Or you could explicitly design the package so that your pre/postinstall scripts ensure that you install to a separate directory, and rename-replace the old dire

Or you could explicitly design the package so that your pre/postinstall scripts ensure that you install to a separate directory, and rename-replace the old directory, so you can’t get half-finished updates. Regarding the rest, if your code has incompatible API breaks between two patch or minor version changes, you’ll need to rethink your development model.