From 63398d9f34639dc81aaaf05b2625508945a3b20d Mon Sep 17 00:00:00 2001
From: Dayuan Jiang <34411969+DayuanJiang@users.noreply.github.com>
Date: Wed, 24 Dec 2025 10:47:34 +0900
Subject: [PATCH] fix: filter Langfuse traces to only export chat and AI SDK
 spans (#392)

Switch from blocklist to whitelist approach - only export spans named
'chat' or starting with 'ai.' to filter out Next.js infrastructure noise
(HEAD, fetch, POST requests).
---
 instrumentation.ts | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/instrumentation.ts b/instrumentation.ts
index 7fe59fb..d6d4506 100644
--- a/instrumentation.ts
+++ b/instrumentation.ts
@@ -14,22 +14,14 @@ export function register() {
         publicKey: process.env.LANGFUSE_PUBLIC_KEY,
         secretKey: process.env.LANGFUSE_SECRET_KEY,
         baseUrl: process.env.LANGFUSE_BASEURL,
-        // Filter out Next.js HTTP request spans so AI SDK spans become root traces
+        // Whitelist approach: only export AI-related spans
         shouldExportSpan: ({ otelSpan }) => {
             const spanName = otelSpan.name
-            // Skip Next.js HTTP infrastructure spans
-            if (
-                spanName.startsWith("POST") ||
-                spanName.startsWith("GET") ||
-                spanName.startsWith("RSC") ||
-                spanName.includes("BaseServer") ||
-                spanName.includes("handleRequest") ||
-                spanName.includes("resolve page") ||
-                spanName.includes("start response")
-            ) {
-                return false
+            // Only export AI SDK spans (ai.*) and our explicit "chat" wrapper
+            if (spanName === "chat" || spanName.startsWith("ai.")) {
+                return true
             }
-            return true
+            return false
         },
     })