Add OpenCode context metadata to Langfuse traces

README.md

@@ -58,6 +58,8 @@ That's it! All traces appear automatically in your Langfuse dashboard.
 
 This plugin initializes a `LangfuseSpanProcessor` that captures all OpenTelemetry spans emitted by OpenCode when `experimental.openTelemetry` is enabled.
 
+It also adds the OpenCode project ID, working directory, and worktree to every span as filterable Langfuse trace metadata (`project`, `directory`, and `worktree`).
+
 ```
 OpenCode (OTEL spans) → LangfuseSpanProcessor → Langfuse Dashboard
 ```

src/index.test.ts

@@ -3,6 +3,7 @@ import { LangfusePlugin } from "./index";
 
 const mockForceFlush = mock(() => Promise.resolve());
 const mockStart = mock(() => {});
+let sdkOptions: any;
 
 mock.module("@langfuse/otel", () => ({
   LangfuseSpanProcessor: mock(() => ({
@@ -11,9 +12,10 @@ mock.module("@langfuse/otel", () => ({
 }));
 
 mock.module("@opentelemetry/sdk-node", () => ({
-  NodeSDK: mock(() => ({
-    start: mockStart,
-  })),
+  NodeSDK: mock((options: any) => {
+    sdkOptions = options;
+    return { start: mockStart };
+  }),
 }));
 
 const mockLog = mock(() => {});
@@ -41,6 +43,7 @@ describe("LangfusePlugin", () => {
     mockForceFlush.mockClear();
     mockStart.mockClear();
     mockLog.mockClear();
+    sdkOptions = undefined;
   });
 
   afterEach(() => {
@@ -50,6 +53,7 @@ describe("LangfusePlugin", () => {
   const setupEnv = (overrides: Record<string, string> = {}) => {
     process.env.LANGFUSE_PUBLIC_KEY = "pk-test";
     process.env.LANGFUSE_SECRET_KEY = "sk-test";
+    delete process.env.LANGFUSE_BASEURL;
     Object.assign(process.env, overrides);
   };
 
@@ -86,6 +90,27 @@ describe("LangfusePlugin", () => {
         },
       });
     });
+
+    it("adds OpenCode context as filterable Langfuse trace metadata", async () => {
+      setupEnv();
+      await LangfusePlugin(mockPluginInput());
+
+      const span = { setAttribute: mock(() => {}) };
+      sdkOptions.spanProcessors[0].onStart(span, {});
+
+      expect(span.setAttribute).toHaveBeenCalledWith(
+        "langfuse.trace.metadata.project",
+        "proj-123"
+      );
+      expect(span.setAttribute).toHaveBeenCalledWith(
+        "langfuse.trace.metadata.directory",
+        "/test/dir"
+      );
+      expect(span.setAttribute).toHaveBeenCalledWith(
+        "langfuse.trace.metadata.worktree",
+        "/test/worktree"
+      );
+    });
   });
 
   describe("config hook", () => {

src/index.ts

@@ -1,8 +1,27 @@
 import { LangfuseSpanProcessor } from "@langfuse/otel";
 import type { Plugin } from "@opencode-ai/plugin";
+import type { SpanProcessor } from "@opentelemetry/sdk-trace-base";
 import { NodeSDK } from "@opentelemetry/sdk-node";
 
-export const LangfusePlugin: Plugin = async ({ client }) => {
+const createMetadataSpanProcessor = (
+  metadata: Record<string, string>
+): SpanProcessor => ({
+  onStart: (span) => {
+    for (const [key, value] of Object.entries(metadata)) {
+      span.setAttribute(`langfuse.trace.metadata.${key}`, value);
+    }
+  },
+  onEnd: () => {},
+  forceFlush: async () => {},
+  shutdown: async () => {},
+});
+
+export const LangfusePlugin: Plugin = async ({
+  client,
+  project,
+  directory,
+  worktree,
+}) => {
   const publicKey = process.env.LANGFUSE_PUBLIC_KEY;
   const secretKey = process.env.LANGFUSE_SECRET_KEY;
   const baseUrl = process.env.LANGFUSE_BASEURL ?? "https://cloud.langfuse.com";
@@ -29,8 +48,14 @@ export const LangfusePlugin: Plugin = async ({ client }) => {
     environment,
   });
 
+  const metadataProcessor = createMetadataSpanProcessor({
+    project: project.id,
+    directory,
+    worktree,
+  });
+
   const sdk = new NodeSDK({
-    spanProcessors: [processor],
+    spanProcessors: [metadataProcessor, processor],
   });
 
   sdk.start();