TypeChat

TypeChat is a library that makes it easy to build natural language interfaces using types.

Building natural language interfaces has traditionally been difficult. These apps often relied on complex decision trees to determine intent and collect the required inputs to take action. Large language models (LLMs) have made this easier by enabling us to take natural language input from a user and match to intent. This has introduced its own challenges including the need to constrain the model's reply for safety, structure responses from the model for further processing, and ensuring that the reply from the model is valid. Prompt engineering aims to solve these problems, but comes with a steep learning curve and increased fragility as the prompt increases in size.

TypeChat replaces prompt engineering with schema engineering.

Simply define types that represent the intents supported in your natural language application. That could be as simple as an interface for categorizing sentiment or more complex examples like types for a shopping cart or music application. For example, to add additional intents to a schema, a developer can add additional types into a discriminated union. To make schemas hierarchical, a developer can use a "meta-schema" to choose one or more sub-schemas based on user input.

After defining your types, TypeChat takes care of the rest by:

1. Constructing a prompt to the LLM using types.
2. Validating the LLM response conforms to the schema. If the validation fails, repair the non-conforming output through further language model interaction.
3. Summarizing succinctly (without use of a LLM) the instance and confirm that it aligns with user intent.

Types are all you need!

Getting Started

The TypeScript/JavaScript package requires Node.js 24.22.1 or newer. Development uses Node.js 24.22.1, pinned in .nvmrc, which includes the October 21, 2026 security fixes.

Install TypeChat for TypeScript/JavaScript:

npm install typechat

You can also work with TypeChat from source for:

• Python
• TypeScript
• C#/.NET

To see TypeChat in action, we recommend exploring the TypeChat example projects. You can try them on your local machine or in a GitHub Codespace.

To learn more about TypeChat, visit the documentation which includes more information on TypeChat and how to get started.

Project direction

GOALS.md defines what belongs in TypeChat, what does not, and what is still under consideration. It is the primary repository policy for product scope. Changes require explicit approval from the human project owner, @robgruen; community interest and AI recommendations do not change it. Read it before proposing a new direction. Ordinary in-scope maintenance follows the normal contribution process.

Repository automation experiment

We are experimenting with a gradual transition to a semi-automated repository. The initial agent-assisted workflow keeps humans in the loop, while our longer-term goal is to help community proposals progress from discussion to accepted, reviewed changes with less manual coordination. Read about the automation experiment and how to participate.

Status as of 2026-11-03 (UTC): The latest backlog assessment completed successfully after the control hardening merged through #491. It inventories 20 issues and 13 open PRs. The earlier saved draft inventories 21 open issues and 25 open pull requests at the assessment time, with plain-language next steps and project-direction classifications.

The latest run used 23 model calls and 148.42 of the main assessment's 400 AI credits. Detection used a separate 7.89 credits. Its 216 tool calls stayed within the allowed set; native diagnostics recorded one failure and no repeated requests. Verification remains partial: tests, CI definitions, and job logs were not checked. The earlier CI access restriction was not retested. Reports are not acceptance of work, GitHub Copilot code reviews, or merge approval.

The owner-approved discussion pilot has verified Issue draft generation, conversational /typechat reply delivery, and a duplicate-free reply retry after #498 merged. Manual response publication, Discussion replies, and Discussion acceptance still need live verification. /typechat draft remains preview-only, with exact-text response approval through /typechat publish. Owner-only /typechat accept and its no-op retry have also been verified on an Issue after #503 merged. Completion-only operational receipts were merged through #506; selected live checks verified Issue/Discussion input-needed draft receipts, invalid-command reporting, and controller-only no-op retries. Cancellation, uncertain-write recovery, acceptance-ready receipt wording, and direct-reply reuse remain unverified live. Receipts do not publish draft content or accept work. Generation keeps its 50-credit main budget and separately budgeted detection. Acceptance does not launch a coding agent or activate implementation spending.

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