Flash memory endurance

Since the flash memory endurance is limited to 10000 cycles and there is no counter registry inside the MCU to keep count of how many time a sketch is loaded, in order to estimate remaining board life, how about to introduce a counter handled by bootloader (or something like this) to keep trace of total programming cycle?
Of course this counter should be accessible bay the sketch code...

Start by investigating how the bootloader programs flash memory and how sketch code could access persistent state on the MCU. Determine whether a programming-cycle counter can be stored without undermining flash endurance, and define how its value would be exposed to sketches. Done would require an agreed design and implementation path for tracking and reading the total programming cycles.

Written by the indexing model from the issue text.