diff --git a/laf-cloud/functions/dailyTaskConfig.ts b/laf-cloud/functions/dailyTaskConfig.ts
index 1edd9c6..940ebce 100644
--- a/laf-cloud/functions/dailyTaskConfig.ts
+++ b/laf-cloud/functions/dailyTaskConfig.ts
@@ -30,6 +30,7 @@ export type DailyWeeklyTaskData = {
   version: 2;
   dayKey: string;
   weekKey: string;
+  dayEndsAt: number;
   weekEndsAt: number;
   serverNow: number;
   dailyTasks: DailyTask[];
diff --git a/laf-cloud/functions/dailyTaskService.ts b/laf-cloud/functions/dailyTaskService.ts
index 230f858..533b1c5 100644
--- a/laf-cloud/functions/dailyTaskService.ts
+++ b/laf-cloud/functions/dailyTaskService.ts
@@ -12,6 +12,10 @@ export function getDayKey(nowMs = Date.now()): string {
   return new Date(nowMs + SHANGHAI_OFFSET_MS).toISOString().slice(0, 10);
 }
 
+export function getDayEndsAt(nowMs = Date.now()): number {
+  return Date.parse(`${getDayKey(nowMs)}T00:00:00+08:00`) + DAY_MS;
+}
+
 export function getWeekKey(nowMs = Date.now()): string {
   const shifted = new Date(nowMs + SHANGHAI_OFFSET_MS);
   const day = shifted.getUTCDay() || 7;
@@ -61,6 +65,7 @@ export function refreshTaskData(
 ): { data: DailyWeeklyTaskData; changed: boolean } {
   const dayKey = getDayKey(nowMs);
   const weekKey = getWeekKey(nowMs);
+  const dayEndsAt = getDayEndsAt(nowMs);
   const weekEndsAt = getWeekEndsAt(nowMs);
   const parsed = typeof stored === "string" ? safeParse(stored) : stored;
   const valid = parsed && (parsed as DailyWeeklyTaskData).version === 2
@@ -72,7 +77,8 @@ export function refreshTaskData(
   const newDay = !old || old.dayKey !== dayKey;
 
   if (!newDay && !newWeek) {
-    const changed = old.weekEndsAt !== weekEndsAt;
+    const changed = old.dayEndsAt !== dayEndsAt || old.weekEndsAt !== weekEndsAt;
+    old.dayEndsAt = dayEndsAt;
     old.weekEndsAt = weekEndsAt;
     old.serverNow = nowMs;
     applyLocks(old.dailyTasks);
@@ -85,6 +91,7 @@ export function refreshTaskData(
     version: 2,
     dayKey,
     weekKey,
+    dayEndsAt,
     weekEndsAt,
     serverNow: nowMs,
     dailyTasks: selectDailyTasks(uid, dayKey, Math.max(1, level), previousTaskIds),
diff --git a/laf-cloud/tests/daily-task-v2.test.mjs b/laf-cloud/tests/daily-task-v2.test.mjs
index cd8974b..fc4d493 100644
--- a/laf-cloud/tests/daily-task-v2.test.mjs
+++ b/laf-cloud/tests/daily-task-v2.test.mjs
@@ -12,11 +12,12 @@ registerHooks({
   },
 });
 
-const { getDayKey, getWeekKey, getWeekEndsAt, refreshTaskData, mergeClientProgress, claimDaily, claimWeekly } = await import(serviceUrl);
+const { getDayKey, getDayEndsAt, getWeekKey, getWeekEndsAt, refreshTaskData, mergeClientProgress, claimDaily, claimWeekly } = await import(serviceUrl);
 
 test("uses Shanghai natural day and Monday week keys", () => {
   assert.equal(getDayKey(Date.parse("2026-09-06T15:59:59Z")), "2026-09-06");
   assert.equal(getDayKey(Date.parse("2026-09-06T16:00:00Z")), "2026-09-07");
+  assert.equal(getDayEndsAt(Date.parse("2026-09-06T16:00:00Z")), Date.parse("2026-09-08T00:00:00+08:00"));
   assert.equal(getWeekKey(Date.parse("2026-09-06T16:00:00Z")), "2026-09-07");
   assert.equal(getWeekEndsAt(Date.parse("2026-09-06T16:00:00Z")), Date.parse("2026-09-14T00:00:00+08:00"));
 });
@@ -28,6 +29,7 @@ test("returns current server time and refreshes it on repeated reads", () => {
   const second = refreshTaskData(JSON.stringify(first), "user-time", 20, secondNow);
   assert.equal(second.changed, false);
   assert.equal(second.data.serverNow, secondNow);
+  assert.equal(second.data.dayEndsAt, Date.parse("2026-09-08T00:00:00+08:00"));
   assert.equal(second.data.weekEndsAt, Date.parse("2026-09-14T00:00:00+08:00"));
 });