Getting started¶

Prerequisites¶

Node.js >= 24 (development is pinned via volta).
Yarn Classic 1.22.22 (older-style lockfile workspace monorepo).
On Windows, a full Visual Studio toolchain with the Desktop development with C++ workload for native module rebuilds.

Install¶

corepack enable
corepack prepare yarn@1.22.22 --activate
yarn install --frozen-lockfile
yarn verify

Run the browser app (development target)¶

yarn watch

in one terminal, and in another:

yarn start

The frontend is served at http://localhost:3000. No native rebuild is needed per edit, which makes the browser target the fastest way to iterate.

Tip

The test workspace ships .theia/settings.json with recommend files.autoSave: "off", matching Notepad++'s "never auto-save" convention.

For running the app for other people - a LAN server, a TLS-terminated shared instance, or a Docker image - see the deployment guide. It opens with the caveat that Theia's browser backend offers no per-user isolation, which decides what you can safely deploy.

Run the desktop app (unpackaged)¶

yarn --cwd applications/electron start

This launches Electron directly against the built sources (lib/backend/electron-main.js).

Tests¶

yarn lint            # eslint across all workspaces
yarn test            # unit tests
yarn test:e2e        # puppeteer end-to-end suites

See Development for the full workflow.

Project layout¶

Path	Purpose
`applications/browser`	Browser/development application
`applications/electron`	Electron application and packaging config
`extensions/notepadia`	Product extension (all Notepad++-style behavior)
`docs`	This documentation site (MkDocs)
`e2e`	Puppeteer end-to-end suites
`.github/workflows`	CI, e2e, release, and docs workflows