Fixes #392183 by adding an option to the factorio NixOS module to specify a custom mod-list.json file. This is particularly helpful for disabling built-in mods like space-age when playing with others without the DLC, or when using incompatible mods like Pyanodon's.

  services.factorio = {
    # ...
    mods =
      let
        inherit (pkgs) lib;
        modDir = /home/username/factorio-mods;
        modList = lib.pipe modDir [
          builtins.readDir
          (lib.filterAttrs (k: v: v == "regular"))
          (lib.mapAttrsToList (k: v: k))
          (builtins.filter (lib.hasSuffix ".zip"))
        ];
        modToDrv = modFileName:
          pkgs.runCommand "copy-factorio-mods" {} ''
            mkdir $out
            cp ${modDir + "/${modFileName}"} $out/${modFileName}
          ''
          // { deps = []; };
      in
        builtins.map modToDrv modList;
    mods-dat = builtins.path {
      path = "/home/username/factorio-mods/mod-settings.dat";
      name = "mod-settings.dat";
    };
    # NEW:
    mods-list = builtins.path {
      path = "/home/username/factorio-mods/mod-list.json";
      name = "mod-list.json";
    };
  };

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• Nixpkgs 25.11 Release Notes (or backporting 25.05 Nixpkgs Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
• NixOS 25.11 Release Notes (or backporting 25.05 NixOS Release notes)
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other contributing documentation in corresponding paths.

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