I figure they'll tell me if I'm not free to leave, at which point I submit to arrest and say, "I want my lawyer.", and practice KYBMS.
In your earlier post you said you would say you prefer not to chat and walk away.
I'm not so sure that's such a good idea anymore. While a distinguished looking fella your age might be able to do that confident he'll only be told to stay, we've already got reports on this forum of police being deliberately deceptive, telling an OCer he wasn't being detained, but then telling the OCer he wasn't free to leave.
The last thing I'm going to do is give a cop an excuse to lay hands on me, and maybe prone me out. It is plain some cops have moved in the direction of seeming to make an encounter consensual in order to lull the detainee into talking, strengthening the cop's 4A position that even though he had reasonable articulable suspicion (RAS) for a detention, the target divulged the information consensually. Lets face it, when was the last time anybody heard a cop announce at the outset that he was detaining somebody? It has been in the cop's interest to keep the issue foggy at the outset.
Deliberately pretending a consensual encounter when he considers he has RAS is only a tiny refinement. No way I'm going to risk being proned-out by walking away.
I favor much more the tactic of telling the police at the outset, "No offense, officer. I know you're just doing your job. But, I do not consent to an encounter with you." A federal judge in (MD?) recently advocated that very tactic in his/her dissent after I'd been recommending it for a few years now. By refusing consent to the encounter itself at the outset, I put the 4A legal ball back in the cop's court. Now, he
must play that ball. He either has to let me go, or commit to a detention. The next words out of his mouth tell me all I need to know. If he says anything other than "have a nice day, sir", then I just assume I am detained.