/** A bare CSS HSL channel triplet, `"H S% L%"` — the shape every `@godxjp/ui` colour role uses. */
export type HslTriplet = string;
/** WCAG 2.2 SC 1.4.3 Contrast (Minimum) — normal text. */
export declare const AA_NORMAL_TEXT = 4.5;
/** WCAG 2.2 SC 1.4.3 Contrast (Minimum) — large text (≥18.66px bold / ≥24px). */
export declare const AA_LARGE_TEXT = 3;
/**
 * L = 0.179, the pivot of the label choice (solve 1.05/(L+0.05) = (L+0.05)/0.05). A surface above it
 * is one an ink walks DOWN away from, below it one an ink walks UP — and either end of the ramp is
 * achromatic, since `hsl(h s 0%)` is black and `hsl(h s 100%)` is white at every hue and saturation.
 * So the walk always reaches at least 4.58:1 and the guarantee is a property of the whole sRGB cube
 * rather than of the seeds we happened to try.
 *
 * EXPORTED because a component that paints its own fill has to make the same choice against it and
 * must not re-derive the number (gh#884: `Sidebar`'s brand mark).
 */
export declare const CONTRAST_PIVOT = 0.179;
/**
 * WCAG 2.2 relative luminance of an sRGB colour, per the definition quoted at the top of this file.
 * Accepts `#abc` / `#aabbcc`; returns null for anything else.
 */
export declare function relativeLuminance(hex: string): number | null;
/**
 * WCAG 2.2 contrast ratio between two hex colours, `(L_lighter + 0.05) / (L_darker + 0.05)`, in
 * 1–21. Returns null if either colour is not a hex. Compare against {@link AA_NORMAL_TEXT}.
 */
export declare function contrastRatio(a: string, b: string): number | null;
/**
 * `#0071bd` → `"204.13 100% 37.06%"` — the direction the package was missing (gh#868: `hslToHex`
 * appears 9 times in `dist/`, `hexToHsl` zero). The exact inverse of
 * {@link import("../email/color.js").hslToHex} within one hex step, which `tenant-theme.test.ts`
 * round-trips over a grid. Returns null for anything that is not a 3- or 6-digit hex, so an
 * unparseable customer value is ignored rather than breaking the page.
 */
export declare function hexToHsl(hex: string): HslTriplet | null;
export type TenantThemeOptions = {
    /**
     * The label to paint ON the seed, as hex. Omit and the contrast-safe choice is made here. Supply
     * it — Platform stores a server-computed, WCAG-checked pair — and it is used as given, with
     * `contrast` / `meetsAA` reporting what it achieves and a dev warning under 4.5:1.
     */
    foreground?: string | null;
    /**
     * The surface the brand INK sits on, as hex — the DARKEST one it lands on in a light theme, the
     * LIGHTEST in a dark one, because the guarantee has to hold in the hovered state too. Default: the
     * package's light `--accent`, `#ebe9e5`. A region inside the dark theme passes `#3c3a34`
     * (`--accent` there); a themed consumer passes its own. Anything that is not a hex is ignored.
     */
    surface?: string | null;
};
export type TenantTheme = {
    /** The seed, normalized to `#rrggbb`, or null when the input was not a hex colour. */
    primary: string | null;
    /** The label on that seed, `#rrggbb`, or null when there is no seed. */
    foreground: string | null;
    /** WCAG 2.2 ratio of `foreground` on `primary`, 1–21. `0` when there is no seed. */
    contrast: number;
    /** `contrast >= 4.5` — WCAG 2.2 SC 1.4.3, normal text. */
    meetsAA: boolean;
    /**
     * The custom properties to declare on the scope. Spread straight into a `style` prop, or
     * serialize into a `<style>` block for SSR. EMPTY for an unusable seed, so an invalid customer
     * value degrades to the app's own theme instead of breaking the page.
     */
    vars: Readonly<Record<string, string>>;
};
/**
 * Turn a customer's hex into the scoped token declarations that make one REGION wear it —
 * `--primary`, `--primary-foreground`, `--ring`, the hover / pressed steps, and the three brand INKS
 * (`--text-link` / `--text-brand` / `--text-primary`) — all as literals, so the colour cannot
 * half-apply on an engine without CSS relative colour and the ink cannot land under 4.5:1.
 *
 * ```tsx
 * const brand = tenantTheme(tenant.primary_color, { foreground: tenant.primary_foreground });
 * <div data-tenant={tenant.slug} style={brand.vars}>…</div>
 * ```
 *
 * Never throws and never returns null: an unusable seed yields empty `vars`.
 */
export declare function tenantTheme(primary: string, options?: TenantThemeOptions): TenantTheme;