plugin-vite: electron-forge start loads the renderer twice, as the first preload build sends a full-reload #4439

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Forge version

8.0.1 (same in 8.0.0-alpha.10)

Electron version

v44.5.1

Operating system

macOS 27.0.1

Last known working Forge version

No response

Expected behavior

electron-forge start loads the window's page once.

Actual behavior

It loads it twice. Whatever happens on the first load is lost; we hit it as a flaky UI check that acts on the page right after launch.

Steps to reproduce

npx create-electron-app@8.0.1 repro --template vite --typescript
cd repro

In src/main.ts, right after the BrowserWindow is created:

mainWindow.webContents.on('did-finish-load', () => console.log('did-finish-load'));

npm start

The terminal prints did-finish-load twice, in 3 runs out of 3.

Additional information

The preload's watch build sends reload-renderers from closeBundle on every build, the first one included (dist/subprocess-worker.js, target === 'preload'), and VitePlugin turns it into server.ws.send({ type: 'full-reload' }). On the first build Electron has not started yet, so no client is connected. Vite (8.3.3 here) keeps a full-reload that finds no client and sends it to the first client that connects (bufferedMessage in its createWebSocketServer), so the first page reloads right after it connects.

Not sending reload-renderers for the first build would fix it. Our workaround, a plugin in the renderer's Vite config:

{
  name: 'skip-forge-reload-before-first-page',
  configureServer(server) {
    let connected = false;
    server.ws.on('connection', () => {
      connected = true;
    });
    const send = server.ws.send.bind(server.ws) as (...args: unknown[]) => void;
    server.ws.send = (...args: unknown[]) => {
      if (connected || JSON.stringify(args[0]) !== '{"type":"full-reload"}') {
        send(...args);
      }
    };
  },
}