diff --git a/changes/sync-ui-window.md b/changes/sync-ui-window.md
index 3daecd90..d9bea86a 100644
--- a/changes/sync-ui-window.md
+++ b/changes/sync-ui-window.md
@@ -1,5 +1,5 @@
 type: added
 area: sync
 
-- Added a sync window (`subminer sync --ui`, or **Sync Stats & History** in the tray menu) for cross-machine immersion sync: saved devices with per-host direction (two-way/push/pull) and remove, one-click sync with live stage-by-stage progress and merge summaries, connection testing for first-time setup, cancellable runs with a one-click `--force` retry when the running-app guard trips, and manual database snapshots (create/merge/reveal/delete, stored in `/tmp/subminer-db-snapshots/` by default). Hosts with auto-sync enabled are synced in the background on a configurable interval while no mpv session or stats server is writing the database, with results reported as overlay notifications. Hosts synced from the CLI are remembered in `<config dir>/sync-hosts.json` and show up in the window automatically.
+- Added a sync window (`subminer sync --ui`, or **Sync Stats & History** in the tray menu) for cross-machine immersion sync: saved devices with per-host direction (two-way/push/pull) and remove, one-click sync with live stage-by-stage progress and merge summaries, connection testing for first-time setup, cancellable runs with a one-click `--force` retry when the running-app guard trips, and manual database snapshots (create/merge/reveal/delete, stored in `/tmp/subminer-db-snapshots/` by default). Hosts with auto-sync enabled are synced in the background on a configurable interval while no mpv session or stats server is writing the database, with results reported as overlay notifications. Hosts synced from the CLI are remembered in `<config dir>/sync-hosts.json` and show up in the window automatically. When launched with `subminer sync --ui`, closing the window also exits the attached CLI process cleanly.
 - Added `subminer sync <host> --check` to test the SSH connection and remote launcher availability without syncing, and `subminer sync --json` for machine-readable NDJSON progress output (the protocol the sync window consumes).
diff --git a/launcher/commands/app-command.ts b/launcher/commands/app-command.ts
index bb2d31af..47a4d46b 100644
--- a/launcher/commands/app-command.ts
+++ b/launcher/commands/app-command.ts
@@ -1,12 +1,14 @@
 import {
   launchAppBackgroundDetached,
   launchTexthookerOnly,
+  runAppCommandInteractive,
   runAppCommandWithInherit,
 } from '../mpv.js';
 import type { LauncherCommandContext } from './context.js';
 
 type AppCommandDeps = {
   runAppCommandWithInherit: (appPath: string, appArgs: string[]) => void;
+  runAppCommandInteractive: (appPath: string, appArgs: string[]) => void;
   launchAppBackgroundDetached: (
     appPath: string,
     logLevel: LauncherCommandContext['args']['logLevel'],
@@ -15,6 +17,7 @@ type AppCommandDeps = {
 
 const defaultAppCommandDeps: AppCommandDeps = {
   runAppCommandWithInherit,
+  runAppCommandInteractive,
   launchAppBackgroundDetached,
 };
 
@@ -31,7 +34,7 @@ export function runAppPassthroughCommand(
     return true;
   }
   if (args.syncUi) {
-    deps.runAppCommandWithInherit(appPath, ['--sync-window']);
+    deps.runAppCommandInteractive(appPath, ['--sync-window']);
     return true;
   }
   if (!args.appPassthrough) {
diff --git a/launcher/commands/command-modules.test.ts b/launcher/commands/command-modules.test.ts
index c709b423..25e34f12 100644
--- a/launcher/commands/command-modules.test.ts
+++ b/launcher/commands/command-modules.test.ts
@@ -206,6 +206,7 @@ test('app command starts default macOS background app detached from launcher', (
     runAppCommandWithInherit: () => {
       calls.push('attached');
     },
+    runAppCommandInteractive: () => calls.push('interactive'),
     launchAppBackgroundDetached: (appPath, logLevel) => {
       calls.push(`detached:${appPath}:${logLevel}`);
     },
@@ -225,6 +226,7 @@ test('app command starts default Linux background app detached from launcher', (
     runAppCommandWithInherit: () => {
       calls.push('attached');
     },
+    runAppCommandInteractive: () => calls.push('interactive'),
     launchAppBackgroundDetached: (appPath, logLevel) => {
       calls.push(`detached:${appPath}:${logLevel}`);
     },
@@ -245,6 +247,7 @@ test('app command keeps explicit passthrough args attached', () => {
     runAppCommandWithInherit: (_appPath, appArgs) => {
       forwarded.push(appArgs);
     },
+    runAppCommandInteractive: () => detached.push('interactive'),
     launchAppBackgroundDetached: () => {
       detached.push('detached');
     },
@@ -255,6 +258,21 @@ test('app command keeps explicit passthrough args attached', () => {
   assert.deepEqual(detached, []);
 });
 
+test('sync UI command attaches the app directly to the terminal', () => {
+  const context = createContext();
+  context.args.syncUi = true;
+  const calls: string[] = [];
+
+  const handled = runAppPassthroughCommand(context, {
+    runAppCommandWithInherit: () => calls.push('piped'),
+    runAppCommandInteractive: (_appPath, appArgs) => calls.push(`direct:${appArgs.join(' ')}`),
+    launchAppBackgroundDetached: () => calls.push('detached'),
+  });
+
+  assert.equal(handled, true);
+  assert.deepEqual(calls, ['direct:--sync-window']);
+});
+
 test('mpv pre-app command exits non-zero when socket is not ready', async () => {
   const context = createContext();
   context.args.mpvStatus = true;
diff --git a/src/core/services/app-lifecycle.test.ts b/src/core/services/app-lifecycle.test.ts
index b939d3d9..bba2d4e4 100644
--- a/src/core/services/app-lifecycle.test.ts
+++ b/src/core/services/app-lifecycle.test.ts
@@ -172,6 +172,26 @@ test('startAppLifecycle defers quit until async cleanup settles', async () => {
   assert.deepEqual(calls, ['quitApp']);
 });
 
+test('startAppLifecycle contains synchronous quit cleanup failures', () => {
+  let willQuit: ((event: { preventDefault(): void }) => void) | null = null;
+  const { deps, calls } = createDeps({
+    shouldStartApp: () => true,
+    onWillQuit: (handler) => {
+      willQuit = handler;
+    },
+    onWillQuitCleanup: () => {
+      throw new Error('cleanup exploded');
+    },
+  });
+
+  startAppLifecycle(makeArgs({ start: true }), deps);
+  assert.ok(willQuit);
+  assert.doesNotThrow(() =>
+    (willQuit as (event: { preventDefault(): void }) => void)({ preventDefault: () => {} }),
+  );
+  assert.deepEqual(calls, []);
+});
+
 test('startAppLifecycle app ping exits non-zero immediately when no running instance owns the lock', () => {
   const { deps, calls, getLockCalls } = createDeps({
     shouldStartApp: () => false,
@@ -385,3 +405,22 @@ test('startAppLifecycle quits macOS setup-only launch when all windows close', (
   handler();
   assert.deepEqual(calls, ['quitApp']);
 });
+
+test('startAppLifecycle quits macOS sync-window launch when its window closes', () => {
+  let windowAllClosedHandler: (() => void) | null = null;
+  const { deps, calls } = createDeps({
+    shouldStartApp: () => true,
+    isDarwinPlatform: () => true,
+    shouldQuitOnWindowAllClosed: () => true,
+    onWindowAllClosed: (handler) => {
+      windowAllClosedHandler = handler;
+    },
+  });
+
+  startAppLifecycle(makeArgs({ syncWindow: true }), deps);
+
+  const handler = windowAllClosedHandler as (() => void) | null;
+  assert.ok(handler);
+  handler();
+  assert.deepEqual(calls, ['quitApp']);
+});
diff --git a/src/core/services/app-lifecycle.ts b/src/core/services/app-lifecycle.ts
index e6c7dd08..e74643cd 100644
--- a/src/core/services/app-lifecycle.ts
+++ b/src/core/services/app-lifecycle.ts
@@ -183,7 +183,10 @@ export function startAppLifecycle(initialArgs: CliArgs, deps: AppLifecycleServic
   deps.onWindowAllClosed(() => {
     if (
       deps.shouldQuitOnWindowAllClosed() &&
-      (!deps.isDarwinPlatform() || initialArgs.settings || initialArgs.setup)
+      (!deps.isDarwinPlatform() ||
+        initialArgs.settings ||
+        initialArgs.setup ||
+        initialArgs.syncWindow)
     ) {
       deps.quitApp();
     }
@@ -199,7 +202,13 @@ export function startAppLifecycle(initialArgs: CliArgs, deps: AppLifecycleServic
       event.preventDefault();
       return;
     }
-    const cleanup = deps.onWillQuitCleanup();
+    let cleanup: void | Promise<void>;
+    try {
+      cleanup = deps.onWillQuitCleanup();
+    } catch (error) {
+      logger.error('App quit cleanup failed:', error);
+      return;
+    }
     if (!(cleanup instanceof Promise)) return;
     quitCleanupPending = true;
     event.preventDefault();