Diagnosed: the transcript's MessageContent boxes carry overflow-hidden
(ai-elements/message.tsx) — the absolutely-positioned box rendered fine
over its own message block's content (the closing-words text under the
conclude card) and clipped the moment it crossed that block's bottom
edge onto the next message. Exactly the reported cut-off.
Fix: the box portals to document.body in fixed position (the dialogs'
law) — placed from the trigger's viewport rect at open time, below the
trigger, left-clamped to the viewport; z-50. Any-scroll-close means
there is nothing to track.