nonara · nonara · May 1, 2026 · Apr 28, 2026 · Apr 28, 2026 · Apr 28, 2026
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
@@ -14,20 +14,19 @@ jobs:
 
     strategy:
       matrix:
-        # NOTE - 21+ is failing due to odd bug - maybe bug in node - see https://github.com/nonara/ts-patch/issues/153
-        node-version: [ 18.x, 20.x ]
+        node-version: [ 22.x, 24.x ]
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v6
 
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v2
+        uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node-version }}
 
       - name: Cache dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v5
         with:
           path: |
             ~/.cache/yarn

diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
@@ -12,12 +12,12 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v6
 
       - name: Setup Node.js to publish to npmjs.org
-        uses: actions/setup-node@v2
+        uses: actions/setup-node@v6
         with:
-          node-version: '20.x'
+          node-version: '24.x'
           registry-url: 'https://registry.npmjs.org'
 
       - name: Install Packages

diff --git a/.gitignore b/.gitignore
@@ -26,8 +26,12 @@ generated/
 .env
 .vscode
 .idea/jsLibraryMappings.xml
+.idea/copilot.*.xml
 todo/
 TODO.ts
+.agents/
+.claude/
+/.codex
 
 # Junk
 temp/

diff --git a/README.md b/README.md
@@ -8,12 +8,15 @@ Patch typescript to allow custom transformers (plugins) during build.
 
 Plugins are specified in `tsconfig.json`, or provided programmatically in `CompilerOptions`.
 
+> [!IMPORTANT]
+> ts-patch v4 supports TypeScript 6 and later only. For TypeScript 5 projects, use ts-patch v3.
+
 _Migrating from ttypescript is easy! See: [Method 1: Live Compiler](#method-1-live-compiler)_
 
 ## Features
 
-* Patch typescript installation via on-the-fly, in-memory patching _or_ as a persistent patch
-* Can patch individual libraries (see `ts-patch /?`)
+* Patch typescript via on-the-fly, in-memory compiler routes _or_ persistent patches for supported files
+* Can patch supported compiler libraries (see `ts-patch /?`)
 * Hook build process by transforming the `Program` (see: [Transforming Program](#transforming-program))
 * Add, remove, or modify diagnostics (see: [Altering Diagnostics](#altering-diagnostics))
 * Fully compatible with legacy [ttypescript](https://github.com/cevek/ttypescript) projects
@@ -48,6 +51,7 @@ _Migrating from ttypescript is easy! See: [Method 1: Live Compiler](#method-1-li
     * [Recommended Tools](#recommended-tools)
     * [Discussion](#discussion)
 * [Advanced Options](#advanced-options)
+* [Compatibility Direction](#compatibility-direction)
 * [Maintainers](#maintainers)
   * [Help Wanted](#help-wanted)
 * [License](#license)
@@ -70,29 +74,42 @@ The live compiler patches on-the-fly, each time it is run.
 
 **With tools such as ts-node, webpack, ts-jest, etc:** specify the compiler as  `ts-patch/compiler`
 
+Additional live routes are available for tools that need a specific TypeScript entry:
+
+| Route | Library identity supplied to transformers |
+|-------|-------------------------------------------|
+| `ts-patch/compiler` | `typescript` |
+| `ts-patch/compiler/typescript` | `typescript` |
+| `ts-patch/compiler/tsc` | `tsc` |
+| `ts-patch/compiler/tsserver` | `tsserver` |
+| `ts-patch/compiler/tsserverlibrary` | `tsserverlibrary` |
+
 ## Method 2: Persistent Patch
 
-Persistent patch modifies the typescript installation within the node_modules path. It requires additional configuration
-to remain persisted, but it carries less load time and complexity compared to the live compiler.
+Persistent patching modifies supported TypeScript files inside `node_modules`. It is still available for TypeScript 6,
+but the patchable surface is narrower than it was in earlier TypeScript versions.
+
+TypeScript 6 ships thin entry shims for several library files. Some service entries delegate to shared implementation
+files; for example, `tsserverlibrary.js` delegates to `typescript.js`. Rewriting those service files in place would not
+preserve enough entry context to distinguish direct compiler API use from `tsc`, `tsserver`, or `tsserverlibrary` use.
+For those entries, use the live compiler routes instead.
 
-1. Install the patch
+`install` and `uninstall` remain available, but they now affect only `typescript.js` and `tsc.js`:
 
 ```shell
-# For advanced options, see: ts-patch /?
 ts-patch install
+ts-patch uninstall
 ```
 
-2. Add `prepare` script (keeps patch persisted after npm install)
+The lower-level `patch` and `unpatch` commands are also limited to those two targets:
 
-`package.json`
- ```jsonc
-{
-  /* ... */
-  "scripts": {
-    "prepare": "ts-patch install -s"
-  }
-}
- ```
+```shell
+ts-patch patch typescript tsc
+ts-patch unpatch typescript tsc
+```
+
+`tsserver.js` and `tsserverlibrary.js` are not persistent patch targets on TypeScript 6. Use the live routes above so
+transformers still receive the correct library identity for those service entries.
 
 # Configuration
 
@@ -107,7 +124,7 @@ ts-patch install
             { "transform": "transformer-module" },
             { "transform": "transformer2", "extraOption": 123 },
             { "transform": "trans-with-mapping", "resolvePathAliases": true },
-            { "transform": "esm-transformer", "isEsm": true },
+            { "transform": "esm-transformer.mjs" },
 
             // Program Transformer
             { "transform": "transformer-module5", "transformProgram": true }
@@ -124,7 +141,6 @@ ts-patch install
 | after              | boolean | Apply transformer after stock TS transformers                                                                 |
 | afterDeclarations  | boolean | Apply transformer to declaration (*.d.ts) files                                                               |
 | transformProgram   | boolean | Transform `Program` during `ts.createProgram()` _(see: [Program Transformers](#program-transformers))_        |
-| isEsm              | boolean | Transformer is ES Module (_note: experimental_ — requires [esm](https://www.npmjs.com/package/esm))           |
 | resolvePathAliases | boolean | Resolve path aliases in transformer (requires [tsconfig-paths](https://www.npmjs.com/package/tsconfig-paths)) |
 | type               | string  | See: [Source Transformer Entry Point](#source-transformer-entry-point) (default: 'program')                   |
 | import             | string  | Name of exported transformer function _(defaults to `default` export)_                                        |
@@ -133,6 +149,8 @@ ts-patch install
 
 _Note: Required options are bold_
 
+_As of v4, `isEsm` has been removed. Transformer module format is inferred from the file extension and package metadata._
+
 # Writing Transformers
 
 For an overview of the typescript compiler (such as what a `SourceFile` and `Program` is) see: [Typescript Compiler Notes](https://github.com/microsoft/TypeScript-Compiler-Notes).
@@ -329,6 +347,19 @@ Override patch cache directory
 
 Cleans patch cache & lockfiles
 
+# Compatibility Direction
+
+TypeScript 6 changed the compiler distribution shape by introducing thin CommonJS shims around several implementation
+files. ts-patch uses live routing where entry identity matters because a live route can preserve whether a tool requested
+`typescript`, `tsc`, `tsserver`, or `tsserverlibrary` without permanently rewriting service-entry shims.
+
+For TypeScript 6, persistent patching is intentionally narrow: only `typescript.js` and `tsc.js` are patchable targets.
+Service entries should be loaded through `ts-patch/compiler/tsserver` or `ts-patch/compiler/tsserverlibrary`.
+
+The TypeScript team has also announced a future Go-based compiler line. ts-patch will evaluate that implementation as a
+separate compatibility track, including whether the JavaScript compiler API and transformer hooks remain available or
+whether a redesigned integration is required.
+
 # Maintainers
 
 <!-- prettier-ignore-start -->

diff --git a/jest.config.ts → jest.config.js b/jest.config.ts → jest.config.js
@@ -1,16 +1,16 @@
-import type { Config } from '@jest/types';
-import * as os from 'os';
+const os = require('os');
 
-const config: Config.InitialOptions = {
-  testEnvironment: "node",
+/** @type {import('@jest/types').Config.InitialOptions} */
+const config = {
+  testEnvironment: 'node',
   preset: 'ts-jest',
   roots: [ '<rootDir>/test/tests' ],
   testRegex: '.*(test|spec)\\.tsx?$',
-  moduleFileExtensions: [ 'ts', 'tsx', 'js', 'jsx', 'json', 'node' ],
+  moduleFileExtensions: [ 'ts', 'tsx', 'mts', 'cts', 'js', 'jsx', 'mjs', 'cjs', 'json', 'node' ],
   transform: {
     '^.+\\.(ts|tsx)$': ['ts-jest', { tsconfig: './test/tsconfig.json' }],
   },
-  modulePaths: [ "<rootDir>/node_modules" ],
+  modulePaths: [ '<rootDir>/node_modules' ],
   // coveragePathIgnorePatterns: [
   //   'src/installer/lib/system/errors.ts$'
   // ],
@@ -21,6 +21,6 @@ const config: Config.InitialOptions = {
     '/node_modules/(?!(ts-transformer-keys|ts-transformer-enumerate|ts-nameof)/)'
   ],
   maxConcurrency: os.cpus().length
-}
+};
 
-export default config;
+module.exports = config;
diff --git a/package.json b/package.json
@@ -4,6 +4,18 @@
   "description": "Patch typescript to support custom transformers in tsconfig.json",
   "main": "./dist/index.js",
   "types": "./dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
+    },
+    "./compiler": "./dist/compiler/typescript.js",
+    "./compiler/typescript": "./dist/compiler/typescript.js",
+    "./compiler/tsc": "./dist/compiler/tsc.js",
+    "./compiler/tsserver": "./dist/compiler/tsserver.js",
+    "./compiler/tsserverlibrary": "./dist/compiler/tsserverlibrary.js",
+    "./package.json": "./package.json"
+  },
   "scripts": {
     "compile": "yarn run compile:core && yarn run compile:patch",
     "build": "yarn run clean && yarn run compile:patch && yarn run compile:core",
@@ -47,35 +59,36 @@
     "chalk": "^4.1.2",
     "global-prefix": "^4.0.0",
     "minimist": "^1.2.8",
-    "resolve": "^1.22.2",
-    "semver": "^7.6.3",
+    "resolve": "^1.22.12",
+    "semver": "^7.7.4",
     "strip-ansi": "^6.0.1"
   },
   "bin": {
     "ts-patch": "./dist/bin/ts-patch.js",
     "tspc": "./dist/bin/tspc.js"
   },
+  "engines": {
+    "node": ">=22.15.0"
+  },
   "devDependencies": {
-    "@types/esm": "^3.2.2",
-    "@types/jest": "^29.5.10",
+    "@types/jest": "^30.0.0",
     "@types/minimist": "^1.2.2",
     "@types/mock-fs": "^4.13.1",
-    "@types/node": "^16.11.5",
+    "@types/node": "^25.6.0",
     "@types/resolve": "^1.20.1",
-    "@types/semver": "^7.3.13",
-    "@types/shelljs": "^0.8.9",
-    "esm": "^3.2.25",
-    "jest": "^29.7.0",
-    "rimraf": "^5.0.7",
-    "shelljs": "^0.8.5",
+    "@types/semver": "^7.7.1",
+    "@types/shelljs": "^0.10.0",
+    "jest": "^30.3.0",
+    "rimraf": "^6.1.3",
+    "shelljs": "^0.10.0",
     "standard-version": "^9.5.0",
-    "ts-jest": "^29.1.1",
+    "ts-expose-internals": "npm:[email protected]",
+    "ts-jest": "^29.4.9",
+    "ts-next": "npm:[email protected]",
     "ts-node": "^10.9.1",
     "ts-patch": "^3.3.0",
     "tsconfig-paths": "^4.2.0",
-    "typescript": "5.7.2",
-    "ts-next": "npm:typescript@beta",
-    "ts-expose-internals": "npm:[email protected]"
+    "typescript": "6.0.3"
   },
   "workspaces": {
     "packages": [

diff --git a/projects/core/resolver-hook.js b/projects/core/resolver-hook.js
diff --git a/projects/core/shared/plugin-types.ts b/projects/core/shared/plugin-types.ts
@@ -37,11 +37,6 @@ export interface PluginConfig {
    */
   import?: string;
 
-  /**
-   * Is the transformer an ES Module
-   */
-  isEsm?: boolean
-
   /**
    * Plugin entry point format type, default is program
    */

diff --git a/projects/core/src/actions/check.ts b/projects/core/src/actions/check.ts
@@ -1,8 +1,8 @@
-import { LogLevel, PatchError } from '../system';
+import { assertSupportedTypeScript, LogLevel, PatchError } from '../system';
 import chalk from 'chalk';
 import { getTsPackage } from '../ts-package';
 import { PatchDetail } from "../patch/patch-detail";
-import { getTsModule } from "../module";
+import { getTsModule, TsModule } from "../module";
 import { getInstallerOptions, InstallerOptions } from "../options";
 
 
@@ -33,10 +33,12 @@ export function check(moduleNameOrNames?: string | string[], opts?: Partial<Inst
 
   /* Load Package */
   const tsPackage = getTsPackage(dir);
+  assertSupportedTypeScript(tsPackage);
   const { packageDir, version } = tsPackage;
 
-
-  targetModuleNames ??= tsPackage.moduleNames;
+  targetModuleNames = targetModuleNames
+    ? targetModuleNames.map(name => TsModule.normalizePatchableName(name))
+    : tsPackage.moduleNames.filter(name => (TsModule.patchableNames as readonly string[]).includes(name));
 
   /* Check Modules */
   log(`Checking TypeScript ${chalk.blueBright(`v${version}`)} installation in ${chalk.blueBright(packageDir)}\r\n`);
@@ -45,7 +47,7 @@ export function check(moduleNameOrNames?: string | string[], opts?: Partial<Inst
   for (const moduleName of targetModuleNames) {
     /* Validate */
     if (!tsPackage.moduleNames.includes(moduleName))
-      throw new PatchError(`${moduleName} is not a valid TypeScript module in ${packageDir}`);
+      throw new PatchError(`${moduleName} is not present in ${packageDir}`);
 
     /* Report */
     const tsModule = getTsModule(tsPackage, moduleName, { skipCache: options.skipCache });