You have an obligation as the DM to narrate exactly what the intention is unless you have a valid in game reason for doing otherwise
Yes, I have, the SYSTEM (the initiative roll) has shown that the PC has lost the initiative. So it is my DUTY as the DM to narrate the consequences of what the player declared, and while it has extremely infrequently happened that my narration did not please a player, that player just told me "actually, I think this is rather what happened...", I went with his narration and everything was fine.
Now, you can either be a good sport and accept that this is the gentlemanly way to deal with this in games that I've run and played with for 42 years and with hundreds of players without any problem, or continue to hijack the thread with the extremely annoying subject of player agency (which, by the way, has very little grounding in the books as published as it's subject to table rules anyway, so this is ANOTHER way of telling other players that they are playing wrong, please stop), in which case my response will be extremely simple:
"So, you don't want me to describe what happens, but the fact is that you lost initiative. So either you let me describe it, or you do the proper description, now and then, without disrupting the game for the other players.
But it'd better be conform to what the other players, the system, the dice throws and my DM knowledge of the situation indicate."
I have played "inductive games" like HeroWars/HeroQuest where the roll precedes any description, and basically when attempting a diplomacy check, you don't say anything in character, you roll the dice, and then you roleplay the result of the die. It's great, but it requires really good players, able to roleplay a success or a failure properly, inventing the reason for that. It so happens that not all players are confident with that and that most of them are usually extremely happy to have a nice description of what is happening, not only to them, but to the environment.
Again, I'm absolutely fine with it, but the ways I've seen it derailed is players STILL TRYING TO EXPLAIN WHY THEY SHOULD HAVE SUCCEEDED, which is basically what you are trying to do with your "but I had the dagger already in hand, why did I get jumped by that guy 30 feet away". And that is NOT an acceptable way to play collaboratively, if you attempt that, you will not even have the time to derail the discussion with player agency, you will be shown the door for derailing the game.
Now, if you will please stop being extremely insulting about other players' ways of playing the game than your personal preferences, maybe we could come back to the subject of the thread ?