The builder composer was rebuilt. Anything you reference now shows up as a chip you can see and remove: an @file attachment, a /link to a collection in another app, or an element you clicked in the preview. No more reading back through raw text to work out what you actually attached.
The chips are real objects, not decoration. Copy a message, paste it into another chat, and the references come with it, including a linked collection that re-establishes its link on send. On mobile the @ menu now anchors above the composer instead of hiding behind the keyboard, /link works mid-sentence, and Escape closes the menu without collapsing the chat sheet.