First slice of the tier 2 offline mode work tracked in Fable #147.
Notes are the only domain wired so far; this PR establishes the
shape and proves the round-trip end-to-end before extending to tasks
/ projects / events / etc. in phase 2.
Local store
- Adds drift ^2.20.0 + sqlite3_flutter_libs ^0.5.24 + path ^1.9.0
runtime deps and drift_dev / build_runner dev deps.
- New lib/data/local/database.dart: FabledDatabase with CachedNotes
(mirroring the Note model 1:1; tags stored as JSON-encoded text) and
SyncMetadata (per-domain last_synced_at). Database file lives at
$appDocs/fabled_cache.sqlite; opened lazily in a background isolate.
- fabledDatabaseProvider on the existing api_client_provider; closes
the DB when the ProviderScope disposes.
Repository pattern
- NotesRepository now takes (NotesApi, FabledDatabase). Reads attempt
the network first; on success the response is written to the cache.
On NetworkException reads fall back to the cache (rethrowing if it
is empty so fresh-install offline still surfaces the network error).
- Writes (create/update/delete) hit the server then sync the cache;
offline write queueing is phase 3 and explicitly not wired here.
- AuthStatus.offline stays owned by AuthNotifier.verify()'s heartbeat;
this repo deliberately doesn't poke that state.
OfflineBanner
- Reads notesRepository.lastSyncedAt(); when present, swaps
"Offline — showing cached data." for "Offline — last sync X min
ago." A 30s timer refreshes the relative-time string while the
banner is mounted.
- Falls back to the generic message if no cache exists yet (fresh
install offline).
Verification
- flutter analyze: No issues found
Out of scope (later phases per the task body)
- Tasks / projects / milestones / events / conversation list / journal
day caching (phase 2 — same wrapper pattern, repeated)
- Generic write queue with conflict resolution on updated_at (phase 3)
- Read-only UI indicators on screens that depend on cached data
(phase 4)
- Full offline chat (out of scope; needs a local model)
- RAG / search over cached content (out of scope)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
