test(startup): cover window initialization lifecycle

Extract the startup window boundary so hidden creation, ready-to-show ordering, single display, and load rejection handling are verified without Electron UI timing.

lib/startup-renderer.js

@@ -2,4 +2,18 @@ function configureStartupRenderer(app) {
   app.disableHardwareAcceleration();
 }
 
-module.exports = { configureStartupRenderer };
+function createStartupWindow(BrowserWindow, options) {
+  const window = new BrowserWindow({ ...options, show: false });
+  window.once('ready-to-show', () => {
+    window.show();
+  });
+
+  return {
+    window,
+    load(target, onLoadError) {
+      return window.loadFile(target).catch(onLoadError);
+    }
+  };
+}
+
+module.exports = { configureStartupRenderer, createStartupWindow };

main.js

@@ -1,7 +1,7 @@
 process.env.UV_THREADPOOL_SIZE = process.env.UV_THREADPOOL_SIZE || '8';
 const { monitorEventLoopDelay, PerformanceObserver } = require('perf_hooks');
 const { app, BrowserWindow, ipcMain, dialog, clipboard, nativeTheme, Tray, Menu, nativeImage } = require('electron');
-const { configureStartupRenderer } = require('./lib/startup-renderer');
+const { configureStartupRenderer, createStartupWindow } = require('./lib/startup-renderer');
 configureStartupRenderer(app);
 nativeTheme.themeSource = 'dark';
 const path = require('path');
@@ -1222,13 +1222,12 @@ async function runHosterHealthCheck(config, requestedChecks) {
 }
 
 function createWindow() {
-  mainWindow = new BrowserWindow({
+  const startupWindow = createStartupWindow(BrowserWindow, {
     width: 1100,
     height: 750,
     minWidth: 800,
     minHeight: 550,
     backgroundColor: '#16181c',
-    show: false,
     autoHideMenuBar: true,
     webPreferences: {
       contextIsolation: true,
@@ -1236,11 +1235,9 @@ function createWindow() {
       preload: path.join(__dirname, 'preload.js')
     }
   });
+  mainWindow = startupWindow.window;
 
   mainWindow.webContents.setBackgroundThrottling(false);
-  mainWindow.once('ready-to-show', () => {
-    mainWindow.show();
-  });
 
   mainWindow.webContents.on('render-process-gone', (_event, details) => {
     _writeCrashLog('RENDER PROCESS GONE', new Error(details.reason || 'unknown'), details);
@@ -1286,7 +1283,7 @@ function createWindow() {
     debugLog(`CHILD PROCESS GONE: type=${details.type} reason=${details.reason} exitCode=${details.exitCode}`);
   });
 
-  mainWindow.loadFile(path.join(__dirname, 'renderer', 'index.html')).catch((err) => {
+  startupWindow.load(path.join(__dirname, 'renderer', 'index.html'), (err) => {
     _writeCrashLog('LOAD FILE FAILED', err);
     debugLog(`LOAD FILE FAILED: ${err && err.stack ? err.stack : err}`);
   });

tests/startup-renderer.test.js

@@ -1,9 +1,68 @@
 const test = require('node:test');
 const assert = require('node:assert/strict');
-const { configureStartupRenderer } = require('../lib/startup-renderer');
+const { EventEmitter } = require('node:events');
+const { configureStartupRenderer, createStartupWindow } = require('../lib/startup-renderer');
+
+class TestBrowserWindow extends EventEmitter {
+  constructor(options) {
+    super();
+    this.options = options;
+    this.showCalls = 0;
+    this.startupEvents = [];
+    this.loadError = new Error('renderer load failed');
+  }
+
+  once(eventName, listener) {
+    this.startupEvents.push(`listen:${eventName}`);
+    return super.once(eventName, listener);
+  }
+
+  show() {
+    this.showCalls++;
+  }
+
+  loadFile(target) {
+    this.startupEvents.push(`load:${target}`);
+    return Promise.reject(this.loadError);
+  }
+}
 
 test('configureStartupRenderer disables hardware acceleration', () => {
   let calls = 0;
   configureStartupRenderer({ disableHardwareAcceleration() { calls++; } });
   assert.equal(calls, 1);
 });
+
+test('createStartupWindow forces the main window to start hidden', () => {
+  const startup = createStartupWindow(TestBrowserWindow, { width: 1100, show: true });
+
+  assert.equal(startup.window.options.width, 1100);
+  assert.equal(startup.window.options.show, false);
+});
+
+test('startup load registers visibility before navigation and shows only once', async () => {
+  const startup = createStartupWindow(TestBrowserWindow, {});
+  const loading = startup.load('renderer/index.html', () => {});
+
+  assert.deepEqual(startup.window.startupEvents, [
+    'listen:ready-to-show',
+    'load:renderer/index.html'
+  ]);
+
+  startup.window.emit('ready-to-show');
+  startup.window.emit('ready-to-show');
+  await loading;
+
+  assert.equal(startup.window.showCalls, 1);
+});
+
+test('startup load forwards a rejected navigation to the error handler', async () => {
+  const startup = createStartupWindow(TestBrowserWindow, {});
+  let handledError;
+
+  await startup.load('renderer/index.html', (err) => {
+    handledError = err;
+  });
+
+  assert.equal(handledError, startup.window.loadError);
+});