[Bug] Built-in claude_design MCP server returns 404 on every session

Bug Description
Built-in claude_design MCP server (dynamic scope) fails on every session: Streamable HTTP error: 404 page not found POSTing to https://api.anthropic.com/v1/design/mcp. The endpoint returns 404. Not user-configurable — can't be removed (Cannot remove MCP server from scope: dynamic) and /mcp auth doesn't apply since it's a 404, not an auth failure.

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.1.181
• Feedback ID: a0b7a97c-93b9-4222-b2be-6d0aa73b6ff9

Errors

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