nix-shared/system/default/nix.nix

{ lib, ... }:
{
  # Nix package manager configuration
  nix = {
    enable = true;

    settings = {
      # Enable experimental features for modern Nix functionality
      # - "nix-command": Enables the new unified 'nix' command interface
      # - "flakes": Enables Nix flakes for reproducible and composable configurations
      experimental-features = [ "nix-command" "flakes" ];

      # Specify which users are allowed to run nix commands
      allowed-users = lib.mkDefault [ "tb" ];

      # Users who can act as trusted users (can override settings)
      # Trusted users can use --option flags and import from derivations
      trusted-users = lib.mkDefault [ "root" "tb" ];

      # Show more lines of build output on failure
      log-lines = 50;
    };

    # Automatic garbage collection configuration
    # Helps manage disk space by cleaning up unused store paths
    gc = {
      # Enable automatic garbage collection
      automatic = true;

      # Delete store paths older than 30 days during garbage collection
      options = "--delete-older-than 30d";
    };

    # Automatic store optimization configuration
    # Reduces disk usage by hard-linking identical files in the Nix store
    optimise = {
      # Enable automatic store optimization
      # This deduplicates files to save disk space
      automatic = true;
    };
  };

  # Nixpkgs package collection configuration
  nixpkgs = {
    config = {
      # Allow installation of packages with non-free licenses
      # This includes proprietary software like Discord, Slack, etc.
      # Without this, only free/open-source packages can be installed
      allowUnfree = true;

      # Allow packages marked as broken (use with caution)
      #allowBroken = false;
    };
  };
}