The other half of the blank bottom row, on a library still filling its
thumbnail store: the cells were in the model, and nobody had asked the server
for them yet.
A batch is fetched one image at a time, two round trips each, and it is
abandoned wholesale the moment the window moves. Issued in model order, the
front of that queue was the quarter-window of cells sitting *above* the view —
which nobody is looking at — and the back of it was the bottom of the screen
and the screenfuls below. So the last rows of the grid waited behind three
quarters of a window's worth of fetches for photographs off screen, and every
scroll threw the queue away and started over from above the view again. For as
long as the scrolling continued, the bottom of the grid could be starved.
The rows still address the model they were built against; only the order they
are asked for in changes. On screen first, in reading order, then the rows
below the view, then the rows above it. Below before above because that is
where the view is going — scrolling back over cells already fetched is served
from the store, and from `requested` without a fetch at all.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
dtourolleandClaude Opus 5
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