diff --git a/Normal/Services/DeviceActivityScheduleFactory.swift b/Normal/Services/DeviceActivityScheduleFactory.swift
index f7ad21d..a057c16 100644
--- a/Normal/Services/DeviceActivityScheduleFactory.swift
+++ b/Normal/Services/DeviceActivityScheduleFactory.swift
@@ -20,6 +20,14 @@ enum DeviceActivityScheduleFactory {
         )
     }
 
+    static func heartbeat() -> DeviceActivitySchedule {
+        DeviceActivitySchedule(
+            intervalStart: DateComponents(minute: 0, second: 0),
+            intervalEnd: DateComponents(minute: 30, second: 0),
+            repeats: true
+        )
+    }
+
     static func daily(resetMinutes: Int, warningMinutes: Int) -> DeviceActivitySchedule {
         let startSeconds = resetMinutes * 60
         let endSeconds = (startSeconds - 1 + 86400) % 86400
diff --git a/Normal/Services/TimedUnblockService.swift b/Normal/Services/TimedUnblockService.swift
index 4ea45eb..ddc9377 100644
--- a/Normal/Services/TimedUnblockService.swift
+++ b/Normal/Services/TimedUnblockService.swift
@@ -271,6 +271,23 @@ final class TimedUnblockService {
             during: schedule,
             events: [:]
         )
+        startHeartbeat()
+    }
+
+    private func startHeartbeat() {
+        try? activityCenter.startMonitoring(
+            DeviceActivityName(SharedConstants.reblockHeartbeatActivityName),
+            during: DeviceActivityScheduleFactory.heartbeat(),
+            events: [:]
+        )
+    }
+
+    private func syncHeartbeat() {
+        if sharedStore.loadTimedUnblocks().isEmpty {
+            activityCenter.stopMonitoring([DeviceActivityName(SharedConstants.reblockHeartbeatActivityName)])
+        } else {
+            startHeartbeat()
+        }
     }
 
     func refresh(screenTimeService: any ScreenTimeProviding) {
@@ -299,6 +316,7 @@ final class TimedUnblockService {
                 sharedStore.removeTimedUnblock(id: unblock.id)
             }
         }
+        syncHeartbeat()
     }
 
     private func reapplyShield(
diff --git a/NormalMonitor/NormalMonitor.swift b/NormalMonitor/NormalMonitor.swift
index 19ae551..f421a1f 100644
--- a/NormalMonitor/NormalMonitor.swift
+++ b/NormalMonitor/NormalMonitor.swift
@@ -12,6 +12,7 @@ final class NormalMonitor: DeviceActivityMonitor {
     private static let scheduleStartToleranceSeconds: TimeInterval = 60
 
     override func intervalDidStart(for activity: DeviceActivityName) {
+        reblockExpiredUnblocks()
         let name = activity.rawValue
         if name == SharedConstants.usageLimitsActivityName {
             sharedStore.resetUsageDayIfStale()
@@ -23,6 +24,7 @@ final class NormalMonitor: DeviceActivityMonitor {
     }
 
     override func intervalDidEnd(for activity: DeviceActivityName) {
+        reblockExpiredUnblocks()
         let name = activity.rawValue
         if name.hasPrefix("timedUnblock_") {
             handleTimedUnblockExpired(activityName: name)
@@ -35,6 +37,7 @@ final class NormalMonitor: DeviceActivityMonitor {
         _ event: DeviceActivityEvent.Name,
         activity _: DeviceActivityName
     ) {
+        reblockExpiredUnblocks()
         guard let limit = credibleUsageLimit(eventName: event.rawValue, minutes: \.minutesPerDay) else { return }
         sharedStore.recordUsageState(.reached, for: limit.id)
         limitStore.syncDailyLimits(from: sharedStore)
@@ -44,6 +47,7 @@ final class NormalMonitor: DeviceActivityMonitor {
         _ event: DeviceActivityEvent.Name,
         activity _: DeviceActivityName
     ) {
+        reblockExpiredUnblocks()
         guard let limit = credibleUsageLimit(
             eventName: event.rawValue,
             minutes: { $0.minutesPerDay - SharedConstants.usageLimitWarningMinutes }
@@ -69,10 +73,20 @@ final class NormalMonitor: DeviceActivityMonitor {
         return limit
     }
 
+    private func reblockExpiredUnblocks() {
+        let now = Date.now
+        for dto in sharedStore.loadTimedUnblocks() where dto.endDate <= now {
+            reblock(dto)
+        }
+    }
+
     private func handleTimedUnblockExpired(activityName: String) {
-        guard let dto = sharedStore.findTimedUnblock(activityName: activityName),
-              let selection = try? FamilyActivitySelection.fromData(dto.selectionData)
-        else { return }
+        guard let dto = sharedStore.findTimedUnblock(activityName: activityName) else { return }
+        reblock(dto)
+    }
+
+    private func reblock(_ dto: TimedUnblockDTO) {
+        guard let selection = try? FamilyActivitySelection.fromData(dto.selectionData) else { return }
 
         let domains = gatedDomains(dto.customDomains)
         let allowing = activeSchedules(shouldBlock: false)
diff --git a/NormalTests/Services/TimedUnblockServiceTests.swift b/NormalTests/Services/TimedUnblockServiceTests.swift
index 3ac63ca..c7f0010 100644
--- a/NormalTests/Services/TimedUnblockServiceTests.swift
+++ b/NormalTests/Services/TimedUnblockServiceTests.swift
@@ -32,7 +32,10 @@ struct TimedUnblockServiceTests {
         )
 
         #expect(screenTime.removeShieldOnAllCalled)
-        #expect(activity.startCalls.count == 1)
+        #expect(activity.startCalls.map(\.name.rawValue) == [
+            SharedConstants.mainTimedUnblockActivityName,
+            SharedConstants.reblockHeartbeatActivityName,
+        ])
         #expect(store.timedUnblocks.count == 1)
         #expect(service.isMainUnblockActive)
     }
@@ -50,7 +53,10 @@ struct TimedUnblockServiceTests {
         )
 
         #expect(screenTime.removeFromShieldsCalled)
-        #expect(activity.startCalls.count == 1)
+        #expect(activity.startCalls.map(\.name.rawValue) == [
+            SharedConstants.groupTimedUnblockActivityName(for: groupId),
+            SharedConstants.reblockHeartbeatActivityName,
+        ])
         #expect(store.timedUnblocks.count == 1)
         #expect(service.isGroupUnblockActive(groupId: groupId))
     }
@@ -327,6 +333,39 @@ struct TimedUnblockServiceTests {
         #expect(store.timedUnblocks.count == 1)
     }
 
+    @Test func heartbeatRepeatsEveryHalfHour() {
+        let heartbeat = DeviceActivityScheduleFactory.heartbeat()
+        #expect(heartbeat.intervalStart == DateComponents(minute: 0, second: 0))
+        #expect(heartbeat.intervalEnd == DateComponents(minute: 30, second: 0))
+        #expect(heartbeat.repeats)
+    }
+
+    @Test func reconcileStopsHeartbeatOnceNoUnblocksRemain() {
+        let (service, activity, store) = makeService()
+        store.timedUnblocks = [expiredMainDTO()]
+
+        service.reconcile(screenTimeService: FakeScreenTimeService())
+
+        #expect(activity.stopCalls.last == [DeviceActivityName(SharedConstants.reblockHeartbeatActivityName)])
+        #expect(!activity.startCalls.map(\.name.rawValue).contains(SharedConstants.reblockHeartbeatActivityName))
+    }
+
+    @Test func reconcileRegistersHeartbeatWhileUnblocksArePending() throws {
+        let (service, activity, store) = makeService()
+        store.timedUnblocks = try [TimedUnblockDTO(
+            id: TimedUnblockService.mainID,
+            selectionData: FamilyActivitySelection().toData(),
+            endDate: .now.addingTimeInterval(.hours(1)),
+            activityName: SharedConstants.mainTimedUnblockActivityName,
+            isGroupUnblock: false
+        )]
+
+        service.reconcile(screenTimeService: FakeScreenTimeService())
+
+        #expect(activity.startCalls.last?.name.rawValue == SharedConstants.reblockHeartbeatActivityName)
+        #expect(activity.startCalls.last?.schedule == DeviceActivityScheduleFactory.heartbeat())
+    }
+
     @Test func reconcileReblocksUnblockThatExpiredWhileAppWasDead() {
         let store = FakeSharedStore()
         store.timedUnblocks = [expiredMainDTO()]
diff --git a/Shared/SharedConstants.swift b/Shared/SharedConstants.swift
index b92fe54..5bd9c85 100644
--- a/Shared/SharedConstants.swift
+++ b/Shared/SharedConstants.swift
@@ -32,6 +32,8 @@ nonisolated enum SharedConstants {
 
     static let usageLimitsActivityName = "usageLimits_daily"
 
+    static let reblockHeartbeatActivityName = "reblockHeartbeat"
+
     static let usageLimitWarningMinutes = 3
 
     private static let usageEventPrefix = "usage_"