scikit-ci-addons was initially developed in May 2016 by Omar Padron to facilitate the continuous integration of the scikit-build project.
At that time, it consisted of code directly embedded in the CI script used in scikit-build project.
Then, in early September 2016, with the desire to setup cross-platform continuous integration for other project and avoid duplication or maintenance hell, the code was factored out by Jean-Christophe Fillion-Robin into a set of reusable scripts available in the scikit-ci project. By simply cloning the repository, it was possible to more easily enable CI for other projects.
While this was an improvement, this prevented the distribution of standalone and simple scikit-ci package. To better separate concerns and facilitate testing and maintenance, in late September 2016, the scripts were moved into their own project and scikit-ci-addons was born.
Finally, in late October 2016, Jean-Christophe came up with the concept of scikit-ci-addons command line tool allowing to execute the scripts (or add-ons) distributed within the scikit-ci-addons package.