microsoft · jakebailey · Feb 5, 2026 · Feb 5, 2026 · Feb 5, 2026 · Feb 5, 2026
diff --git a/.github/ISSUE_TEMPLATE/02-behavior-difference.md b/.github/ISSUE_TEMPLATE/02-behavior-difference.md
@@ -1,6 +1,6 @@
 ---
 name: Behavior Difference
-about: tsgo produces different results than TypeScript 5.9
+about: tsgo produces different results than TypeScript 6.0
 title: ''
 labels: ''
 assignees: ''
@@ -11,6 +11,6 @@ assignees: ''
 
 <!-- Share a repository link or a code sample -->
 
-## Behavior with `typescript@5.9`
+## Behavior with `typescript@6.0`
 
 ## Behavior with `tsgo`
diff --git a/README.md b/README.md
@@ -27,11 +27,11 @@ This is still a work in progress and is not yet at full feature parity with Type
 
 | Feature | Status | Notes |
 |---------|--------|-------|
-| Program creation | done | Same files and module resolution as TS 5.9. Not all resolution modes supported yet. |
-| Parsing/scanning | done | Exact same syntax errors as TS 5.9 |
+| Program creation | done | Same files and module resolution as TS 6.0. Not all resolution modes supported yet. |
+| Parsing/scanning | done | Exact same syntax errors as TS 6.0 |
 | Commandline and `tsconfig.json` parsing | done | Done, though `tsconfig` errors may not be as helpful. |
-| Type resolution | done | Same types as TS 5.9. |
-| Type checking | done | Same errors, locations, and messages as TS 5.9. Types printback in errors may display differently. |
+| Type resolution | done | Same types as TS 6.0. |
+| Type checking | done | Same errors, locations, and messages as TS 6.0. Types printback in errors may display differently. |
 | JavaScript-specific inference and JSDoc | in progress | Mostly complete, but intentionally lacking some features. Declaration emit not complete. |
 | JSX | done | - |
 | Declaration emit | in progress | Most common features are in place, but some edge cases and feature flags are still unhandled. |
@@ -54,7 +54,7 @@ Definitions:
 Long-term, we expect that this repo and its contents will be merged into `microsoft/TypeScript`.
 As a result, the repo and issue tracker for typescript-go will eventually be closed, so treat discussions/issues accordingly.
 
-For a list of intentional changes with respect to TypeScript 5.9, see CHANGES.md.
+For a list of intentional changes with respect to TypeScript 6.0, see CHANGES.md.
 
 ## Contributing
 

diff --git a/_submodules/TypeScript b/_submodules/TypeScript
diff --git a/internal/bundled/embed_generated.go b/internal/bundled/embed_generated.go
diff --git a/internal/bundled/generate.go b/internal/bundled/generate.go
@@ -188,7 +188,7 @@ func readLibs() []lib {
 
 	var libs []lib
 	for _, libName := range libNames {
-		sources := []string{"header.d.ts", libName + ".d.ts"}
+		sources := []string{libName + ".d.ts"}
 		var target string
 		if path, ok := paths[libName]; ok {
 			target = path

diff --git a/internal/bundled/libs/lib.d.ts b/internal/bundled/libs/lib.d.ts
@@ -7,15 +7,13 @@ License at http://www.apache.org/licenses/LICENSE-2.0
 THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
 WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
-MERCHANTABLITY OR NON-INFRINGEMENT.
+MERCHANTABILITY OR NON-INFRINGEMENT.
 
 See the Apache Version 2.0 License for specific language governing permissions
 and limitations under the License.
 ***************************************************************************** */
 
 
-/// <reference no-default-lib="true"/>
-
 /// <reference lib="es5" />
 /// <reference lib="dom" />
 /// <reference lib="webworker.importscripts" />

diff --git a/internal/bundled/libs/lib.decorators.d.ts b/internal/bundled/libs/lib.decorators.d.ts
@@ -7,15 +7,13 @@ License at http://www.apache.org/licenses/LICENSE-2.0
 THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
 WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
-MERCHANTABLITY OR NON-INFRINGEMENT.
+MERCHANTABILITY OR NON-INFRINGEMENT.
 
 See the Apache Version 2.0 License for specific language governing permissions
 and limitations under the License.
 ***************************************************************************** */
 
 
-/// <reference no-default-lib="true"/>
-
 /**
  * The decorator context types provided to class element decorators.
  */

diff --git a/internal/bundled/libs/lib.decorators.legacy.d.ts b/internal/bundled/libs/lib.decorators.legacy.d.ts
@@ -7,15 +7,13 @@ License at http://www.apache.org/licenses/LICENSE-2.0
 THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
 WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
-MERCHANTABLITY OR NON-INFRINGEMENT.
+MERCHANTABILITY OR NON-INFRINGEMENT.
 
 See the Apache Version 2.0 License for specific language governing permissions
 and limitations under the License.
 ***************************************************************************** */
 
 
-/// <reference no-default-lib="true"/>
-
 declare type ClassDecorator = <TFunction extends Function>(target: TFunction) => TFunction | void;
 declare type PropertyDecorator = (target: Object, propertyKey: string | symbol) => void;
 declare type MethodDecorator = <T>(target: Object, propertyKey: string | symbol, descriptor: TypedPropertyDescriptor<T>) => TypedPropertyDescriptor<T> | void;

diff --git a/internal/bundled/libs/lib.dom.asynciterable.d.ts b/internal/bundled/libs/lib.dom.asynciterable.d.ts
@@ -7,35 +7,12 @@ License at http://www.apache.org/licenses/LICENSE-2.0
 THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
 WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
-MERCHANTABLITY OR NON-INFRINGEMENT.
+MERCHANTABILITY OR NON-INFRINGEMENT.
 
 See the Apache Version 2.0 License for specific language governing permissions
 and limitations under the License.
 ***************************************************************************** */
 
 
-/// <reference no-default-lib="true"/>
-
-/////////////////////////////
-/// Window Async Iterable APIs
-/////////////////////////////
-
-interface FileSystemDirectoryHandleAsyncIterator<T> extends AsyncIteratorObject<T, BuiltinIteratorReturn, unknown> {
-    [Symbol.asyncIterator](): FileSystemDirectoryHandleAsyncIterator<T>;
-}
-
-interface FileSystemDirectoryHandle {
-    [Symbol.asyncIterator](): FileSystemDirectoryHandleAsyncIterator<[string, FileSystemHandle]>;
-    entries(): FileSystemDirectoryHandleAsyncIterator<[string, FileSystemHandle]>;
-    keys(): FileSystemDirectoryHandleAsyncIterator<string>;
-    values(): FileSystemDirectoryHandleAsyncIterator<FileSystemHandle>;
-}
-
-interface ReadableStreamAsyncIterator<T> extends AsyncIteratorObject<T, BuiltinIteratorReturn, unknown> {
-    [Symbol.asyncIterator](): ReadableStreamAsyncIterator<T>;
-}
-
-interface ReadableStream<R = any> {
-    [Symbol.asyncIterator](options?: ReadableStreamIteratorOptions): ReadableStreamAsyncIterator<R>;
-    values(options?: ReadableStreamIteratorOptions): ReadableStreamAsyncIterator<R>;
-}
+// This file's contents are now included in the main types file.
+// The file has been left for backward compatibility.