Fish
nix
completion function reliably erases/writes over the shell prompt.
I also tried using asciinema rec -c "NIX_GET_COMPLETIONS=1 nix '' >/dev/null"
to see what Lix is actually printing:
[0.020591, "o", "\r\u001b[K"]
[0.021163, "o", "\r\u001b[K\r\u001b[…