/**
 * Contract interface for class-candidate CSS processing engines.
 *
 * Implementations are supplied by explicit extensions such as
 * `@veryfront/ext-css-tailwind`.
 *
 * The contract exposes a provider-neutral compile surface: a stateful
 * compiler is constructed once per stylesheet and emits CSS output for the
 * set of class-name candidates discovered at render time. Core scans the
 * rendered HTML for candidates and calls `CSSCompiler.build(candidates)`
 * on each request; the compiler accumulates state across calls, so exact
 * candidate-snapshot isolation is the caller's responsibility (see
 * `css-compiler-cache.ts`).
 *
 * @module extensions/css/css-processor
 */
/** Registry name used for the CSS compiler extension contract. */
export declare const CSSProcessorName: "CSSProcessor";
export declare const MAX_CSS_PROCESSOR_IDENTITY_CHARACTERS = 512;
export declare const MAX_CSS_PROCESSOR_DEFAULT_STYLESHEET_CHARACTERS: number;
/** Stateful compiler returned by {@link CSSProcessor.compile}. */
export interface CSSCompiler {
    /**
     * Emit CSS for the supplied list of class-name candidates. Stateful — the
     * compiler accumulates candidates across calls for the lifetime of the
     * underlying compile session.
     */
    build(candidates: string[]): string;
}
/**
 * CSSProcessor contract interface.
 *
 * Implementations wire a class-candidate CSS compiler so
 * core's styles-builder can emit per-request CSS without importing the
 * underlying engine directly.
 */
export interface CSSProcessor {
    /** Stable identity for every processor/compiler input that can change emitted CSS. */
    readonly cacheIdentity: string;
    /** Provider-owned stylesheet used when an application does not supply one. */
    readonly defaultStylesheet: string;
    /**
     * Compile a stylesheet. Implementations own all vendor imports, base
     * stylesheets, module resolution, and plugin loading behind this operation.
     */
    compile(stylesheet: string): Promise<CSSCompiler>;
}
/** Capture a compiler method once so accessors and later mutation cannot redirect a build. */
export declare function captureCSSCompiler(value: unknown): CSSCompiler;
/** Validate an implementation received through the dynamic extension registry. */
export declare function assertCSSProcessor(value: unknown): asserts value is CSSProcessor;
/**
 * Capture the complete processor surface once. A registry or implementation
 * mutation can therefore affect only a subsequently acquired operation.
 */
export declare function captureCSSProcessor(value: unknown): CSSProcessor;
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