On Android, pressing the back button/gesture on the root page (eg. the room list page) does nothing. Kirigami's PageRow register an unconditional StandardKey.Back shortcut, which consumes the key press before it can be delivered to QML as a key event. At the root page its goBack() has nowhere to go, so the key is silently swallowed.
Accept the ShortcutOverride event for the back key on the page stack only when there is nothing to go back to (currentIndex === 0 && layers.depth <= 1). This takes the key away from the shortcut, so the press is delivered as a regular key event and the application quits on its release. In all other states the override is not accepted, leaving the normal back navigation (pop room / layer) unchanged. Android-only, guarded by Qt.platform.os === 'android'.
The above content was generated by OpenCode (DeepSeek V4.1 Flash Free). I reviewed and verified it.