DayProfileChart

No Base UI part, so nothing from Base UI here. The plot is one focus stop, and the keys move its highlight while focus stays on it.

The pointer and touch reach the same tip: moving the pointer over the plot highlights the point nearest it in time, pressing or touching the plot does the same and focuses it, and a mouse or pen leaving clears the highlight unless the plot has focus, while a finger leaving keeps it, so a tap keeps the tip until the person taps elsewhere. Escape closes a tip the pointer showed wherever focus is, as a hover card closes with Esc (CR-7).

A point reads "08:00 1 260", and one with no count "05:00 Unknown". A screen reader in browse mode reads the whole list in order; one that tabs to the plot hears "Vehicles in service, group", then each point as the arrow keys reach it.

What axe won't catch, from the contract, each with how this component meets it:

• Everything the eye is told, the ear is told, for every shape each prop accepts: every point's time and count, which the line, the tip and the guide show, is heard from its list item, an unknown count as "Unknown", while the tip's "—" is aria-hidden; the caption, which says what the line counts, names the figure and the plot; the axis ticks and the scale's top count, eye-only context for the line's shape, are hidden, since each point says its own time and count
• Every landmark and named region has an accessible name: the figure and the plot's group are named by the caption; the chart adds no landmark
• Every default label can be overridden: unknownLabel
• Every shape the type accepts renders, in every variant: label as a string, an element and an array; points empty, one point, a whole day of 24, 96 points a quarter-hour apart, a part of a day, every count unknown, a lone known count between unknown ones, a count of 0, and a time that doesn't read as HH:MM (CR-2)
• A hidden copy kept for animation is aria-hidden, and a collapsed region is inert: none here; nothing animates or collapses. The graph, scale, tip and axis are aria-hidden because the points say what they show, not because they are copies
• Native semantics first: <figure> and <figcaption>, <ol> and <li> for the points, <time> for each point's time; role="group" and aria-activedescendant on the plot only, where no element says a focus stop that moves through its items
• Focus moves in reading order and returns on close: the plot is one stop between the caption and whatever follows; Escape clears the tip and leaves focus on the plot, and closes a tip the pointer showed wherever focus is; nothing opens elsewhere
• Every target is at least size.target-min square: the one target is the whole plot, at least 107 px tall at 320 px wide; the points are not targets of their own
• Loops stop when the system asks for less motion: none here; nothing moves

One string, and it is in packages/perron/src/locale/en.ts already. Every other word is the caller's label; the times and counts are digits, which expectOwnedStrings passes.

For a caller using the pattern, with the reason. Each row is a rule: a must row's Don't is never right, a should row's needs a reason, and Checked by says what catches the Don't in a caller's code.