createForwardedAsyncState

Description#

Wraps a changing source of async state in a stable CngxAsyncState façade.

A component that receives its state through an Input cannot publish that object through CNGX_STATEFUL directly: the token is resolved once when a bridge injects it, while the input can be rebound or absent. Capturing the object would hand the bridge a stale state - or undefined before the first binding.

This returns one object whose every member is a computed() that reads the source on each access, so bridges observe transitions of whatever is bound right now. With nothing bound it reports a quiet idle state rather than throwing, which is what lets a bridge sit inside a timeline that has not been given a state yet.

Contrast the select family, which provides CNGX_STATEFUL with useFactory over a concrete commitState field - no forwarding needed there, because the state is created by the component rather than passed in. The split is not about the component, it is about where the state is born: created locally, capture it; arriving through an Input, forward it.

readonly asyncState = createForwardedAsyncState(this.state);

// providers:
{ provide: CNGX_STATEFUL, useFactory: () => ({ state: inject(Host).asyncState }) }