/**
 * ADR 0194, the public CSS custom-property contract.
 *
 * ## Why this exists
 *
 * Every Olotalk surface renders inside a shadow root, so a host page's CSS
 * cannot reach in. That is deliberate: it is what keeps citations, the grounding
 * badge, the refusal state and the "Powered by" attribution *structural* rather
 * than dismantlable. A host can restyle what we render; it cannot delete what we
 * say.
 *
 * But the same boundary made the assistant impossible to blend into a host page.
 * Everything it drew used our type and our colours, and the only escape hatch
 * was a JS `theme` object with a handful of named fields, set once at init,
 * invisible to the stylesheet the developer is actually editing.
 *
 * CSS custom properties are the one exception to shadow encapsulation: they
 * **inherit across the boundary**. So a small, curated set of `--olotalk-*`
 * properties gives hosts genuine control over appearance without exposing
 * structure. Tokens change how a surface looks; they can never change what it
 * discloses.
 *
 * ## Scope, typography, colour and radius only
 *
 * Spacing and layout primitives are deliberately NOT exposed. Inheriting a
 * host's full styling is what makes an embedded component look broken on any
 * page with unusual CSS, and we would own that support burden.
 *
 * ## Precedence
 *
 *   host CSS token  >  operator dashboard setting  >  built-in default
 *
 * The token wins because it is the most local expression of intent: a developer
 * editing the page they are embedding into. If the dashboard value won, setting
 * `--olotalk-accent` would silently do nothing, the exact failure mode this
 * contract exists to remove.
 *
 * ## Backward compatibility
 *
 * Every token falls back to the value the surface used *before* this contract
 * existed. A page that sets no tokens renders identically to before, verified,
 * not assumed (see the ADR). Adding the contract is not a restyle.
 */
/** The public namespace. Anything outside it is private implementation detail. */
export declare const PUBLIC_TOKEN_PREFIX = "--olotalk-";
/**
 * The complete public contract. Adding a name here widens the API surface we
 * are committing to support across surfaces, do it deliberately.
 *
 * Internal properties (`--otw-*` on the chat assistant) are NOT part of this
 * contract and may change in any release.
 */
export declare const PUBLIC_TOKENS: readonly ["font-family", "font-size", "line-height", "accent", "text", "muted", "surface", "surface-alt", "border", "radius", "radius-panel", "shadow"];
export type PublicToken = (typeof PUBLIC_TOKENS)[number];
/**
 * Build a `var()` reference to a public token with the pre-contract value as its
 * fallback.
 *
 * The fallback is what guarantees backward compatibility, so pass the value the
 * surface would have used anyway, never a fresh guess.
 *
 * @example
 *   "--otw-surface": cssToken("surface", surface)
 *   // → "var(--olotalk-surface, #ffffff)"
 */
export declare function cssToken(name: PublicToken, fallback: string): string;