From 964bf68439a82ec51925631cf317153b9c536f7f Mon Sep 17 00:00:00 2001
From: Rahul Verma <rahul@langchain.dev>
Date: Fri, 19 Sep 2025 18:44:32 -0400
Subject: [PATCH 1/2] Add example for configuring an anonymizer for LangGraph

---
 src/oss/langgraph/observability.mdx | 56 ++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

diff --git a/src/oss/langgraph/observability.mdx b/src/oss/langgraph/observability.mdx
index dc67ae0aa..c601aa6b8 100644
--- a/src/oss/langgraph/observability.mdx
+++ b/src/oss/langgraph/observability.mdx
@@ -30,6 +30,60 @@ export LANGSMITH_API_KEY=<your-api-key>
 
 By default, the trace will be logged to the project with the name `default`. To configure a custom project name, see [Log to a project](#log-to-a-project).
 
-For more information, see [Trace with LangGraph](langsmith/trace-with-langgraph).
+For more information, see [Trace with LangGraph](/langsmith/trace-with-langgraph).
 
 <observability />
+
+## Use anonymizers to prevent logging of sensitive data in traces
+
+You may want to mask sensitive data to prevent it from being logged to LangSmith. You can create [anonymizers](/langsmith/mask-inputs-outputs#rule-based-masking-of-inputs-and-outputs) and apply them to
+your graph using configuration. This example will redact anything matching the Social Security Number format XXX-XX-XXXX from traces sent to LangSmith.
+
+<CodeGroup>
+```python Python
+from langchain_core.tracers.langchain import LangChainTracer
+from langgraph.graph import StateGraph, MessagesState
+from langsmith import Client
+from langsmith.anonymizer import create_anonymizer
+
+anonymizer = create_anonymizer([
+    # Matches SSNs
+    { "pattern": r"\b\d{3}-?\d{2}-?\d{4}\b", "replace": "<ssn>" }
+])
+
+tracer_client = Client(anonymizer=anonymizer)
+tracer = LangChainTracer(client=tracer_client)
+# Define the graph
+graph = (
+    StateGraph(MessagesState)
+    ...
+    .compile()
+    .with_config({'callbacks': [tracer]})
+)
+```
+
+```typescript TypeScript
+import { StateGraph } from "@langchain/langgraph";
+import { LangChainTracer } from "@langchain/core/tracers/tracer_langchain";
+import { StateAnnotation } from "./state.js";
+import { createAnonymizer } from "langsmith/anonymizer"
+import { Client } from "langsmith"
+
+
+const anonymizer = createAnonymizer([
+    # Matches SSNs
+    { pattern: /\b\d{3}-?\d{2}-?\d{4}\b/, replace: "<ssn>" }
+])
+
+const langsmithClient = new Client({ anonymizer })
+const tracer = new LangChainTracer({
+  client: langsmithClient,
+});
+
+export const graph = new StateGraph(StateAnnotation)
+  .compile()
+  .withConfig({
+    callbacks: [tracer],
+});
+```
+</CodeGroup>

From 4d67fac7fb0ef74e0a36c1fd6efbf55c73398402 Mon Sep 17 00:00:00 2001
From: Lauren Hirata Singh <lauren@langchain.dev>
Date: Mon, 22 Sep 2025 10:54:31 -0400
Subject: [PATCH 2/2] Apply suggestions from code review

---
 src/oss/langgraph/observability.mdx | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/oss/langgraph/observability.mdx b/src/oss/langgraph/observability.mdx
index c601aa6b8..89821a23a 100644
--- a/src/oss/langgraph/observability.mdx
+++ b/src/oss/langgraph/observability.mdx
@@ -39,7 +39,7 @@ For more information, see [Trace with LangGraph](/langsmith/trace-with-langgraph
 You may want to mask sensitive data to prevent it from being logged to LangSmith. You can create [anonymizers](/langsmith/mask-inputs-outputs#rule-based-masking-of-inputs-and-outputs) and apply them to
 your graph using configuration. This example will redact anything matching the Social Security Number format XXX-XX-XXXX from traces sent to LangSmith.
 
-<CodeGroup>
+:::python
 ```python Python
 from langchain_core.tracers.langchain import LangChainTracer
 from langgraph.graph import StateGraph, MessagesState
@@ -61,7 +61,8 @@ graph = (
     .with_config({'callbacks': [tracer]})
 )
 ```
-
+:::
+:::js
 ```typescript TypeScript
 import { StateGraph } from "@langchain/langgraph";
 import { LangChainTracer } from "@langchain/core/tracers/tracer_langchain";
@@ -86,4 +87,4 @@ export const graph = new StateGraph(StateAnnotation)
     callbacks: [tracer],
 });
 ```
-</CodeGroup>
+:::