feat(langgraph): allow explicit type declaration for interrupt and custom stream events

.changeset/tame-humans-tap.md

@@ -0,0 +1,5 @@
+---
+"@langchain/langgraph": patch
+---
+
+Allow defining types for interrupt and custom events upfront

libs/langgraph/src/constants.ts

@@ -99,8 +99,16 @@ const COMMAND_SYMBOL = Symbol.for("langgraph.command");
  * @see {@link Command}
  * @internal
  */
-export class CommandInstance {
-  [COMMAND_SYMBOL]: true;
+export class CommandInstance<
+  Resume = unknown,
+  Update extends Record<string, unknown> = Record<string, unknown>,
+  Nodes extends string = string
+> {
+  [COMMAND_SYMBOL]: CommandParams<Resume, Update, Nodes>;
+
+  constructor(args: CommandParams<Resume, Update, Nodes>) {
+    this[COMMAND_SYMBOL] = args;
+  }
 }
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -329,7 +337,7 @@ export class Command<
   Resume = unknown,
   Update extends Record<string, unknown> = Record<string, unknown>,
   Nodes extends string = string
-> extends CommandInstance {
+> extends CommandInstance<Resume, Update, Nodes> {
   readonly lg_name = "Command";
 
   lc_direct_tool_output = true;
@@ -364,8 +372,8 @@ export class Command<
 
   static PARENT = "__parent__";
 
-  constructor(args: CommandParams<Resume, Update, Nodes>) {
-    super();
+  constructor(args: Omit<CommandParams<Resume, Update, Nodes>, "lg_name">) {
+    super(args);
     this.resume = args.resume;
     this.graph = args.graph;
     this.update = args.update;

libs/langgraph/src/graph/graph.ts

@@ -12,7 +12,7 @@ import {
   Graph as DrawableGraph,
 } from "@langchain/core/runnables/graph";
 import { All, BaseCheckpointSaver } from "@langchain/langgraph-checkpoint";
-import { z } from "zod";
+import { z } from "zod/v4";
 import { validate as isUuid } from "uuid";
 import type {
   RunnableLike,
@@ -581,7 +581,10 @@ export class CompiledGraph<
   InputType = any,
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   OutputType = any,
-  NodeReturnType = unknown
+  NodeReturnType = unknown,
+  CommandType = unknown,
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  StreamCustomType = any
 > extends Pregel<
   Record<N | typeof START, PregelNode<State, Update>>,
   Record<N | typeof START | typeof END | string, BaseChannel>,
@@ -591,7 +594,9 @@ export class CompiledGraph<
   OutputType,
   InputType,
   OutputType,
-  NodeReturnType
+  NodeReturnType,
+  CommandType,
+  StreamCustomType
 > {
   declare NodeType: N;
 
@@ -694,12 +699,7 @@ export class CompiledGraph<
     const xray = config?.xray;
     const graph = new DrawableGraph();
     const startNodes: Record<string, DrawableGraphNode> = {
-      [START]: graph.addNode(
-        {
-          schema: z.any(),
-        },
-        START
-      ),
+      [START]: graph.addNode({ schema: z.any() }, START),
     };
     const endNodes: Record<string, DrawableGraphNode> = {};
     // eslint-disable-next-line @typescript-eslint/no-explicit-any

libs/langgraph/src/graph/index.ts

@@ -12,7 +12,6 @@ export {
   type StateGraphArgs,
   StateGraph,
   CompiledStateGraph,
-  typedNode,
 } from "./state.js";
 export {
   MessageGraph,