.mcpb files show a blank document icon in Finder — dxt.icns missing from Claude.app

[viljamilaurila]

Describe the bug
Downloaded .mcpb files show a blank generic document icon in Finder on macOS. Claude.app registers the "Desktop Extension" document type (extensions dxt and mcpb) with CFBundleTypeIconFile = dxt.icns, but that file is not in the app bundle: Claude.app/Contents/Resources contains only electron.icns. Finder therefore has no icon to show. Extension authors can't work around this from the bundle side, since Finder icons come from the handling app, not the file.

To Reproduce

1. Download any .mcpb, e.g. https://github.com/viljamilaurila/html-cloud/releases/download/mcp-v0.3.0/html-cloud.mcpb
2. Look at it in Finder or on the Desktop: blank document icon.
3. Run plutil -p /Applications/Claude.app/Contents/Info.plist | grep -B3 -A4 mcpb → shows CFBundleTypeIconFile => dxt.icns
4. Run ls /Applications/Claude.app/Contents/Resources/*.icns → only electron.icns
5. Run mdls -name kMDItemContentType <file>.mcpb → a dynamic UTI (dyn.ah62d4rv4ge80425uqk), no declared type

Expected behavior
The .mcpb shows a Claude or extension icon in Finder, like other document types associated with an app.

Logs
Claude Desktop 1.46388.4, macOS 26.6.2.
Info.plist excerpt:
CFBundleTypeExtensions => ["dxt", "mcpb"]
CFBundleTypeIconFile => "dxt.icns"
CFBundleTypeName => "Desktop Extension"
CFBundleTypeRole => "Viewer"

Additional context
The fix is presumably to ship dxt.icns in the app bundle, and ideally an exported UTI declaration for .mcpb so Spotlight and Quick Look recognise the type. The icon field in manifest.json works fine inside the Extensions list; this is only about the file as it sits on disk before install.