/**
 * Constant-time string comparison for hash values.
 * Prevents timing side-channel attacks on alphabet hash checks.
 */
export declare function timingSafeHashEqual(a: string, b: string): boolean;
export declare class SigmaError extends Error {
    constructor(message: string);
}
export declare function computeAlphabetHash(nodes: Record<string, any>, edges: Record<string, any>): string;
export declare class Sigma {
    readonly version: string;
    readonly alphabetHash: string;
    readonly nodes: Record<string, {
        ops: string[];
        doc: string;
    }>;
    readonly edges: Record<string, {
        doc: string;
        normative: boolean;
    }>;
    constructor(version: string, alphabetHash: string, nodes: Record<string, {
        ops: string[];
        doc: string;
    }>, edges: Record<string, {
        doc: string;
        normative: boolean;
    }>);
    isClass(cls: string): boolean;
    isLabel(cls: string, op?: string): boolean;
    isEdge(edgeType: string): boolean;
    normativeEdges(): string[];
    requireLabel(cls: string, op?: string): void;
    classes(): string[];
    ops(cls: string): string[];
}
export declare function loadSigma(filePath?: string, verifyHash?: boolean): Sigma;
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