@langchain/langgraph-sdk/dist/stream/projections/channel.js

Client library for interacting with the LangGraph API

import { inferChannel } from "../../client/stream/subscription.js";
import { isRootNamespace, namespaceKey } from "../namespace.js";
import { openProjectionSubscription } from "./runtime.js";
//#region src/stream/projections/channel.ts
/** Max events retained per raw subscription. Older events are dropped. */
const DEFAULT_BUFFER = 4096;
function channelProjection(channels, namespace, options = {}) {
	const chs = [...channels].sort();
	const ns = [...namespace];
	const bufferSize = options.bufferSize ?? DEFAULT_BUFFER;
	const replay = options.replay ?? true;
	return {
		key: `channel|${bufferSize}|${replay ? "replay" : "live"}|${chs.join(",")}|${namespaceKey(ns)}`,
		namespace: ns,
		initial: [],
		open({ thread, store, rootBus }) {
			if (!replay && isRootNamespace(ns) && chs.every((c) => rootBus.channels.includes(c))) {
				const requestedSet = new Set(chs);
				const matches = (event) => {
					const channel = inferChannel(event);
					if (channel === void 0) return false;
					return requestedSet.has(channel) || channel.startsWith("custom:") && requestedSet.has("custom");
				};
				const push = (event) => {
					if (!matches(event)) return;
					const current = store.getSnapshot();
					const next = current.length >= bufferSize ? [...current.slice(current.length - bufferSize + 1), event] : [...current, event];
					store.setValue(next);
				};
				const unsubscribe = rootBus.subscribe(push);
				return { dispose() {
					unsubscribe();
				} };
			}
			return openProjectionSubscription({
				thread,
				channels: chs,
				namespace: ns,
				resumeOnPause: true,
				onEvent(event) {
					const current = store.getSnapshot();
					const next = current.length >= bufferSize ? [...current.slice(current.length - bufferSize + 1), event] : [...current, event];
					store.setValue(next);
				}
			});
		}
	};
}
//#endregion
export { channelProjection };

//# sourceMappingURL=channel.js.map