The viewer's own profile's actions: the bottom tab bar's way back to the
feed. Its type is written out because the feed's own tab bar opens this
screen: the registry reads both definitions, so an action type inferred from
opens would close a loop the compiler cannot break. It is the type
opens('FeedTimeline', …) yields — a tab edge whose call returns the union
of the feed tab's retained stack, which the caller narrows with is.
The viewer's own profile's actions: the bottom tab bar's way back to the feed. Its type is written out because the feed's own tab bar opens this screen: the registry reads both definitions, so an action type inferred from
openswould close a loop the compiler cannot break. It is the typeopens('FeedTimeline', …)yields — a tab edge whose call returns the union of the feed tab's retained stack, which the caller narrows withis.