diff --git a/packages/api/src/__tests__/notification-router.test.ts b/packages/api/src/__tests__/notification-router.test.ts
index 49427f5..1d4679f 100644
--- a/packages/api/src/__tests__/notification-router.test.ts
+++ b/packages/api/src/__tests__/notification-router.test.ts
@@ -336,6 +336,45 @@ describe("notification.createBroadcast", () => {
     );
   });
 
+  it("rejects broadcasts with no recipients before opening a broadcast transaction", async () => {
+    resolveRecipientsMock.mockResolvedValue([]);
+
+    const txCreateBroadcast = vi.fn();
+    const txUpdateBroadcast = vi.fn();
+    const tx = {
+      notificationBroadcast: {
+        create: txCreateBroadcast,
+        update: txUpdateBroadcast,
+      },
+    };
+    const transaction = vi.fn(async (callback: (db: typeof tx) => Promise<unknown>) => callback(tx));
+    const create = vi.fn();
+    const update = vi.fn();
+    const db = {
+      $transaction: transaction,
+      notificationBroadcast: {
+        create,
+        update,
+      },
+    };
+
+    const caller = createManagerCaller(db);
+
+    await expect(caller.createBroadcast({
+      title: "Ops update",
+      targetType: "all",
+    })).rejects.toMatchObject({
+      code: "BAD_REQUEST",
+      message: "No recipients matched the broadcast target.",
+    });
+
+    expect(transaction).not.toHaveBeenCalled();
+    expect(create).not.toHaveBeenCalled();
+    expect(update).not.toHaveBeenCalled();
+    expect(txCreateBroadcast).not.toHaveBeenCalled();
+    expect(txUpdateBroadcast).not.toHaveBeenCalled();
+  });
+
   it("rejects scheduled broadcasts when no recipients match the target", async () => {
     resolveRecipientsMock.mockResolvedValue([]);
 
@@ -1103,6 +1142,7 @@ describe("notification.updateTaskStatus", () => {
       where: {
         id: "task_1",
         OR: [{ userId: "user_1" }, { assigneeId: "user_1" }],
+        category: { in: ["TASK", "APPROVAL"] },
       },
     });
     expect(update).toHaveBeenCalledWith({
@@ -1138,11 +1178,87 @@ describe("notification.updateTaskStatus", () => {
 
     expect(db.notification.update).toHaveBeenCalledWith({
       where: { id: "task_2" },
-      data: { taskStatus: "IN_PROGRESS" },
+      data: {
+        taskStatus: "IN_PROGRESS",
+        completedAt: null,
+        completedBy: null,
+      },
     });
     expect(emitTaskStatusChanged).toHaveBeenNthCalledWith(1, "user_1", "task_2");
     expect(emitTaskStatusChanged).toHaveBeenNthCalledWith(2, "user_3", "task_2");
   });
+
+  it("clears completion metadata when reopening a completed task", async () => {
+    const db = withUserLookup({
+      notification: {
+        findFirst: vi.fn().mockResolvedValue({
+          id: "task_3",
+          userId: "user_1",
+          assigneeId: "user_3",
+          taskStatus: "DONE",
+          completedAt: new Date("2026-04-01T10:00:00Z"),
+          completedBy: "user_2",
+        }),
+        update: vi.fn().mockResolvedValue({
+          id: "task_3",
+          taskStatus: "OPEN",
+          completedAt: null,
+          completedBy: null,
+        }),
+      },
+    });
+
+    const caller = createProtectedCaller(db);
+    const result = await caller.updateTaskStatus({ id: "task_3", status: "OPEN" });
+
+    expect(result).toMatchObject({
+      id: "task_3",
+      taskStatus: "OPEN",
+      completedAt: null,
+      completedBy: null,
+    });
+    expect(db.notification.update).toHaveBeenCalledWith({
+      where: { id: "task_3" },
+      data: {
+        taskStatus: "OPEN",
+        completedAt: null,
+        completedBy: null,
+      },
+    });
+    expect(emitTaskStatusChanged).toHaveBeenNthCalledWith(1, "user_1", "task_3");
+    expect(emitTaskStatusChanged).toHaveBeenNthCalledWith(2, "user_3", "task_3");
+    expect(emitTaskCompleted).not.toHaveBeenCalled();
+  });
+
+  it("rejects task status updates for non-task notifications", async () => {
+    const findFirst = vi.fn().mockResolvedValue(null);
+    const update = vi.fn();
+    const db = withUserLookup({
+      notification: {
+        findFirst,
+        update,
+      },
+    });
+
+    const caller = createProtectedCaller(db);
+    await expect(caller.updateTaskStatus({ id: "notif_info_1", status: "DONE" })).rejects.toMatchObject(
+      {
+        code: "NOT_FOUND",
+        message: "Task not found or you do not have permission",
+      },
+    );
+
+    expect(findFirst).toHaveBeenCalledWith({
+      where: {
+        id: "notif_info_1",
+        OR: [{ userId: "user_1" }, { assigneeId: "user_1" }],
+        category: { in: ["TASK", "APPROVAL"] },
+      },
+    });
+    expect(update).not.toHaveBeenCalled();
+    expect(emitTaskCompleted).not.toHaveBeenCalled();
+    expect(emitTaskStatusChanged).not.toHaveBeenCalled();
+  });
 });
 
 describe("notification.assignTask", () => {
diff --git a/packages/api/src/router/notification-task-procedure-support.ts b/packages/api/src/router/notification-task-procedure-support.ts
index ab664f4..acc3cca 100644
--- a/packages/api/src/router/notification-task-procedure-support.ts
+++ b/packages/api/src/router/notification-task-procedure-support.ts
@@ -131,6 +131,7 @@ export async function updateNotificationTaskStatus(
     where: {
       id: input.id,
       OR: [{ userId }, { assigneeId: userId }],
+      category: { in: ["TASK", "APPROVAL"] },
     },
   });
 
@@ -146,7 +147,9 @@ export async function updateNotificationTaskStatus(
     where: { id: input.id },
     data: {
       taskStatus: input.status,
-      ...(isCompleting ? { completedAt: new Date(), completedBy: userId } : {}),
+      ...(isCompleting
+        ? { completedAt: new Date(), completedBy: userId }
+        : { completedAt: null, completedBy: null }),
     },
   });