fix(electron): fix data migration path mismatch after package extraction

The extraction of Electron code to apps/desktop/ changed the package name
from "ChatLab" to "@openchatlab/desktop", which caused app.getPath('userData')
to return a wrong path in dev mode. This made the migration system unable to
find existing databases, resulting in a fresh-app experience for upgrading users.

- Add productName "ChatLab" to desktop package.json to ensure correct userData path
- Add verifyDataPath() safety net: auto-correct config.toml when configured dir
  has no databases but old Electron path does

apps/desktop/main/index.ts

@@ -12,6 +12,7 @@ import {
   cleanupPendingDeleteDir,
   needsUnifiedDirMigration,
   migrateToUnifiedDirs,
+  verifyDataPath,
   getSystemDataDir,
   getAiDataDir,
 } from './paths'
@@ -96,6 +97,9 @@ class MainProcess {
       this.migrateToUnifiedDirsIfNeeded()
     }
 
+    // 验证数据路径是否正确（安全网：防止 config.toml 指向空目录）
+    verifyDataPath()
+
     // 确保应用目录存在
     ensureAppDirs()
 

apps/desktop/main/paths.ts

@@ -720,3 +720,33 @@ export function migrateToUnifiedDirs(): { success: boolean; error?: string } {
     return { success: false, error: errorMsg }
   }
 }
+
+/**
+ * Verify that the configured user_data_dir actually has database files.
+ * If the configured dir is empty but the old Electron path has databases,
+ * auto-correct config.toml to point to the old path.
+ *
+ * This acts as a safety net in case migration was skipped or config was overwritten.
+ */
+export function verifyDataPath(): void {
+  const currentDir = getUserDataDir()
+  const currentDbDir = path.join(currentDir, 'databases')
+  const hasCurrentDbs = fs.existsSync(currentDbDir) && fs.readdirSync(currentDbDir).some((f) => f.endsWith('.db'))
+
+  if (hasCurrentDbs) return
+
+  const oldDir = getElectronLegacyDataDir()
+  if (path.resolve(currentDir) === path.resolve(oldDir)) return
+
+  const oldDbDir = path.join(oldDir, 'databases')
+  if (!fs.existsSync(oldDbDir)) return
+
+  const hasOldDbs = fs.readdirSync(oldDbDir).some((f) => f.endsWith('.db'))
+  if (!hasOldDbs) return
+
+  console.warn(
+    `[Paths] Data path mismatch: configured dir ${currentDir} has no databases, but old path ${oldDir} does. Auto-correcting config.toml.`
+  )
+  writeConfigField('data', 'user_data_dir', oldDir)
+  _userDataDir = oldDir
+}

apps/desktop/package.json

@@ -1,6 +1,7 @@
 {
   "name": "@openchatlab/desktop",
   "version": "0.19.0",
+  "productName": "ChatLab",
   "private": true,
   "description": "ChatLab Desktop — Electron 桌面客户端",
   "main": "./out/main/index.js",