TypeScript language support for .gtsx generator components: hover types, completion, diagnostics, definitions, references, and rename. JSX expressions retain the component's yield, return, and next types.

// example.gtsx
function* Test() {
  yield 123;
  return <p>Hello</p>;
}

const Result = <Test />;
// JSX.GeneratorElement<number, JSX.GeneratorElement<never, never, never>, unknown>

TypeScript infers unknown for this generator's next parameter. An explicit Generator<Yield, Return, Next> annotation preserves all three parameters, including never when requested. The mapper also preserves yielded Effect v4 types; the mapper guide documents the runtime and Effect examples.

Install and enable #

Requires VS Code 1.126 or later and the TypeScript Native Preview extension (TypeScriptTeam.native-preview) plus TypeScript 7 Nightly (TypeScriptTeam.vscode-typescript-nightly). GTSX declares both as extension dependencies. Native Preview 1.0.1 bundles TypeScript 7.0.2, which does not support content mappers; Nightly supplies the required 7.1 compiler. The API is experimental, and the compiler integration tests pin 7.1.0-dev.20261002.1. Update Native Preview if GTSX reports an unsupported API.

Install GTSX from the Visual Studio Marketplace, or use the extension's ID with the VS Code CLI:

code --install-extension CauseEffect.causeeffect-gtsx

Install and enable both TypeScript extensions above. For packaging GTSX from source, see the contributor guide.

Trust the workspace, open a .gtsx file, and run GTSX: Enable TypeScript Native Language Support from the Command Palette. The command enables these settings in the current workspace, or in user settings when no workspace is open, then restarts Native Preview so it picks up Nightly:

{
  "js/ts.experimental.useTsgo": true,
  "js/ts.contentMappers.enabled": true
}

Activation itself leaves settings unchanged. Untrusted workspaces get syntax highlighting; starting mapper processes requires workspace trust and enabled content mappers. Virtual workspaces are unsupported. The GTSX output channel reports the selected mapper and startup failures.

If hover and other language actions are missing, check the TypeScript 7 output channel. An unknown method 'custom/setContentMapperContributions' error means the selected compiler is too old. Install TypeScript 7 Nightly and run the GTSX enable command again. Explicit js/ts.tsdk.path settings and selected workspace SDKs take precedence over Nightly; they must also point to TypeScript 7.1 or later. Use TypeScript: Select TypeScript Version from a .ts file to select Use TypeScript 7, or configure the project's 7.1 SDK. The GTSX extension keeps explicit SDK settings intact.

Projects and loose files #

Projects with tsconfig.json install and configure their own mapper from npm:

npm install @causeeffect/jsx-content-mapper

{
  "compilerOptions": {
    "target": "es2022",
    "module": "esnext",
    "moduleResolution": "bundler",
    "strict": true
  },
  "contentMappers": [
    {
      "package": "@causeeffect/jsx-content-mapper",
      "extensions": [".gtsx"]
    }
  ],
  "include": ["src"]
}

The extension registers the file extension with the native language service; configured projects use their own package and mapper options. Use the same options in the build tool; language support does not emit application JavaScript. The mapper setup guide covers installing the CLI compiler and runtime, and the Foldkit JSX guide covers Foldkit's classic factory configuration.

Loose files work without installing the mapper. For one local workspace folder, the extension prefers a valid installed @causeeffect/jsx-content-mapper and falls back to its bundled copy. With no folder or multiple folders, it uses the bundled copy. TypeScript allows one inferred mapper registration per extension across the window, so multiple workspace folders share this fallback. Their configured projects can still use different installed mapper versions.

Set gtsx.inferredProjectOptions to customize loose files:

{
  "gtsx.inferredProjectOptions": {
    "jsxRuntime": "classic",
    "jsxFactory": "jsx.createElement",
    "jsxFragmentFactory": "jsx.Fragment"
  }
}

The default is generator mode with the selected mapper's runtime. To use a future framework runtime, set runtimeModule instead. In a configured project, put these options on the contentMappers entry in tsconfig.json. Run GTSX: Refresh Language Support after installing or rebuilding a workspace mapper; changing inferred options or workspace folders refreshes automatically.

The VSIX bundles the extension, mapper process, runtime declarations, and dependency license notices. Loose files do not need a separate Node installation. Workspace-installed mappers in configured projects require Node.js ^22.18.0 || >=24.11.0.

Integration #

The extension calls the native provider's registerContentMappers API using its current inferredProjectContribution manifest. The native language service handles LSP transport, project discovery, and mapped positions through the implementation introduced in typescript-go#4712. The existing mapper uses Babel and ts-content-mapper; syntax highlighting reuses VS Code's TypeScript React grammar.