diff --git a/src/main/services/ptyManager.ts b/src/main/services/ptyManager.ts
index ff4cf36b7..75bf49ae1 100644
--- a/src/main/services/ptyManager.ts
+++ b/src/main/services/ptyManager.ts
@@ -19,10 +19,10 @@ import { LOCALE_ENV_VARS, DEFAULT_UTF8_LOCALE, isUtf8Locale } from '../utils/loc
  * so EPIPE becomes an uncaught exception. Registering an additional error
  * listener bumps the listener count to >= 2, which causes node-pty to
  * swallow the error instead of throwing.
+ *
+ * The same pattern helps on Unix when the PTY is torn down during session close.
  */
 function suppressPtyPipeErrors(proc: IPty): void {
-  if (process.platform !== 'win32') return;
-
   // IPty doesn't expose .on() in its type, but the underlying Terminal
   // class extends EventEmitter and proxies to the socket.
   (proc as any).on?.('error', (err: NodeJS.ErrnoException) => {
@@ -30,6 +30,14 @@ function suppressPtyPipeErrors(proc: IPty): void {
     log.warn('ptyManager: unexpected PTY error', { code: err.code, message: err.message });
   });
 }
+
+function isBenignStreamShutdownError(err: unknown): boolean {
+  const code =
+    err && typeof err === 'object' && 'code' in err
+      ? (err as NodeJS.ErrnoException).code
+      : undefined;
+  return code === 'EPIPE' || code === 'EIO' || code === 'ECONNRESET';
+}
 import { getProviderCustomConfig } from '../settings';
 import { agentEventService } from './AgentEventService';
 import { OpenCodeHookService } from './OpenCodeHookService';
@@ -1757,8 +1765,14 @@ export function createUtf8StreamForwarder(emitData: (data: string) => void): {
 }
 
 type LifecycleSpawnFallbackChild = {
-  stdout?: { on: (event: 'data', listener: (buf: Buffer) => void) => void } | null;
-  stderr?: { on: (event: 'data', listener: (buf: Buffer) => void) => void } | null;
+  stdout?: {
+    on(event: 'data', listener: (buf: Buffer) => void): void;
+    on(event: 'error', listener: (err: unknown) => void): void;
+  } | null;
+  stderr?: {
+    on(event: 'data', listener: (buf: Buffer) => void): void;
+    on(event: 'error', listener: (err: unknown) => void): void;
+  } | null;
   on: (event: 'error' | 'exit' | 'close', listener: (...args: any[]) => void) => void;
 };
 
@@ -1783,6 +1797,16 @@ export function attachLifecycleSpawnFallbackHandlers(
     forwarder.pushStderr(buf);
   });
 
+  // Without these, closing the child can emit EPIPE on stdio streams (Node reads
+  // from a broken pipe) and surface as an uncaught exception in the main process.
+  const onStdioError = (err: unknown) => {
+    if (isBenignStreamShutdownError(err)) return;
+    forwarder.flush();
+    onError(err instanceof Error ? err : new Error(String(err)));
+  };
+  child.stdout?.on('error', onStdioError);
+  child.stderr?.on('error', onStdioError);
+
   child.on('error', (error: Error) => {
     forwarder.flush();
     onError(error);
diff --git a/src/test/main/ptyManager.test.ts b/src/test/main/ptyManager.test.ts
index 6be7784b4..013e3861f 100644
--- a/src/test/main/ptyManager.test.ts
+++ b/src/test/main/ptyManager.test.ts
@@ -401,7 +401,7 @@ describe('ptyManager provider command resolution', () => {
     );
   });
 
-  it('attaches PTY pipe error suppression on Windows only', async () => {
+  it('attaches PTY pipe error suppression on all platforms', async () => {
     const originalPlatformDescriptor = Object.getOwnPropertyDescriptor(process, 'platform');
     const onWin32 = vi.fn();
     const onDarwin = vi.fn();
@@ -450,7 +450,7 @@ describe('ptyManager provider command resolution', () => {
         shell: '/bin/zsh',
       });
 
-      expect(onDarwin).not.toHaveBeenCalledWith('error', expect.any(Function));
+      expect(onDarwin).toHaveBeenCalledWith('error', expect.any(Function));
     } finally {
       if (originalPlatformDescriptor) {
         Object.defineProperty(process, 'platform', originalPlatformDescriptor);
@@ -606,6 +606,32 @@ describe('ptyManager provider command resolution', () => {
     expect(received.join('')).toBe('Marko Ranđ');
     expect(exits).toEqual([[0, null]]);
   });
+
+  it('ignores EPIPE on stdio streams during lifecycle fallback', async () => {
+    const stdout = new EventEmitter();
+    const stderr = new EventEmitter();
+    const child = new EventEmitter() as EventEmitter & {
+      stdout: EventEmitter;
+      stderr: EventEmitter;
+    };
+    child.stdout = stdout;
+    child.stderr = stderr;
+
+    const { attachLifecycleSpawnFallbackHandlers } = await import('../../main/services/ptyManager');
+    const errors: Error[] = [];
+    attachLifecycleSpawnFallbackHandlers(child, {
+      onData: () => {},
+      onExit: () => {},
+      onError: (error) => {
+        errors.push(error);
+      },
+    });
+
+    const epipe = Object.assign(new Error('read EPIPE'), { code: 'EPIPE' as const });
+    stdout.emit('error', epipe);
+    stderr.emit('error', epipe);
+    expect(errors).toEqual([]);
+  });
 });
 
 describe('stale Claude session detection', () => {