In the games industry we have a role called “tools programmer” which is a person who works on tooling to accelerate development, sometimes these can be extensio

In the games industry we have a role called “tools programmer” which is a person who works on tooling to accelerate development, sometimes these can be extensions to the editor for a specialisation for a game (say, a tyre builder for a racing game) and sometimes they can be more broad (a distribution tool using libtorrent so that a new build of the game can be shipped worldwide very quickly). There are people who might refer to you as a backend programmer (if the focus is services and daemons), or platform engineer (if the focus is developer velocity). Largely it depends what your primary focus is.