/**
 * Audit Logger — Core audit logging for HoloScript
 *
 * Provides append-only audit event logging with query, export,
 * and retention management capabilities.
 *
 * @version 3.3.0
 * @Sprint Sprint 9: Audit Logging & Compliance
 */
/**
 * Represents a single audit event.
 */
export interface AuditEvent {
    id: string;
    timestamp: Date;
    tenantId: string;
    actorId: string;
    actorType: 'user' | 'agent' | 'system';
    action: string;
    resource: string;
    resourceId?: string;
    outcome: 'success' | 'failure' | 'denied';
    metadata: Record<string, unknown>;
    clientIp?: string;
    userAgent?: string;
}
/**
 * Input type for creating a new audit event (ID and timestamp are auto-generated).
 */
export type AuditEventInput = Omit<AuditEvent, 'id' | 'timestamp'>;
/**
 * Filter criteria for querying audit events.
 */
export interface AuditQueryFilter {
    tenantId?: string;
    actorId?: string;
    actorType?: 'user' | 'agent' | 'system';
    action?: string;
    resource?: string;
    resourceId?: string;
    outcome?: 'success' | 'failure' | 'denied';
    since?: Date;
    until?: Date;
    limit?: number;
    offset?: number;
}
/**
 * Storage backend interface for pluggable persistence.
 */
export interface AuditStorageBackend {
    append(event: AuditEvent): void;
    getAll(): AuditEvent[];
    getCount(): number;
    removeWhere(predicate: (event: AuditEvent) => boolean): number;
}
/**
 * Default in-memory storage backend using an append-only array.
 */
export declare class InMemoryAuditStorage implements AuditStorageBackend {
    private events;
    append(event: AuditEvent): void;
    getAll(): AuditEvent[];
    getCount(): number;
    removeWhere(predicate: (event: AuditEvent) => boolean): number;
}
/**
 * Core audit logger that provides append-only event logging,
 * querying, export, and retention management.
 */
export declare class AuditLogger {
    private storage;
    private retentionPolicies;
    constructor(storage?: AuditStorageBackend);
    /**
     * Log a new audit event. Generates ID and timestamp automatically.
     * Events are immutable once logged (append-only).
     */
    log(input: AuditEventInput): AuditEvent;
    /**
     * Query audit events matching the given filter criteria.
     */
    query(filter: AuditQueryFilter): AuditEvent[];
    /**
     * Export filtered events in the specified format.
     */
    export(filter: AuditQueryFilter, format: 'json' | 'csv'): string;
    /**
     * Set retention policy for a specific tenant (in days).
     */
    setRetentionPolicy(tenantId: string, days: number): void;
    /**
     * Get retention policy for a tenant, or undefined if none set.
     */
    getRetentionPolicy(tenantId: string): number | undefined;
    /**
     * Purge events that have exceeded their tenant's retention period.
     * Returns the number of events purged.
     */
    purgeExpired(): number;
    /**
     * Get count of events matching the optional filter.
     */
    getEventCount(filter?: AuditQueryFilter): number;
    private applyFilter;
}
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