@langchain/langgraph/dist/graph/messages_annotation.js

LangGraph

/* __LC_ALLOW_ENTRYPOINT_SIDE_EFFECTS__ */
import { z } from "zod";
import { Annotation } from "./annotation.js";
import { messagesStateReducer } from "./message.js";
import { withLangGraph } from "./zod/state.js";
/**
 * Prebuilt state annotation that combines returned messages.
 * Can handle standard messages and special modifiers like {@link RemoveMessage}
 * instances.
 *
 * Specifically, importing and using the prebuilt MessagesAnnotation like this:
 *
 * @example
 * ```ts
 * import { MessagesAnnotation, StateGraph } from "@langchain/langgraph";
 *
 * const graph = new StateGraph(MessagesAnnotation)
 *   .addNode(...)
 *   ...
 * ```
 *
 * Is equivalent to initializing your state manually like this:
 *
 * @example
 * ```ts
 * import { BaseMessage } from "@langchain/core/messages";
 * import { Annotation, StateGraph, messagesStateReducer } from "@langchain/langgraph";
 *
 * export const StateAnnotation = Annotation.Root({
 *   messages: Annotation<BaseMessage[]>({
 *     reducer: messagesStateReducer,
 *     default: () => [],
 *   }),
 * });
 *
 * const graph = new StateGraph(StateAnnotation)
 *   .addNode(...)
 *   ...
 * ```
 */
export const MessagesAnnotation = Annotation.Root({
    messages: Annotation({
        reducer: messagesStateReducer,
        default: () => [],
    }),
});
/**
 * Prebuilt state object that uses Zod to combine returned messages.
 * This utility is synonymous with the `MessagesAnnotation` annotation,
 * but uses Zod as the way to express messages state.
 *
 * You can use import and use this prebuilt schema like this:
 *
 * @example
 * ```ts
 * import { MessagesZodState, StateGraph } from "@langchain/langgraph";
 *
 * const graph = new StateGraph(MessagesZodState)
 *   .addNode(...)
 *   ...
 * ```
 *
 * Which is equivalent to initializing the schema object manually like this:
 *
 * @example
 * ```ts
 * import { z } from "zod";
 * import type { BaseMessage, BaseMessageLike } from "@langchain/core/messages";
 * import { StateGraph, messagesStateReducer } from "@langchain/langgraph";
 * import "@langchain/langgraph/zod";
 *
 * const AgentState = z.object({
 *   messages: z
 *     .custom<BaseMessage[]>()
 *     .default(() => [])
 *     .langgraph.reducer(
 *        messagesStateReducer,
 *        z.custom<BaseMessageLike | BaseMessageLike[]>()
 *     ),
 * });
 * const graph = new StateGraph(AgentState)
 *   .addNode(...)
 *   ...
 * ```
 */
export const MessagesZodState = z.object({
    messages: withLangGraph(z.custom(), {
        reducer: {
            schema: z.custom(),
            fn: messagesStateReducer,
        },
        jsonSchemaExtra: {
            langgraph_type: "messages",
        },
        default: () => [],
    }),
});
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