Third durability layer beside GitHub auto-sync and Android Auto Backup:
a plain, human/LLM-readable Markdown file kept current on local disk.
- LocalBackup (lib/sync): pure, injectable file IO. scheduleExport()
debounces writes (a burst of keystrokes → one export); recover() parses
the file back into notes. Reused NotesMarkdown serializer.
- CaptureScreen wires it: on launch, recover into an *empty* DB only (so a
stale backup never clobbers existing notes), then keep the backup current
as notes change. Platform path = ~/todo/BACKLOG.md on desktop (the path
the user's workflow already reads) or the app documents dir on mobile
(covered by Android Auto Backup). File IO is injected in tests.
- Added fake_async dev dep to unit-test the debounce with a virtual clock.
151 tests, 100% line coverage.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
