/**
 * Pipeline Event Ledger — simple append-only event log.
 *
 * Records stage lifecycle events (start, complete, fail, gate results)
 * for audit and debugging. Distinct from LedgerEngine (which records
 * pipeline-level delivery outcomes); this is the per-pipeline event trail.
 *
 * (arc42 §5.2, internal sub-module of PipelineEngine)
 */
import type { NotificationAdapter } from '../notification/notification-adapter.js';
export interface LedgerEvent {
    timestamp: string;
    pipelineId: string;
    type: 'pipeline_created' | 'pipeline_running' | 'pipeline_completed' | 'pipeline_failed' | 'pipeline_blocked' | 'pipeline_paused' | 'pipeline_resumed' | 'pipeline_cancelled' | 'stage_started' | 'stage_completed' | 'stage_failed' | 'stage_blocked' | 'gate_passed' | 'gate_rejected' | 'artifact_passed';
    stageId?: string;
    detail?: Record<string, unknown>;
}
/**
 * In-memory event ledger with append-only semantics.
 * Each pipeline gets its own event stream, keyed by pipelineId.
 */
export declare class EventLedger {
    private readonly events;
    private notificationAdapter;
    /** Attach a notification adapter. Events will be forwarded to it. */
    setNotificationAdapter(adapter: NotificationAdapter): void;
    /** Append an event for a pipeline. */
    append(pipelineId: string, event: Omit<LedgerEvent, 'timestamp' | 'pipelineId'>): LedgerEvent;
    /** Get the full event history for a pipeline. Returns empty array if unknown. */
    getHistory(pipelineId: string): readonly LedgerEvent[];
    /** Get events across all pipelines (most recent first). */
    getAllEvents(): readonly LedgerEvent[];
    /** Clear all events (useful for testing). */
    clear(): void;
}
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