When the user long-presses Send in the main chat and the composed text passes the
same rich-markdown gate used at send time (richMarkdownAttributeIfNeeded), the
send-options preview bubble renders the message as rich InstantPage content,
crossfading from the raw text as the menu animates in. Plain text and custom chat
contents / edit previews are unchanged.
ChatSendMessageActionUI cannot depend on InstantPageUI (it closes a dependency
cycle via LocationUI -> AttachmentUI -> ... -> ChatTextInputActionButtonsNode), so
the rich view is built in TelegramUI (ChatSendMessageRichTextPreview, wrapping
InstantPageV2View + the outgoing message theme) and injected into the screen via a
new ChatSendMessageContextScreenRichTextPreview protocol, mirroring the existing
media-preview pattern. The main-chat send call site classifies the compose text
and injects the preview; MessageItemView lays it out within the send-button-bounded
bubble envelope and crossfades between the raw text and the rich layout.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
