The create button's call, typed by the mode the caller asks for: naming a
mode answers that mode's first screen — the post gallery picker, the story
camera or the reel gallery — never a union. The app opens the creation in
the mode the account's app was last left in (lastCreationMode): when that
is the mode asked for, that mode's first screen opens directly; when it is
POST, the gallery picker's own mode selector moves it to STORY or REEL the
way a person's tap does (both moves are modelled). A move out of STORY or
REEL is not modelled and
fails with the typed PostingCreationModeNotRecordedError.
The last signature is not a call — mode: never matches nothing — and its
answer is not an Effect; it keeps the framework from flattening this
argument → screen map into one union (a member's bound type reads a single
call signature).
FeedCreationCall( mode:"__mode-map__", ):{"each creation mode answers its own first screen":true}
Not a call a caller makes: no creation mode is this string. It exists so the
framework reads this argument → screen map as a map — a member whose last
signature answers an Effect is flattened into that one surrogate; this
signature takes a mode no real call names and answers a non-Effect, so
ScreenBoundMember keeps the three overloads above intact.
Parameters
mode: "__mode-map__"
Returns {"each creation mode answers its own first screen":true}
The create button's call, typed by the mode the caller asks for: naming a mode answers that mode's first screen — the post gallery picker, the story camera or the reel gallery — never a union. The app opens the creation in the mode the account's app was last left in (
lastCreationMode): when that is the mode asked for, that mode's first screen opens directly; when it is POST, the gallery picker's own mode selector moves it to STORY or REEL theThe last signature is not a call —
mode: nevermatches nothing — and its answer is not an Effect; it keeps the framework from flattening this argument → screen map into one union (a member's bound type reads a single call signature).