import type { Context, MiddlewareHandler } from 'hono';
/** Hono variables used to collect Server-Timing metrics. */
export type Variables = {
    /** Operations that have started but not finished. */
    activeTimings?: Active[] | undefined;
    /** Metrics emitted in the `Server-Timing` response header. */
    serverTiming?: Metric[] | undefined;
};
/** Hono environment shape used by timing helpers. */
export type Environment = {
    Variables: Variables;
};
/** One Server-Timing metric. */
export type Metric = {
    /** Metric duration in milliseconds. */
    duration: number;
    /** Metric name. */
    name: string;
};
/** One operation that has started but not finished. */
export type Active = {
    /** Metric name. */
    name: string;
    /** Monotonic start time. */
    start: number;
};
/** Adds a `Server-Timing` header with total request duration. */
export declare function middleware<environment extends Environment = Environment>(): MiddlewareHandler<environment>;
/** Measures one async operation and adds it to the current request timings. */
export declare function time<environment extends Environment, value>(c: Context<environment>, name: string, fn: () => Promise<value> | value): Promise<value>;
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