Uh.... Have you tried Fish? Or even a modern ZSH? Like oh my ZSH?

I guess I don't want notepad tools. But I can set my key bindings in ZSH to vi bindings and do things like:

$ cat <<EOF | sparql --data=some.ttl --query=/dev/stdin
SELECT ?s ?p ?o
WHERE {
  ?s ?p ?o . 
} 
LIMIT 10
EOF

And that gives me a real basic text editor. Granted with syntax highlighting on, it thinks I'm trying to do ZSH scripts. But if you needed a ZSH script it would be perfect.

Second, tab works great for auto complete, it even suggests stuff (as long as you have that enabled, or the command supports it. Some clis do not have support for auto complete, but the shell does)

Modern shells are pretty fucking awesome.