[BUG] Mods: Svg with isInteractive never shows a <title> tooltip in the desktop Code tab

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

SvgProps.isInteractive is documented (claude-code types, build 2.1.293) as drawing the SVG "in a script-less sandboxed frame so hover, CSS :hover, SMIL animation and <title> tooltips work". In the desktop app's Code tab, hover and CSS do reach the frame, but a <title> never produces a tooltip.

Two probes in the same mod, both observed by hovering the bar in the Code tab:

| Added to the SVG | Observed | Rules out |
|---|---|---|
| <style>svg:hover{opacity:.3}</style> | bar dims on hover | hover not reaching the frame |
| <style>title~rect{fill:#3c3}</style> | bar turns green (no hover needed) | <title> stripped before reaching the frame |

So the <title> element is present in the frame and the frame receives hover, yet no tooltip is shown.

What Should Happen?

Hovering the Svg shows a native tooltip with the <title> text, as the isInteractive doc comment states.

Error Messages/Logs

None. No `ui.render … refused` line in the transcript; the SVG renders.

Steps to Reproduce

1. A mod with a ui.render hook on { component: 'AbovePrompt' } that returns, for the desktop surface:

<Svg
  source={'<svg xmlns="http://www.w3.org/2000/svg" width="80" height="12"><style>:root{color-scheme:light dark}</style><title>ctx 9% · compacts at 80%</title><rect y="2" width="80" height="8" rx="4" fill="#888" fill-opacity="0.25"/></svg>'}
  alt="ctx 9% · compacts at 80%"
  width={80}
  height={12}
  isInteractive
/>

1. Load it in the desktop app's Code tab (CLAUDE_CODE_PLUGIN_DIRS pointing at the plugin folder).
2. Hover the bar.

Expected: a tooltip reading ctx 9% · compacts at 80%. Actual: nothing.

(The color-scheme style is there to avoid a separate issue with the frame's backdrop, filed separately.)

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.294 (Claude Code)
Still reproduces on Claude desktop app 2.31226.1 (857652)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

The mod is public: https://github.com/zexion7873/usage-band — the attempt and the two probes are in the closed PR https://github.com/zexion7873/usage-band/pull/7. The alt text is read by a screen reader as expected; it is only the hover tooltip that is missing, so right now there is no way for a mod to show hover detail on a desktop bar.