Earlier quoted context omitted.
I had the same thing happen to me a couple times. Long and tiring process. Blackboard, make a project, lots of dirty laundry about "long gone incompetent developers" that made the current system a giant mess. Lots of red flags but lots of promises including a large maximum salary, including bonuses and stock options. The final offer, however, was 60% of my current pay. Lower than the average for someone with my exper…
Rule number 1, IMO, never discuss salary. I find listing your salary requirements before starting a process weeds out a lot of silly interviews. If you know your worth and have a goal for your salary, it is the most effective way I know to avoid dumb offers.
My non-negotiable requirement was 20% more than I was getting. I gave a hard number and they said "yeah we can give that" before the interview.
However the recruiter just assumed I was bluffing and went ahead with that colossal waste of time.