/** The single shape of the JSON error envelope (see PROTOCOL.md). Everything that
 * records an error — a handler exception, a missing handler, lease expiry, a thrown
 * TaskError — builds it here, so the contract's fields live in one place. */
export declare function errorEnvelope(e: {
    type: string;
    code: string;
    message: string;
    retryable: boolean;
    details?: Record<string, unknown>;
}): Record<string, unknown>;
export declare class CairnQError extends Error {
}
export declare class AlreadyExists extends CairnQError {
    key: string;
    constructor(key: string);
}
/** wait/call did not reach a terminal status in time. The task keeps running. */
export declare class TaskTimeout extends CairnQError {
    taskId: string;
    constructor(taskId: string);
}
/** A waited-on task ended in `failed`. The envelope's fields are unpacked onto the
 * error — read `e.code` / `e.message` / `e.retryable` / `e.details` instead of
 * digging into `e.error` (the raw envelope stays available on `e.error`). */
export declare class TaskFailed extends CairnQError {
    error: unknown;
    readonly type: string;
    readonly code: string;
    readonly retryable: boolean;
    readonly details: Record<string, unknown>;
    constructor(error: unknown);
}
export declare class TaskCanceled extends CairnQError {
    taskId: string;
    constructor(taskId: string);
}
/** A worker write affected 0 rows: the lease expired and was reclaimed. */
export declare class LostLease extends CairnQError {
    taskId: string;
    constructor(taskId: string);
}
export declare class ProtocolVersionMismatch extends CairnQError {
    constructor(message: string);
}
/** Throw inside a handler to control how the failure is recorded. Defaults to
 * non-retryable so deterministic errors fail fast instead of burning retries.
 * Any other thrown value is treated as retryable. */
export declare class TaskError extends CairnQError {
    code: string;
    retryable: boolean;
    type: string;
    details: Record<string, unknown>;
    constructor(message: string, opts?: {
        code?: string;
        retryable?: boolean;
        type?: string;
        details?: Record<string, unknown>;
    });
    envelope(): Record<string, unknown>;
}