feat(js): Expose light interface for tracing client (#1266)

Allows for interoperability in LangChain when initializing tracer with
clients if different LangSmith versions are resolved:

```ts
import { Client } from "langsmith";
// `@langchain/core` may have a different internal version of `langsmith`
import { LangChainTracer } from "@langchain/core/tracers";

const client = new Client();

const tracer = new LangChainTracer({
  client, // Will type error if resolutions are bad
});
```

js/package.json

@@ -1,6 +1,6 @@
 {
   "name": "langsmith",
-  "version": "0.2.7",
+  "version": "0.2.8",
   "description": "Client library to connect to the LangSmith LLM Tracing and Evaluation Platform.",
   "packageManager": "[email protected]",
   "files": [

js/src/client.ts

@@ -437,7 +437,7 @@ export const DEFAULT_BATCH_SIZE_LIMIT_BYTES = 20_971_520;
 
 const SERVER_INFO_REQUEST_TIMEOUT = 1000;
 
-export class Client {
+export class Client implements LangSmithTracingClientInterface {
   private apiKey?: string;
 
   private apiUrl: string;
@@ -4171,3 +4171,9 @@ export class Client {
     ]);
   }
 }
+
+export interface LangSmithTracingClientInterface {
+  createRun: (run: CreateRunParams) => Promise<void>;
+
+  updateRun: (runId: string, run: RunUpdate) => Promise<void>;
+}

js/src/index.ts

@@ -1,4 +1,8 @@
-export { Client, type ClientConfig } from "./client.js";
+export {
+  Client,
+  type ClientConfig,
+  type LangSmithTracingClientInterface,
+} from "./client.js";
 
 export type {
   Dataset,
@@ -14,4 +18,4 @@ export { RunTree, type RunTreeConfig } from "./run_trees.js";
 export { overrideFetchImplementation } from "./singletons/fetch.js";
 
 // Update using yarn bump-version
-export const __version__ = "0.2.7";
+export const __version__ = "0.2.8";