{
  # Human-readable description of what this flake produces
  description = "Minimal NixOS Docker Swarm server";

  # Inputs — external dependencies that this flake depends on
  # Each input is fetched and locked in flake.lock for reproducibility
  inputs = {
    # The NixOS package collection, pinned to the 25.05 release branch
    # This is the source of all packages and NixOS modules used in configuration.nix
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
  };

  # Outputs — what this flake produces (NixOS configs, formatter, etc.)
  # self = this flake's source tree, nixpkgs = the input defined above
  # @inputs captures all inputs for passing to modules via specialArgs
  outputs = { self, nixpkgs, ... }@inputs: {
    # NixOS system configuration named "server"
    # Referenced with --flake .#server in nixos-rebuild commands
    nixosConfigurations.server = nixpkgs.lib.nixosSystem {
      # Target architecture — change to aarch64-linux for ARM servers
      system = "x86_64-linux";
      # Pass all flake inputs into modules so they can access them via `inputs` arg
      specialArgs = { inherit inputs; };
      # List of NixOS module files that make up the system configuration
      modules = [
        # Main system configuration (packages, services, firewall, etc.)
        ./configuration.nix
        # Inline module for flake-specific Nix settings
        {
          # Enable experimental Nix features required for flakes and nix command
          nix.settings.experimental-features = [ "nix-command" "flakes" ];
          # Register this flake's nixpkgs input as the system-wide nixpkgs registry
          # This lets you run `nix run nixpkgs#htop` without needing channels
          nix.registry.nixpkgs.flake = nixpkgs;
          # Point legacy Nix tools (nix-build, nix-shell) at this flake's nixpkgs
          # Eliminates the need for /nix/var/nix/profiles/per-user/root/channels
          nix.nixPath = [ "nixpkgs=flake:nixpkgs" ];
        }
      ];
    };

    # Formatter for `nix fmt` — auto-formats .nix files using the official RFC 166 style
    formatter.x86_64-linux = nixpkgs.legacyPackages.x86_64-linux.nixfmt-rfc-style;
  };
}