it seem kicad do remove older auto saved zip files after some time. is it possible to protect this from happen, to be able to save all auto backup files and handle eventual delete by manual?
You could try setting a very high number for maximums:
thanks that’s also good, almost as good as never delete anything.
I would suggest using a version control system like git…
what is that you mean?
Many user create a git or other VCS repository for a KiCad project and commit changes there. It can be local only, then it works as an annotated file history without a bunch of zip files. But if it’s pushed into a server, it works also as a remote backup – and possibly even as a way to sync with different machines or to collaborate (although in a limited way).
KiCad’s own backups are not meant for long term. It really does not make sense to have so many backups of unknown states of your project.
I’m not very good with GIT, and mostly use manually created zip files that I copy to another location. I also have notes, datasheets and more in a KiCad project, and often also firmware for an uC. KiCad does not backup those things, so you need another more robust backup strategy anyway.