Every chunk restarting from the input image on the rental. The prompt and the
anchor shared one cache chunk, so pinning the prompt pinned the anchor with it —
for the whole clip, in a context of three visible blocks. In a dense render the
anchor is one pin among hundreds of frames' worth of rows; there it was a third
of everything the model could see, and the model did what it was trained to do
with a conditioning row: compose from it.
They are now two chunks. The prompt is 0 and always pinned — it is every moment
of the clip. The conditioning is 1, so `sink` decides how long it stays: 1
releases the anchor after the opening, 2 keeps it (today's behaviour), 3 also
pins the opening shot. Media chunks moved to i + 2, and the conditioning slot is
reserved even on a t2v run so `sink` counts the same either way.
The prefill is two forwards, and the conditioning pass reads the text already in
the cache — so the anchor is still represented WITH the prompt rather than in
isolation.
Note the widget's meaning shifted by one: sink 2 was prompt+anchor+opening shot
and is now prompt+anchor.
Tests: 1806 python, 68 JS. The upstream check now prefills a real keyframe and
confirms sink 1 releases it while keeping the prompt.
digital-garbage
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