fix(core): honor enabled=false in nested tracing (#31986)

Co-authored-by: Mason Daugherty <mason@langchain.dev>
Co-authored-by: Mason Daugherty <github@mdrxy.com>

libs/core/langchain_core/tracers/langchain.py

@@ -8,7 +8,7 @@ from datetime import datetime, timezone
 from typing import TYPE_CHECKING, Any, Optional, Union
 from uuid import UUID
 
-from langsmith import Client
+from langsmith import Client, get_tracing_context
 from langsmith import run_trees as rt
 from langsmith import utils as ls_utils
 from tenacity import (
@@ -113,6 +113,8 @@ class LangChainTracer(BaseTracer):
         super()._start_trace(run)
         if run.ls_client is None:
             run.ls_client = self.client
+        if get_tracing_context().get("enabled") is False:
+            run.extra["__disabled"] = True
 
     def on_chat_model_start(
         self,
@@ -205,6 +207,8 @@ class LangChainTracer(BaseTracer):
 
     def _persist_run_single(self, run: Run) -> None:
         """Persist a run."""
+        if run.extra.get("__disabled"):
+            return
         try:
             run.extra["runtime"] = get_runtime_environment()
             run.tags = self._get_tags(run)
@@ -218,6 +222,8 @@ class LangChainTracer(BaseTracer):
 
     def _update_run_single(self, run: Run) -> None:
         """Update a run."""
+        if run.extra.get("__disabled"):
+            return
         try:
             run.patch(exclude_inputs=run.extra.get("inputs_is_truthy", False))
         except Exception as e: