fix: add shutdownTracing() to flush chrome trace before process exit

Rust statics stored in OnceLock are never dropped on process exit,
so the ChromeLayer FlushGuard never flushes trace data to disk.
Add an explicit shutdown_tracing() NAPI function that drops the guard,
and call it from bin.ts before process.exit().

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: branchseer

packages/cli/binding/src/lib.rs

@@ -40,6 +40,18 @@ pub fn init() {
     TRACING_GUARD.get_or_init(|| std::sync::Mutex::new(crate::cli::init_tracing()));
 }
 
+/// Flush and drop the tracing guard. Must be called before process.exit()
+/// because Rust statics in OnceLock are never dropped, and the ChromeLayer
+/// FlushGuard only writes trace data to disk when dropped.
+#[napi]
+pub fn shutdown_tracing() {
+    if let Some(mutex) = TRACING_GUARD.get() {
+        if let Ok(mut guard) = mutex.lock() {
+            drop(guard.take());
+        }
+    }
+}
+
 /// Configuration options passed from JavaScript to Rust.
 #[napi(object, object_to_js = false)]
 pub struct CliOptions {

packages/cli/src/bin.ts

@@ -12,7 +12,7 @@
 
 const jsStartTime = performance.now();
 
-import { run } from '../binding/index.js';
+import { run, shutdownTracing } from '../binding/index.js';
 import { doc } from './resolve-doc.js';
 import { fmt } from './resolve-fmt.js';
 import { lint } from './resolve-lint.js';
@@ -63,10 +63,12 @@ if (command === 'create') {
     args: process.argv.slice(2),
   })
     .then((exitCode) => {
+      shutdownTracing();
       process.exit(exitCode);
     })
     .catch((err) => {
       console.error('[Vite+] run error:', err);
+      shutdownTracing();
       process.exit(1);
     });
 }