[Core] respect tracing project name cvar (#28792)

libs/core/langchain_core/callbacks/manager.py

@@ -2379,6 +2379,7 @@ def _configure(
                             if run_tree is not None
                             else tracing_context["client"]
                         ),
+                        tags=tracing_tags,
                     )
                     callback_manager.add_handler(handler, True)
                 except Exception as e:

libs/core/langchain_core/tracers/context.py

@@ -13,8 +13,8 @@ from typing import (
 )
 from uuid import UUID
 
+from langsmith import run_helpers as ls_rh
 from langsmith import utils as ls_utils
-from langsmith.run_helpers import get_run_tree_context
 
 from langchain_core.tracers.langchain import LangChainTracer
 from langchain_core.tracers.run_collector import RunCollectorCallbackHandler
@@ -149,7 +149,10 @@ def _tracing_v2_is_enabled() -> Union[bool, Literal["local"]]:
 
 
 def _get_tracer_project() -> str:
-    run_tree = get_run_tree_context()
+    tracing_context = ls_rh.get_tracing_context()
+    run_tree = tracing_context["parent"]
+    if run_tree is None and tracing_context["project_name"] is not None:
+        return tracing_context["project_name"]
     return getattr(
         run_tree,
         "session_name",

libs/core/tests/unit_tests/runnables/test_tracing_interops.py

@@ -35,6 +35,25 @@ def _get_posts(client: Client) -> list:
     return posts
 
 
+def test_tracing_context() -> None:
+    mock_session = MagicMock()
+    mock_client_ = Client(
+        session=mock_session, api_key="test", auto_batch_tracing=False
+    )
+
+    @RunnableLambda
+    def my_function(a: int) -> int:
+        return a + 1
+
+    name = uuid.uuid4().hex
+    project_name = f"Some project {name}"
+    with tracing_context(project_name=project_name, client=mock_client_, enabled=True):
+        assert my_function.invoke(1) == 2
+    posts = _get_posts(mock_client_)
+    assert posts
+    assert all(post["session_name"] == project_name for post in posts)
+
+
 def test_config_traceable_handoff() -> None:
     get_env_var.cache_clear()
     mock_session = MagicMock()