The catalogue closes its cursor and survives a device with no alarm tones at all: the picker is never empty, because "Silent" and the app default are always offerable. A chosen URI that later becomes unreadable is disclosed on the row rather than quietly rewritten — the user should know their alarm cannot play what they picked. The previewer serialises behind a mutex and releases a tone that finished preparing after a stop, so two taps cannot leave two alarm sounds playing. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Wmy1BpCKi8KeSjaWhYuCPV