Slice B part 2 (final). On a cold watch-history load (nothing cached to
show yet) the service now decrypts only the newest chunks first
(chunkDecryptLimit = 3) so the UI renders recent history immediately
instead of freezing behind a deep, monthly-chunked history — the original
NIP-46 symptom. If older chunks were deferred, a single background pass
then backfills them (no chunk cap; already-decrypted chunks are served
from cache, so only the deferred older chunks cost signer RPCs) and emits
"fingerprint", which the history view already re-renders on. The serial
NIP-46 request queue paces the backfill, so there is no rate-limit flood.
Scoped to cold loads only: a warm refresh (items already on screen)
resolves the full history directly, avoiding a transient "history shrank
then grew" flicker. No view / feed-engine changes and no change to the
shared For You / explore paths beyond a fast first render then a fill-in.
Chosen over strict scroll-triggered lazy loading, which would have
required risky surgery on the history view's feed-engine + cursor
pagination and the shared loadLatest path pre-launch.
Tests: cold load passes a finite chunk limit on the first resolve, then an
unbounded background backfill runs and emits recent-only -> full; warm
refresh is unbounded. Both mutation-verified (removing the bound and
no-op'ing the backfill each fail).
Co-Authored-By: Claude Opus 4.8 <[email protected]>
