KeelrLeek
52b1b8e622
Opening an album juddered: the page ran at the clicked row, then stopped dead just short of it. revealIntoView lifts the row to the banner line, which needs a pane-height of content beneath that row. Until the previous commit the pane's ~2000px of dead scroll always supplied it. With the range ending at the content, a row in the last screenful no longer has it, so the reveal eased toward a scrollTop the range could not hold and slammed into the clamp — measured on a 29-album artist: target 1846 against a max of 1594, 272px in a single frame, then 39 frames pinned, and the row parked 598px below the line instead of on it. Not a race with the expander either; it finishes growing at ~500ms and the target is still 252px out of reach. Reserve the row's own pane-height, the same way the grid already reserves one for the tab bar so a tab switch cannot clamp the scroll — extended to the open expander's row and released when it closes. - On the grid's min-height, because that is what moves this page: .scrollbody's height does not answer to padding at all (border-box against a fixed height — 0px, 200px and 600px of padding-bottom all measured the same 1787px box). - Reserved, not predicted. The expander's height is not the page's growth: the slack in this very reserve swallowed 435 of a 486px panel, so a 486px expander grew the page by 66. - Stood up synchronously by the reveal as well as by measureCols, which only recomputes off a ResizeObserver — that fires after the 420ms animation has already parked against the old clamp. - Released on the expander's destroy. measureCols cannot notice the panel leaving: the raised min-height is exactly what stops the grid's box from changing, so the observer sees nothing and the reserve would stick for the rest of the visit, leaving a screenful of empty page under the grid. - Re-measured across the settle after an open. What moves the target row is the card art this very click asked for; those images land over the following few hundred ms and rows above the row grow as they do (measured: the row sat 488px into the grid when the reveal read it, 555px once settled). Only the first open of a page pays this. - The reveal clamps its target regardless and idles on it for up to a second, so a corrected reserve still completes the travel instead of ending short. Verified on a 29-album artist and an 11-album one: every open lands the row at exactly the 280px line, first open of a fresh page included, with no direction reversals and no frames against the clamp. Frame timing improves on both — cold 13 frames over 16ms (worst 79.6) to 2 (worst 60.6, the album fetch and decode, which predates this), warm 2 (worst 18.4) to 0 (worst 9). The pane's scroll range still ends exactly at the content with no expander open, and returns to it on close.