Huh?
I don't know what you mean by "fiats" here. In many forum discussions, that's a word that carries a derogatory meaning by those who have a problem with the DM making decisions appropriate to his or her role as described by the rules of the game. But I'll be charitable and simply ask what you mean by it. Because despite all the little digs you've been making this entire conversation (from which you frequently retreat when called out on it), maybe this time you don't actually mean it to be derogatory.
In any case, what a player describes comes first. The character can't do anything unless the player puts him or her in the fictional position to do so via reasonable specificity. The context of the fictional situation plus the stated approach to the goal informs the DM as to whether the task succeeds, fails, or is uncertain. It's smart play in my view to undertake tasks your character is good at, in case you have to roll, but to aim for automatic success as much as possible to avoid rolling.
fiat as in a unilateral decisions made by the GM - say contrasted with one determined by some mechanical check of character vs difficulty.
Would you be happier with "executive order"? If so, fine call it an executive order.
And thanska agin for reiterating what we agree on - the player must declare then the process begins (well except for say passive checks and except for when things happen to the character and those other cases but other than those and maybe others...) and then at some point there is a GM decision between "do we use mechanics to resolve" and "do i just tell them a result" (oft portrayed as the decision of uncertainty) and that is true for both sides it seems on this difference in style of resolution.
Where the difference lies is in what goes into the pot to make that decision of uncertainty and how much it should play a role (or be played/playable to get ahead) and the key difference seems to be the roles and impact of the character stats (possibly for some skills over others) in this soup vs the way the player chooses to describe their "character's actions" (which may well vary greatly from player to player.
heck, in one case, its even the behavior of the player at the table - they seem to take notes - being used for the "executive order - yay or nay"