so i read on pcgamer today - that using any console command will render achievements useless.

now i have to ask - is this permanently or per-session?... the reason i ask, is i recently got stuck on an object ingame and used the noclip / tcl command to free myself.

ive played the game a bit since then but havnt gotten too far (i can always go back in my savegame(s)) so im curious to know whether or not this will flag your savegame permanently, or just for that session where you've used the console.

it would svck if you were penalized for legitimately using the console, or inadvertently opening it and mashing a key combo in - i can understand it for things like godmode / level up / move to quest etc etc.

can anyone comment officially?

Officially? No. Unofficially, perhaps yes.
I used tcl for the same reason, once on one of my initial and 2nd longest running characters. No achievements were logged, even after dozens of sessions.

Achievements started relogging with the stealth patch which reset everything (long story excluded, but, I do mean EVERYTHING, everywhere on my machine.)

I think it's pernament and I think Steam achievements are rather stupid thing, so I don't really care unless they plan on giving me 10 € for each one.
Not using console in PC version of a game like this is just nonsense, it's a bit funny they kind of forgot about that in the first place.
And yes, anything in console locks it, not sure if you actually need to write something or just open it.

I use tcl and tgm all the time and still get achievements so either in those long sessions you didnt get achievements anyways or your game is bugged...using the console commands does NOT prevent you from getting achievements

Certain console commands disable some achievements from happening. Using the console in general does not.

"Set Timescale" can stop you from gaining achievements related to completing quests - but won't affect your achievements for leveling.

Using the console to "disable" a rogue dragon corpse won't do anything to your achievements at all.

I think you're fine, I used the console to despawn a bugged dragon, saved, reloaded and received the Eye of Magnus achievement afterwards.

I've used it to set the FOV, disable/enable followers and get their stats. I got achievements.