What the Linux client (in contrast to the Windows client) does not support is having virtual files in a folder and only downloading files on demand.

This is specifically what I want.

And…somehow I missed opencloud in all of my searching? I think I may have mentally combined it with OwnCloud/OCIS. It looks promising. Diving into the docs, now.

Seafile apparently obfuscates the files, which is not great. If it dies, or they pull some weird shutdown shenanigans, what happens to my files? Nexcloud, at least, is readable and organized, if (in my opinion) weird.

I thought the same thing, but I’ve spent a good chunk of time looking at every button in the linux client, and it’s just options of “sync: y/n”, with an initial choice of “do not sync if folder size is 500MB+”. And the files/folders not synced do not show up locally. The windows client lets you see everything, but only download when you open or pick “save locally”. But not on Linux.