This is great! Very similar to “The Null Pointer” – https://0x0.st.
Nice work. I think there’s something to be said for small programs that solve a simple problem and are easy to fit into other systems. I’ve been meaning write something very similar to this but using content-addressable storage. (Instead of a random filename, each image or blob is named after a hash of its content). That of course slows the whole thing down a lot but for the applications I have in mind, that’s a fair trade-off.