My flake is being non-deterministic.

[Krutonium]

Okay so here's the issue, as best as I can lay it out (And please forgive me if this is the wrong place to open this - I'm really not sure where this should go.)

My NixOS config, as seen here: With today's flake update specifically linked, to ensure future accessibility seems to be non deterministic during evaluation.

Specifically, if I run nix flake check or nixos-rebuild [boot/switch] --flake [device] has a solid chance of not evaluating correctly. But sometimes, it does. And when it doesn't evaluate correctly, the resulting error can be anything from "a file is missing" (from the nixpkgs stdenv) to a setting in firefox that I never set, I think it's coming from Home Manager? But I can't find it, to something to do with bluetooth, or the man pages for SDL2 not existing.

https://paste.ubuntu.com/p/sFHz6WBccr/
https://paste.ubuntu.com/p/f5sntbtFQq/
https://paste.ubuntu.com/p/zcPcXdgH3w/ <= This one has show trace
https://paste.ubuntu.com/p/smVbjCYhBC/

And yet, somtimes, (as it produces these random errors more often than not) it'll evaluate entirely correctly and work.

I've experienced this behavior across all 3 of my machines (herein known as uWebServer, uGamingPC and uMsiLaptop in the flake)

uMsiLaptop struggles to build the config (getting old) but seems to be able to evaluate it fine usually
uGamingPC will fail to evaluate almost every time
uWebServer evaluates fine 50/50

And thus why I am here. This feels like there is some kind of race condition or somthing that is interacting badly with my configuration, and it seems to get worse with speed.

uMsiLaptop has a 4th gen i7 Laptop CPU (i7 4720HQ/16GB LPDDR3)
uWebServer has a 6th gen i7 Desktop CPU (i7 6700k/32GB DDR4)
uGamingPC has a Ryzen 7 5800X3D (32GB DDR4)

I have nix store verify --all'd on the advice of others; other than a single untrusted entry (from the day of install) there's nothing wrong there.

Thanks for reading this absolute wall of text.

• system: "x86_64-linux"
• host os: Linux 6.12.9, NixOS, 24.11 (Vicuna), 24.11.20250115.e24b4c0
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.24.11
• nixpkgs: /nix/store/awsvw44jla0idziiks2zwgzslfd2dczn-source