export type LifecycleTimingLabel = "process-entry" | "interactive-engine-spawn" | "engine-ready" | "tui-start" | "header-mounted" | "first-terminal-write" | "startup-coherent" | "startup-complete" | "engine-bound" | "engine-resources-ready" | "chat-output-release" | "interactive-input-handler-ready" | "interactive-first-submit" | "before-provider-request";
export interface LifecycleTimingRecord {
    readonly label: LifecycleTimingLabel;
    readonly atNs: bigint;
    readonly pid: number;
}
export type LifecycleTimingSink = (record: LifecycleTimingRecord) => void;
/** True only when an internal diagnostic adapter has installed a synchronous sink. */
export declare function isLifecycleTimingEnabled(): boolean;
/**
 * Install a process-local diagnostic sink.
 *
 * The sink must stay synchronous and must not write to the terminal. External
 * ConPTY and TCP timestamps remain authoritative; these records only attribute
 * time inside the process. Installing a sink resets the one-shot labels for a
 * new diagnostic run. The returned function restores the previous adapter.
 */
export declare function installLifecycleTimingSink(sink: LifecycleTimingSink, clock?: () => bigint): () => void;
/** Record the first occurrence of a lifecycle boundary when diagnostics are active. */
export declare function markLifecycleTiming(label: LifecycleTimingLabel): void;
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