# UseBlockNavigationParams

Configures the optional Effectful predicate used before a transition is blocked.

## Signatures

```ts
export interface UseBlockNavigationParams<R = never> {
    readonly shouldBlock?: (event: BeforeNavigationEvent) => Effect.Effect<boolean, RedirectError | CancelNavigation, R>;
}
```

## Why

Applications can restrict blocking to dirty forms or selected destinations while keeping that
decision in the same typed Effect environment as their state.

## Ownership and lifetime

This object acquires no resources. Its predicate runs in the Scope and captured context of
{@link useBlockNavigation}; redirects and cancellations remain typed navigation control flow.

## Property: shouldBlock

Decides Effectfully whether a proposed transition should be blocked.

## Property: shouldBlock: Why

Dirty-state checks can use services and still redirect or cancel through typed control flow.

## Property: shouldBlock: Ownership and lifetime

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