Execlens

Execlens is an IDE function execution simulator. The goal is to let a developer place the cursor on a function, inspect generated inputs, run the function in a controlled runtime, and read the result directly from the editor.

The project is designed to grow through adapters: new languages, IDEs, runtimes, and UI surfaces should plug into stable contracts instead of changing the core.

Status

This repository is still early. The current implementation focuses on:

• VS Code as the first IDE adapter
• TypeScript/JavaScript as the first language adapter
• Node.js as the first runtime adapter
• a webview-based simulator UI

Packages

packages/
  protocol/                    shared contracts and ports
  core/                        stack-independent use cases
  adapters/
    ide/vscode/                VS Code composition root
    language/tsjs/             TypeScript/JavaScript analysis
    runtime/node/              Node.js execution
  ui/                          simulator webview rendering

Architecture

Execlens follows a hexagonal architecture.

• protocol defines shared contracts.
• core orchestrates use cases and depends only on protocol.
• language adapters analyze code.
• runtime adapters execute code.
• IDE adapters wire concrete adapters together.
• UI renders simulator input/output.

Read:

• Architecture
• Protocol
• Adding adapters
• Testing
• Contributing

Getting Started

pnpm install
pnpm build

Development

Run the VS Code extension in development mode:

pnpm dev:vscode

Then start the Run Execlens Extension debug configuration from VS Code.

In the Extension Development Host:

1. Open playground/languages/tsjs.
2. Open a file under src.
3. Place the cursor inside a supported function.
4. Run Execlens: Open Simulator from the editor context menu.

Tests

pnpm test

Runs the full Vitest suite.

pnpm test:unit
pnpm test:playground
pnpm test:ui

Run focused subsets.

pnpm test:coverage
pnpm quality

Run coverage and full quality checks.

Electron-based VS Code end-to-end tests are intentionally not enabled yet. The VS Code adapter is currently covered with mocked vscode APIs, and the shared TS/JS behavior is covered through playground analysis/runtime tests.

Playground

Shared language playgrounds live under:

playground/languages/<language-id>

The current TS/JS playground is:

playground/languages/tsjs

These scenarios are IDE-neutral. Future IDE adapters should reuse the same language playgrounds instead of duplicating code scenarios per IDE.

Contributing

Before opening a pull request:

pnpm quality

If you change behavior or tests:

pnpm test:coverage

See CONTRIBUTING.md for adapter boundaries, test layout, and pull request guidance.

Security

Execlens executes code from the workspace you open it in. Only run it on code you trust. See SECURITY.md for the trust model and how to report a vulnerability.

License

MIT © decazed and Execlens contributors.