/**
 * FileSystem class for managing sandboxed file storage
 * Handles task tracking files (todo.md, results.md) with validation and archiving
 */
export declare class FileSystem {
    private workspaceDir;
    private initialized;
    constructor(workspaceDir?: string);
    /**
     * Initialize the file system by creating workspace directory
     * Creates todo.md and results.md if they don't exist
     */
    initialize(): Promise<void>;
    /**
     * Write content to a file with validation
     * Only allows .md and .txt extensions
     */
    writeFile(fileName: string, content: string): Promise<boolean>;
    /**
     * Append content to an existing file
     * Creates the file if it doesn't exist
     */
    appendFile(fileName: string, content: string): Promise<boolean>;
    /**
     * Read file content with line count tracking
     * Returns content and line count
     */
    readFile(fileName: string): Promise<{
        content: string;
        lineCount: number;
    }>;
    /**
     * List all files in the workspace directory
     * Returns array of file names (not full paths)
     */
    listFiles(): Promise<string[]>;
    /**
     * Archive old files with timestamp suffixes
     * Moves files to archive/ subdirectory with timestamp
     */
    archiveOldFiles(): Promise<void>;
    /**
     * Get the workspace directory path
     */
    getWorkspaceDir(): string;
    /**
     * Check if file system is initialized
     */
    isInitialized(): boolean;
    private ensureInitialized;
    private isValidExtension;
    private containsPathTraversal;
    private getTimestamp;
}
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