The guard polled for `scrollHeight > clientHeight + 40` and the next
line asserted the container could be scrolled to 80, so any range in
41-79 satisfied the precondition and could not satisfy the assertion.
The grid passes through exactly that while it settles, because it
recomputes its columns after a viewport change rather than during it,
so the test read a clamped scrollTop and reported 10 against 80.
It failed CI on a pull request that changes one paragraph of CLAUDE.md
and nothing else, while WebKit passed in the same run. Reproduced
locally: 0 failures in 6 runs before #132, 2 in 9 after, 0 in 10 with
this change.
#132 is what made it reachable rather than what broke it. The queue
panel's mode is measured rather than media-queried, so a viewport
change at this width costs one more layout pass, and cover-grid settles
after it instead of before. The settled range is 330 and stable, the
main panel is 700px, and the panel is correctly display:none while
closed — there is no user-visible defect, only a wider window for a
race the spec already had.
A threshold below the value its caller depends on is not a guard, so
the target is one constant that both the guard and the assertion read.
Closes#133
`RovingGridController.measureColumns` read `offsetTop`, and every card
in these grids is drawn by a `lit-virtualizer`, which positions its
children with a transform — which `offsetTop` does not see. So all of
them reported 0, every rendered card counted as one row, and ArrowDown
was `min(i + everything, last)` while ArrowUp was `max(i - everything,
0)`: the vertical arrows have been End and Home in the albums, artists
and genres grids since the day this was written. At 700x700 with three
real rows of 3/3/2, ArrowDown from card 0 landed on card 7.
Two things behind it, both only visible once the grid splits:
`cover-grid`'s scrollToIndex was `querySelector('lit-virtualizer')` —
always `#grid-before` — while the roving index spans the whole album
list, so with a dropdown open End scrolled the wrong half to an index
it does not contain. It now picks the half that holds the index and
rebases it.
And the focus is retried on a deadline rather than taken once at the
host's `updateComplete`: a scroll of 5 000 rows produces the card a few
hundred ms later, so the tab stop moved and nothing took focus, which
looks exactly like the key not being handled.
Also waits for the virtualizer in album-dropdown.spec's expandCard,
which flaked on roughly one run in two on main.
Enter on an album card fetched the album's tracks over the IPC and ran
the whole split state machine (splitMode true, splitIndex measured
against the real container), then render() drew the single grid because
it never consulted splitMode; connectedCallback referenced
renderSplitGrid only to satisfy noUnusedLocals. perf.p2 files this as
dead code — it is the only route from the albums grid to track-details,
since a plain click navigates to the catalog page instead.
Two things it needed that the audit does not mention. The grid could
not scroll: .grid-scroll-container is the markup artists-view and
genres-view use, and cover-grid had the class with no rule for it, so
186984px of albums sat in a 772px box at 5000 albums, unreachable by
wheel, keyboard or scrollbar — and that is the element scroll-manager
saves and restores, so its scrollTop was permanently 0. And the shared
context menu was labelled 'Album actions' unconditionally, which nothing
could observe while a track menu was unreachable.
Both halves of the split grid carry the listbox semantics the single
grid gained in the ARIA pass.