1) servicing WDT in an interrupt is NOT a taboo if you have a reason to do so.....
2)For example, the condition can be - WDT will only be serviced when the background code has serviced it previously

1) feding the puppy inside interrupts does defeat the purpose. There is no guarantee that interrupts will not be serviced when the codse runs away.
2) Why on earth service the watchdog in an interrupt if the background code has serviced it previously

Erik