/**
 * WebSocket delegation channel handler.
 *
 * Manages WS upgrade requests, message parsing, and delegation event
 * forwarding for the `/ws/delegation` channel.
 *
 * @module sidecar/server/ws/delegation
 */
import type { IncomingMessage } from "node:http";
import type { Duplex } from "node:stream";
import type { SidecarDependencyRegistry } from "../registry.js";
import type { WsConnectionPool } from "./pool.js";
/** Valid WS message types. */
export declare const WsMessageType: readonly ["subscribe", "unsubscribe", "ping", "event"];
export type WsMessageType = (typeof WsMessageType)[number];
/** Dependencies for creating a WS delegation handler. */
export interface WsDelegationHandlerDeps {
    registry: SidecarDependencyRegistry;
    pool: WsConnectionPool;
}
/**
 * Create a WS delegation handler bound to the given dependencies.
 *
 * Returns a callable upgrade handler function with an `onMessage`
 * property for test assertions (duck-typed per WS test expectations).
 *
 * @param deps - Dependencies including registry and WS pool.
 * @returns A callable handler function with onMessage property.
 */
export declare function createWsDelegationHandler(deps: WsDelegationHandlerDeps): ((req: IncomingMessage, socket: Duplex, head: Buffer) => Promise<void>) & {
    onMessage: (msg: unknown) => {
        code?: number;
    } | void;
};
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