v2.0.0

Major version bump: the full-mailbox backfill mechanism was broken through v1.19.5 and is fixed here, then validated live against a real account with 57,000+ indexed messages across 62 folders/labels — including a from-scratch, UID-window-by-window backfill of a 22,836-message Archive folder to completion, with zero data loss across restarts, transient IMAP disconnects, and request timeouts. This is the first release where sync_emails({full:true}) on a large pre-existing folder actually works end-to-end rather than silently looping on the newest window or deleting older mail.

Fixed

• Full sync could never backfill folder history, and silently deleted it. full:true always fetched the newest N UIDs from scratch on every call, ignoring any previous progress — and expunge-detection compared each freshly-fetched window against every stored message in the folder, so each new backfill window deleted everything outside itself. Repeated full:true calls converged to only the last-fetched window, making a large pre-existing folder (tens of thousands of messages) permanently unindexable beyond its newest slice. Now tracks a backfilledToUid checkpoint and walks the mailbox backward one window at a time, restarting cleanly if UIDVALIDITY changes, with expunge-detection scoped strictly to the UID range just re-scanned.
• backfilledToUid read back from SQLite as NULL broke the very first backfill call after a restart. NULL mapped to JavaScript null instead of undefined, and null <= 1 evaluates to true — so the very first post-restart backfill call looked like backfill was already complete and fetched nothing.
• get_index_status reported storedMessageCount/dedupedMessageCount capped at 5000 regardless of actual index size — it read off the thread-builder snapshot (deliberately capped for performance) instead of a real COUNT(*). A 45,000-message index reported exactly 5000 stored messages.
• sync_emails silently ignored its own folder/full/limitPerFolder/includeAttachmentText arguments and always ran whatever the background auto-sync was already configured for — calling sync_emails({folder:"Archive", full:true}) had no effect at all.
• bulk_update_labels (and other bulk operations) failed completely on a single transient IMAP/IDLE disconnect that bulk_delete recovered from automatically — the UID-matching search path inside resolveUidsForBulkOp had no reconnect-and-retry, unlike every other mutation.