ElementChoices says what a new list element, dictionary value or union
pick may be (a union's declared subtypes, or the slot type itself), and
CreateElement makes one or returns a notice when a subtype has no
parameterless constructor. It replaces CreateUnionValue, whose throw the
IMGUI caught and sent to the console. A dictionary with a union value
type now offers the subtypes too instead of adding a null value.
NarrowInteger clamps an integer edit to its type's range; the IMGUI no
longer converts and swallows overflow itself. IMGUI renders the model's
answers and shows its notices.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>