feat(main): initialize updater, crash writer, and migration on app start

src/main/index.js

@@ -1,4 +1,10 @@
 const { app, BrowserWindow, Menu, dialog, ipcMain, shell } = require('electron');
+const { autoUpdater } = require('electron-updater');
+const { UpdaterService } = require('./updater/updater-service');
+const { CrashWriter } = require('./updater/crash-writer');
+const { MigrationRunner } = require('./updater/migration-runner');
+const updaterHandlers = require('./ipc/updater-handlers');
+const crashHandlers = require('./ipc/crash-handlers');
 const path = require('path');
 const fs = require('fs');
 const { exec, execFile, spawn } = require('child_process');
@@ -3066,6 +3072,37 @@ app.whenReady().then(() => {
   mainWindow = createMainWindow();
   mainWindow.on('closed', () => { mainWindow = null; });
 
+  // --- Updater, crash writer, migration (must run before any settings read) ---
+  const userData = app.getPath('userData');
+
+  // Migration
+  const migration = new MigrationRunner({
+    dir: userData,
+    transform: (v4) => {
+      const { migrateV4ToV5 } = require('./updater/migration-transform');
+      return migrateV4ToV5(v4);
+    },
+  });
+  migration.run();
+
+  // Crash writer
+  const crash = new CrashWriter(path.join(userData, 'crashDumps'));
+  process.on('uncaughtException', (err) => crash.handleUncaught(err, 'uncaughtException'));
+  process.on('unhandledRejection', (err) => crash.handleUncaught(err, 'unhandledRejection'));
+
+  // Updater
+  const updater = new UpdaterService(autoUpdater);
+  updaterHandlers.register({
+    updater,
+    getMainWindow: () => mainWindow,
+    getChannel: () => store.get('updateChannel') || 'github',
+  });
+  crashHandlers.register({
+    crash,
+    getMainWindow: () => mainWindow,
+  });
+  // --------------------------------------------------------------------
+
   // Register file ops IPC handlers
   fileOps.register({
     validatePath,

src/main/updater/migration-transform.js

@@ -0,0 +1,55 @@
+// Mirror of src/renderer/lib/migrations/v4-to-v5.ts, plain JS, for main-process use.
+// Kept in sync manually; if the renderer transform changes, update this too.
+const { z } = require('zod');
+
+const v4SettingsSchema = z.object({
+  theme: z.enum(['light', 'dark', 'auto']).default('auto'),
+  customCss: z.string().optional().nullable(),
+  recentFiles: z.array(z.string()).default([]),
+  editorFontSize: z.number().min(10).max(28).default(14),
+  keyBindings: z.record(z.string(), z.string()).optional(),
+  snippets: z.array(z.unknown()).default([]),
+}).passthrough();
+
+const v5SettingsShape = {
+  fontSize: 14,
+  tabSize: 4,
+  lineNumbers: true,
+  wordWrap: true,
+  minimap: true,
+  theme: 'system',
+  accentColor: 'brand',
+  fontFamily: 'system',
+  pdfFormat: 'a4',
+  pdfMargins: 'normal',
+  pdfEmbedFonts: true,
+  docxTemplate: 'standard',
+  docxCustomTemplatePath: null,
+  replOpen: false,
+  breadcrumbSymbols: true,
+  htmlHighlightStyle: 'github',
+  renderTablesAsAscii: false,
+  welcomeDismissed: false,
+  editorFontSize: 14,
+  customCssPath: null,
+  userBindings: {},
+  updateChannel: 'github',
+  autoCheckUpdates: true,
+  firstRun: true,
+};
+
+function migrateV4ToV5(v4) {
+  const parsed = v4SettingsSchema.parse(v4 || {});
+  return {
+    ...v5SettingsShape,
+    ...parsed,
+    theme: parsed.theme === 'auto' ? 'system' : parsed.theme,
+    customCssPath: parsed.customCss ?? null,
+    recentFiles: parsed.recentFiles,
+    editorFontSize: parsed.editorFontSize,
+    userBindings: parsed.keyBindings ?? v5SettingsShape.userBindings,
+    snippets: parsed.snippets,
+  };
+}
+
+module.exports = { migrateV4ToV5, v5SettingsShape };