/**
 * Three-state readiness contract for `GET /health`.
 *
 * S5 (lifecycle layer) wires the lifecycle to flip these states:
 *  - `"starting"` — initial state; server is binding or warming up.
 *  - `"ok"`       — server is bound and ready to handle traffic.
 *  - `"draining"` — graceful-shutdown in progress; stop routing new requests.
 *
 * `GET /health` returns `200` for `"ok"` and `503` for the other two states
 * so load balancers stop routing before the process exits.
 */
/** Three valid readiness states. */
export type ReadinessState = "starting" | "ok" | "draining";
/**
 * Read-only interface consumed by `GET /health` and any other component that
 * needs to observe readiness without being able to mutate it.
 */
export interface Readiness {
    /** Return the current readiness state synchronously. */
    state(): ReadinessState;
}
/**
 * Create a mutable readiness object.
 *
 * The returned object satisfies both the read-only {@link Readiness} interface
 * and exposes `setOk()` / `setDraining()` mutators for the lifecycle layer
 * (S5) to call at the appropriate moments.
 *
 * Initial state is `"starting"`.
 *
 * @returns A combined readiness + mutator object.
 */
export declare function createReadiness(): Readiness & {
    setOk(): void;
    setDraining(): void;
};
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