Ok, thanks for that.
So these are the conditions under which a full rebuild is supposed to occur:
So, that leave the possibility of a bug (there was one around ‘build’ seemingly working ok, but sequential uploads triggering full rebuilds) . There has been mention of the suspicion that the version of python may have some impact, but if you’re using the current version of PIO with the current PIO VSCode extension I’m pretty sure that issue should be resolved. I seem to remember mention that that with mbed full rebuilds happen for another reason by design, but I can’t put my finger on that thread at the moment.