@langchain/typesafe 0.1.0: questions move from the constructor to invoke, and its middleware is deprecated (November 11, 2026)

What changed

On November 11, 2026 LangChain.js released @langchain/typesafe 0.1.0. TypeSafeClassifier now extends BaseDecisionModel from @langchain/core/decisions, and the release notes mark it as a breaking change:

• Questions go with each request. new TypeSafeClassifier().invoke({ state, questions }) replaces new TypeSafeClassifier({ questions }).invoke(state).
• Every question needs instructions.
• Token usage is usage_metadata (input_tokens, output_tokens, total_tokens) instead of usage (inputTokens, outputTokens).
• ClassificationResponse, QuestionContent (now Content), Usage, ValidatedQuestions, JsonValue and TypeSafeClassifierCallOptions are removed.
• An invalid question throws a plain Error from invoke, not a TypeSafeError from the constructor.
• Box questions and image content are new.
• autoModeMiddleware and modelRouterMiddleware from @langchain/typesafe/middleware are deprecated. They warn once and will be removed in 0.2.0.

The package now needs @langchain/core 1.4.0 or newer and Zod 4.6.6 or newer.

The Python package langchain-typesafe 0.1.0 shipped the same day. It needs Python 3.11 and langchain-core 1.8.0, and deprecates its experimental middleware too.

What to do

Upgrade @langchain/core to 1.4.0 with the package, then move questions into the invoke call. You need a TypeSafe API key in TYPESAFE_API_KEY. The docs example:

import { TypeSafeClassifier } from "@langchain/typesafe";

const classifier = new TypeSafeClassifier();

const response = await classifier.invoke({
  state:
    "The deploy failed twice and customers are seeing 500s. Can someone look now?",
  questions: {
    urgent: {
      type: "noul",
      instructions: "Does this need attention right now?",
    },
    team: {
      type: "choice",
      instructions: "Which team should pick this up?",
      criteria: {
        infra: "Deploys, availability, and on-call incidents.",
        billing: "Payments, invoices, and subscriptions.",
      },
    },
    severity: {
      type: "score",
      instructions: "How severe is the impact?",
      criteria: ["Cosmetic.", "Degraded for some users.", "Full outage."],
    },
  },
});

console.log(response.nouls.urgent.noul);
console.log(response.choices.team.choice, response.choices.team.confidence);
console.log(response.scores.severity.score);