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NotificationVM

When To Use It

Use NotificationVM when a host wants to render pending notifications from INotificationHub as bindable view state with auto-dismiss timing.

This is a render-side VM, not the notification hub itself. In C#, the shipped type lives in the VMx.Notifications package/namespace rather than the core VMx assembly.

Shape And Ownership

NotificationVM wraps one Notification value and owns:

  • lifespan and remaining time
  • derived opacity
  • resolved state
  • dismiss command that resolves through the hub

It is usually created by a higher-level notifications list VM that subscribes to INotificationHub.Pending.

Lifecycle And Messaging

The hub still owns the source notification state. NotificationVM adds the render-time lifecycle:

  • timer starts at construction
  • timer expiry resolves with Approve
  • manual dismiss resolves immediately and cancels the timer
  • external hub resolution updates IsResolved
  • dispose tears down timer and subscriptions

Cross-Language Surface

Concept C# Python TypeScript Swift
Type NotificationVM NotificationVM NotificationVM NotificationVM
Lifespan default 60 s 60 s 60 s 60 s
Dismiss command DismissCommand dismiss_command dismissCommand dismissCommand

Example

The Notes Workspace notifications feature projects pending notifications into render VMs:

Those VMs subscribe to Pending, build a bounded visible list, and let each NotificationVM manage its own fade and dismissal timing.

var vm = new NotificationVM(n, _notificationHub, _scheduler, _lifespan);
_map[n] = vm;
_visible.Add(vm);

vm = NotificationVM(
    notification=n,
    hub=self._notification_hub,
    scheduler=self._scheduler,
    lifespan=self._lifespan,
)
self._map[n] = vm
self._visible.append(vm)

const vm = new NotificationVM(
  n,
  this.#notificationHub,
  this.#scheduler,
  this.#lifespanMs,
);
this.#map.set(n, vm);
this.#visible.push(vm);

let lifespan = _lifespan ?? 60.0
let vm = NotificationVM(
    notification: n,
    hub: _notificationHub,
    scheduler: _scheduler,
    lifespan: lifespan
)
_map[key] = vm
_visible.append(vm)

Common Pitfalls

  • Treating the render VM as the source of truth. The hub owns pending state.
  • Forgetting to inject a deterministic scheduler in tests.
  • Using NotificationVM for prompts that require explicit approve/reject actions. That is ConfirmationVM.