nixfiles/system/modules/common-nixos.nix

# Options shared by every NixOS host (laptops and the WSL box). Imported via
# baseModules in flake.nix. Host- and platform-specific settings stay in the
# per-machine configs; laptop-only settings live in ./laptop.nix.
{ pkgs, ... }:
{
  time.timeZone = "Europe/London";
  i18n.defaultLocale = "en_GB.UTF-8";

  # Store hygiene. auto-optimise-store hard-links identical files in the store
  # after each build (cheap dedupe; NOT a garbage collector -- there is
  # deliberately no automatic GC timer). The larger download buffer avoids
  # "buffer full" stalls when fetching big NARs over a fast link.
  nix.settings.auto-optimise-store = true;
  nix.settings.download-buffer-size = 134217728; # 128 MiB

  # Extra binary cache for the nix-community toolchain (home-manager, nixvim,
  # treefmt, ...). Merges with any host-specific caches (e.g. the Asahi cache on
  # the MBP) rather than replacing them.
  nix.settings.substituters = [ "https://nix-community.cachix.org" ];
  nix.settings.trusted-public-keys = [
    "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
  ];

  # Run dynamically-linked foreign binaries (VS Code remote server, prebuilt
  # toolchains, language-server downloads) on every NixOS host, not just WSL.
  programs.nix-ld.enable = true;

  # Minimal system-level CLI available before the home-manager profile loads
  # (e.g. early boot / rescue). User-level tooling lives in home-manager.
  environment.systemPackages = with pkgs; [
    git
    fastfetch
  ];

  # Fonts on every host. The Nerd Font carries the powerline/Nerd glyphs the
  # tmux statusline uses (foot names it explicitly in home/sway.nix); Noto sans +
  # colour emoji prevent tofu in terminals/TUIs/Firefox -- important on the WSL
  # box, which does not pull the graphical hosts' default Noto stack. The Mac
  # installs the Nerd Font via the Darwin config.
  fonts.packages = with pkgs; [
    nerd-fonts.jetbrains-mono
    noto-fonts
    noto-fonts-color-emoji
  ];
  # Map the generic fontconfig families so anything asking for "monospace" gets
  # the Nerd Font (with emoji fallback), not DejaVu.
  fonts.fontconfig.defaultFonts = {
    monospace = [
      "JetBrainsMono Nerd Font"
      "Noto Color Emoji"
    ];
    sansSerif = [
      "Noto Sans"
      "Noto Color Emoji"
    ];
    serif = [
      "Noto Serif"
      "Noto Color Emoji"
    ];
    emoji = [ "Noto Color Emoji" ];
  };
}