This would be in contrast to other more narrative systems where the players can author methods in which their characters could have multiple paths forward. Blades in the Dark seems to be the most popular game currently for describing that method of play.
You don't have to go that far, either. 4e skill challenges are enough, because they establish a framework in which the players can achieve a success that is binding on the GM in a finite series of action declarations.
Any system with binding conflict resolution that covers all significant sorts of action declarations will fit the bill. At the moment I'm GMing Prince Valiant and Cortex+ Heroic campaigns that fit this description, and also Classic Traveller which mostly does as well (it has a few weak spots which I carefully manoeuvre around as a referee).
The characters do things, the DM decides how to handle them (which could be autofail, autosuccess, roll, something else)? That seems a lot different to me than "figuring out what the GM has in mind and then doing that." The latter at least implies to me there's one and only one solution for the PCs to hit upon in some way. The former implies multiple solutions--in the case of my games, at least sometimes they're solutions I didn't think of.
It's possible one of us is misunderstanding the other, here.
I've bolded the key bit. I think you are putting a lot of stock in the surface temporal grammar of my statement
figuring out what the GM has in mind whereas I'm not very interested in that particuarl feature of it - the GM might apply his/her mind in advance of or subsequent to the action declaration - but rather in the fact that we have
GM decides as the resolution method.
That may be a good or bad method - I've got my own views but they're not really relevant to this thread - but if that's the method being used, then the GM incurs a lot of responsibility for what unfolds. Because almost tautologically, everything is up to him/her.
And in D&D there's an extra consideration that combat is normally
not resolved as "GM decides", which means that the players can feel a pressure to shift the arena of conflict to combat if they feel things are spiralling out of their control or comprehension.
Originally during the session when the Druid killed the Lord in the upstairs chamber and alerted the party by roaring, our Ranger attempted to cause a distraction by acting drunk on the lower level. With the guards seeing this they attempted to control the situation by grappling him first. There were no weapons drawn.
Yes there are other ways to defuse the situations, but in the moment, I was shocked that the PCs chose to attack the Lord and Bodyguard in stead of trying to come clean and talk their way out of it.
I really mean it when I say I'm not expressing any criticism of how you handled it.
My disagreement is with some other posters who are saying - in effect - that the players should be punished for having resorted to combat.
As I said in my first post in this thread, I think you've got an interesting situation and I'd run with it rather than try and shut it down.