0f9096be3c
The recent-uploads panel had a cheap append-only fast path, but it was gated on
`rows.length > _recentLastRenderedLen`. maybeAddSessionFile caps sessionFilesData
by push-then-slice (2000 -> 2001 -> sliced back to 2000), so once a session
produces more than SESSION_FILES_CAP rows the length is pinned at the cap and the
gate is false forever. Every subsequent completion then fell through to the full
`tbody.innerHTML = rows.map(...).join('')` rebuild of all ~2000 rows.
The cap is per (link x file x hoster), so with 4-5 selected hosters the 2000 cap
is hit at only ~400-500 distinct files — very reachable in a long folder-monitor
session. Profiled in Chromium (same Blink engine as Electron, table-layout:fixed):
the full 2000-row rebuild costs ~80ms and ran on EVERY completion past the cap — a
repeating ~80ms main-thread freeze. That is the "fine on a fresh start, gets laggy
after many uploads while CPU (~40%) and RAM (~6GB, stable) stay normal" symptom: a
render-thread stall, not CPU saturation or a memory leak.
Fix: track newly-pushed rows in _recentPendingAppends (incremented in
maybeAddSessionFile, consumed every render) and gate the fast path on
`pendingAppends > 0` instead of length growth, so it survives the cap. Prepend the
new rows, then evict the same overflow count from the DOM bottom (oldest rows,
which is where the date-desc view places the front-of-array entries the cap slices
off). DOM work is O(added) again. The fast path is gated behind an explicit
`appendOnly` flag passed only by scheduleRecentRender's rAF, so selection / delete
/ clear / sort / batch-done renders stay full rebuilds and cannot wrong-evict or
double-prepend.
Verified in Blink over a simulated 5000-completion session (3/frame, far past the
cap): per-frame render 80ms -> median 7.4ms (>10x), and the DOM stays exactly equal
to the data (cap held at 2000, newest-on-top, oldest evicted, zero duplicates).
397/397 tests pass, eslint clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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| app.js | ||
| drop-target.html | ||
| index.html | ||
| styles.css | ||