update CLAUDE.md

CLAUDE.md

@@ -43,16 +43,11 @@ Tests use Bun's Jest-compatible test runner with proper test fixtures:
 
 ```typescript
 import { test, expect } from "bun:test";
-import {
-  bunEnv,
-  bunExe,
-  normalizeBunSnapshot,
-  tempDirWithFiles,
-} from "harness";
+import { bunEnv, bunExe, normalizeBunSnapshot, tempDir } from "harness";
 
 test("my feature", async () => {
   // Create temp directory with test files
-  const dir = tempDirWithFiles("test-prefix", {
+  using dir = tempDir("test-prefix", {
     "index.js": `console.log("hello");`,
   });
 
@@ -60,7 +55,7 @@ test("my feature", async () => {
   await using proc = Bun.spawn({
     cmd: [bunExe(), "index.js"],
     env: bunEnv,
-    cwd: dir,
+    cwd: String(dir),
     stderr: "pipe",
   });