diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
index 5f1f7bd..0ac6d8f 100644
--- a/DEVELOPMENT.md
+++ b/DEVELOPMENT.md
@@ -55,6 +55,7 @@ GitHub Actions 只在分支 push 且 `server/**` 发生变化时构建并发布
 有 Developer ID Application 证书时，Taskfile 会自动使用钥匙串中第一个证书的唯一指纹；否则使用项目默认的 ad-hoc 签名。
 桌面小组件与主应用通过 `group.work.12306.xstats` App Group 共享只读展示摘要。
 菜单栏日历提供“日期与星期”“日期与农历”“农历”“自定义”四种显示方式，自定义可自由组合 y/M/d 字段与分隔符，年份可省略，输入时显示预览并提示无效格式，独立于月历的星期开关；支持农历字号与对比度、可选悬停展开，按分钟刷新，休眠或关闭功能后停止。日程和到期提醒默认关闭，通过明确的授权按钮请求 EventKit 权限，只在日历面板可见时查询当前 42 格日期范围；只读展示，不修改日程，也不向 Widget、设置备份或服务端传递内容。列表 ID 仅保存在本机，显示偏好参与设置备份。节假日覆盖年份来自内置 Tyme 数据并随应用更新；假期倒计时与最多 3 天的请假建议只基于已公布的中国调休与双休安排，跨到未知年份时停止推算。
+月历计算仅缓存最近一个月份（包含周起始日和时区），供实际面板、高度测量和重复打开共用；翻月替换缓存，避免浏览历史导致内存累积。日程日期标记在工作 actor 内随查询结果生成，界面不再逐格扫描日程列表；连续 EventKit 通知按 300 毫秒窗口合并，关闭面板时取消待执行刷新。
 用于正式签名的 Apple Developer 团队须为主应用和 Widget 扩展启用同一个 App Group；
 EventKit 授权还依赖主 App 的 `com.apple.security.personal-information.calendars` entitlement，配置来源为 `project.yml`。即使已有 Info.plist 权限说明，Hardened Runtime 缺少此 entitlement 仍会直接拒绝授权且不弹窗。本地预览和发布时应检查最终 App 签名中的 entitlement；系统授权必须由用户点击允许访问后决定。
 
diff --git a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarAgenda.swift b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarAgenda.swift
index f00908a..2b7871b 100644
--- a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarAgenda.swift
+++ b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarAgenda.swift
@@ -43,6 +43,38 @@ struct CalendarAgendaQuery: Equatable, Sendable {
     let eventIDs: Set<String>?
     let reminderIDs: Set<String>?
     let revision: Int
+    var timeZone: TimeZone = .current
+}
+
+/// 只保存有日程的日期，不复制跨天事件列表；在工作 actor 内随查询结果生成一次。
+struct CalendarAgendaResult: Sendable {
+    let items: [CalendarAgendaItem]
+    let markedDays: Set<Date>
+
+    init(items: [CalendarAgendaItem], query: CalendarAgendaQuery) {
+        self.items = items
+        var calendar = Calendar(identifier: .gregorian)
+        calendar.timeZone = query.timeZone
+        var marks: Set<Date> = []
+        for item in items {
+            if item.isReminder || item.end <= item.start {
+                if item.start >= query.start && item.start < query.end {
+                    marks.insert(calendar.startOfDay(for: item.start))
+                }
+                continue
+            }
+            let end = min(item.end, query.end)
+            var day = calendar.startOfDay(for: max(item.start, query.start))
+            // 结束时间是开区间；按实际日界线推进。午夜切换夏令时当天可能从 01:00 开始，
+            // 不能直接加一天，否则之后每一天都会保留 01:00，无法匹配界面的 startOfDay。
+            while day < end {
+                marks.insert(day)
+                guard let next = calendar.dateInterval(of: .day, for: day)?.end, next > day else { break }
+                day = next
+            }
+        }
+        markedDays = marks
+    }
 }
 
 /// EventKit 对象留在工作 actor 内；界面只接收值类型，不在主线程同步查询日程。
@@ -70,7 +102,7 @@ private actor CalendarAgendaReader {
             .sorted { $0.title.localizedStandardCompare($1.title) == .orderedAscending }
     }
 
-    func load(_ query: CalendarAgendaQuery) async -> [CalendarAgendaItem]? {
+    func load(_ query: CalendarAgendaQuery) async -> CalendarAgendaResult? {
         guard !Task.isCancelled else { return nil }
         let store = self.store
         var result: [CalendarAgendaItem] = []
@@ -93,10 +125,12 @@ private actor CalendarAgendaReader {
                 result += reminders
             }
         }
-        return result.sorted {
+        guard !Task.isCancelled else { return nil }
+        let sorted = result.sorted {
             if $0.start != $1.start { return $0.start < $1.start }
             return $0.id < $1.id
         }
+        return CalendarAgendaResult(items: sorted, query: query)
     }
 
     private func reminders(_ query: CalendarAgendaQuery, calendars: [EKCalendar], store: EKEventStore) async -> [CalendarAgendaItem]? {
@@ -143,6 +177,7 @@ private actor CalendarAgendaReader {
 @Observable
 final class CalendarAgendaController {
     private(set) var items: [CalendarAgendaItem] = []
+    private(set) var markedDays: Set<Date> = []
     private(set) var eventSources: [CalendarAgendaSource] = []
     private(set) var reminderSources: [CalendarAgendaSource] = []
     private(set) var eventsAccess = EKEventStore.authorizationStatus(for: .event)
@@ -153,6 +188,7 @@ final class CalendarAgendaController {
     var revision = 0
     @ObservationIgnored private let reader = CalendarAgendaReader()
     @ObservationIgnored private var generation = UUID()
+    @ObservationIgnored private var storeChangeTask: Task<Void, Never>?
 
     /// 打开面板、应用激活时调用；授权确实变化才重新查询，避免每次打开都取消刚开始的查询再重来
     func refreshAuthorization() {
@@ -164,10 +200,18 @@ final class CalendarAgendaController {
         revision += 1
     }
 
-    /// 日历或提醒事项内容变化（EKEventStoreChanged）时重新查询
+    /// iCloud 同步可能连续发出通知；每个短窗口只刷新一次，不因持续通知无限延后。
     func storeChanged() {
-        refreshAuthorization()
-        revision += 1
+        guard storeChangeTask == nil else { return }
+        storeChangeTask = Task { @MainActor [weak self] in
+            do { try await Task.sleep(for: .milliseconds(300)) }
+            catch { return }
+            guard let self else { return }
+            self.storeChangeTask = nil
+            let before = self.revision
+            self.refreshAuthorization()
+            if self.revision == before { self.revision += 1 }
+        }
     }
 
     /// 只能由明确的授权按钮调用；启用功能、导入偏好和打开日历均不自动弹出系统授权。
@@ -197,18 +241,22 @@ final class CalendarAgendaController {
         generation = current
         failed = false
         // 新结果返回前保留旧列表，刷新时日程和日期圆点不会先消失再出现；按日期过滤，跨月也不会显示错位
-        guard query.events || query.reminders else { items = []; isLoading = false; return }
+        guard query.events || query.reminders else { items = []; markedDays = []; isLoading = false; return }
         isLoading = true
         let result = await reader.load(query)
         guard generation == current, !Task.isCancelled else { return }
-        items = result ?? []
+        items = result?.items ?? []
+        markedDays = result?.markedDays ?? []
         failed = result == nil
         isLoading = false
     }
 
     func clear() {
+        storeChangeTask?.cancel()
+        storeChangeTask = nil
         generation = UUID()
         items = []
+        markedDays = []
         isLoading = false
         failed = false
     }
diff --git a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarAgendaView.swift b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarAgendaView.swift
index 5b54036..4cef17e 100644
--- a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarAgendaView.swift
+++ b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarAgendaView.swift
@@ -15,6 +15,7 @@ struct CalendarAgendaView: View {
 
     var body: some View {
         let agenda = model.calendarAgenda
+        let items = self.items
         let preferences = model.settings.calendarPreferences
         VStack(alignment: .leading, spacing: 10) {
             HStack {
diff --git a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarEngine.swift b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarEngine.swift
index 95ed6e0..8bee8b0 100644
--- a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarEngine.swift
+++ b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarEngine.swift
@@ -92,6 +92,9 @@ struct CalendarDetail: Identifiable {
 /// Tyme 使用可变的静态表；统一在主线程读取，不把其引用类型暴露给界面或跨线程共享。
 @MainActor
 enum CalendarEngine {
+    // 实际面板、测量视图和 onAppear 共用一次计算；只保留最近一个月，翻月不会累积内存。
+    private static var monthCache: (month: CalendarMonth, firstWeekday: Int, timeZone: TimeZone, days: [CalendarDay])?
+
     static func gregorian(timeZone: TimeZone = .autoupdatingCurrent) -> Calendar {
         var calendar = Calendar(identifier: .gregorian)
         calendar.timeZone = timeZone
@@ -101,6 +104,10 @@ enum CalendarEngine {
     static func today(at date: Date = Date(), timeZone: TimeZone = .autoupdatingCurrent) -> CalendarDay? {
         let parts = gregorian(timeZone: timeZone).dateComponents([.year, .month, .day], from: date)
         guard let year = parts.year, let month = parts.month, let day = parts.day else { return nil }
+        if let cached = monthCache, cached.timeZone.identifier == timeZone.identifier,
+           let existing = cached.days.first(where: { $0.year == year && $0.month == month && $0.day == day }) {
+            return existing
+        }
         return self.day(year: year, month: month, day: day, timeZone: timeZone)
     }
 
@@ -133,16 +140,23 @@ enum CalendarEngine {
 
     static func month(year: Int, month: Int, firstWeekday: Int,
                       timeZone: TimeZone = .autoupdatingCurrent) -> [CalendarDay] {
-        guard CalendarMonth.years.contains(year), (1...12).contains(month),
-              let first = day(year: year, month: month, day: 1, timeZone: timeZone) else { return [] }
-        let calendar = gregorian(timeZone: timeZone)
+        let requested = CalendarMonth(year: year, month: month)
         let weekStart = firstWeekday == 1 ? 1 : 2
+        // 固定自动更新时区的当前值，避免缓存里的时区也跟着系统变化，误判为可复用。
+        let zone = TimeZone(identifier: timeZone.identifier) ?? timeZone
+        if let cached = monthCache, cached.month == requested,
+           cached.firstWeekday == weekStart, cached.timeZone == zone { return cached.days }
+        guard CalendarMonth.years.contains(year), (1...12).contains(month),
+              let first = day(year: year, month: month, day: 1, timeZone: zone) else { return [] }
+        let calendar = gregorian(timeZone: zone)
         let offset = (first.weekday - weekStart + 7) % 7
         // 用日历加天而非 86400 秒；夏令时切换不能导致重复日期或漏掉日期。
-        return (0..<42).compactMap { index in
+        let days: [CalendarDay] = (0..<42).compactMap { index in
             guard let date = calendar.date(byAdding: .day, value: index - offset, to: first.date) else { return nil }
-            return today(at: date, timeZone: timeZone)
+            return today(at: date, timeZone: zone)
         }
+        monthCache = (requested, weekStart, zone, days)
+        return days
     }
 
     static func day(year: Int, month: Int, day: Int,
diff --git a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarMenuBarController.swift b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarMenuBarController.swift
index 982f521..911e3c4 100644
--- a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarMenuBarController.swift
+++ b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarMenuBarController.swift
@@ -174,8 +174,8 @@ final class CalendarMenuBarController: NSObject {
         if panel == nil || (panel?.isVisible == false && panelSizing != sizing) {
             let model = self.model
             let panel = StatusPanel(width: sizing.width, minHeight: 380, maxHeight: sizing.maxHeight,
-                                    content: { CalendarPopover(sizing: sizing).environment(model) },
-                                    measuring: { CalendarPopover(sizing: sizing).environment(model).environment(\.isSnapshot, true) })
+                                    content: { CalendarPopover(sizing: sizing, firstWeekday: model.settings.calendarFirstWeekday).environment(model) },
+                                    measuring: { CalendarPopover(sizing: sizing, firstWeekday: model.settings.calendarFirstWeekday).environment(model).environment(\.isSnapshot, true) })
             panel.onVisibilityChange = { [weak self] visible in self?.item?.button?.highlight(visible) }
             self.panel = panel
             panelSizing = sizing
diff --git a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarPopover.swift b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarPopover.swift
index e8f23d6..9292573 100644
--- a/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarPopover.swift
+++ b/Packages/XStatsKit/Sources/XStatsUI/Calendar/CalendarPopover.swift
@@ -47,7 +47,7 @@ struct CalendarPopover: View {
     private let sizing: CalendarPopoverSizing
 
     init(referenceDate: Date? = nil, showsDayDetails: Bool = false,
-         sizing: CalendarPopoverSizing = .standard) {
+         sizing: CalendarPopoverSizing = .standard, firstWeekday: Int = 2) {
         self.referenceDate = referenceDate
         self.sizing = sizing
         let today = CalendarEngine.today(at: referenceDate ?? Date())
@@ -58,7 +58,7 @@ struct CalendarPopover: View {
         _showsDayDetails = State(initialValue: showsDayDetails)
         _almanac = State(initialValue: showsDayDetails ? today.flatMap { CalendarEngine.almanac(for: $0) } : nil)
         _lastTodayID = State(initialValue: today?.id)
-        _days = State(initialValue: CalendarEngine.month(year: month.year, month: month.month, firstWeekday: 2))
+        _days = State(initialValue: CalendarEngine.month(year: month.year, month: month.month, firstWeekday: firstWeekday))
         _holidayPlan = State(initialValue: CalendarEngine.holidayPlan(from: referenceDate ?? Date()))
     }
 
@@ -126,7 +126,9 @@ struct CalendarPopover: View {
         }
         .onDisappear { if !isSnapshot { model.calendarAgenda.clear() } }
         .onReceive(NotificationCenter.default.publisher(for: .EKEventStoreChanged)) { _ in
-            if !isSnapshot { model.calendarAgenda.storeChanged() }
+            if !isSnapshot && (model.settings.calendarPreferences.showEvents || model.settings.calendarPreferences.showReminders) {
+                model.calendarAgenda.storeChanged()
+            }
         }
         .onReceive(NotificationCenter.default.publisher(for: NSApplication.didBecomeActiveNotification)) { _ in
             if !isSnapshot { model.calendarAgenda.refreshAuthorization() }
@@ -157,7 +159,7 @@ struct CalendarPopover: View {
         return .init(start: start, end: end,
                      events: settings.calendarPreferences.showEvents, reminders: settings.calendarPreferences.showReminders,
                      eventIDs: settings.calendarEventSourceIDs, reminderIDs: settings.calendarReminderSourceIDs,
-                     revision: model.calendarAgenda.revision)
+                     revision: model.calendarAgenda.revision, timeZone: .current)
     }
 
     private func header(today: CalendarDay?) -> some View {
@@ -212,7 +214,7 @@ struct CalendarPopover: View {
                     CalendarDayCell(day: day, features: features, isCurrentMonth: day.month == month.month,
                                     isToday: day.id == today?.id, isSelected: day.id == selected?.id,
                                     preferences: model.settings.calendarPreferences, sizing: sizing,
-                                    hasAgenda: model.calendarAgenda.items.contains { $0.occurs(on: day.date, calendar: CalendarEngine.gregorian()) }) {
+                                    hasAgenda: model.calendarAgenda.markedDays.contains(CalendarEngine.gregorian().startOfDay(for: day.date))) {
                         selected = day
                         if day.month != month.month, CalendarMonth.years.contains(day.year) {
                             month = CalendarMonth(year: day.year, month: day.month)
diff --git a/Packages/XStatsKit/Tests/XStatsUITests/CalendarEnhancementTests.swift b/Packages/XStatsKit/Tests/XStatsUITests/CalendarEnhancementTests.swift
index 737429f..0b04de6 100644
--- a/Packages/XStatsKit/Tests/XStatsUITests/CalendarEnhancementTests.swift
+++ b/Packages/XStatsKit/Tests/XStatsUITests/CalendarEnhancementTests.swift
@@ -130,15 +130,92 @@ struct CalendarEnhancementTests {
         #expect(allDay.timeLabel(on: nextDay, calendar: calendar) == tr("全天"))
     }
 
-    @Test func refreshingUnchangedAuthorizationDoesNotRestartTheQuery() {
+    @Test func refreshingUnchangedAuthorizationDoesNotRestartTheQuery() async throws {
         let agenda = CalendarAgendaController()
         let before = agenda.revision
         // 打开面板、应用激活都会调用；授权没变时不能改动查询的 id，否则刚开始的查询会被取消重来
         agenda.refreshAuthorization()
         agenda.refreshAuthorization()
         #expect(agenda.revision == before)
-        agenda.storeChanged()
+        for _ in 0..<100 { agenda.storeChanged() }
+        #expect(agenda.revision == before, "a burst of store notifications should be coalesced")
+        for _ in 0..<30 {
+            if agenda.revision != before { break }
+            try await Task.sleep(for: .milliseconds(100))
+        }
         #expect(agenda.revision == before + 1, "calendar content changes must trigger a reload")
+        agenda.storeChanged()
+        agenda.clear()
+        try await Task.sleep(for: .milliseconds(500))
+        #expect(agenda.revision == before + 1, "closing the panel must cancel scheduled refreshes")
+    }
+
+    @Test func repeatedMonthCalculationReusesStorageAndInvalidatesForCalendarChanges() throws {
+        let first = CalendarEngine.month(year: 2026, month: 9, firstWeekday: 2, timeZone: zone)
+        let repeated = CalendarEngine.month(year: 2026, month: 9, firstWeekday: 2, timeZone: zone)
+        // 两份结果同时存活：共享 CoW 存储证明测量视图和实际视图没有再次生成 42 天数据。
+        first.withUnsafeBufferPointer { a in
+            repeated.withUnsafeBufferPointer { b in #expect(a.baseAddress == b.baseAddress) }
+        }
+        let sunday = CalendarEngine.month(year: 2026, month: 9, firstWeekday: 1, timeZone: zone)
+        #expect(sunday.first?.id == "2026-08-30")
+        let utc = CalendarEngine.month(year: 2026, month: 9, firstWeekday: 2, timeZone: TimeZone(secondsFromGMT: 0)!)
+        #expect(utc.map(\.id) == first.map(\.id))
+        #expect(utc.first?.date != first.first?.date)
+        #expect(CalendarEngine.month(year: 2026, month: 10, firstWeekday: 2, timeZone: zone).first?.id == "2026-09-28")
+        let evicted = CalendarEngine.month(year: 2026, month: 9, firstWeekday: 2, timeZone: zone)
+        #expect(evicted == first)
+        first.withUnsafeBufferPointer { a in
+            evicted.withUnsafeBufferPointer { b in #expect(a.baseAddress != b.baseAddress) }
+        }
+    }
+
+    @Test(arguments: [3, 11])
+    func agendaMarkersMatchEventSemanticsAcrossDST(month: Int) throws {
+        let zone = try #require(TimeZone(identifier: "America/Los_Angeles"))
+        let calendar = CalendarEngine.gregorian(timeZone: zone)
+        let start = try #require(calendar.date(from: DateComponents(year: 2026, month: month, day: 1)))
+        let end = try #require(calendar.date(byAdding: .day, value: 42, to: start))
+        let query = CalendarAgendaQuery(start: start, end: end, events: true, reminders: true,
+                                       eventIDs: nil, reminderIDs: nil, revision: 0, timeZone: zone)
+        // 覆盖跨月、跨午夜、零时长、提醒、结束边界及窗口外数据，与旧逐日判断逐一对照。
+        for offset in [-10, -1, 0, 7, 8, 30, 41, 42, 50] {
+            let date = try #require(calendar.date(byAdding: .day, value: offset, to: start))
+            for duration in [-3600.0, 0, 3600, 86_400, 4_000_000] {
+                for reminder in [false, true] {
+                    let item = CalendarAgendaItem(id: "test", title: "", source: "", start: date,
+                                                 end: date.addingTimeInterval(duration), isAllDay: false, isReminder: reminder)
+                    let result = CalendarAgendaResult(items: [item], query: query)
+                    for dayIndex in 0..<42 {
+                        let day = try #require(calendar.date(byAdding: .day, value: dayIndex, to: start))
+                        #expect(result.markedDays.contains(day) == item.occurs(on: day, calendar: calendar))
+                    }
+                    #expect(result.markedDays.count <= 42)
+                    #expect(result.markedDays.allSatisfy { $0 >= start && $0 < end })
+                }
+            }
+        }
+    }
+
+    @Test(arguments: [("America/Havana", 2026, 3, 7), ("America/Sao_Paulo", 2018, 11, 3)])
+    func agendaMarkersRemainAtDayStartAfterMidnightDST(_ sample: (String, Int, Int, Int)) throws {
+        let zone = try #require(TimeZone(identifier: sample.0))
+        let calendar = CalendarEngine.gregorian(timeZone: zone)
+        // 每个日期独立求日界线，不能沿用待测算法按前一天的小时递增。
+        let days = try (0..<5).map { offset in
+            let noon = try #require(calendar.date(from: DateComponents(year: sample.1, month: sample.2,
+                                                                      day: sample.3 + offset, hour: 12)))
+            return calendar.startOfDay(for: noon)
+        }
+        #expect(calendar.component(.hour, from: days[1]) == 1)
+        #expect(calendar.component(.hour, from: days[2]) == 0)
+        let query = CalendarAgendaQuery(start: days[0], end: days[4], events: true, reminders: false,
+                                       eventIDs: nil, reminderIDs: nil, revision: 0, timeZone: zone)
+        let item = CalendarAgendaItem(id: "midnight-dst", title: "", source: "", start: days[0],
+                                     end: days[4], isAllDay: true, isReminder: false)
+        let result = CalendarAgendaResult(items: [item], query: query)
+        #expect(result.markedDays == Set(days.prefix(4)))
+        #expect(!result.markedDays.contains(days[4]), "event end remains exclusive")
     }
 
     @Test func holidayPlanCacheStillFollowsDayAndTimeZone() throws {