fix(langchain): handle prompts created from runs

Author: hntrl

langchain/src/hub/node.ts

@@ -7,6 +7,7 @@ import {
   bindOutputSchema,
 } from "./base.js";
 import { load } from "../load/index.js";
+import { arraysEqual } from "../util/misc.js";
 
 // TODO: Make this the default, add web entrypoint in next breaking release
 
@@ -33,9 +34,15 @@ export async function pull<T extends Runnable>(
   const promptObject = await basePull(ownerRepoCommit, options);
   let modelClass;
   if (options?.includeModel) {
-    if (Array.isArray(promptObject.manifest.kwargs?.last?.kwargs?.bound?.id)) {
-      const modelName =
-        promptObject.manifest.kwargs?.last?.kwargs?.bound?.id.at(-1);
+    const chatModelObject = arraysEqual(
+      promptObject.manifest.kwargs?.last?.id,
+      ["langchain_core", "runnables", "RunnableBinding"]
+    )
+      ? promptObject.manifest.kwargs?.last?.kwargs?.bound
+      : promptObject.manifest.kwargs?.last;
+
+    if (Array.isArray(chatModelObject?.id)) {
+      const modelName = chatModelObject?.id.at(-1);
       if (modelName === "ChatOpenAI") {
         modelClass = (await import("@langchain/openai")).ChatOpenAI;
       } else if (modelName === "ChatAnthropic") {

langchain/src/hub/tests/hub.int.test.ts

@@ -112,3 +112,14 @@ test("Test LangChain Hub while loading model with dynamic imports and structured
   expect(res).not.toBeInstanceOf(AIMessage);
   expect(typeof res.correctness).toBe("boolean");
 });
+
+test("Test LangChain Hub while loading model not defined in a RunnableBinding", async () => {
+  const promptA = await nodePull("hntrl/binding-manifest", {
+    includeModel: true,
+  });
+  const resA = await promptA.invoke({
+    question: "What's the capital of the USA?",
+  });
+  expect(resA).toBeInstanceOf(AIMessage);
+  expect(resA.content).toBeDefined();
+});

langchain/src/util/misc.ts

@@ -0,0 +1,17 @@
+/**
+ * Helper function to check if two arrays are deeply equal
+ */
+export function arraysEqual<T>(a: T[], b: T[]): boolean {
+  if (!Array.isArray(a) || !Array.isArray(b)) {
+    return false;
+  }
+  if (a.length !== b.length) {
+    return false;
+  }
+  for (let i = 0; i < a.length; i++) {
+    if (a[i] !== b[i]) {
+      return false;
+    }
+  }
+  return true;
+}