Two latent defects in the announcement path this branch adds.
- lanesId was keyed by render row alone, so a second TimelineLanes on the
page (a mini-timeline beside the main one) would mint the same
timeline-lanes-track-0 and every caret's aria-controls would resolve to
whichever instance mounted first. The prefix now comes from useId, with the
colons stripped so the id stays a legal CSS selector.
- trackDisplayNumber returned trackOrder.length + 1 for a key it could not
find, which is indistinguishable from a real row: the label announced a row
the user can see is wrong and nothing upstream could tell it had guessed. It
returns null now, and trackDisplaySuffix drops the number from the label
rather than inventing one.
The timeline track key is a fractional z-order sort key: an expanded
sub-composition child gets `host.track + n / (siblings + 2)`. The undo
history entry for the eye toggle interpolated that key directly, so
hiding an expanded child recorded "Hide track 0.16666666666666666".
Give the key-to-display-row conversion a single owner
(timelineTrackDisplay.ts) and route both the track header labels and the
history label through it, so the two cannot drift apart again. The raw
key still routes the callbacks and lookups that need it.
Adds a regression test that toggles a track keyed 1 / 6; a test on track
0 formats cleanly and proves nothing.
Miguel Angel Simon Sierra