feat(langfuse): filter out non-tool-call spans from export

src/lib/langfuse-transport.ts

@@ -65,8 +65,12 @@ export function initializeLangfuseTransport(): void {
   provider = new NodeTracerProvider({
     spanProcessors: [
       new LangfuseSpanProcessor({
-        // Export all spans, not just LLM-relevant ones
+        // Only export tool-call spans, skip health checks and protocol noise
-        shouldExportSpan: () => true,
+        shouldExportSpan: (span) => {
+          const mcpMethod = span.otelSpan.attributes["mcp_method"];
+          if (mcpMethod === "tools/call") return true;
+          return !mcpMethod;
+        },
       }),
     ],
   });

src/mcp-server-http.ts

@@ -329,6 +329,7 @@ export async function main() {
         }),
         method: c.req.method,
         client_ip: clientIp,
+        mcp_method: mcpInfo.method ?? "",
       },
       async () => {
         const op = log.start(LogOperation.HANDLING_MCP_HTTP_REQUEST, {