OptionalautoOptionalchromeOpt-in window chrome (ADR 0006 D7): the close button and the ⋮ display-mode menu. The kit renders them and fires the intent callbacks below — applying the mode (resizing the panel, going fullscreen, floating an overlay) and any postMessage is the host's.
OptionaldisplayThe mode the host currently applies. Controlled: given, it wins over the kit's last pick.
OptionalonOptional host hook to clear the focused problem (context is host-declared, ADR 0004 §7); absent → the problem chip renders without a dismiss X.
OptionalonOptionalon
Scroll-follow policy (CopilotChat-shaped, ADR 0006 D1 + the Cavell 'hold-on-send' extension, which is the DEFAULT): a send shows your message once, then the answer streams in place and is read from the top. 'pin-to-bottom' follows streaming output; 'pin-to-send' jumps only when the user sends; 'none' never auto-scrolls. Boolean sugar per upstream: true → 'pin-to-bottom', false → 'none'.