diff --git a/entry/src/main/ets/common/AccountStore.ets b/entry/src/main/ets/common/AccountStore.ets
index 80c46a8..53d52e9 100644
--- a/entry/src/main/ets/common/AccountStore.ets
+++ b/entry/src/main/ets/common/AccountStore.ets
@@ -126,9 +126,11 @@ export class AccountStore {
       const store: preferences.Preferences =
         await preferences.getPreferences(context, AccountStore.STORE);
       const count: number = await store.get(AccountStore.COUNT_KEY, 0) as number;
+      console.info(`[AccountStore] loadAll: count=${count}`);
       for (let i = 0; i < count; i++) {
         const raw = await store.get(`acc_${i}`, '') as string;
         if (raw === '') {
+          console.warn(`[AccountStore] loadAll: acc_${i} 为空`);
           continue;
         }
         const acc = AccountStore.decodeAccount(raw);
@@ -139,6 +141,8 @@ export class AccountStore {
             migrated = true;
           }
           result.push(acc);
+        } else {
+          console.error(`[AccountStore] loadAll: acc_${i} 解码失败，raw 长度=${raw.length}`);
         }
       }
     } catch (err) {
@@ -157,10 +161,19 @@ export class AccountStore {
     return result;
   }
 
-  static async saveAll(context: common.Context, accounts: DavAccount[]): Promise<void> {
+  /**
+   * 保存全部账号。
+   * 防御：存储里已有账号时，禁止用空列表覆盖（调用方若因读取异常拿到空列表再回写，
+   * 会把所有账号抹掉）。仅删除账号的合法场景通过 force=true 放行。
+   */
+  static async saveAll(context: common.Context, accounts: DavAccount[], force: boolean = false): Promise<void> {
     const store: preferences.Preferences =
       await preferences.getPreferences(context, AccountStore.STORE);
     const oldCount: number = await store.get(AccountStore.COUNT_KEY, 0) as number;
+    if (accounts.length === 0 && oldCount > 0 && !force) {
+      console.error(`[AccountStore] 拒绝用空列表覆盖账号存储（原有 ${oldCount} 个账号）`);
+      throw new Error('账号列表为空，已阻止覆盖存储（保护原有账号数据）');
+    }
     for (let i = 0; i < oldCount; i++) {
       store.delete(`acc_${i}`);
     }
diff --git a/entry/src/main/ets/common/AppSettings.ets b/entry/src/main/ets/common/AppSettings.ets
index 567b76e..ef9bdee 100644
--- a/entry/src/main/ets/common/AppSettings.ets
+++ b/entry/src/main/ets/common/AppSettings.ets
@@ -3,6 +3,7 @@
 import { preferences } from '@kit.ArkData';
 import { common } from '@kit.AbilityKit';
 import { BusinessError } from '@kit.BasicServicesKit';
+import { LogUtil } from './LogUtil';
 
 export class AppSettings {
   private static readonly STORE: string = 'sync_settings';
@@ -12,6 +13,50 @@ export class AppSettings {
   private static readonly KEY_SYS_MODE: string = 'sys_cal_mode';       // 'display' | 'backup'
   private static readonly KEY_BACKUP_KEY: string = 'sys_backup_cal_key'; // 备份目标 DAV 日历本
   private static readonly KEY_MANUAL_READONLY: string = 'manual_readonly_keys'; // 手动标记只读的 calKey
+  private static readonly KEY_FULL_REFETCH: string = 'full_refetch_done'; // 一次性全量重拉已完成
+
+  /**
+   * 是否还需要一次性全量重拉：修复历史同步（REPORT 剥离 VALARM 时期）落库的残缺数据。
+   * 全量重拉期间忽略 etag 复用，所有资源 GET 完整 ICS；成功完成后标记，恢复增量模式。
+   */
+  static async isFullRefetchPending(context: common.Context): Promise<boolean> {
+    try {
+      const store: preferences.Preferences =
+        await preferences.getPreferences(context, AppSettings.STORE);
+      return !(await store.get(AppSettings.KEY_FULL_REFETCH, false) as boolean);
+    } catch (err) {
+      return true;
+    }
+  }
+
+  static async markFullRefetchDone(context: common.Context): Promise<void> {
+    try {
+      const store: preferences.Preferences =
+        await preferences.getPreferences(context, AppSettings.STORE);
+      await store.put(AppSettings.KEY_FULL_REFETCH, true);
+      await store.flush();
+    } catch (err) {
+      const e = err as BusinessError;
+      console.error(`标记全量重拉完成失败: ${e.message}`);
+    }
+  }
+
+  /**
+   * 手动重置全量重拉标记：下次同步忽略 etag 复用，所有资源 GET 完整 ICS 重建本地数据。
+   * 用于修复历史落库的残缺字段（如 reminder=0 但 etag 从未变化，增量同步永远无法纠正）。
+   */
+  static async resetFullRefetch(context: common.Context): Promise<void> {
+    try {
+      const store: preferences.Preferences =
+        await preferences.getPreferences(context, AppSettings.STORE);
+      await store.put(AppSettings.KEY_FULL_REFETCH, false);
+      await store.flush();
+      LogUtil.write('已重置全量重拉标记：下次同步将 GET 全部资源重建本地数据');
+    } catch (err) {
+      const e = err as BusinessError;
+      console.error(`重置全量重拉标记失败: ${e.message}`);
+    }
+  }
 
   /**
    * 手动标记为只读的日历本 calKey 列表。
diff --git a/entry/src/main/ets/common/DavClient.ets b/entry/src/main/ets/common/DavClient.ets
index 1ceb878..50264f7 100644
--- a/entry/src/main/ets/common/DavClient.ets
+++ b/entry/src/main/ets/common/DavClient.ets
@@ -110,6 +110,28 @@ export class DavClient {
     return 'Basic ' + buffer.from(`${username}:${password}`).toString('base64');
   }
 
+  /** GET 拉取单个资源的原始 ICS（调试诊断用） */
+  static async getRaw(url: string, auth: string): Promise<string> {
+    const httpRequest = http.createHttp();
+    try {
+      const resp: http.HttpResponse = await httpRequest.request(url, {
+        method: http.RequestMethod.GET,
+        header: {
+          'Authorization': auth,
+          'User-Agent': 'SyncCalendar/1.0'
+        },
+        connectTimeout: 10000,
+        readTimeout: 15000
+      });
+      if (resp.responseCode >= 200 && resp.responseCode < 300) {
+        return resp.result as string;
+      }
+      return `HTTP ${resp.responseCode}`;
+    } finally {
+      httpRequest.destroy();
+    }
+  }
+
   /**
    * 写权限探测：向日历本 PUT 一个探测资源——
    * 2xx → 可写（随后删除探测资源）；403/401 等 → 只读；网络异常 → 乐观按可写。
@@ -170,6 +192,58 @@ export class DavClient {
     return DavClient.reportComponents(href, auth, 'VEVENT', '');
   }
 
+  /**
+   * REPORT calendar-query：仅拉取 href + getetag（不含 calendar-data）。
+   * 部分服务器（如群晖）的 REPORT calendar-data 会剥离 VALARM 导致提醒丢失，
+   * 因此数据改为对变更资源逐个 GET 补拉（GET 返回完整 ICS）。
+   */
+  static async reportEtags(href: string, auth: string): Promise<RemoteItem[]> {
+    const body: string = '<?xml version="1.0" encoding="utf-8"?>' +
+      '<c:calendar-query xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">' +
+      '<d:prop><d:getetag/></d:prop>' +
+      '<c:filter><c:comp-filter name="VCALENDAR">' +
+      '<c:comp-filter name="VEVENT">' +
+      '</c:comp-filter></c:comp-filter></c:filter></c:calendar-query>';
+    const httpRequest = http.createHttp();
+    try {
+      const resp: http.HttpResponse = await httpRequest.request(href, {
+        method: 'REPORT' as http.RequestMethod,
+        header: {
+          'Authorization': auth,
+          'Content-Type': 'application/xml; charset=utf-8',
+          'Depth': '1',
+          'User-Agent': 'SyncCalendar/1.0'
+        },
+        extraData: body,
+        connectTimeout: 10000,
+        readTimeout: 30000
+      });
+      LogUtil.write(`HTTP REPORT(etag) ${href} → ${resp.responseCode}`);
+      if (resp.responseCode < 200 || resp.responseCode >= 300) {
+        throw new Error(`服务器返回状态码 ${resp.responseCode}`);
+      }
+      const xml: string = resp.result as string;
+      const items: RemoteItem[] = [];
+      const blocks: string[] = xml.split(/<\/[\w-]*:?response>/i);
+      for (const block of blocks) {
+        if (!/<[\w-]*:?response[\s>]/i.test(block)) {
+          continue;
+        }
+        const resHref: string = DavClient.extractTag(block, 'href');
+        if (resHref === '') {
+          continue;
+        }
+        const item = new RemoteItem();
+        item.href = resHref;
+        item.etag = DavClient.extractTag(block, 'getetag').replace(/"/g, '');
+        items.push(item);
+      }
+      return items;
+    } finally {
+      httpRequest.destroy();
+    }
+  }
+
   /** REPORT calendar-query：拉取某日历本内所有 VTODO 待办（不限时间范围，量小） */
   static async reportTodos(href: string, auth: string): Promise<RemoteItem[]> {
     return DavClient.reportComponents(href, auth, 'VTODO', '');
diff --git a/entry/src/main/ets/common/EventDb.ets b/entry/src/main/ets/common/EventDb.ets
index e08aea1..1ffb904 100644
--- a/entry/src/main/ets/common/EventDb.ets
+++ b/entry/src/main/ets/common/EventDb.ets
@@ -409,6 +409,23 @@ export class EventDb {
     return `新增${added} 更新${updated} 删除${removed} 不变${unchanged}`;
   }
 
+  /** 查询某日历本下同类型的全部行（同步 etag 比对用，含 dirty 行） */
+  static async queryByCalKey(context: common.Context, calKey: string, kind: string): Promise<LocalEvent[]> {
+    const store = await EventDb.getDb(context);
+    const predicates = new relationalStore.RdbPredicates('events');
+    predicates.equalTo('cal_key', calKey).and().equalTo('kind', kind);
+    const rs = await store.query(predicates);
+    const list: LocalEvent[] = [];
+    try {
+      while (rs.goToNextRow()) {
+        list.push(EventDb.fromRow(rs));
+      }
+    } finally {
+      rs.close();
+    }
+    return list;
+  }
+
   /** 按 UID 判断事件是否已存在（系统日历备份导入的幂等判重） */
   static async uidExists(context: common.Context, uid: string): Promise<boolean> {
     const store = await EventDb.getDb(context);
diff --git a/entry/src/main/ets/common/ScreenKeeper.ets b/entry/src/main/ets/common/ScreenKeeper.ets
new file mode 100644
index 0000000..1cf83c5
--- /dev/null
+++ b/entry/src/main/ets/common/ScreenKeeper.ets
@@ -0,0 +1,34 @@
+// entry/src/main/ets/common/ScreenKeeper.ets
+// 同步期间保持屏幕常亮：鸿蒙熄屏后应用进程会被挂起，网络请求停摆导致同步超时。
+// 引用计数支持多处同步（首页/账号页/后台入口）叠加，最后一个释放时才恢复熄屏。
+import { window } from '@kit.ArkUI';
+import { common } from '@kit.AbilityKit';
+
+export class ScreenKeeper {
+  private static count: number = 0;
+
+  /** 同步开始时调用：保持屏幕常亮（失败静默，不影响同步） */
+  static async acquire(context: common.UIAbilityContext): Promise<void> {
+    ScreenKeeper.count++;
+    try {
+      const win = await window.getLastWindow(context);
+      await win.setWindowKeepScreenOn(true);
+    } catch (err) {
+      // 获取窗口失败（如页面已销毁）不影响同步
+    }
+  }
+
+  /** 同步结束时调用：恢复系统默认熄屏策略 */
+  static async release(context: common.UIAbilityContext): Promise<void> {
+    ScreenKeeper.count = Math.max(0, ScreenKeeper.count - 1);
+    if (ScreenKeeper.count > 0) {
+      return; // 还有其他同步在进行，保持常亮
+    }
+    try {
+      const win = await window.getLastWindow(context);
+      await win.setWindowKeepScreenOn(false);
+    } catch (err) {
+      // 忽略
+    }
+  }
+}
diff --git a/entry/src/main/ets/common/SyncEngine.ets b/entry/src/main/ets/common/SyncEngine.ets
index 698fc63..bc2874d 100644
--- a/entry/src/main/ets/common/SyncEngine.ets
+++ b/entry/src/main/ets/common/SyncEngine.ets
@@ -5,10 +5,16 @@ import { BusinessError } from '@kit.BasicServicesKit';
 import { DavAccount } from './AccountStore';
 import { EventDb, LocalEvent, RemoteEvent } from './EventDb';
 import { IcsUtil } from './IcsUtil';
-import { DavClient, DavColorEntry } from './DavClient';
+import { DavClient, DavColorEntry, RemoteItem } from './DavClient';
 import { LogUtil } from './LogUtil';
+import { AppSettings } from './AppSettings';
 
 export class SyncEngine {
+  /** 正在同步中的账号 id → 开始时间：防止超时后的"僵尸同步"与新一轮同步并发写库 */
+  private static activeSyncs: Map<string, number> = new Map();
+  /** 互斥锁最长持有时间：超过视为异常残留（如进程挂起后网络停摆），允许抢占 */
+  private static readonly LOCK_STALE_MS: number = 15 * 60 * 1000;
+
   /**
    * 给异步操作加超时保护，防止网络挂起导致界面一直转圈
    */
@@ -26,11 +32,28 @@ export class SyncEngine {
    * 返回远端事件总数（拉取侧）。带 120 秒超时保护。
    */
   static async syncAccount(context: common.Context, acc: DavAccount): Promise<number> {
+    // 同一账号互斥：超时被掐断后内层任务仍在后台运行，期间不允许再次同步该账号。
+    // 锁超过 LOCK_STALE_MS 未释放（如熄屏挂起导致任务冻结）则视为残留，允许抢占
+    const heldSince: number | undefined = SyncEngine.activeSyncs.get(acc.id);
+    if (heldSince !== undefined) {
+      if (Date.now() - heldSince < SyncEngine.LOCK_STALE_MS) {
+        throw new Error('该账号正在同步中，请稍后再试');
+      }
+      LogUtil.write(`同步互斥锁超时残留（${acc.name}），强制释放并重新同步`);
+    }
+    SyncEngine.activeSyncs.set(acc.id, Date.now());
     const t0: number = Date.now();
     LogUtil.write(`========== 同步账号「${acc.name}」开始：服务器 ${acc.serverUrl}，共 ${acc.calendarHrefs.length} 个日历本 ==========`);
     try {
-      const r: number = await SyncEngine.withTimeout<number>(
-        SyncEngine.syncAccountInner(context, acc), 120000);
+      // 全量重拉（升级后首次）要逐个 GET 所有资源，放宽超时到 10 分钟；常规 5 分钟
+      const fullRefetch: boolean = await AppSettings.isFullRefetchPending(context);
+      const timeoutMs: number = fullRefetch ? 600000 : 300000;
+      // 内层任务真正结束（无论成败）才释放互斥锁；超时后它仍会在后台跑完
+      const inner: Promise<number> = SyncEngine.syncAccountInner(context, acc);
+      inner.catch((): void => {}).finally((): void => {
+        SyncEngine.activeSyncs.delete(acc.id);
+      });
+      const r: number = await SyncEngine.withTimeout<number>(inner, timeoutMs);
       LogUtil.write(`同步账号「${acc.name}」完成：拉取 ${r} 条日程，耗时 ${Math.round((Date.now() - t0) / 1000)} 秒`);
       return r;
     } catch (err) {
@@ -46,7 +69,14 @@ export class SyncEngine {
     await SyncEngine.refreshCalendarColors(acc, auth);
     // 1) 推送该账号日历本下的本地修改
     await SyncEngine.pushDirtyForAccount(context, acc, auth);
-    // 2) 拉取远端变更（全量 REPORT，etag 增量落库）
+    // 2) 拉取远端变更：REPORT 仅取 etag；新增/变化的资源用 GET 补拉完整 ICS。
+    //    原因：群晖等服务器的 REPORT calendar-data 会剥离 VALARM（提醒丢失），
+    //    而 GET 返回完整 ICS；etag 未变的资源直接复用本地完整数据，几乎零开销。
+    //    首次升级后执行一次全量重拉，修复旧模式落库的残缺数据（如 reminder=0）。
+    const fullRefetch: boolean = await AppSettings.isFullRefetchPending(context);
+    if (fullRefetch) {
+      LogUtil.write('一次性全量重拉：忽略 etag 复用，全部资源 GET 完整 ICS');
+    }
     let changed: number = 0;
     for (let i = 0; i < acc.calendarHrefs.length; i++) {
       const href: string = acc.calendarHrefs[i];
@@ -54,36 +84,82 @@ export class SyncEngine {
       const calName: string = i < acc.calendarNames.length ? acc.calendarNames[i] : `日历本${i}`;
       LogUtil.write(`日历本[${i}]「${calName}」开始同步：${href}`);
       const t1: number = Date.now();
-      const items = await DavClient.reportCalendar(href, auth);
+      const items: RemoteItem[] = await DavClient.reportEtags(href, auth);
       LogUtil.write(`日历本[${i}]「${calName}」REPORT 返回 ${items.length} 个资源`);
+      // 现有行按 uid 分组（同一资源的覆盖实例共享 uid 与 etag）
+      const existingRows: LocalEvent[] = await EventDb.queryByCalKey(context, calKey, 'event');
+      const byUid: Map<string, LocalEvent[]> = new Map();
+      for (const row of existingRows) {
+        const arr: LocalEvent[] | undefined = byUid.get(row.uid);
+        if (arr === undefined) {
+          byUid.set(row.uid, [row]);
+        } else {
+          arr.push(row);
+        }
+      }
+      const originMatch = /https?:\/\/[^/]+/i.exec(href);
+      const origin: string = originMatch !== null ? originMatch[0] : '';
       const remote: RemoteEvent[] = [];
+      let fetched: number = 0;
       let parseFail: number = 0;
-      let failSample: string = '';
+      const needFetch: RemoteItem[] = [];
       for (const it of items) {
-        const parsed: RemoteEvent[] = IcsUtil.parse(it.ics);
-        if (parsed.length === 0) {
-          parseFail++;
-          if (failSample === '') {
-            failSample = it.ics.replace(/\r?\n/g, ' ⏎ ').substring(0, 600);
+        const resUid: string = SyncEngine.resUidFromHref(it.href);
+        const group: LocalEvent[] | undefined = byUid.get(resUid);
+        if (!fullRefetch && group !== undefined && group.length > 0 && !group[0].dirty
+          && group[0].etag === it.etag) {
+          // etag 未变：直接用本地行还原远端数据（含 reminder 等完整字段）
+          for (const row of group) {
+            remote.push(SyncEngine.rowToRemote(row, it.etag));
           }
           continue;
         }
-        // 一个资源可能包含主事件 + 单次覆盖实例（RECURRENCE-ID），全部入库
-        for (const r of parsed) {
-          if (r.uid === 'syncprobe') {
-            continue; // 写权限探测资源（万一删除失败），不入库展示
+        needFetch.push(it);
+      }
+      // 并发 GET 补拉（每批 5 个），避免全量重拉时串行请求超时
+      const batchSize: number = 5;
+      for (let b: number = 0; b < needFetch.length; b += batchSize) {
+        const batch: RemoteItem[] = needFetch.slice(b, b + batchSize);
+        const results: RemoteEvent[][] = await Promise.all(batch.map(async (it: RemoteItem): Promise<RemoteEvent[]> => {
+          const url: string = it.href.startsWith('http') ? it.href : origin + it.href;
+          try {
+            const raw: string = await DavClient.getRaw(url, auth);
+            if (!raw.startsWith('BEGIN:VCALENDAR')) {
+              return [];
+            }
+            const resUid: string = SyncEngine.resUidFromHref(it.href);
+            const parsed: RemoteEvent[] = IcsUtil.parse(raw);
+            const out: RemoteEvent[] = [];
+            for (const r of parsed) {
+              if (r.uid === 'syncprobe') {
+                continue; // 写权限探测资源（万一删除失败），不入库展示
+              }
+              if (r.uid === '') {
+                r.uid = resUid;
+              }
+              r.etag = it.etag;
+              out.push(r);
+            }
+            return out;
+          } catch (err) {
+            return [];
           }
-          if (r.uid === '') {
-            r.uid = SyncEngine.uidFromHref(it.href);
+        }));
+        for (const arr of results) {
+          if (arr.length === 0) {
+            parseFail++;
+          } else {
+            fetched++;
+            for (const r of arr) {
+              remote.push(r);
+            }
           }
-          r.etag = it.etag;
-          remote.push(r);
         }
       }
       if (parseFail > 0) {
-        LogUtil.write(`日历本[${i}]「${calName}」有 ${parseFail} 个资源解析出 0 条日程，首个样本: ${failSample}`);
+        LogUtil.write(`日历本[${i}]「${calName}」有 ${parseFail} 个资源拉取/解析失败`);
       }
-      LogUtil.write(`日历本[${i}]「${calName}」解析出 ${remote.length} 条日程，开始落库`);
+      LogUtil.write(`日历本[${i}]「${calName}」补拉变更资源 ${fetched} 个，共 ${remote.length} 条日程，开始落库`);
       const stat: string = await EventDb.applyRemote(context, calKey, href, remote, false);
       LogUtil.write(`日历本[${i}]「${calName}」日程落库完成：${stat}，耗时 ${Math.round((Date.now() - t1) / 1000)} 秒`);
       changed += remote.length;
@@ -167,6 +243,43 @@ export class SyncEngine {
     return last.endsWith('.ics') ? last.substring(0, last.length - 4) : last;
   }
 
+  /** 从资源 URL 提取 UID（URL 解码后，用于与 DB 中 parse 出的真实 uid 匹配） */
+  private static resUidFromHref(href: string): string {
+    const segs: string[] = href.split('/').filter((s: string): boolean => s !== '');
+    if (segs.length === 0) {
+      return String(Date.now());
+    }
+    let last: string = segs[segs.length - 1];
+    if (last.endsWith('.ics')) {
+      last = last.substring(0, last.length - 4);
+    }
+    try {
+      last = decodeURIComponent(last);
+    } catch (err) {
+      // 解码失败保持原样
+    }
+    return last;
+  }
+
+  /** 本地行 → 远端事件（etag 未变的资源复用本地完整数据，含 reminder） */
+  private static rowToRemote(e: LocalEvent, etag: string): RemoteEvent {
+    const r = new RemoteEvent();
+    r.uid = e.uid;
+    r.etag = etag;
+    r.title = e.title;
+    r.description = e.description;
+    r.location = e.location;
+    r.startTime = e.startTime;
+    r.endTime = e.endTime;
+    r.isAllDay = e.isAllDay;
+    r.recurring = e.recurring;
+    r.completed = e.completed;
+    r.rrule = e.rrule;
+    r.exdate = e.exdate;
+    r.reminder = e.reminder;
+    return r;
+  }
+
   /**
    * 推送指定账号日历本下的待同步事件（新建/修改 → PUT；删除 → DELETE）
    */
@@ -237,6 +350,11 @@ export class SyncEngine {
    */
   static async pruneOrphanRows(context: common.Context, accounts: DavAccount[]): Promise<void> {
     try {
+      // 防御：账号列表为空时（如同步中途读取异常），绝不能把所有 CalDAV 日程当孤儿清理
+      if (accounts.length === 0) {
+        LogUtil.write('清理孤儿日程行跳过：账号列表为空（防御保护）');
+        return;
+      }
       const accIds: string[] = accounts.map((a: DavAccount): string => a.id);
       const removed: number = await EventDb.pruneOrphanCalKeys(context, accIds);
       if (removed > 0) {
diff --git a/entry/src/main/ets/pages/AccountsPage.ets b/entry/src/main/ets/pages/AccountsPage.ets
index b4e990b..a95350c 100644
--- a/entry/src/main/ets/pages/AccountsPage.ets
+++ b/entry/src/main/ets/pages/AccountsPage.ets
@@ -8,6 +8,7 @@ import { SyncEngine } from '../common/SyncEngine';
 import { EditNavParams } from './EditAccountPage';
 import { EventDb } from '../common/EventDb';
 import { LogUtil } from '../common/LogUtil';
+import { ScreenKeeper } from '../common/ScreenKeeper';
 
 @Entry
 @Component
@@ -68,14 +69,19 @@ struct AccountsPage {
     }
     this.syncing = true;
     this.syncingId = acc.id;
+    // 同步期间保持屏幕常亮：熄屏会挂起进程导致请求停摆、同步超时
+    const uiCtx = this.getUIContext().getHostContext();
+    if (uiCtx !== undefined) {
+      await ScreenKeeper.acquire(uiCtx as common.UIAbilityContext);
+    }
     try {
       const context = this.getUIContext().getHostContext();
       if (context === undefined) {
         return;
       }
       if (acc.type === TYPE_CALDAV) {
-        await SyncEngine.withTimeout(
-          SyncEngine.syncAccount(context as common.UIAbilityContext, acc), 120000);
+        // 超时保护由 syncAccount 内部处理（全量重拉 10 分钟 / 常规 2 分钟），不再套外层超时
+        await SyncEngine.syncAccount(context as common.UIAbilityContext, acc);
         await SyncEngine.pruneOrphanRows(context, this.accounts);
       }
       acc.itemCount = acc.calendarHrefs.length;
@@ -90,6 +96,9 @@ struct AccountsPage {
     } finally {
       this.syncing = false;
       this.syncingId = '';
+      if (uiCtx !== undefined) {
+        await ScreenKeeper.release(uiCtx as common.UIAbilityContext);
+      }
     }
   }
 
diff --git a/entry/src/main/ets/pages/Index.ets b/entry/src/main/ets/pages/Index.ets
index f446ab8..9204180 100644
--- a/entry/src/main/ets/pages/Index.ets
+++ b/entry/src/main/ets/pages/Index.ets
@@ -12,10 +12,12 @@ import { LunarUtil } from '../common/LunarUtil';
 import { CardDataService } from '../common/CardDataService';
 import { ReminderService } from '../common/ReminderService';
 import { AppSettings } from '../common/AppSettings';
-import { EventDb, LocalEvent } from '../common/EventDb';
+import { EventDb, LocalEvent, RemoteEvent } from '../common/EventDb';
 import { RruleUtil } from '../common/RruleUtil';
 import { IcsUtil } from '../common/IcsUtil';
+import { DavClient, RemoteItem } from '../common/DavClient';
 import { SystemCalendarImport } from '../common/SystemCalendarImport';
+import { ScreenKeeper } from '../common/ScreenKeeper';
 
 /** 月视图单元格 */
 class MonthCell {
@@ -92,11 +94,9 @@ struct Index {
 
   /** 从设置页/账号页返回时刷新（同步间隔、系统日历开关立即生效），并处理编辑账号后的待同步 */
   onPageShow(): void {
-    if (this.lastSyncTime > 0 || this.accounts.length > 0) {
-      this.reloadAll().then((): Promise<void> => this.handlePendingSync());
-    } else {
-      this.handlePendingSync();
-    }
+    // 无条件刷新：之前"列表为空就跳过"的条件会导致账号列表卡死在空状态，
+    // 同步时误报"没有可同步的账号"
+    this.reloadAll().then((): Promise<void> => this.handlePendingSync());
   }
 
   private async handlePendingSync(): Promise<void> {
@@ -298,13 +298,17 @@ struct Index {
       return;
     }
     this.syncing = true;
+    // 同步期间保持屏幕常亮：熄屏会挂起进程导致请求停摆、同步超时
+    const uiCtx = this.getUIContext().getHostContext();
+    if (uiCtx !== undefined) {
+      await ScreenKeeper.acquire(uiCtx as common.UIAbilityContext);
+    }
     try {
       const context = this.getUIContext().getHostContext();
       if (context === undefined) {
         return;
       }
-      await SyncEngine.withTimeout(
-        SyncEngine.syncAccount(context as common.UIAbilityContext, acc), 120000);
+      await SyncEngine.syncAccount(context as common.UIAbilityContext, acc);
       await SyncEngine.pruneOrphanRows(context, this.accounts);
       acc.lastSyncTime = this.formatNow();
       await AccountStore.saveAll(context, this.accounts);
@@ -316,6 +320,9 @@ struct Index {
         .showToast({ message: `同步失败：${e.message}` });
     } finally {
       this.syncing = false;
+      if (uiCtx !== undefined) {
+        await ScreenKeeper.release(uiCtx as common.UIAbilityContext);
+      }
       await this.reloadAll();
       // 同步后刷新服务卡片
       try {
@@ -339,12 +346,22 @@ struct Index {
     if (this.syncing) {
       return;
     }
+    // 防御：账号列表为空时不执行同步、不清理孤儿行、不回写账号存储，
+    // 防止异常状态下把所有 CalDAV 日程和账号配置抹掉
+    if (this.accounts.length === 0) {
+      if (manual) {
+        this.getUIContext().getPromptAction().showToast({ message: '没有可同步的账号' });
+      }
+      return;
+    }
     this.syncing = true;
     const context = this.getUIContext().getHostContext();
     if (context === undefined) {
       this.syncing = false;
       return;
     }
+    // 同步期间保持屏幕常亮：熄屏会挂起进程导致请求停摆、同步超时
+    await ScreenKeeper.acquire(context as common.UIAbilityContext);
     let ok: number = 0;
     let failMsg: string = '';
     // 备份模式：先把系统本地日历导入目标日历本（幂等），再随正常同步推送上服务器
@@ -358,8 +375,7 @@ struct Index {
         continue;
       }
       try {
-        await SyncEngine.withTimeout(
-          SyncEngine.syncAccount(context as common.UIAbilityContext, acc), 120000);
+        await SyncEngine.syncAccount(context as common.UIAbilityContext, acc);
         acc.lastSyncTime = this.formatNow();
         ok++;
       } catch (err) {
@@ -371,11 +387,16 @@ struct Index {
       await SyncEngine.settleLocalEvents(context);
       await SyncEngine.pruneOrphanRows(context, this.accounts);
       await AccountStore.saveAll(context, this.accounts);
+      // 全部账号同步成功才结束"一次性全量重拉"状态（修复旧模式落库的残缺数据）
+      if (failMsg === '') {
+        await AppSettings.markFullRefetchDone(context);
+      }
     } catch (err) {
       const e = err as BusinessError;
       failMsg = e.message;
     }
     this.syncing = false;
+    await ScreenKeeper.release(context as common.UIAbilityContext);
     if (failMsg !== '') {
       this.getUIContext().getPromptAction()
         .showToast({ message: ok > 0 ? `同步完成 ${ok} 个，失败：${failMsg}` : `同步失败：${failMsg}` });
@@ -910,6 +931,7 @@ struct Index {
       };
       const lines: string[] = [`调试 ${this.fmtDateCn(dateMs)}`, `visibleKeys=${visibleKeys.join(',')}`];
       let idx: number = 0;
+      let netChecked: boolean = false;
       for (const m of masters.values()) {
         if (idx >= 6) {
           lines.push('…（更多系列省略）');
@@ -939,13 +961,54 @@ struct Index {
         lines.push(`  rrule=${m.rrule === '' ? '(空!)' : m.rrule}`);
         lines.push(`  exdate=${m.exdate === '' ? '无' : m.exdate}`);
         lines.push(`  展开条数=${occs.length} 含首次=${hasFirst ? '是' : '否'} 首次=${occs.length > 0 ? fmt(occs[0]) : '无'} 该日发生=${hitsDay ? '是' : '否'}`);
+        lines.push(`  数据库提醒=${m.reminder}分钟 DB同UID行数=${rows.filter((r: LocalEvent): boolean => r.uid === m.uid).length}`);
+        // 网络诊断（仅第一个命中该日的系列）：GET 服务器原始 ICS，看 VALARM 是否还在
+        if (hitsDay && !netChecked) {
+          netChecked = true;
+          try {
+            const accounts2: DavAccount[] = await AccountStore.loadAll(context);
+            const acc2 = accounts2.find((a: DavAccount): boolean => a.calendarHrefs.includes(m.href));
+            if (acc2 !== undefined) {
+              const auth2: string = DavClient.authHeader(acc2.username, acc2.password);
+              const url: string = m.href.endsWith('/')
+                ? m.href + m.remotePath : `${m.href}/${m.remotePath}`;
+              const raw: string = await DavClient.getRaw(url, auth2);
+              const upper: string = raw.toUpperCase();
+              const trigIdx: number = upper.indexOf('TRIGGER');
+              lines.push(`  服务器ICS：${raw.length}字节 VALARM=${upper.includes('BEGIN:VALARM') ? '有' : '无'}` +
+                (trigIdx >= 0 ? ` TRIGGER=${raw.substring(trigIdx, trigIdx + 40).replace(/\r?\n/g, ' ')}` : ''));
+              // 用解析函数当场重解析这份 ICS，验证解析是否丢提醒
+              const reParsed: RemoteEvent[] = IcsUtil.parse(raw);
+              const hit = reParsed.find((p: RemoteEvent): boolean => p.uid === m.uid);
+              lines.push(`  重新解析：提醒=${hit !== undefined ? hit.reminder : '?'}分钟 rec=${hit !== undefined ? (hit.recurring ? 1 : 0) : '?'} rrule=${hit !== undefined && hit.rrule !== '' ? hit.rrule : '无'}`);
+              // 模拟同步路径：REPORT 拉取（与 SyncEngine 完全一致）再解析
+              try {
+                const repItems: RemoteItem[] = await DavClient.reportCalendar(m.href, auth2);
+                const repIt = repItems.find((x: RemoteItem): boolean => x.ics.includes(m.uid));
+                if (repIt !== undefined) {
+                  const rp: RemoteEvent[] = IcsUtil.parse(repIt.ics);
+                  const hit2 = rp.find((p: RemoteEvent): boolean => p.uid === m.uid);
+                  lines.push(`  REPORT重解析：提醒=${hit2 !== undefined ? hit2.reminder : '?'}分钟 VALARM=${repIt.ics.toUpperCase().includes('BEGIN:VALARM') ? '有' : '无'} 字节=${repIt.ics.length}`);
+                  lines.push(`  etag对比：DB=${m.etag === '' ? '(空)' : m.etag.substring(0, 16)} REPORT=${repIt.etag === '' ? '(空)' : repIt.etag.substring(0, 16)}`);
+                } else {
+                  lines.push(`  REPORT重解析：未找到该UID（共${repItems.length}条）`);
+                }
+              } catch (err2) {
+                lines.push('  REPORT拉取失败：同步可能一直在此失败！');
+              }
+              lines.push(`  ICS原文：${raw.substring(0, 380).replace(/\r?\n/g, ' ⏎ ')}`);
+            }
+          } catch (err) {
+            lines.push('  服务器ICS获取失败(网络)');
+          }
+        }
         const ovs = overrides.get(m.uid) ?? [];
         if (ovs.length === 0) {
           lines.push('  覆盖实例: 无');
         } else {
           for (const o of ovs.slice(0, 5)) {
             const oVis: boolean = visibleKeys.includes(o.calKey);
-            lines.push(`  覆盖: ${fmt(o.startTime)}~${fmt(o.endTime)} rec=${o.recurring ? 1 : 0} calKey=${o.calKey} vis=${oVis ? 1 : 0} dirty=${o.dirty ? 1 : 0}`);
+            lines.push(`  覆盖: ${fmt(o.startTime)}~${fmt(o.endTime)} rec=${o.recurring ? 1 : 0} calKey=${o.calKey} vis=${oVis ? 1 : 0} dirty=${o.dirty ? 1 : 0} 提醒=${o.reminder}分钟`);
           }
           if (ovs.length > 5) {
             lines.push(`  覆盖共 ${ovs.length} 条`);
@@ -955,6 +1018,18 @@ struct Index {
       if (lines.length <= 2) {
         lines.push('（该日期附近没有重复主事件）');
       }
+      // 当日非重复日程（含覆盖实例）：核对 DB 中实际存储的提醒值，定位提醒丢失环节
+      const plain: LocalEvent[] = rows.filter((r: LocalEvent): boolean =>
+        r.rrule === '' && r.startTime < dayEnd && r.endTime >= dayStart);
+      if (plain.length > 0) {
+        lines.push(`—— 当日非重复日程 ${plain.length} 条 ——`);
+        for (const r of plain.slice(0, 8)) {
+          lines.push(`◇ ${r.title === '' ? '(无标题)' : r.title} 提醒=${r.reminder}分钟 rec=${r.recurring ? 1 : 0} calKey=${r.calKey}`);
+        }
+        if (plain.length > 8) {
+          lines.push(`…（其余 ${plain.length - 8} 条省略）`);
+        }
+      }
       const text: string = lines.join('\n').substring(0, 3500);
       this.getUIContext().showAlertDialog({
         title: '重复日程调试',
diff --git a/entry/src/main/ets/pages/SettingsPage.ets b/entry/src/main/ets/pages/SettingsPage.ets
index b9c56a9..7796a9e 100644
--- a/entry/src/main/ets/pages/SettingsPage.ets
+++ b/entry/src/main/ets/pages/SettingsPage.ets
@@ -210,6 +210,36 @@ struct SettingsPage {
     return minutes >= 60 ? `${minutes / 60} 小时` : `${minutes} 分钟`;
   }
 
+  /** 确认后重置全量重拉标记，下次同步重建全部日程数据 */
+  private askRebuildData(): void {
+    this.getUIContext().showAlertDialog({
+      title: '重建日程数据',
+      message: '将重新从服务器拉取所有日程的完整数据（包括提醒），本地已修改未同步的内容不受影响。\n\n全量拉取可能需要几分钟，期间请保持 App 在前台、不要熄屏。',
+      autoCancel: true,
+      alignment: DialogAlignment.Center,
+      primaryButton: {
+        value: '取消',
+        action: (): void => {}
+      },
+      secondaryButton: {
+        value: '开始重建',
+        action: (): void => {
+          this.doRebuildData();
+        }
+      }
+    });
+  }
+
+  private async doRebuildData(): Promise<void> {
+    if (this.context === undefined) {
+      return;
+    }
+    await AppSettings.resetFullRefetch(this.context);
+    this.getUIContext().getPromptAction().showToast({
+      message: '已开启，返回首页后点一次同步即可，请保持屏幕常亮'
+    });
+  }
+
   build() {
     Column() {
       // 顶部
@@ -349,6 +379,32 @@ struct SettingsPage {
           .backgroundColor($r('app.color.card_bg'))
           .border({ width: 1, color: $r('app.color.shadow_color') })
 
+          // 数据修复：手动触发一次性全量重拉（重建提醒等本地残缺字段）
+          Row({ space: 10 }) {
+            Column({ space: 2 }) {
+              Text('重建日程数据')
+                .fontSize(15)
+                .fontWeight(FontWeight.Medium)
+                .fontColor($r('app.color.text_primary'))
+              Text('同步时重新从服务器拉取全部日程的完整数据，修复提醒丢失等本地数据问题。耗时段落请保持 App 在前台、屏幕常亮')
+                .fontSize(12)
+                .fontColor($r('app.color.text_secondary'))
+            }
+            .alignItems(HorizontalAlign.Start)
+            .layoutWeight(1)
+            Button('重建')
+              .fontSize(13)
+              .backgroundColor($r('app.color.brand'))
+              .onClick(() => {
+                this.askRebuildData();
+              })
+          }
+          .width('100%')
+          .padding(14)
+          .borderRadius(12)
+          .backgroundColor($r('app.color.card_bg'))
+          .border({ width: 1, color: $r('app.color.shadow_color') })
+
           // 混合显示系统日历
           Row({ space: 10 }) {
             Column({ space: 2 }) {
diff --git a/entry/src/main/ets/syncwork/SyncWorkAbility.ets b/entry/src/main/ets/syncwork/SyncWorkAbility.ets
index 677c3f8..d1f2b00 100644
--- a/entry/src/main/ets/syncwork/SyncWorkAbility.ets
+++ b/entry/src/main/ets/syncwork/SyncWorkAbility.ets
@@ -8,6 +8,7 @@ import { SyncEngine } from '../common/SyncEngine';
 import { CardDataService } from '../common/CardDataService';
 import { ReminderService } from '../common/ReminderService';
 import { SystemCalendarImport } from '../common/SystemCalendarImport';
+import { AppSettings } from '../common/AppSettings';
 import { LogUtil } from '../common/LogUtil';
 
 export default class SyncWorkAbility extends WorkSchedulerExtensionAbility {
@@ -32,19 +33,25 @@ export default class SyncWorkAbility extends WorkSchedulerExtensionAbility {
         // 导入失败不影响正常同步
       }
       let ok: number = 0;
+      let attempted: number = 0;
       for (const acc of accounts) {
         if (acc.type !== TYPE_CALDAV) {
           continue;
         }
+        attempted++;
         try {
-          await SyncEngine.withTimeout(
-            SyncEngine.syncAccount(context, acc), 100000);
+          // 超时保护由 syncAccount 内部处理（全量重拉 10 分钟 / 常规 5 分钟），不再套外层超时
+          await SyncEngine.syncAccount(context, acc);
           ok++;
         } catch (err) {
           const e = err as BusinessError;
           LogUtil.write(`延迟任务同步「${acc.name}」失败: ${e.message}`);
         }
       }
+      // 全部账号同步成功才结束"一次性全量重拉"状态
+      if (attempted > 0 && ok === attempted) {
+        await AppSettings.markFullRefetchDone(context);
+      }
       await SyncEngine.settleLocalEvents(context);
       await SyncEngine.pruneOrphanRows(context, accounts);
       // 同步后刷新卡片 + 重建提醒，保证后台同步的成果直接可见