v0.13.0

Why

Anthropic is retiring the standalone Claude Design site: claude.ai/design closes on 2026-12-14, and Claude Design now lives inside Claude, where new designs, design systems and decks are Artifacts. trailhead's hosted mockup mode was built on that site (canvases made by hand or with /design, design systems driven through the claude-design MCP and DesignSync), so it had to move before the site goes away. Artifacts also make the flow simpler: Claude Code already ships the Artifact tool, so there is nothing to install and no separate login, the canvas is shareable and commentable like any other artifact, and DesignSync, which is now meant only for the user-started /design-sync skill and explicitly not for making designs, drops out of trailhead entirely.

Changed

• UI mockups move to Claude Artifacts (design: artifacts). The Prototype technique builds each mockup as a Design canvas Artifact through Claude Code's built-in Artifact tool: one canvas per map (picked, pasted or created, cached in design.project), one artboard per screen or variant grouped in a canvas page per ticket, and the design system named by the new design.system key (or the account's default) installed on the canvas so its tokens and components are at hand. Approval asks carry the canvas URL plus each artboard's name, and the approved artboards are re-read before any UI code. Screens are never pushed into a design system any more, so the DesignSync path, its MCP install offer and its manifest rules are gone; design.surface now applies to stitch only.
• Legacy claude.ai/design config keeps working. It is read as artifacts with a one-time notice and an offer to rewrite the key. A cached claude.ai/design project id can't be reused (standalone projects don't migrate on their own), so at the next mockup trailhead offers first the canvases and design systems whose name matches the repo, then the usual pick / paste / create, and drops the legacy design.surface when it writes the new keys. Where the Artifact tool is missing (Codex, API-key sessions) it offers stitch before falling to local disk.
• Website (site only; not part of the npm package). A new Design mockups guide explains the Artifacts, Stitch and disk flows, the fallbacks, and the step-by-step migration from claude.ai/design (design systems from the Artifacts page banner, project archives, chats and comments, organization settings); the Configuration page now summarises the design keys and links to it.