/**
 * QA360 Content-Addressable Storage (CAS)
 * Stores files by their SHA256 hash with deduplication
 */
export interface CASArtifact {
    sha256: string;
    path: string;
    size: number;
    exists: boolean;
}
export interface CASStats {
    totalFiles: number;
    totalBytes: number;
    orphanedFiles: number;
    orphanedBytes: number;
}
export declare class ContentAddressableStorage {
    private readonly casRoot;
    constructor(baseDir: string);
    /**
     * Save content to CAS, returns artifact metadata
     */
    saveArtifact(content: Buffer, mimeType: string, originalName?: string): Promise<CASArtifact>;
    /**
     * Save file to CAS by path
     */
    saveFile(filePath: string, mimeType: string): Promise<CASArtifact>;
    /**
     * Retrieve content from CAS
     */
    getArtifact(sha256: string): Promise<Buffer | null>;
    /**
     * Check if artifact exists in CAS
     */
    exists(sha256: string): boolean;
    /**
     * Get artifact metadata
     */
    getArtifactInfo(sha256: string): Promise<{
        size: number;
        mtime: Date;
    } | null>;
    /**
     * List all artifacts in CAS
     */
    listArtifacts(): Promise<string[]>;
    /**
     * Get CAS statistics
     */
    getStats(referencedHashes?: Set<string>): Promise<CASStats>;
    /**
     * Remove orphaned artifacts
     */
    cleanupOrphans(referencedHashes: Set<string>): Promise<{
        removedFiles: number;
        freedBytes: number;
    }>;
    /**
     * Calculate SHA256 hash of content
     */
    calculateHash(content: Buffer): string;
    /**
     * Calculate SHA256 hash of content (static utility)
     */
    static hashContent(content: Buffer): string;
    /**
     * Get CAS file path for a given hash (with sharding)
     */
    private getCASPath;
    /**
     * Ensure CAS directory structure exists
     */
    private ensureCASDirectory;
    /**
     * Clean up empty shard directories
     */
    private cleanupEmptyDirectories;
    /**
     * Verify artifact integrity
     */
    verifyArtifact(sha256: string): Promise<boolean>;
    /**
     * Copy artifact to external path
     */
    exportArtifact(sha256: string, targetPath: string): Promise<boolean>;
    /**
     * Get human-readable size
     */
    static formatBytes(bytes: number): string;
}