/**
 * Checkpointer Implementations
 *
 * Built-in checkpointers for state persistence.
 */
import type { AgentState, Checkpointer, SessionMetadata, SessionInfo, ListSessionsOptions, StateSerializer } from './types.js';
/**
 * In-memory checkpointer for development and testing.
 * State is lost when the process exits.
 */
export declare class MemoryCheckpointer implements Checkpointer {
    private readonly sessions;
    /**
     * Save state to memory
     *
     * Pre-validates state before saving to prevent corrupted checkpoints.
     * This catches issues like invalid data types that would fail on reload.
     */
    save(sessionId: string, state: AgentState, metadataOverrides?: Partial<SessionMetadata>): Promise<void>;
    /**
     * Load state from memory
     */
    load(sessionId: string): Promise<AgentState | null>;
    /**
     * List all sessions
     */
    list(options?: ListSessionsOptions): Promise<SessionInfo[]>;
    /**
     * Delete a session
     */
    delete(sessionId: string): Promise<boolean>;
    /**
     * Check if session exists
     */
    exists(sessionId: string): Promise<boolean>;
    /**
     * Get session metadata
     */
    getMetadata(sessionId: string): Promise<SessionMetadata | null>;
    /**
     * Clear all sessions (useful for testing)
     */
    clear(): void;
    /**
     * Get current session count
     */
    get size(): number;
}
/**
 * Options for FileCheckpointer
 */
export interface FileCheckpointerOptions {
    /**
     * Custom serializer (defaults to JsonSerializer)
     */
    serializer?: StateSerializer;
    /**
     * File extension (defaults to '.json')
     */
    extension?: string;
}
/**
 * File-based checkpointer for simple persistence.
 * Stores each session as a separate JSON file.
 */
export declare class FileCheckpointer implements Checkpointer {
    private readonly baseDir;
    private readonly serializer;
    private readonly extension;
    constructor(baseDir: string, options?: FileCheckpointerOptions);
    /**
     * Get file path for a session
     */
    private getStatePath;
    /**
     * Get metadata file path for a session
     */
    private getMetadataPath;
    /**
     * Ensure base directory exists
     */
    private ensureDir;
    /**
     * Save state to file
     *
     * Pre-validates state before saving to prevent corrupted checkpoints.
     * This catches issues like invalid data types that would fail on reload.
     */
    save(sessionId: string, state: AgentState, metadataOverrides?: Partial<SessionMetadata>): Promise<void>;
    /**
     * Load state from file
     */
    load(sessionId: string): Promise<AgentState | null>;
    /**
     * List all sessions
     */
    list(options?: ListSessionsOptions): Promise<SessionInfo[]>;
    /**
     * Delete a session
     */
    delete(sessionId: string): Promise<boolean>;
    /**
     * Check if session exists
     */
    exists(sessionId: string): Promise<boolean>;
    /**
     * Get session metadata
     */
    getMetadata(sessionId: string): Promise<SessionMetadata | null>;
}