Add optional @langchain/core dependency for backwards compatibility, …

…expose LangChain handoff functions outside

js/.gitignore

@@ -51,6 +51,10 @@ Chinook_Sqlite.sql
 /schemas.js
 /schemas.d.ts
 /schemas.d.cts
+/langchain.cjs
+/langchain.js
+/langchain.d.ts
+/langchain.d.cts
 /wrappers.cjs
 /wrappers.js
 /wrappers.d.ts

js/package.json

@@ -25,6 +25,10 @@
  "schemas.js",
  "schemas.d.ts",
  "schemas.d.cts",
+ "langchain.cjs",
+ "langchain.js",
+ "langchain.d.ts",
+ "langchain.d.cts",
  "wrappers.cjs",
  "wrappers.js",
  "wrappers.d.ts",
@@ -108,11 +112,15 @@
  "typescript": "^5.4.5"
  },
  "peerDependencies": {
- "openai": "*"
+ "openai": "*",
+ "@langchain/core": "*"
  },
  "peerDependenciesMeta": {
  "openai": {
  "optional": true
+ },
+ "@langchain/core": {
+ "optional": true
  }
  },
  "resolutions": {
@@ -179,6 +187,15 @@
  "import": "./schemas.js",
  "require": "./schemas.cjs"
  },
+ "./langchain": {
+ "types": {
+ "import": "./langchain.d.ts",
+ "require": "./langchain.d.cts",
+ "default": "./langchain.d.ts"
+ },
+ "import": "./langchain.js",
+ "require": "./langchain.cjs"
+ },
  "./wrappers": {
  "types": {
  "import": "./wrappers.d.ts",

js/scripts/create-entrypoints.js

@@ -12,6 +12,7 @@ const entrypoints = {
  traceable: "traceable",
  evaluation: "evaluation/index",
  schemas: "schemas",
+ langchain: "langchain",
  wrappers: "wrappers/index",
  "wrappers/openai": "wrappers/openai",
 };

js/src/langchain.ts

@@ -1,17 +1,27 @@
-/* eslint-disable import/no-extraneous-dependencies */
 import { CallbackManager } from "@langchain/core/callbacks/manager";
 import { LangChainTracer } from "@langchain/core/tracers/tracer_langchain";
+import { Runnable, RunnableConfig } from "@langchain/core/runnables";
+
 import { RunTree } from "./run_trees.js";
 import { Run } from "./schemas.js";
-import { Runnable, RunnableConfig } from "@langchain/core/runnables";
 import {
  TraceableFunction,
  getCurrentRunTree,
  isTraceableFunction,
 } from "./traceable.js";
 
-export async function getLangchainCallbacks() {
- const runTree: RunTree | undefined = getCurrentRunTree();
+/**
+ * Converts the current run tree active within a traceable-wrapped function
+ * into a LangChain compatible callback manager. This is useful to handoff tracing
+ * from LangSmith to LangChain Runnables and LLMs.
+ *
+ * @param {RunTree | undefined} currentRunTree Current RunTree from within a traceable-wrapped function. If not provided, the current run tree will be inferred from AsyncLocalStorage.
+ * @returns {CallbackManager | undefined} Callback manager used by LangChain Runnable objects.
+ */
+export async function getLangchainCallbacks(
+ currentRunTree?: RunTree | undefined
+) {
+ const runTree: RunTree | undefined = currentRunTree ?? getCurrentRunTree();
  if (!runTree) return undefined;
 
  // TODO: CallbackManager.configure() is only async due to LangChainTracer
@@ -70,6 +80,10 @@ export async function getLangchainCallbacks() {
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 type AnyTraceableFunction = TraceableFunction<(...any: any[]) => any>;
 
+/**
+ * RunnableTraceable is a Runnable that wraps a traceable function.
+ * This allows adding Langsmith traced functions into LangChain sequences.
+ */
 export class RunnableTraceable<RunInput, RunOutput> extends Runnable<
  RunInput,
  RunOutput
@@ -126,4 +140,8 @@ export class RunnableTraceable<RunInput, RunOutput> extends Runnable<
 
  return (await this.func(config, input)) as RunOutput;
  }
+
+ static from(func: AnyTraceableFunction) {
+ return new RunnableTraceable({ func });
+ }
 }

js/src/tests/traceable.test.ts

@@ -6,9 +6,9 @@ import { FakeChatModel } from "@langchain/core/utils/testing";
 import { ChatPromptTemplate } from "@langchain/core/prompts";
 import { StringOutputParser } from "@langchain/core/output_parsers";
 import { LangChainTracer } from "@langchain/core/tracers/tracer_langchain";
-import { RunnableTraceable, getLangchainCallbacks } from "../langchain.js";
 import { BaseMessage, HumanMessage } from "@langchain/core/messages";
 import { awaitAllCallbacks } from "@langchain/core/callbacks/promises";
+import { RunnableTraceable, getLangchainCallbacks } from "../langchain.js";
 
 test("basic traceable implementation", async () => {
  const { client, callSpy } = mockClient();
@@ -723,7 +723,7 @@ describe("langchain", () => {
 
  const chain = prompt
  .pipe(llm)
- .pipe(new RunnableTraceable({ func: addValueTraceable }))
+ .pipe(RunnableTraceable.from(addValueTraceable))
  .pipe(parser);
 
  // eslint-disable-next-line @typescript-eslint/ban-ts-comment

js/tsconfig.json

@@ -37,6 +37,7 @@
  "src/traceable.ts",
  "src/evaluation/index.ts",
  "src/schemas.ts",
+ "src/langchain.ts",
  "src/wrappers/index.ts",
  "src/wrappers/openai.ts"
  ]