feat: return mcp ui resource for playground

[paoloricciuti]

This returns an MCP-UI resource from the playground...the advantage of this is that the user will be able to interact with the playground directly in their MCP client chat!

A few notes:

• Currently this is an extension to the MCP protocol...is fully back compatible (clients that don't support it will just show nothing) but it's pretty clear that it will probably become part of the standard (Shopify is betting heavily on it and apparently VS Code will also soon implement it) in their client.
• There are not many clients that actually supports it, but again it's fully back compatible (I tried in VS Code, and it just shows the link for the moment).

I would say it's definitely a win since waiting for the whole URL to show up is very annoying, while with this you can have IMMEDIATE feedback.

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🦋 Changeset detected

Latest commit: 7f52a2b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sveltejs/mcp	Patch

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Project	Deployment	Preview	Comments	Updated (UTC)
mcp	Ready	Preview	Comment	Oct 22, 2025 0:57am

[Rich-Harris]

This is awesome. Would be good to get rid of the rest of the site though - @dummdidumm built a version of the playground for v0 that could probably be reused here?

[paoloricciuti]

This is awesome. Would be good to get rid of the rest of the site though - @dummdidumm built a version of the playground for v0 that could probably be reused here?

You are absolutely right! (Pun semi intended). I wanted to use that actually but completely forgot...gonna update it

[paoloricciuti]

Here's how it looks now (toggled to light mode to get a better view since AI doesn't account for that) 😅