fix(auth): return to guest session on logout

src/data/repositories/auth_repository.ts

@@ -116,6 +116,46 @@ export class AuthRepository implements IAuthRepository {
     }
   }
 
+  /**
+   * 退出真实用户登录并恢复游客态。
+   *
+   * 与 `logout()` 不同，这里不会删除 guestToken / deviceId。退出后会尝试
+   * 重新跑游客登录，以便恢复游客 userId；如果游客登录接口失败但本地仍有
+   * guestToken，则降级回本地游客态，避免用户从聊天页被打回 splash。
+   */
+  async logoutToGuest(deviceId: string): Promise<Result<void>> {
+    try {
+      await this.api.logout();
+    } catch (e) {
+      log.warn("[AuthRepository] logout API failed, restoring guest anyway", e);
+    }
+
+    try {
+      await this.storage.clearBusinessAuthData();
+      await this.userStorage.clearUserData();
+    } catch (e) {
+      return Result.err(e);
+    }
+
+    const guestResult = await this.guestLogin(deviceId);
+    if (Result.isOk(guestResult)) return Result.ok(undefined);
+
+    const hasGuestToken = await this.storage.hasGuestToken();
+    if (hasGuestToken.success && hasGuestToken.data) {
+      const providerResult = await this.storage.setLoginProvider(
+        LoginStatus.Guest,
+      );
+      if (Result.isErr(providerResult)) return providerResult;
+      log.warn(
+        "[AuthRepository] guest login failed after logout, falling back to local guest token",
+        guestResult.error,
+      );
+      return Result.ok(undefined);
+    }
+
+    return Result.err(guestResult.error);
+  }
+
   /**
    * 游客登录：使用 deviceId 换取 guest token。
    * 成功后写 guest token + deviceId + userId。