Live watching is now event-driven, no tree polling:
- Android: MainActivity registers a MediaStore ContentObserver
(Images, notifyForDescendants) and wakes the Rust watcher thread via
a JNI call (Java_wow_gmp_gallery_MainActivity_nativeFsChange) — a
single channel send, no main-thread work. Covers camera saves,
media-scanner indexing, other apps' indexed writes.
- Desktop: inotify/FSEvents via notify on the scan roots.
- On wake: coalesce + debounce, diff dir mtimes, rescan only the
changed subtrees. The 1 s recv timeout doubles as a cheap backstop
(raw out-of-band copies the scanner hasn't indexed yet); a 5-minute
full pass is the safety net. minSdk 30 (3-arg ContentObserver API).
Stale-listing truncation bug found and fixed (reproduced on the
emulator's 9p /sdcard; the phone's FUSE does the same): a readdir over
a large directory can return a SILENT early EOF — a stale cached
listing with NO error. The phone's 9961-file Camera dir truncated at
~8400 once and db::apply deleted ~1700 good rows. Three layers now:
1. scan::read_dir_full — retry whole-dir reads on mid-stream errors;
2. per-directory cross-check in walk_dir: if the enumeration is far
below the DB's count for that dir, re-read up to 3x keeping the
best listing; whole-walk re-check in rescan keeps the larger of two
walks;
3. db::apply mass-delete guard: never delete >20% of the DB in one
apply unless a previous walk already saw the low count (two-strike;
a meta.walked row tracks it). Genuine gradual deletions still flow
through (verified: a 4000-file mass move streams the grid down
progressively), and a second consecutive low walk still deletes.
Emulator reliability suite (all pass): 3x launch count stability,
add +1 / remove -1 in ~2 s, 20-file burst, DB recovery from damage,
stale-listing refusal (0 rows lost), two-strike delete, live restore,
idle 0.0% dropped frames, deep fling loads thumbnails. A/B vs ttimg
(no-backend CSS-scroll control): adb-swipe drop deltas are at the
input-injection artifact level, idle identical (0.0%).
Greg Pomerantz
58b203e4fa