwargs: Any,
-        ) -> None:
-            captured_callback_metadata.append({"tags": tags, "metadata": metadata})
-
-    # Create a mock client to capture what gets sent to LangSmith
-    mock_session = MagicMock()
-    mock_client = Client(session=mock_session, api_key="test", auto_batch_tracing=False)
-
-    agent = create_agent(
-        model=FakeToolCallingModel(tool_calls=[[], []]),
-        tools=[],
-        system_prompt="You are a helpful assistant.",
-    )
-
-    # Use tracing_context to enable tracing with the mock client
-    with tracing_context(client=mock_client, enabled=True):
-        agent.invoke(
-            {"messages": [HumanMessage("hi?")]},
-            config={"callbacks": [CaptureHandler()]},
-        )
-
-    # Verify that ls_agent_type is NOT in the regular callback metadata
-    # (it should only go to the tracer via langsmith_inheritable_metadata)
-    assert len(captured_callback_metadata) > 0
-    for captured in captured_callback_metadata:
-        metadata = captured.get("metadata") or {}
-        assert metadata.get("ls_agent_type") is None, (
-            f"ls_agent_type should not be in callback metadata, but got: {metadata}"
-        )
-
-    # Verify that ls_agent_type IS in the tracer metadata (sent to LangSmith)
-    # Get the POST requests to the LangSmith API
-    posts = []
-    for call in mock_session.request.mock_calls:
-        if call.args and call.args[0] == "POST":
-            body = json.loads(call.kwargs["data"])
-            if "post" in body:
-                posts.extend(body["post"])
-            else:
-                posts.append(body)
-
-    assert len(posts) >= 1
-    # Find the root run (the agent execution)
-    root_post = posts[0]
-    metadata = root_post.get("extra", {}).get("metadata", {})
-    assert metadata.get("ls_agent_type") == "root", (
-        f"ls_agent_type should be 'root' in tracer metadata, but got: {metadata}"
-    )
-
-
-def test_ls_agent_type_is_overridable() -> None:
-    """Test that ls_agent_type can be overridden via configurable in invoke config."""
-    # Create a mock client to capture what gets sent to LangSmith
-    mock_session = MagicMock()
-    mock_client = Client(session=mock_session, api_key="test", auto_batch_tracing=False)
-
-    agent = create_agent(
-        model=FakeToolCallingModel(tool_calls=[[], []]),
-        tools=[],
-        system_prompt="You are a helpful assistant.",
-    )
-
-    # Use tracing_context to enable tracing with the mock client
-    with tracing_context(client=mock_client, enabled=True):
-        agent.invoke(
-            {"messages": [HumanMessage("hi?")]},
-            config={"configurable": {"ls_agent_type": "subagent", "custom_key": "custom_value"}},
-        )
-
-    # Verify that ls_agent_type is overridden and configurable is merged in the tracer metadata
-    posts = []
-    for call in mock_session.request.mock_calls:
-        if call.args and call.args[0] == "POST":
-            body = json.loads(call.kwargs["data"])
-            if "post" in body:
-                posts.extend(body["post"])
-            else:
-                posts.append(body)
-
-    assert len(posts) >= 1
-    root_post = posts[0]
-    metadata = root_post.get("extra", {}).get("metadata", {})
-    assert metadata.get("ls_agent_type") == "subagent", (
-        f"ls_agent_type should be 'subagent' in tracer metadata, but got: {metadata}"
-    )
-    # Verify that the additional configurable key is merged into metadata
-    assert metadata.get("custom_key") == "custom_value", (
-        f"custom_key should be 'custom_value' in tracer metadata, but got: {metadata}"
-    )

libs/langchain_v1/tests/unit_tests/agents/test_subagent_streaming.py

@@ -0,0 +1,86 @@
+"""Regression tests for subagent stream event propagation.
+
+Reproduces a bug where `create_agent` set ``ls_agent_type`` inside the
+parent agent's ``configurable`` and, as a side effect, ``updates``,
+``values``, and ``custom`` stream events from sub-agents invoked through
+tools were dropped during ``stream(..., subgraphs=True)``.
+"""
+
+from __future__ import annotations
+
+from langchain_core.messages import HumanMessage, ToolCall
+from langchain_core.tools import tool
+
+from langchain.agents import create_agent
+from tests.unit_tests.agents.model import FakeToolCallingModel
+
+
+def _make_subagent_caller_tool():
+    """Build a subagent and a tool that invokes it."""
+    subagent = create_agent(
+        model=FakeToolCallingModel(tool_calls=[[]]),
+        name="subagent",
+    )
+
+    @tool
+    def call_subagent(query: str) -> str:
+        """Delegate the query to a sub-agent."""
+        result = subagent.invoke({"messages": [HumanMessage(query)]})
+        return result["messages"][-1].text
+
+    return call_subagent
+
+
+def _make_parent_agent(call_subagent_tool) -> object:
+    parent_tool_calls: list[list[ToolCall]] = [
+        [{"args": {"query": "hi"}, "id": "call_1", "name": "call_subagent"}],
+        [],
+    ]
+    return create_agent(
+        model=FakeToolCallingModel(tool_calls=parent_tool_calls),
+        tools=[call_subagent_tool],
+        name="parent",
+    )
+
+
+def test_subagent_updates_emitted_when_streaming_with_subgraphs() -> None:
+    """`updates` events from a tool-invoked sub-agent must be streamed.
+
+    Without the fix, the parent agent's ``configurable`` overrode the
+    streaming machinery's per-run state, suppressing ``updates`` events
+    from any sub-graph invoked inside a tool.
+    """
+    call_subagent_tool = _make_subagent_caller_tool()
+    parent = _make_parent_agent(call_subagent_tool)
+
+    subagent_update_events = []
+    for namespace, mode, _data in parent.stream(
+        {"messages": [HumanMessage("hi")]},
+        stream_mode=["updates", "messages"],
+        subgraphs=True,
+    ):
+        if mode == "updates" and namespace:
+            subagent_update_events.append(namespace)
+
+    assert subagent_update_events, (
+        "expected `updates` events from the sub-agent's subgraph namespace, but none were emitted"
+    )
+
+
+async def test_subagent_updates_emitted_when_astreaming_with_subgraphs() -> None:
+    """Async counterpart of the sync regression test."""
+    call_subagent_tool = _make_subagent_caller_tool()
+    parent = _make_parent_agent(call_subagent_tool)
+
+    subagent_update_events = []
+    async for namespace, mode, _data in parent.astream(
+        {"messages": [HumanMessage("hi")]},
+        stream_mode=["updates", "messages"],
+        subgraphs=True,
+    ):
+        if mode == "updates" and namespace:
+            subagent_update_events.append(namespace)
+
+    assert subagent_update_events, (
+        "expected `updates` events from the sub-agent's subgraph namespace, but none were emitted"
+    )