/**
 * CLEO Observability — Vendor-Agnostic Agent Event Bus (ADR-071 / T1651).
 *
 * Provides `appendEvent` — a zero-dependency SDK operation that emits
 * structured lifecycle events from autonomous workers. Two transports:
 *
 * - **Conduit** (default, `CLEO_EVENTS_TRANSPORT=conduit`):
 *   Publishes to the `agent.events.<agentId>` topic via LocalTransport
 *   (SQLite) or HttpTransport (cloud), enabling live streaming and
 *   distributed orchestration.
 *
 * - **File** (`CLEO_EVENTS_TRANSPORT=file`):
 *   Appends NDJSON lines to `.cleo/agent-events/<agentId>.jsonl`.
 *   Zero-infra fallback for bare harnesses that cannot initialize Conduit.
 *
 * When Conduit init fails, the function automatically falls back to the
 * file transport and logs a `[events] WARN` line (silent degradation).
 *
 * ## Event Schema
 *
 * All events conform to {@link CleoAgentEvent}. Stable `kind` values:
 * `spawn`, `heartbeat`, `tool-start`, `tool-end`, `commit`, `blocked`, `complete`.
 *
 * @see ADR-071
 * @task T1135
 * @task T1651
 */
/**
 * Stable event kinds for the CLEO agent observability bus.
 *
 * - `spawn`      — worker has started and loaded its task context.
 * - `heartbeat`  — periodic ping (every N seconds or on phase transition).
 * - `tool-start` — a tool call is about to be executed.
 * - `tool-end`   — a tool call returned (includes exit code / result size).
 * - `commit`     — worker committed code to its branch.
 * - `blocked`    — worker is waiting on a dependency or HITL approval.
 * - `complete`   — worker finished; manifest appended.
 *
 * @task T1651
 */
export type CleoAgentEventKind = 'spawn' | 'heartbeat' | 'tool-start' | 'tool-end' | 'commit' | 'blocked' | 'complete';
/**
 * Stable envelope for all agent lifecycle events (ADR-071).
 *
 * `payload` is kind-specific but always serializable to JSON. Workers MUST
 * NOT include secrets or PII in `payload`.
 */
export interface CleoAgentEvent {
    /** Discriminated union for the event type. */
    kind: CleoAgentEventKind;
    /** Task the worker is executing. */
    taskId: string;
    /** Agent identity string (e.g. `cleo-worker-T1234`). */
    agentId: string;
    /** ISO-8601 timestamp of the event. */
    timestamp: string;
    /** Optional kind-specific structured payload. */
    payload?: Record<string, unknown>;
}
/** Transport mode for agent event emission. */
export type EventTransportMode = 'conduit' | 'file';
/**
 * Resolve the active transport mode.
 *
 * Priority:
 * 1. `CLEO_EVENTS_TRANSPORT` environment variable (`conduit` | `file`).
 * 2. Default: `conduit`.
 */
export declare function resolveEventTransportMode(): EventTransportMode;
/**
 * Append a structured lifecycle event from an autonomous worker.
 *
 * Transport is selected by {@link resolveEventTransportMode}:
 * - `conduit` (default): publishes to `agent.events.<agentId>` topic.
 * - `file`: appends to `.cleo/agent-events/<agentId>.jsonl`.
 *
 * Conduit failures silently fall back to file transport and log a warning.
 * All failures are swallowed — observability code MUST NOT crash a worker.
 *
 * @param kind        - Event kind (see {@link CleoAgentEventKind}).
 * @param taskId      - Task the worker is executing.
 * @param agentId     - Agent identity string.
 * @param projectRoot - Absolute path to the project root.
 * @param payload     - Optional kind-specific structured payload.
 *
 * @example
 * ```typescript
 * await appendEvent('heartbeat', 'T1234', 'cleo-worker-T1234', '/mnt/projects/foo');
 * await appendEvent('tool-start', 'T1234', 'cleo-worker-T1234', '/mnt/projects/foo', { tool: 'Bash' });
 * ```
 *
 * @task T1651
 */
export declare function appendEvent(kind: CleoAgentEventKind, taskId: string, agentId: string, projectRoot: string, payload?: Record<string, unknown>): Promise<void>;
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