Adds a debounced periodic draft save alongside the existing exit-time
save, so an in-progress compose survives a background-kill without going
through the back gesture. Observes the persisted body/recipient/subject/
attachment fields, coalescing rapid keystrokes into one write after a
~1.5s idle window (viewModelScope), and flushes immediately on ON_STOP
from ComposeScreen so the last keystrokes within the window aren't lost.
Prerequisite bug fix: draftId was a nullable val, so
saveOrDeleteDraft()'s `id = draftId ?: UUID.randomUUID()` minted a fresh
id on every call. Harmless when it ran only once at exit, but periodic
autosave would insert a new duplicate draft row per tick. The persist id
is now generated once (persistedDraftId) and reused for every save this
session; a draftPersisted flag drives delete-on-empty and delete-on-send
so an autosaved new draft is never orphaned.
onExit()'s save-or-delete-on-back behavior and the "don't save mid-send"
guard are unchanged; autosave mirrors the same guard (plus a navigated
guard so a post-send tick can't re-create a sent message's draft).
Closes#177
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
JMR-devandClaude Opus 4.8
bbc0715666