[thesnide]

That stuff that disappears, do you have means to patch and rebuild it?

Otherwise, you're directly heading for a nasty surprise at the worst moment.

[immibis]

The build dependencies are the problem. The build process downloads them from hardcoded internet URLs and they are cached for 30 days. By backing up the cache, I can (probably) rummage around it later to find anything that's been deleted from the internet.