diff --git a/strix/interface/tui/runtime.py b/strix/interface/tui/runtime.py
index a20960ce..be8aa978 100644
--- a/strix/interface/tui/runtime.py
+++ b/strix/interface/tui/runtime.py
@@ -71,6 +71,7 @@ class GoTuiRuntime:
         self._error_noted_agents: set[str] = set()
         self.model_verified = False
         self._setup_preflight: asyncio.Task[None] | None = None
+        self._quit_task: asyncio.Task[None] | None = None
         self.controller = TuiController(
             args,
             live_view=self.live_view,
@@ -378,6 +379,21 @@ class GoTuiRuntime:
             await asyncio.sleep(0.5)
 
     async def quit(self) -> None:
+        """Stop the scan once, however many callers ask for it.
+
+        Ctrl+Q quits twice: the sidecar sends ``app.quit`` and exits in the
+        same batch, so the command handler and ``run``'s finally both land
+        here. A second cancel while the first is tearing the sandbox down
+        interrupts the docker delete and leaves the container running, so
+        callers after the first wait on the quit already in flight.
+        """
+        if self._quit_task is None:
+            self._quit_task = asyncio.create_task(self._quit_once())
+        # Shielded: awaiting a task hands it the waiter's own cancellation,
+        # which is what this guard exists to keep out of the teardown.
+        await asyncio.shield(self._quit_task)
+
+    async def _quit_once(self) -> None:
         self.controller.close_viewer()
         self.coordinator.mark_shutting_down()
         scan_task = self.scan_task
diff --git a/tests/test_go_tui_runtime.py b/tests/test_go_tui_runtime.py
index afae99f1..ffdd82ea 100644
--- a/tests/test_go_tui_runtime.py
+++ b/tests/test_go_tui_runtime.py
@@ -877,6 +877,50 @@ async def test_scan_passes_max_turns_and_budget(monkeypatch: pytest.MonkeyPatch)
     assert runtime.controller.scan_state == "stopped"
 
 
+@pytest.mark.asyncio
+async def test_quitting_twice_lets_the_sandbox_teardown_finish(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Ctrl+Q quits twice: the app.quit command and run()'s finally."""
+    runtime = GoTuiRuntime(args())
+    runtime.scan_config = {"run_name": "test-run"}
+    torn_down: list[str] = []
+    scanning = asyncio.Event()
+    tearing_down = asyncio.Event()
+    docker_replied = asyncio.Event()
+
+    async def run_scan(**kwargs: Any) -> None:
+        try:
+            scanning.set()
+            await asyncio.sleep(3600)
+        finally:
+            # session_manager.cleanup() waits on the docker daemon here
+            tearing_down.set()
+            await docker_replied.wait()
+            torn_down.append(kwargs["scan_id"])
+
+    monkeypatch.setattr(
+        go_tui,
+        "load_settings",
+        lambda: SimpleNamespace(runtime=SimpleNamespace(image="test-image")),
+    )
+    monkeypatch.setattr(go_tui, "run_strix_scan", run_scan)
+    monkeypatch.setattr(go_tui, "read_workspace_files", lambda _value: [])
+
+    runtime.start_scan()
+    await scanning.wait()
+
+    command_quit = asyncio.create_task(runtime.quit())
+    await tearing_down.wait()
+    final_quit = asyncio.create_task(runtime.quit())
+    for _ in range(3):
+        await asyncio.sleep(0)
+    docker_replied.set()
+    await asyncio.gather(command_quit, final_quit)
+
+    assert torn_down == ["test-run"], "the sandbox container was left running"
+
+
 @pytest.mark.asyncio
 async def test_setup_preflight_failure_does_not_start_scan(
     monkeypatch: pytest.MonkeyPatch,