Sessions

LanguageModelSession manages conversation state and provides all generation methods. Each session maintains its own context window and transcript.

INFO

The Swift equivalent is LanguageModelSession.

Creating a Session

import { LanguageModelSession } from "tsfm-sdk";

const session = new LanguageModelSession({
  instructions: "You are a concise assistant.",
});

With a Specific Model

const model = new SystemLanguageModel({ useCase: SystemLanguageModelUseCase.CONTENT_TAGGING });
const session = new LanguageModelSession({ model });

With Tools

const session = new LanguageModelSession({
  tools: [weatherTool, calculatorTool],
});

Generating Responses

Text Response

const reply = await session.respond("What is the capital of France?");
console.log(reply); // "The capital of France is Paris."

With Generation Options

const reply = await session.respond("Write a poem", {
  options: {
    temperature: 0.9,
    maximumResponseTokens: 200,
  },
});

See Generation Options for all available options.

Concurrency

Sessions serialize concurrent calls automatically. If you call respond() while another request is in progress, it queues and runs after the first completes:

// These run sequentially, not in parallel
const [a, b] = await Promise.all([
  session.respond("First question"),
  session.respond("Second question"),
]);

Cancellation

Cancel an in-progress request with cancel():

const promise = session.respond("Tell me a long story");
session.cancel();

Cancellation is advisory — the response may still complete if the model finishes before the cancel is processed. After cancellation, the session resets to idle and is ready for new requests.

Checking State

isResponding tells you whether the session is currently processing a request:

if (session.isResponding) {
  // A generation call is in flight
}

Cleanup

Always dispose sessions when done to release native memory:

session.dispose();

TIP

If you prefer a higher-level interface, the Chat API compatibility layer manages sessions automatically behind a more standard chat.completions.create() interface.