# BlockNavigation

Exposes the currently blocked transition as reactive state plus an `isBlocking` projection.

## Signatures

```ts
export interface BlockNavigation extends RefSubject.Filtered<Blocking> {
    readonly isBlocking: RefSubject.Computed<boolean>;
}
```

## Why

A dialog or other UI can observe unsaved-work navigation without owning the navigation service or
coupling state to a renderer.

## Ownership and lifetime

The RefSubject and handler registration belong to the Scope that runs {@link useBlockNavigation}.
Closing that Scope cancels an outstanding block and unregisters the handler.

## Property: isBlocking

Reactively reports whether one transition awaits settlement.

## Property: isBlocking: Why

A renderer can show blocking UI without sampling or owning the Navigation service.

## Property: isBlocking: Ownership and lifetime

The blocker Scope owns this reactive member; observing it does not extend that Scope.