milestone 23: restore the focus ring on select options, check layer order, close preflight gaps

specs/milestone-23.md

@@ -465,21 +465,21 @@ That last clause is the check that keeps the scope honest, and it holds:
 `react-aria-components` is imported only by the four `ui/` wrappers. A RAC
 `Button` in a feature file would still be a breach.
 
-### The focus-ring floor does not reach a listbox option
+### The focus-ring floor was briefly amended on a false premise
 
-`Select.tsx` gives the trigger the shared focus ring, but the popover's options
+S2 left the Select's options with their outline removed, showing keyboard focus
-show keyboard focus as a background inversion — `primary` behind `primaryText`
+as a background inversion alone. This section previously amended ruling 3 to
-— with the outline removed, and the listbox itself has no ring. That is the
+excuse that, arguing RAC drives option focus through an `isFocused` render prop
-selection-highlight convention for a listbox and a strong-contrast indicator,
+so a `:focus-visible` rule could never match. That argument is wrong.
-but it is not ruling 3's 2px focus-token outline, and the code is in breach as
+`useSelectableItem` gives options a roving `tabIndex` and focuses the option's
-the ruling is written. Two things make the ring the wrong mechanism here rather
+own DOM node (`react-aria/dist/private/selection/useSelectableItem.mjs:64`),
-than a missing one: an option inside a scrolling popover clips its own outline,
+which `ListBoxItem` spreads onto its element — so `:focus-visible` matches and
-and RAC drives option focus through its `isFocused` render prop, so a
+the ring was simply missing. The amendment is withdrawn and ruling 3 stands
-`:focus-visible` rule — which is how the shared `focusRing` is written — may
+unchanged. `Select.tsx` now composes the shared inset ring onto every option:
-never match the element at all. The floor is amended to cover controls that
+inset because an option flush against a scrolling popover clips an outset
-take DOM focus; a listbox option instead requires a focus indicator with a
+outline, and recoloured to `primaryText` on the highlighted row because the
-contrast change against both schemes, which the inversion provides. Every other
+focus token is the same blue that row paints behind it. The inversion stays as
-interactive element, the trigger included, keeps the ring.
+the listbox convention; it is no longer the only indicator.
 
 ### Two notes for S3
 

web/scripts/assert-css-layers.mjs

@@ -4,6 +4,16 @@
 // selector says, so a single unlayered rule silently beats the StyleX atomic
 // rules it was written to sit under. That failure renders wrong and passes
 // every other gate: no test asserts computed style, and the bundler is happy.
+// It also checks the layer ORDER, which is the invariant that actually matters:
+// a later layer beats an earlier one, so `reset` has to be declared first.
+//
+// What it does not catch, so nobody reads more into a pass than is there: an
+// unlayered rule that sets only custom properties is allowed, because StyleX
+// emits its token `:root` block exactly that way and this cannot tell that
+// block from an override of it; a declaration value containing `@layer` or a
+// brace inside a string blinds the stripper; and with several stylesheets it
+// judges each alone, not their load order in the document.
+//
 // This check runs from web/ as part of `npm run build`.
 
 import { readdirSync, readFileSync } from "node:fs";
@@ -58,9 +68,36 @@ function stylesSomething(body) {
 		.some((declaration) => declaration.length > 0 && !declaration.startsWith("--"));
 }
 
+/**
+ * Layer names in the order their position is fixed, which is where each name is
+ * first mentioned — a later block under an already-named layer does not move it.
+ */
+function layerOrder(css) {
+	const seen = [];
+	for (const [, names] of css.replace(/\/\*[\s\S]*?\*\//g, "").matchAll(/@layer\s+([^{;]+)[{;]/g)) {
+		for (const name of names.split(",")) {
+			const trimmed = name.trim();
+			if (trimmed.length > 0 && !seen.includes(trimmed)) seen.push(trimmed);
+		}
+	}
+	return seen;
+}
+
 let failed = false;
 for (const sheet of sheets) {
-	const leftover = outsideLayers(readFileSync(join(distDir, sheet), "utf8"));
+	const css = readFileSync(join(distDir, sheet), "utf8");
+
+	// Order is the whole point: a later layer wins, so the reset has to be first.
+	const order = layerOrder(css);
+	if (order.length > 0 && order[0] !== "reset") {
+		console.error(
+			`assert-css-layers: ${sheet} declares layers in the order ${order.join(", ")} — ` +
+				`'reset' must come first or it outranks the StyleX rules written against it.`,
+		);
+		failed = true;
+	}
+
+	const leftover = outsideLayers(css);
 	for (const [, selector, body] of leftover.matchAll(/([^{}]+)\{([^{}]*)\}/g)) {
 		if (!stylesSomething(body)) continue;
 		console.error(

web/src/styles.css

@@ -9,7 +9,7 @@
  * their font. Deleting this block does not restore browser defaults — it
  * silently changes the meaning of every size and spacing value in the app.
  * Rules are limited to what this app renders; it is not a general reset.
- 
+ *
  * The reset lives in its own cascade layer, declared here before StyleX emits
  * its own. Layer order is priority order, and unlayered author CSS outranks
  * every layer: leaving these rules unlayered silently beat every StyleX rule in
@@ -65,9 +65,21 @@
 	kbd,
 	samp,
 	pre {
+		font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
 		font-size: 1em;
 	}
 
+	/* Without this the spinner stretches a number input taller than its row. */
+	::-webkit-inner-spin-button,
+	::-webkit-outer-spin-button {
+		height: auto;
+	}
+
+	/* Firefox draws a red glow on an invalid field; the form shows its own error. */
+	:-moz-ui-invalid {
+		box-shadow: none;
+	}
+
 	table {
 		border-collapse: collapse;
 		text-indent: 0;
@@ -166,7 +178,7 @@
 		height: auto;
 	}
 
-	[hidden] {
+	[hidden]:not([hidden="until-found"]) {
 		display: none !important;
 	}
 }

web/src/ui/Select.tsx

@@ -87,11 +87,18 @@ const styles = stylex.create({
 		fontSize: "0.875rem",
 		lineHeight: "1.25rem",
 		cursor: "pointer",
-		outlineStyle: "none",
 	},
+	/**
+	 * The inverted row is the listbox convention, and the ring is the milestone-9
+	 * floor; an option gets both. RAC focuses the option's own DOM node, so the
+	 * shared `:focus-visible` ring does apply here — it is drawn inset because an
+	 * option flush against a scrolling popover clips an outset one, and recoloured
+	 * because the focus token is the same blue this row just painted behind it.
+	 */
 	itemFocused: {
 		backgroundColor: colors.primary,
 		color: colors.primaryText,
+		outlineColor: { default: null, ":focus-visible": colors.primaryText },
 	},
 	itemSelected: {
 		fontWeight: 600,
@@ -125,6 +132,7 @@ export default function Select({ options, value, onChange, label, "aria-label":
 							className={({ isFocused, isSelected }) =>
 								stylex.props(
 									styles.item,
+									shared.insetFocusRing,
 									isSelected && styles.itemSelected,
 									isFocused && styles.itemFocused,
 								).className ?? ""