diff --git a/frontend/dashboard.css b/frontend/dashboard.css
index 45679c1..0cfd1a4 100644
--- a/frontend/dashboard.css
+++ b/frontend/dashboard.css
@@ -10,6 +10,9 @@ header { position: sticky; top: 0; z-index: 20; padding: 12px 16px; display:flex
 .app-menu > summary { display:none; }
 .app-menu-panel { display:flex; gap:10px; align-items:center; flex-wrap:wrap; }
 button { background: linear-gradient(180deg,#1f3a5f,#15324d); border:1px solid #2a496e; color:#e5e7eb; padding:8px 12px; border-radius:10px; cursor:pointer; }
+.notification-undo { position:fixed; z-index:110; left:50%; bottom:calc(88px + env(safe-area-inset-bottom)); transform:translateX(-50%); box-sizing:border-box; width:min(520px,calc(100vw - 24px)); display:flex; align-items:center; justify-content:space-between; gap:12px; padding:10px 12px; border:1px solid #60a5fa; border-radius:12px; background:#10233d; box-shadow:0 12px 36px rgba(0,0,0,.5); overflow-wrap:anywhere; }
+.notification-undo[hidden] { display:none; }
+.notification-undo button { min-height:44px; min-width:64px; flex:none; }
 .draft-capacity-sheet { position:fixed; inset:0; z-index:96; display:flex; align-items:flex-end; justify-content:center; background:rgba(5,12,21,.82); backdrop-filter:blur(4px); }
 .draft-capacity-sheet[hidden] { display:none; }
 .draft-capacity-panel { box-sizing:border-box; width:min(620px,100%); max-height:100dvh; overflow:auto; overflow-x:hidden; padding:18px; padding-bottom:calc(18px + env(safe-area-inset-bottom)); border:1px solid #b45309; border-radius:18px 18px 0 0; background:#0b1526; }
diff --git a/frontend/dashboard.js b/frontend/dashboard.js
index 3163d24..69cd98c 100644
--- a/frontend/dashboard.js
+++ b/frontend/dashboard.js
@@ -786,6 +786,15 @@
       if (state.message) qs('#update-sheet-status').textContent = state.message;
     },
   });
+  const notificationUndo = createDashboardNotificationUndo({
+    restore: requestNotificationUnread,
+    getItems: () => lastMyWork,
+    setItems: items => { lastMyWork = items; },
+    getNotifications: () => lastNotifications,
+    setNotifications: items => { lastNotifications = items; },
+    refresh: refreshMyWorkView,
+    select: qs,
+  });
   const notificationReader = createNotificationReader({
     load: fetchNotificationDetail,
     loadConversation: fetchNotificationConversation,
@@ -5034,6 +5043,9 @@
       if (result?.accepted) qs('#my-work-action-status').textContent =
         result.delivery === 'posted' ? 'Reply posted and update marked read.' :
           'Reply and read acknowledgement queued for sync.';
+      if (result?.delivery === 'posted' && result?.next) {
+        notificationUndo.offer(item, result.next.items);
+      }
     } catch (error) {
       qs('#update-reply-status').textContent = error.message + ' Your draft is safe; retry.';
       qs('#update-reply').focus();
@@ -5046,7 +5058,8 @@
   qs('#mark-update-read-next').addEventListener('click', async () => {
     qs('#mark-update-read-next').disabled = true;
     try {
-      await notificationReader.markReadAndNext(lastMyWork);
+      const result = await notificationReader.markReadAndNext(lastMyWork);
+      if (result) notificationUndo.offer(result.item, result.items);
     } finally {
       qs('#mark-update-read-next').disabled = false;
     }
@@ -5056,11 +5069,17 @@
     button.disabled = true;
     try {
       const result = await notificationReader.acknowledgeAndNext(lastMyWork);
-      if (result) qs('#my-work-action-status').textContent = 'Update acknowledged with 👍.';
+      if (result) notificationUndo.offer(result.item, result.items);
     } finally {
       button.disabled = offlineWorkMode;
     }
   });
+  qs('#undo-notification').addEventListener('click', async () => {
+    const button = qs('#undo-notification');
+    button.disabled = true;
+    const restored = await notificationUndo.run();
+    button.disabled = restored;
+  });
   qs('#close-review-sheet').addEventListener('click', closeReviewSheet);
   qs('#retry-review-load').addEventListener('click', () => {
     if (selectedReview) openReviewSheet(selectedReview, reviewTrigger);
diff --git a/frontend/index.html b/frontend/index.html
index ef3aa98..ffc6ab3 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -688,6 +688,11 @@
   </section>
 </div>
 
+<div class="notification-undo" id="notification-undo" role="status" aria-live="assertive" hidden>
+  <span id="notification-undo-status"></span>
+  <button id="undo-notification" type="button" aria-label="Undo marking update read">Undo</button>
+</div>
+
 <div class="pull-sheet" id="pull-sheet" role="dialog" aria-modal="true" aria-labelledby="pull-sheet-title">
   <section class="pull-sheet-panel">
     <div class="pull-sheet-header">
@@ -899,6 +904,7 @@
 <script src="static/offline-work.js"></script>
 <script src="static/offline-today.js"></script>
 <script src="static/my-work.js"></script>
+<script src="static/notification-undo.js"></script>
 <script src="static/card-planning.js"></script>
 <script src="static/today-work.js"></script>
 <script src="static/today-timer.js"></script>
diff --git a/frontend/my-work.js b/frontend/my-work.js
index 8bf8832..1c82bca 100644
--- a/frontend/my-work.js
+++ b/frontend/my-work.js
@@ -362,7 +362,7 @@ function createNotificationReader({
       onClose();
       onStatus('Inbox cleared.');
     }
-    return { items: updated, next: next || null };
+    return { items: updated, item: current, next: next || null };
   }
 
   async function open(item, savedDetail = null) {
diff --git a/frontend/notification-undo.js b/frontend/notification-undo.js
new file mode 100644
index 0000000..84aad36
--- /dev/null
+++ b/frontend/notification-undo.js
@@ -0,0 +1,85 @@
+function createNotificationUndo({ restore, onItems, onStatus, onOffer = () => {}, onClear = () => {} }) {
+  let offered = null;
+  let pending = false;
+
+  return {
+    offer(item, items) {
+      if (!item || !Number.isInteger(item.notification_id)) return false;
+      offered = { item, items: Array.isArray(items) ? [...items] : [] };
+      const label = item.key || 'Update';
+      onStatus(label + ' marked read. Undo?');
+      onOffer(item);
+      return true;
+    },
+    async run() {
+      if (!offered || pending) return false;
+      const current = offered;
+      const label = current.item.key || 'Update';
+      pending = true;
+      onStatus('Restoring ' + label + '…');
+      try {
+        await restore(current.item.notification_id);
+        if (offered !== current) return false;
+        const restored = [current.item].concat(current.items.filter(
+          item => item?.notification_id !== current.item.notification_id
+        ));
+        offered = null;
+        onItems(restored, current.item);
+        onStatus(label + ' is unread again.');
+        onClear();
+        return true;
+      } catch (_error) {
+        onStatus('Could not restore ' + label + '. Retry Undo.');
+        return false;
+      } finally {
+        pending = false;
+      }
+    },
+    clear() {
+      offered = null;
+      onClear();
+    },
+  };
+}
+
+async function requestNotificationUnread(notificationId) {
+  const response = await fetch('api/v1/notifications/' + encodeURIComponent(notificationId) + '/unread', {
+    method: 'PATCH', headers: { Accept: 'application/json' },
+  });
+  const payload = await response.json().catch(() => ({}));
+  if (!response.ok) throw new Error(payload.error || 'Restore unread failed.');
+  return payload;
+}
+
+function createDashboardNotificationUndo({ restore, getItems, setItems, getNotifications, setNotifications, refresh, select }) {
+  let timer = null;
+  const controller = createNotificationUndo({
+    restore,
+    onItems: (items, restored) => {
+      setItems(items);
+      const notifications = getNotifications();
+      if (!notifications.some(item => item.id === restored.notification_id)) {
+        setNotifications([{ id:restored.notification_id }].concat(notifications));
+      }
+      refresh();
+    },
+    onStatus: message => {
+      select('#notification-undo-status').textContent = message;
+      select('#my-work-action-status').textContent = message;
+    },
+    onOffer: item => {
+      clearTimeout(timer);
+      select('#notification-undo').hidden = false;
+      select('#undo-notification').disabled = false;
+      select('#undo-notification').setAttribute('aria-label', 'Undo marking ' + (item.key || 'update') + ' read');
+      timer = setTimeout(() => controller.clear(), 10000);
+    },
+    onClear: () => { select('#notification-undo').hidden = true; },
+  });
+  return controller;
+}
+
+if (typeof module !== 'undefined' && module.exports) {
+  module.exports = createNotificationUndo;
+  module.exports.createDashboardNotificationUndo = createDashboardNotificationUndo;
+}
diff --git a/frontend/service-worker.js b/frontend/service-worker.js
index 9edcab1..bc34b5d 100644
--- a/frontend/service-worker.js
+++ b/frontend/service-worker.js
@@ -32,6 +32,7 @@ const SHELL = [
   BASE + 'static/offline-work.js',
   BASE + 'static/offline-today.js',
   BASE + 'static/my-work.js',
+  BASE + 'static/notification-undo.js',
   BASE + 'static/card-planning.js',
   BASE + 'static/today-work.js',
   BASE + 'static/today-timer.js',
diff --git a/src/frontend_bundle.py b/src/frontend_bundle.py
index 01f7b3d..c9bf17e 100644
--- a/src/frontend_bundle.py
+++ b/src/frontend_bundle.py
@@ -28,7 +28,7 @@ FEATURE_SOURCES = {
     "device-setup": ("static/install-app.js", "static/mobile-device-setup.js"),
     "security-center": ("static/security-center.js",),
     "today-timer": (
-        "static/mobile-task-dock.js", "static/today-timer.js", "static/today-recap.js",
+        "static/mobile-task-dock.js", "static/notification-undo.js", "static/today-timer.js", "static/today-recap.js",
         "static/today-rollover.js", "static/drafts.js", "static/unfiled-captures.js",
         "static/draft-filing-session.js", "static/draft-capacity-dialog.js",
     ),
diff --git a/src/gitea_proxy.py b/src/gitea_proxy.py
index 4f0fd48..97a7d39 100644
--- a/src/gitea_proxy.py
+++ b/src/gitea_proxy.py
@@ -804,6 +804,14 @@ async def mark_notification_read(thread_id: int) -> None:
     response.raise_for_status()
 
 
+async def mark_notification_unread(thread_id: int) -> None:
+    response = await _get_client().patch(
+        f"/api/v1/notifications/threads/{thread_id}?to-status=unread",
+        headers=_auth(),
+    )
+    response.raise_for_status()
+
+
 async def acknowledge_notification(thread_id: int) -> dict:
     thread = await fetch(f"notifications/threads/{thread_id}")
     if not isinstance(thread, dict):
diff --git a/src/main.py b/src/main.py
index f9d88e9..51dda31 100644
--- a/src/main.py
+++ b/src/main.py
@@ -3452,6 +3452,27 @@ async def read_notification(thread_id: int = PathParam(gt=0)) -> JSONResponse:
     return JSONResponse({"id": thread_id, "status": "read"})
 
 
+@app.patch("/api/v1/notifications/{thread_id}/unread")
+async def unread_notification(thread_id: int = PathParam(gt=0)) -> JSONResponse:
+    try:
+        await asyncio.wait_for(
+            gitea_proxy.mark_notification_unread(thread_id),
+            timeout=NOTIFICATION_MUTATION_TIMEOUT_SECONDS,
+        )
+    except TimeoutError:
+        return JSONResponse(
+            {"error": "Restoring the update timed out. Retry Undo."},
+            status_code=503,
+            headers={"Retry-After": "1"},
+        )
+    except Exception:
+        return JSONResponse(
+            {"error": "The update could not be restored. Retry Undo."},
+            status_code=503,
+        )
+    return JSONResponse({"id": thread_id, "status": "unread"})
+
+
 @app.patch("/api/v1/notifications/{thread_id}/later")
 async def defer_notification(
     payload: NotificationLaterRequest,
diff --git a/tests/test_my_work.py b/tests/test_my_work.py
index 17b2bba..73fd3dc 100644
--- a/tests/test_my_work.py
+++ b/tests/test_my_work.py
@@ -9,6 +9,7 @@ from tests.dashboard_bundle import dashboard
 
 
 MY_WORK = Path(__file__).parents[1] / "frontend" / "my-work.js"
+NOTIFICATION_UNDO = Path(__file__).parents[1] / "frontend" / "notification-undo.js"
 TODAY_TIMER = Path(__file__).parents[1] / "frontend" / "today-timer.js"
 LATER_WORK = Path(__file__).parents[1] / "frontend" / "later-work.js"
 DETAIL_DEFER = Path(__file__).parents[1] / "frontend" / "detail-defer.js"
@@ -4123,6 +4124,58 @@ const reader = buildMyWork.createNotificationReader({{
     assert output["results"][1] is False
 
 
+def test_notification_undo_restores_exact_item_once_and_keeps_failure_retryable():
+    script = f"""
+const createNotificationUndo = require({json.dumps(str(NOTIFICATION_UNDO))});
+const states = [];
+const statuses = [];
+const calls = [];
+let attempts = 0;
+const item = {{kind:'update', key:'repo#7', notification_id:42, has_update:true}};
+const undo = createNotificationUndo({{
+  restore: async id => {{ calls.push(id); attempts += 1; if (attempts === 1) throw new Error('offline'); }},
+  onItems: items => states.push(items.map(value => value.notification_id)),
+  onStatus: status => statuses.push(status),
+}});
+(async () => {{
+  undo.offer(item, [{{kind:'update', notification_id:43, has_update:true}}]);
+  const first = undo.run();
+  const duplicate = undo.run();
+  const firstResults = await Promise.all([first, duplicate]);
+  const retry = await undo.run();
+  process.stdout.write(JSON.stringify({{calls, states, statuses, firstResults, retry}}));
+}})();
+"""
+    output = json.loads(subprocess.run(
+        ["node", "-e", script], check=True, capture_output=True, text=True
+    ).stdout)
+
+    assert output["calls"] == [42, 42]
+    assert output["states"] == [[42, 43]]
+    assert output["firstResults"] == [False, False]
+    assert output["retry"] is True
+    assert output["statuses"] == [
+        "repo#7 marked read. Undo?",
+        "Restoring repo#7…",
+        "Could not restore repo#7. Retry Undo.",
+        "Restoring repo#7…",
+        "repo#7 is unread again.",
+    ]
+
+
+@pytest.mark.anyio
+async def test_mobile_update_undo_is_accessible_and_safe_area_aware():
+    html = await dashboard()
+
+    assert 'id="notification-undo"' in html
+    assert 'id="undo-notification" type="button"' in html
+    assert "requestNotificationUnread" in html
+    assert "createDashboardNotificationUndo({" in html
+    assert ".notification-undo { position:fixed;" in html
+    assert "env(safe-area-inset-bottom)" in html
+    assert ".notification-undo button { min-height:44px;" in html
+
+
 @pytest.mark.anyio
 async def test_mobile_update_sheet_wires_touch_safe_online_acknowledge_and_next():
     html = await dashboard()
@@ -4401,7 +4454,9 @@ reader.open(item, [item]).then(() => {{
     )
     output = json.loads(result.stdout)
 
-    assert output["result"] == {"items": [], "next": None}
+    assert output["result"] == {"items": [], "item": {
+        "kind": "update", "notification_id": 42, "has_update": True,
+    }, "next": None}
     assert output["events"] == [
         ["status", "Marking update read…"],
         ["items", []],
diff --git a/tests/test_notification_read.py b/tests/test_notification_read.py
index 3826e91..dda6152 100644
--- a/tests/test_notification_read.py
+++ b/tests/test_notification_read.py
@@ -41,6 +41,29 @@ async def test_mark_notification_read_calls_supported_gitea_thread_endpoint(monk
     ]
 
 
+@pytest.mark.anyio
+async def test_mark_notification_unread_calls_supported_gitea_thread_endpoint(monkeypatch):
+    calls = []
+
+    class Response:
+        def raise_for_status(self):
+            return None
+
+    class Client:
+        async def patch(self, path, headers):
+            calls.append((path, headers))
+            return Response()
+
+    monkeypatch.setattr(gitea_proxy, "_get_client", lambda: Client())
+    monkeypatch.setattr(gitea_proxy, "_auth", lambda: {"Authorization": "token test"})
+
+    await gitea_proxy.mark_notification_unread(42)
+
+    assert calls == [
+        ("/api/v1/notifications/threads/42?to-status=unread", {"Authorization": "token test"})
+    ]
+
+
 @pytest.mark.anyio
 async def test_acknowledge_notification_resolves_latest_comment_and_adds_one_reaction(monkeypatch):
     calls = []
@@ -172,6 +195,26 @@ async def test_mark_notification_read_api_is_bounded_and_never_cacheable(monkeyp
     assert marked == [42]
 
 
+@pytest.mark.anyio
+async def test_mark_notification_unread_api_is_bounded_and_never_cacheable(monkeypatch):
+    restored = []
+
+    async def mark_unread(thread_id):
+        restored.append(thread_id)
+
+    monkeypatch.setattr(main.gitea_proxy, "mark_notification_unread", mark_unread, raising=False)
+    transport = httpx.ASGITransport(app=main.app)
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as client:
+        response = await client.patch("/api/v1/notifications/42/unread")
+        invalid = await client.patch("/api/v1/notifications/0/unread")
+
+    assert response.status_code == 200
+    assert response.json() == {"id": 42, "status": "unread"}
+    assert response.headers["cache-control"] == "no-store"
+    assert invalid.status_code == 422
+    assert restored == [42]
+
+
 @pytest.mark.anyio
 async def test_acknowledge_notification_api_confirms_reaction_and_removes_snapshot_item(monkeypatch):
     calls = []
diff --git a/tests/test_service_worker.py b/tests/test_service_worker.py
index 1204daa..3b2cce5 100644
--- a/tests/test_service_worker.py
+++ b/tests/test_service_worker.py
@@ -695,6 +695,7 @@ def test_install_precaches_complete_subpath_scoped_app_shell():
         "/dashboard/static/offline-work.js",
         "/dashboard/static/offline-today.js",
         "/dashboard/static/my-work.js",
+        "/dashboard/static/notification-undo.js",
         "/dashboard/static/card-planning.js",
         "/dashboard/static/today-work.js",
         "/dashboard/static/today-timer.js",