"Plugable" or "pluggable"

When it comes to programming copy edits, there are lots of words that would otherwise be thrown out or replaced.

Hive uses a plugable design.

Should that be plugable or pluggable?

If the paragraph were talking about the Java language, I'd say pluggable, but a search for Hive and plugable has more hits than Hive and pluggable. That doesn't make them right.

The "proper" use definitely seems to be pluggable, based on a dictionary entry and NGram:

Plugable does appear in some mainstream publications such as this one.

Interestingly, the earliest use seems to be a book from IBM written in 1942! Some kind of typewriter thing, it looks like?

The OED has only pluggable alone, dating from 1930. It does not attest plugable.

Based on the existing models of beggable and diggable, huggable and luggable, pluggable seems to be the more likely spelling by far.

The only counterexample the OED attests is the rare legable, meaning heritable (as opposed to something which is entailed).