The comment on `wa-dialog::part(body)` carried bottom-edge pixels from
an intermediate probe (29,33,36) while `.planning/NOTES.md` recorded
the final sample against the shipped rule (22,24,27) — the same
gradient, read a few pixels higher up the box. A measurement written in
two places has to agree, or neither can be trusted.
The bottom sheet's body has scrolled since #60 and said nothing about
it. Measured at 424x439, the track list's menu ended at y=470 with the
fold at 439 — reachable, since the body is `overflow-y: auto`, but with
no affordance saying so, and worst where the cut lands on a row
boundary and the sheet ends in a clean edge that reads as the end of
the list.
The cap stays: `menu-surface`'s own comment says a surface covering the
whole screen is a page, not a sheet. What changes is that the body
draws a fade, from two background layers whose *attachments* are the
feature — a shadow pinned to the box (`scroll`) under a cover of the
sheet's own colour painted at the end of the content (`local`), which
scrolls up over the shadow exactly when there is nothing more to see.
So the fade is absent on a menu that fits, present the moment one does
not, and gone again at the end of the list, with no scroll listener and
nothing reaching into `wa-dialog`'s shadow root for the scroller.
`background-attachment` is Chrome 4; the reference device is Chrome 113.
The other two options in the report — a shortened last row, or a max
height that makes the cut obvious — both need `height mod 48`, which
CSS cannot express, and the observed case is exactly the one where the
cut already lands on a row boundary.
The curve is steep rather than linear because the rows under it stay
live: a scrim over a menu item is that item's text surface, so the
4.5:1 rule reaches it, and the light ramp is what makes that real.
A 48px linear scrim at 0.8 greyed the last label to 5.0:1; 32px already
down to a quarter strength at 14px measures 9.9:1 there and spends its
weight on the strip below it.
The test asserts the pair of attachments rather than the pixels, on
this file's existing grounds that no tier here renders like the device
— it fails on the pre-fix stylesheet with `expected 'scroll' to be
'local, scroll'`. The rendered result was measured in the harness and
is recorded in `.planning/NOTES.md`.
Closes#207
On the reference device every context menu in the app is clipped, and
the two halves of that are structural rather than incidental. Chrome
113 has no Popover API, so wa-popup takes its own documented fallback
and positions with strategy: "fixed"; .main-panel carries
contain: layout style paint, and paint containment clips fixed
descendants. Measured at 424x439 before any of this: the main panel
spans 0-318, the open menu spanned 191-401, and three of its seven
items were cut off with no way to reach them. Rows were 29px against
a 44px floor.
menu-surface is one element with two presentations -- a wa-popup above
600px, a wa-dialog bottom sheet below it -- so the host keeps rendering
the panel it always rendered and ContextMenuController keeps driving
.active and .anchor as though it were talking to a popup. showModal()
is Chrome 37 and uses the real top layer, so the sheet is immune by
construction rather than by styling.
Four things needed measuring on the hardware rather than reading.
"A dialog escapes containment" was the premise and was untested here:
every other dialog in this app is mounted in index.html, outside
.main-panel. A probe dialog appended to track-list's shadow root
paints to y=439, over the mini player and the tab bar.
A native dialog's UA stylesheet centres it and caps its width, which
drew a 354px panel in the middle of a 424px screen -- so four
declarations in this component are pure undoing.
wa-dialog focuses [autofocus] or itself on the frame after
showModal(), and it cannot see our first menu item to prefer it: the
panel is slotted, so its own querySelector stops at the <slot>. A
longer retry budget does not fix that, because the first attempt
succeeds and is then overwritten -- hence menu-shown and
MenuKeyboard.refocus(). The budget became time-based anyway, since
what is being waited for is another component's animation.
And a dismissal has to travel back: wa-dialog closes itself on Escape,
which would leave the controller believing the menu is open. The
failure mode there is not a stuck sheet but the *next* long-press
doing nothing, which reads as the gesture breaking.
logan