import type { CompletionRequest } from '../types/messages.js';
import type { NexusResponse } from '../types/response.js';
import type { PipelineConfig, PipelineContext, PipelineHookName, PipelineShapes, PipelineStep, PipelineStepName } from './types.js';
/**
 * Runs the request pipeline's hooks and custom steps, and times each stage into the request's
 * trace. Generic over the request and response; without `shapes` it runs a completion's.
 */
export declare class PipelineRunner<Req = CompletionRequest, Res = NexusResponse> {
    private config;
    private steps;
    private readonly shapes;
    constructor(config?: PipelineConfig<Req, Res>, shapes?: PipelineShapes<Req, Res>);
    /** Adds a custom step, run after the built-in stages. Returns the runner, for chaining. */
    use(step: PipelineStep<Req, Res>): this;
    /** Runs every handler registered for a hook, in order. */
    runHook(name: PipelineHookName, context: PipelineContext<Req, Res>): Promise<PipelineContext<Req, Res>>;
    /** Runs the custom steps, in order. */
    runCustomSteps(context: PipelineContext<Req, Res>): Promise<PipelineContext<Req, Res>>;
    /**
     * Runs one stage and records its timing, unless tracing is off. `custom` names a custom step,
     * recorded with `name` set to `customStep`.
     */
    trace<T>(context: PipelineContext<Req, Res>, name: PipelineStepName, fn: () => T | Promise<T>, metadata?: Record<string, unknown>, custom?: string): Promise<T>;
    /** Stamps the trace's end time and duration. */
    finish(context: PipelineContext<Req, Res>): PipelineContext<Req, Res>;
    private runMiddleware;
    private handlersForHook;
}
/** A fresh pipeline context for a request. */
export declare function createPipelineContext<Req = CompletionRequest, Res = NexusResponse>(request: Req): PipelineContext<Req, Res>;