Server-sent rich messages can arrive partial (RichMessage isPartial ->
instantPage.isComplete == false). The bubble renders the partial page with
an inline "Show more" link; tapping it fetches the full page once and
expands in place.
- RichTextMessageAttribute keeps the partial instantPage and gains an
optional fullInstantPage, filled by engine.messages.requestFullRichText
via transaction.updateMessage. The seed-config merge preserves a fetched
fullInstantPage across later server updates.
- ChatMessageRichDataBubbleContentNode: node-local, per-message expand
state (collapsed on every fresh display, even when fullInstantPage is
already cached); renders (expanded ? fullInstantPage : nil) ?? instantPage;
gates the link on !expanded && !isComplete (+ not streaming, Cloud-only,
not preview/messageOptions); expand state threaded through both layout
caches; shimmer while fetching (instant when cached); bubble grows
downward on expand via setInvertOffsetDirection.
- New localized string Chat.RichText.ShowMore; docs in
docs/instantpage-richtext.md.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
