/**
 * Resolution of the channel bus from config, environment, or a supplied instance.
 *
 * Opt-in, like every other cross-cutting realtime switch here: with nothing
 * configured a deployment gets the memory bus and behaves exactly as it did
 * before this existed. Unlike `REALTIME_CDC=auto`, there is no "try it and see"
 * default — a bus changes where messages go, and quietly turning on a Postgres
 * NOTIFY per broadcast because a direct URL happened to be set is not a
 * decision to make on the user's behalf.
 *
 * Two transports ship, and neither adds a service to a deployment. A third is
 * not a code change here: `realtime.bus` also accepts an already-constructed
 * {@link ChannelBus}, so a transport published as its own package plugs in
 * without this file learning about it. See `@rebasepro/types` →
 * `types/channel_bus.ts` for the contract such a package implements.
 */
import { NodePgDatabase } from "drizzle-orm/node-postgres";
import { type ChannelBus, type ChannelBusSetting } from "@rebasepro/types";
export * from "./ChannelBus";
export { PostgresChannelBus, CHANNEL_BUS_NOTIFY_CHANNEL, PG_NOTIFY_MAX_PAYLOAD_BYTES, DEFAULT_BATCH_WINDOW_MS, parseChannelBusFrame, parseChannelBusPayload } from "./PostgresChannelBus";
export interface ChannelBusDeps {
    db: NodePgDatabase<Record<string, unknown>>;
    /**
     * Direct (non-pooled) Postgres URL for the LISTEN client. `LISTEN` is
     * session state, so behind PgBouncer in transaction mode this must be the
     * database itself and not the pooler.
     */
    directUrl?: string;
}
/**
 * Merge `REALTIME_CHANNEL_BUS` into the configured bus.
 *
 * The environment wins over a *named* built-in, so the transport can be changed
 * per deployment without a rebuild — the same reason `REALTIME_CDC` is an env
 * var. It does **not** win over a supplied instance: the env var can only name
 * transports this package knows how to construct, so honouring it there would
 * mean silently discarding the object the application handed us.
 */
export declare function resolveChannelBusSetting(configured?: ChannelBusSetting): ChannelBusSetting;
/**
 * Produce the bus a setting asks for.
 *
 * An instance is handed straight back — constructing it was the application's
 * job, and this function has nothing to add. A named built-in that turns out to
 * be unusable degrades to the memory bus, with the reason logged, rather than
 * throwing: a misconfigured bus should cost a deployment its cross-instance
 * fan-out, not its ability to boot.
 */
export declare function createChannelBus(setting: ChannelBusSetting, deps: ChannelBusDeps): ChannelBus;