feat(electron): add persistent UI scale setting

apps/desktop/main/ipc/window.ts

@@ -4,7 +4,8 @@
 
 import { ipcMain, app, dialog, clipboard, shell, nativeTheme } from 'electron'
 import * as fs from 'fs/promises'
-import { loadConfig, setConfigField } from '@openchatlab/config'
+import { desktopConfigSchema, loadConfig, setConfigField } from '@openchatlab/config'
+import { appLogger } from '@openchatlab/node-runtime'
 import type { DesktopCloseBehavior } from '@openchatlab/shared-types'
 import type { IpcContext } from './types'
 import { simulateUpdateDialog, manualCheckForUpdates } from '../update/manager'
@@ -224,6 +225,26 @@ export function registerWindowHandlers(ctx: IpcContext): void {
     }
   })
 
+  // ==================== Desktop UI scale ====================
+  ipcMain.handle('app:getDesktopUiScale', () => loadConfig().desktop.ui_scale)
+
+  ipcMain.handle('app:setDesktopUiScale', (_, scale: number) => {
+    const parsed = desktopConfigSchema.shape.ui_scale.safeParse(scale)
+    if (typeof scale !== 'number' || !parsed.success) {
+      return { success: false, error: 'Unsupported desktop UI scale' }
+    }
+
+    try {
+      setConfigField('desktop.ui_scale', String(parsed.data))
+      win.webContents.setZoomFactor(parsed.data)
+      appLogger.info('window', `Desktop UI scale changed to ${parsed.data}`)
+      return { success: true }
+    } catch (error) {
+      appLogger.error('window', 'Failed to change desktop UI scale', error)
+      return { success: false, error: error instanceof Error ? error.message : String(error) }
+    }
+  })
+
   // ==================== Windows 关闭行为 ====================
   ipcMain.handle('app:getDesktopCloseBehavior', () => {
     return loadConfig().desktop.close_behavior

apps/desktop/main/window/main-window.ts

@@ -28,6 +28,7 @@ export async function createMainWindow(paths: MainWindowPaths): Promise<BrowserW
       preload: paths.preloadPath,
       sandbox: false,
       devTools: true,
+      zoomFactor: loadConfig().desktop.ui_scale,
     },
   }
 
@@ -100,6 +101,8 @@ function handleWindowsClose(win: BrowserWindow): void {
 
 function registerMainWindowEvents(win: BrowserWindow): void {
   win.webContents.on('did-finish-load', () => {
+    // Reapply the preference after navigation, overriding Chromium's per-origin zoom cache.
+    win.webContents.setZoomFactor(loadConfig().desktop.ui_scale)
     setTimeout(() => {
       currentMainWindow?.webContents.send('app-started')
     }, 500)

apps/desktop/preload/apis/core.ts

@@ -123,5 +123,9 @@ export const extendedApi = {
     setDesktopCloseBehavior: (behavior: DesktopCloseBehavior): Promise<{ success: boolean; error?: string }> => {
       return ipcRenderer.invoke('app:setDesktopCloseBehavior', behavior)
     },
+    getDesktopUiScale: (): Promise<number> => ipcRenderer.invoke('app:getDesktopUiScale'),
+    setDesktopUiScale: (scale: number): Promise<{ success: boolean; error?: string }> => {
+      return ipcRenderer.invoke('app:setDesktopUiScale', scale)
+    },
   },
 }

apps/desktop/preload/index.d.ts

@@ -194,6 +194,8 @@ interface Api {
     setOpenAtLogin: (enabled: boolean) => Promise<{ success: boolean; error?: string }>
     getDesktopCloseBehavior: () => Promise<DesktopCloseBehavior>
     setDesktopCloseBehavior: (behavior: DesktopCloseBehavior) => Promise<{ success: boolean; error?: string }>
+    getDesktopUiScale: () => Promise<number>
+    setDesktopUiScale: (scale: number) => Promise<{ success: boolean; error?: string }>
   }
 }