ttsc

A typescript-go toolchain for compiler-powered plugins and type-safe execution.

Benchmarked against the legacy tsc + eslint/prettier path on real repositories; see the benchmark guide for per-project ratios.

• ttsc: build, check, and transform.
• ttsx: execute TypeScript with type checking.
  • native TypeScript-Go execution instead of transpile-only runners.
  • type checking that tsx does not provide.
• @ttsc/lint: replaces eslint and prettier.
  • lint violations as TS compile errors.
  • format autofixes via ttsc format.
• @ttsc/graph: a code map for coding agents, over MCP.
  • what calls what, and a change's blast radius, from the type checker.
• plugin support: compiler-powered libraries, such as typia.

Setup

Install

Install ttsc, @ttsc/lint, and the native TypeScript compiler:

npm install -D ttsc @ttsc/lint typescript@rc

Commands

Run TypeScript directly with ttsx (CLI command):

npx ttsx src/index.ts

Build, check, or watch the project with ttsc:

npx ttsc
npx ttsc --noEmit
npx ttsc --watch

Rewrite source files in place with the @ttsc/lint format rules:

npx ttsc format

Bundlers

Use @ttsc/unplugin when a bundler owns your build.

It runs ttsc plugins inside supported bundlers.

npm install -D ttsc @ttsc/lint typescript@rc
npm install -D @ttsc/unplugin

Minimal Vite setup:

// vite.config.ts
import ttsc from "@ttsc/unplugin/vite";
import { defineConfig } from "vite";

export default defineConfig({
  plugins: [ttsc()],
});

Supported bundlers:

• Vite
• Rollup
• Rolldown
• esbuild
• Webpack
• Rspack
• Next.js
• Farm
• Bun

See @ttsc/unplugin for full setup and adapter options.

React Native / Expo

React Native and Expo bundle with Metro, so the ttsc CLI and @ttsc/unplugin never run. @ttsc/metro is a Metro transformer that runs ttsc plugins on each TypeScript file, then hands the result to your existing Expo or React-Native Babel transformer.

npm install -D ttsc @ttsc/lint typescript@rc
npm install -D @ttsc/metro

Wrap your Metro config (CommonJS, the standard for metro.config.js):

// metro.config.js (Expo)
const { getDefaultConfig } = require("expo/metro-config");
const { withTtsc } = require("@ttsc/metro");

module.exports = withTtsc(getDefaultConfig(__dirname));

For bare React Native, wrap getDefaultConfig from @react-native/metro-config instead. See @ttsc/metro for options and the v1 caveats.

VS Code Extension

Install the VS Code extension for live TypeScript-Go editor features plus saved-state ttsc plugin diagnostics and actions.

Install it from the VS Code Marketplace by searching ttsc, or run:

npx @ttsc/vscode

Then turn on format-on-save in .vscode/settings.json:

"[typescript][typescriptreact]": {
  "editor.defaultFormatter": "samchon.ttsc",
  "editor.formatOnSave": true
}

Lint fixes stay off-save by default; opt in with "editor.codeActionsOnSave": { "source.fixAll.ttsc": "explicit" }.

See @ttsc/vscode for requirements and settings.

Coding Agents (MCP)

@ttsc/graph gives a coding agent a checker-resolved map of your project, over MCP.

It answers what relates to a symbol and what a change affects, straight from the type checker, so the agent stops grepping and re-reading files.

It also carries the project's full diagnostics: type errors, @ttsc/lint violations, and plugin findings. They are fused onto the graph, so an agent sees a change's reach over what is already broken before editing.

npm install -D ttsc @ttsc/graph typescript@rc

Point your agent's MCP client at it. For Claude Code:

{
  "mcpServers": {
    "ttsc-graph": {
      "command": "npx",
      "args": ["-y", "@ttsc/graph"]
    }
  }
}

On codegraph's own agent-cost benchmark, Claude agents answer reading zero files, cutting tokens by 77% to 86% and tool calls by 94% to 95%. See @ttsc/graph and the benchmark.

Your agent picks the tools up from the MCP handshake and uses them on its own. See Setup for the full walk-through.

Plugins

Plugins let libraries add compile-time checks, transforms, and type-driven code generation to normal ttsc and ttsx runs.

# compile
npx ttsc

# execute
npx ttsx src/index.ts

Transform Example

A transform uses TypeScript types to generate JavaScript before runtime.

import typia, { tags } from "typia";
import { v4 } from "uuid";

const matched: boolean = typia.is<IMember>({
  id: v4(),
  email: "samchon.github@gmail.com",
  age: 30,
});
console.log(matched); // true

interface IMember {
  id: string & tags.Format<"uuid">;
  email: string & tags.Format<"email">;
  age: number &
    tags.Type<"uint32"> &
    tags.ExclusiveMinimum<19> &
    tags.Maximum<100>;
}

The transform replaces typia.is<IMember>() with dedicated JavaScript checks at build time:

import typia from "typia";
import * as __typia_transform__isFormatEmail from "typia/lib/internal/_isFormatEmail";
import * as __typia_transform__isFormatUuid from "typia/lib/internal/_isFormatUuid";
import * as __typia_transform__isTypeUint32 from "typia/lib/internal/_isTypeUint32";
import { v4 } from "uuid";

const matched = (() => {
  const _io0 = (input) =>
    "string" === typeof input.id &&
    __typia_transform__isFormatUuid._isFormatUuid(input.id) &&
    "string" === typeof input.email &&
    __typia_transform__isFormatEmail._isFormatEmail(input.email) &&
    "number" === typeof input.age &&
    __typia_transform__isTypeUint32._isTypeUint32(input.age) &&
    19 < input.age &&
    input.age <= 100;
  return (input) => "object" === typeof input && null !== input && _io0(input);
})()({
  id: v4(),
  email: "samchon.github@gmail.com",
  age: 30,
});
console.log(matched); // true

Programmatic API

Embed ttsc from another Node tool with the TtscCompiler class:

import { TtscCompiler } from "ttsc";

const compiler = new TtscCompiler({ cwd: "./project" });
const result = compiler.compile();

if (result.type === "success") {
  for (const [path, text] of Object.entries(result.output)) {
    // path is project-relative ("dist/index.js", "dist/index.d.ts", ...)
    console.log(path, text.length);
  }
} else if (result.type === "failure") {
  for (const d of result.diagnostics) {
    console.error(`${d.file}:${d.line}:${d.character} ${d.messageText}`);
  }
}

When one process transforms a project's files repeatedly (a watch server, an editor, a codegen tool), TtscService keeps the compiler host warm instead of recompiling per call. It compiles the project once, then answers per-file transform requests, and reflects in-memory edits through updateFile:

import { TtscService } from "ttsc";

const service = new TtscService({ cwd: "./project" });
try {
  const code = await service.transformFile("src/index.ts");
  await service.updateFile("src/index.ts", "export const x: number = 2;\n");
  const next = await service.transformFile("src/index.ts");
} finally {
  service.dispose();
}

TtscService runs through the linked-plugin host, so the project must declare at least one transform-stage plugin.

See the Programmatic API guide for the full lifecycle, plugin overrides, and patterns. For browser embedding, see @ttsc/wasm and the higher-level @ttsc/playground package.

List of Plugins

ttsc ships a few small utility plugins in this repository.

• @ttsc/banner: adds @packageDocumentation JSDoc banners.
• @ttsc/lint: lints and formats TypeScript source.
• @ttsc/graph: MCP server exposing a checker-resolved code graph and diagnostics to coding agents.
• @ttsc/paths: rewrites source path aliases so JS and declaration emit receive relative imports.
• @ttsc/strip: removes configured calls and debugger statements.
• @ttsc/unplugin: runs ttsc plugins inside bundlers supported by unplugin.
• @ttsc/metro: runs ttsc plugins inside Metro for React Native and Expo.

Plugin authors should start from the Guide Documents.

Ecosystem plugins are listed below; PRs adding ttsc plugins are welcome.

• nestia: generates NestJS routes, OpenAPI, and SDKs.
• typia: generates validators, serializers, and type-driven runtime code.

Sponsors

Thanks for your support.

Your donation encourages ttsc development.

References

• TypeScript runners: ts-node and tsx
• Transformer tooling: ttypescript and ts-patch
• Inspired by: typical, tsgonest and codegraph.