PruneWorker and BackfillWorker were the only two pre-auth background DB entry
points that opened the database without first checking
EncryptedCacheGuard.isCacheLocked(). With encryptCache + appLock both on and a
headless cold start where the user hasn't authenticated (WorkManager after
reboot, or the periodic backfill/prune window while locked), the first DAO call
runs prepareCache() -> resolvePassphrase() -> session.await(), parking the
worker thread until unlock and serializing other DB openers behind the held
prepareCache mutex. Self-heals on unlock, but wastes wakelock/battery and makes
zero progress while locked.
Switch both workers' MailPruner/MailBackfiller injection to dagger.Lazy and add
the isCacheLocked() guard before resolving it, mirroring SyncWorker/SendWorker.
Add JVM regression tests (locked -> retry with the Lazy dep never resolved;
unlocked -> runs; failure -> retry).
Closes#224
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
JMR-devandClaude Opus 4.8
7b5819021a