/**
 * Dependency-free contract for CSS optimization engines.
 *
 * Core owns request and result validation. Implementations own parser,
 * minifier, browser-query, and source-map details.
 *
 * @module extensions/css/css-optimization-engine
 */
/** Registry name used for the CSS optimization extension contract. */
export declare const CSSOptimizationEngineName: "CSSOptimizationEngine";
/** Maximum stable implementation identity accepted across the runtime boundary. */
export declare const MAX_CSS_OPTIMIZATION_ENGINE_IDENTITY_CHARACTERS = 256;
/** Immutable optimization request supplied by core. */
export interface CSSOptimizationRequest {
    readonly css: string;
    readonly sourcePath: string;
    readonly minify: boolean;
    readonly sourceMap: boolean;
}
/** Portable output returned by a CSS optimization engine. */
export interface CSSOptimizationResult {
    readonly css: string;
    readonly sourceMap?: string;
}
/**
 * Parser-backed CSS optimization contract.
 *
 * The operation is intentionally synchronous so existing synchronous core
 * helpers cannot conceal an asynchronous fallback or dynamic import.
 */
export interface CSSOptimizationEngine {
    /**
     * Includes every implementation/version input capable of changing output.
     * Represented state must remain immutable for the captured engine lifetime.
     */
    readonly cacheIdentity: string;
    optimize(request: CSSOptimizationRequest): CSSOptimizationResult;
}
/** Validate an implementation received through the dynamic contract registry. */
export declare function assertCSSOptimizationEngine(value: unknown): asserts value is CSSOptimizationEngine;
/**
 * Capture dynamic properties once so later mutation or accessors cannot change
 * the implementation that core invokes.
 */
export declare function captureCSSOptimizationEngine(value: unknown): CSSOptimizationEngine;
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