This is a major plot point of The Dispossessed by Le Guinn.

It looks like there is a lever that will spread open for access to the plug. ?Squeeze or twist? Those tabs might slide out of the way and then grip the cord once it’s connected.

Does CC BY-NC-SA meet your intentions?

Slackware. About 1994 or so.

If you can find a new one. They are $45+ on ebay used. None of the usual US sellers has any.