Control what a pasted link reveals

When someone pastes an artifact URL into Slack, iMessage, or anywhere that unfurls links, the chat app shows a preview card. For gated artifacts you decide what that card says from the Link preview card: generic (the platform card — the default), title (just the name), custom (a title and description you write, optionally with the preview image), or full (lifted from the page itself). Anything above generic is visible to anyone with the URL — no sign-in needed. Each share link can override the level in either direction. Chat apps cache one card per URL, so already-posted messages keep the card they got.