fix: 修复微信重装后 openMessageCursor 返回 -3 (no message db) 的问题

- 新增 forceReopen() 方法：清空路径缓存后强制重新初始化账号连接
- openMessageCursor 在 result=-3 时自动触发 forceReopen 并重试一次
- 改善 -3 错误的提示文案，引导用户重新指定数据目录

修复 #591

electron/services/wcdbCore.ts

@@ -2596,13 +2596,34 @@ export class WcdbCore {
     }
   }
 
+  /**
+   * 强制重新打开账号连接（绕过路径缓存），用于微信重装后消息数据库刷新失败时的自动恢复。
+   * 返回重新打开是否成功。
+   */
+  private async forceReopen(): Promise<boolean> {
+    if (!this.currentPath || !this.currentKey || !this.currentWxid) return false
+    const path = this.currentPath
+    const key = this.currentKey
+    const wxid = this.currentWxid
+    this.writeLog('forceReopen: clearing cached handle and reopening...', true)
+    // 清空缓存状态，让 open() 真正重新打开
+    try { this.wcdbShutdown() } catch { }
+    this.handle = null
+    this.currentPath = null
+    this.currentKey = null
+    this.currentWxid = null
+    this.currentDbStoragePath = null
+    this.initialized = false
+    return this.open(path, key, wxid)
+  }
+
   async openMessageCursor(sessionId: string, batchSize: number, ascending: boolean, beginTimestamp: number, endTimestamp: number): Promise<{ success: boolean; cursor?: number; error?: string }> {
     if (!this.ensureReady()) {
       return { success: false, error: 'WCDB 未连接' }
     }
     try {
       const outCursor = [0]
-      const result = this.wcdbOpenMessageCursor(
+      let result = this.wcdbOpenMessageCursor(
         this.handle,
         sessionId,
         batchSize,
@@ -2611,13 +2632,37 @@ export class WcdbCore {
         endTimestamp,
         outCursor
       )
+      // result=-3 表示 WCDB_STATUS_NO_MESSAGE_DB：消息数据库缓存为空（常见于微信重装后）
+      // 自动强制重连并重试一次
+      if (result === -3 && outCursor[0] <= 0) {
+        this.writeLog('openMessageCursor: result=-3 (no message db), attempting forceReopen...', true)
+        const reopened = await this.forceReopen()
+        if (reopened && this.handle !== null) {
+          outCursor[0] = 0
+          result = this.wcdbOpenMessageCursor(
+            this.handle,
+            sessionId,
+            batchSize,
+            ascending ? 1 : 0,
+            beginTimestamp,
+            endTimestamp,
+            outCursor
+          )
+          this.writeLog(`openMessageCursor retry after forceReopen: result=${result} cursor=${outCursor[0]}`, true)
+        } else {
+          this.writeLog('openMessageCursor forceReopen failed, giving up', true)
+        }
+      }
       if (result !== 0 || outCursor[0] <= 0) {
         await this.printLogs(true)
         this.writeLog(
           `openMessageCursor failed: sessionId=${sessionId} batchSize=${batchSize} ascending=${ascending ? 1 : 0} begin=${beginTimestamp} end=${endTimestamp} result=${result} cursor=${outCursor[0]}`,
           true
         )
-        return { success: false, error: `创建游标失败: ${result}，请查看日志` }
+        const hint = result === -3
+          ? `创建游标失败: ${result}（消息数据库未找到）。如果你最近重装过微信，请尝试重新指定数据目录后重试`
+          : `创建游标失败: ${result}，请查看日志`
+        return { success: false, error: hint }
       }
       return { success: true, cursor: outCursor[0] }
     } catch (e) {