diff --git a/packages/cli/src/dualOutput/DualOutputBridge.test.ts b/packages/cli/src/dualOutput/DualOutputBridge.test.ts
index 8c7a7f6db..3a574e727 100644
--- a/packages/cli/src/dualOutput/DualOutputBridge.test.ts
+++ b/packages/cli/src/dualOutput/DualOutputBridge.test.ts
@@ -44,10 +44,8 @@ describe('DualOutputBridge', () => {
   });
 
   afterEach(async () => {
-    bridge?.shutdown();
+    await bridge?.shutdown();
     bridge = null;
-    // Give the stream a tick to flush before removing the directory
-    await new Promise((r) => setTimeout(r, 10));
     fs.rmSync(tmpDir, { recursive: true, force: true });
   });
 
@@ -69,8 +67,7 @@ describe('DualOutputBridge', () => {
       const newFile = path.join(tmpDir, 'does-not-exist.jsonl');
       // newFile is NOT pre-created — tests the ENOENT fallback path
       bridge = new DualOutputBridge(config, { filePath: newFile });
-      bridge.shutdown();
-      await new Promise((r) => setTimeout(r, 10));
+      await bridge.shutdown();
 
       const lines = readJsonl(newFile);
       expect(lines.length).toBeGreaterThan(0);
@@ -82,8 +79,7 @@ describe('DualOutputBridge', () => {
 
     it('emits a session_start event immediately on construction', async () => {
       bridge = new DualOutputBridge(config, { filePath: target });
-      bridge.shutdown();
-      await new Promise((r) => setTimeout(r, 10));
+      await bridge.shutdown();
 
       const lines = readJsonl(target);
       expect(lines.length).toBeGreaterThan(0);
@@ -100,8 +96,7 @@ describe('DualOutputBridge', () => {
         { filePath: target },
         { version: '1.2.3' },
       );
-      bridge.shutdown();
-      await new Promise((r) => setTimeout(r, 10));
+      await bridge.shutdown();
 
       const lines = readJsonl(target);
       const start = lines.find(
@@ -116,8 +111,7 @@ describe('DualOutputBridge', () => {
 
     it('emits session_end on shutdown for a clean termination signal', async () => {
       bridge = new DualOutputBridge(config, { filePath: target });
-      bridge.shutdown();
-      await new Promise((r) => setTimeout(r, 10));
+      await bridge.shutdown();
 
       const lines = readJsonl(target);
       const end = lines.find(
@@ -132,9 +126,8 @@ describe('DualOutputBridge', () => {
 
     it('shutdown is idempotent — calling it twice emits session_end only once', async () => {
       bridge = new DualOutputBridge(config, { filePath: target });
-      bridge.shutdown();
-      bridge.shutdown();
-      await new Promise((r) => setTimeout(r, 10));
+      await bridge.shutdown();
+      await bridge.shutdown();
 
       const lines = readJsonl(target);
       const endEvents = lines.filter(
@@ -146,8 +139,7 @@ describe('DualOutputBridge', () => {
     it('emitControlError routes through the adapter as a control_response error', async () => {
       bridge = new DualOutputBridge(config, { filePath: target });
       bridge.emitControlError('req-missing', 'unknown request_id');
-      bridge.shutdown();
-      await new Promise((r) => setTimeout(r, 10));
+      await bridge.shutdown();
 
       const lines = readJsonl(target);
       const errorResponse = lines.find(
@@ -169,8 +161,7 @@ describe('DualOutputBridge', () => {
       bridge = new DualOutputBridge(config, { filePath: target });
       bridge.emitPermissionRequest('req-1', 'shell', 'tu-1', { cmd: 'ls' });
       bridge.emitControlResponse('req-1', false);
-      bridge.shutdown();
-      await new Promise((r) => setTimeout(r, 10));
+      await bridge.shutdown();
 
       const lines = readJsonl(target);
       const request = lines.find((l) => l['type'] === 'control_request');
@@ -198,7 +189,7 @@ describe('DualOutputBridge', () => {
 
     it('reports isConnected=false after shutdown and silently drops further events', async () => {
       bridge = new DualOutputBridge(config, { filePath: target });
-      bridge.shutdown();
+      await bridge.shutdown();
       expect(bridge.isConnected).toBe(false);
 
       // Should not throw
diff --git a/packages/cli/src/dualOutput/DualOutputBridge.ts b/packages/cli/src/dualOutput/DualOutputBridge.ts
index ec70bcd6e..fb8bc5800 100644
--- a/packages/cli/src/dualOutput/DualOutputBridge.ts
+++ b/packages/cli/src/dualOutput/DualOutputBridge.ts
@@ -77,7 +77,7 @@ export class DualOutputBridge {
   private readonly stream: WriteStream;
   private readonly sessionId: string;
   private active = true;
-  private shutdownCalled = false;
+  private shutdownPromise: Promise<void> | null = null;
 
   constructor(
     config: Config,
@@ -288,9 +288,8 @@ export class DualOutputBridge {
     }
   }
 
-  shutdown(): void {
-    if (this.shutdownCalled) return;
-    this.shutdownCalled = true;
+  shutdown(): Promise<void> {
+    if (this.shutdownPromise) return this.shutdownPromise;
     // Try to emit session_end before tearing the stream down so consumers
     // get a definitive termination signal rather than inferring it from
     // EPIPE. Failures here are swallowed — the stream may already be in an
@@ -305,10 +304,35 @@ export class DualOutputBridge {
       }
     }
     this.active = false;
-    try {
-      this.stream.end();
-    } catch (err) {
-      debugLogger.debug('DualOutput: stream end error during shutdown:', err);
-    }
+    this.shutdownPromise = new Promise((resolve) => {
+      if (this.stream.closed) {
+        resolve();
+        return;
+      }
+
+      const cleanup = () => {
+        this.stream.off('close', onClose);
+        this.stream.off('error', onError);
+      };
+      const onClose = () => {
+        cleanup();
+        resolve();
+      };
+      const onError = (err: Error) => {
+        debugLogger.debug('DualOutput: stream error during shutdown:', err);
+      };
+
+      this.stream.once('close', onClose);
+      this.stream.once('error', onError);
+
+      try {
+        this.stream.end();
+      } catch (err) {
+        cleanup();
+        debugLogger.debug('DualOutput: stream end error during shutdown:', err);
+        resolve();
+      }
+    });
+    return this.shutdownPromise;
   }
 }
diff --git a/packages/cli/src/gemini.tsx b/packages/cli/src/gemini.tsx
index 92845216d..b106f524a 100644
--- a/packages/cli/src/gemini.tsx
+++ b/packages/cli/src/gemini.tsx
@@ -269,9 +269,9 @@ export async function startInteractiveUI(
       });
   }
 
-  registerCleanup(() => {
+  registerCleanup(async () => {
     remoteInputWatcher?.shutdown();
-    dualOutputBridge?.shutdown();
+    await dualOutputBridge?.shutdown();
     instance.unmount();
     restoreTerminalRedrawOptimizer();
   });