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learnharness/components/braille-spinner.tsx
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import { cn } from "@/lib/utils";
/**
* THE BRAILLE SPINNER (owner, minimal-color round): the one working-state
* indicator, in the terminal's own glyph language. Pure function + CSS —
* no JS frame timer, no React re-render per frame; each frame is a tiny
* <g> whose opacity is compositor-animated, so the cost is below the old
* breathing dot's (which animated opacity AND transform).
*
* Geometry: the classic cli-spinner sequence (⠋⠙⠹⠸⠼⠴⠦⠧⠇⠏, 10 frames,
* 80ms each — 800ms cycle) as EXACT dot bitmaps in a 2×4 braille cell
* (dots 1-3 = left column, 4-6 = right). One shared keyframes (globals.css
* .braille-frame) holds each frame visible for its 10% slice; frames
* stagger via positive animation-delay, so frame 0 leads from first paint.
*
* Static fallback (SSR pre-hydrate, prefers-reduced-motion, print): frame
* 0 (⠋) shows — a legible glyph, not a blank. Motion is honest here: it
* exists only while a turn is in flight and vanishes the moment it ends.
*/
const FRAMES: ReadonlyArray<{ dots: ReadonlyArray<readonly [number, number]> }> = [
{ dots: [[1, 1], [1, 3], [3, 1]] },
{ dots: [[1, 1], [3, 1], [3, 3]] },
{ dots: [[1, 1], [3, 1], [3, 3], [3, 5]] },
{ dots: [[3, 1], [3, 3], [3, 5]] },
{ dots: [[1, 5], [3, 1], [3, 3], [3, 5]] },
{ dots: [[1, 5], [3, 3], [3, 5]] },
{ dots: [[1, 3], [1, 5], [3, 5]] },
{ dots: [[1, 1], [1, 3], [1, 5], [3, 5]] },
{ dots: [[1, 1], [1, 3], [1, 5]] },
{ dots: [[1, 1], [1, 3], [1, 5], [3, 1]] },
];
/** The animation constants (mirrors globals.css .braille-frame). */
export const SPINNER_FRAME_MS = 80;
export const SPINNER_FRAMES = FRAMES.length;
export function BrailleSpinner({
className,
label = "Working",
}: {
/** Sizing/position classes; height drives the scale (width is the cell's 1:2 aspect). */
className?: string;
/** The accessible name of the state this spinner announces. */
label?: string;
}) {
return (
<svg
viewBox="0 0 4 8"
data-testid="braille-spinner"
role="status"
aria-label={label}
className={cn("h-3 w-auto shrink-0 text-foreground", className)}
>
{FRAMES.map((frame, k) => (
<g
key={k}
className="braille-frame"
data-frame={k}
style={{ animationDelay: `${k * SPINNER_FRAME_MS}ms` }}
>
{frame.dots.map(([cx, cy]) => (
<circle key={`${cx}-${cy}`} cx={cx} cy={cy} r={0.8} className="fill-current" />
))}
</g>
))}
</svg>
);
}