PastedTextAttachment

A chip for a large paste that was collapsed out of the composer. It looks like a file attachment, shows Pasted text #1 and the line count, opens a read-only preview on click and has a remove button when onRemove is set. InputBar does this automatically: pastes at or above pasteCollapseThreshold (10,000 characters or 50 lines by default, false to turn off) become a [Pasted text #N] placeholder plus this chip, and onSend receives the expanded text. Render the chip yourself only in a custom composer, together with the helpers shouldCollapsePaste, insertPastePlaceholder, expandPastedText, prunePastes, removePastePlaceholder and formatPasteLabel.