What if you don't get up?
If it's a work day and I don't wake up on time, I'll pick away at it over the course of the day - usually I'll get a chance to think about it on my tram ride to work and complete it at lunchtime
If it's a weekend I'll just do it at my leisure at some point during the day when I have some time - maybe head to a nice cafe or something.
I'm nowhere near the top 100 - closest has been iirc top 200 a few years back - so it's not like I need to start at 6am.
I have trouble fitting this kind of thing in consistently. It's hard with work, chores, family, and then motivation to code after coding at work.
I'm in CET too, and 6:00 is not an hour where I’m awake, and if I were, my brain functions would definitely not be at a level where I would be capable of coding.
Midnight would be much more acceptable.
But I luckily managed to avoid the "reusable AoC library" problem around 2019 when a week beforehand I wrote down the sort of functions I wanted to have at my disposal (usually things around representing 2D/3D grids of unknown size and pathfinding/debugging therein, but a few other bits and pieces) and made a simple library that I will sometimes add things to after I'm done with the problem for the day.
I was tempted to some functions (similar to those your CLI harness provided) for retrieving test data and submitting answers but I managed to stop myself short of that! But I am sure you're far from the only one to end up down that road.