### Setting Up a Dendritic Flake with flake-parts and import-tree

Source: https://context7.com/vic/dendritic/llms.txt

The entry point for a Dendritic project is a `flake.nix` that uses `import-tree` to automatically import all module files from a directory. This setup leverages `flake-parts` for module management and `import-tree` for automatic module discovery.

```nix
# flake.nix
{
  inputs = {
    flake-parts = {
      url = "github:hercules-ci/flake-parts";
      inputs.nixpkgs-lib.follows = "nixpkgs";
    };

    import-tree.url = "github:vic/import-tree";

    nixpkgs.url = "github:nixos/nixpkgs/25.11";
  };

  # All .nix files in ./modules are automatically imported as flake-parts modules
  outputs = inputs: inputs.flake-parts.lib.mkFlake { inherit inputs; } (inputs.import-tree ./modules);
}

```

--------------------------------

### Cross-Cutting Concern Module for Shell Configuration

Source: https://context7.com/vic/dendritic/llms.txt

This Nix module defines a single concern, shell configuration, that applies across multiple configuration classes like NixOS, Darwin, and nix-on-droid. Each class gets its own submodule for specific settings.

```nix
# modules/shell.nix
{
  flake.modules = {
    nixos.shell =
      { pkgs, ... }:
      {
        programs.fish.enable = true;
        users.users.${config.meta.username}.shell = pkgs.fish;
      };

    darwin.shell =
      { pkgs, ... }:
      {
        programs.fish.enable = true;
      };

    nixOnDroid.shell =
      { pkgs, ... }:
      {
        user.shell = lib.getExe pkgs.zsh;
      };
  };
}

```

--------------------------------

### Cross-Cutting Concern Module for Admin User Configuration

Source: https://context7.com/vic/dendritic/llms.txt

This Nix module abstracts platform-specific differences for configuring administrator users across NixOS and Darwin systems. It ensures consistent admin user setup while accommodating OS variations.

```nix
# modules/admin.nix
{
  flake.modules = {

    nixos.admin = {
      users.users.${config.meta.username} = {
        isNormalUser = true;
        extraGroups = [ "wheel" ];
      };
    };

    darwin.admin.system.primaryUser = config.meta.username;
  };
}

```

--------------------------------

### Utility Module for Specific Configuration Aspects

Source: https://context7.com/vic/dendritic/llms.txt

This Nix code defines a small utility module for specific configuration aspects, such as bootloader settings. It can be easily imported by host configurations to manage particular settings like disabling the GRUB bootloader.

```nix
# modules/no-boot.nix
{
  flake.modules.nixos.no-boot = {
    boot.loader.grub.enable = false;
    fileSystems."/".device = "/dev/no-boot";
  };
}

```

--------------------------------

### Setting Top-Level Option Values in Nix

Source: https://context7.com/vic/dendritic/llms.txt

This Nix code snippet demonstrates how to set values for custom top-level options. These values can then be read by any module via `config.meta.*`, providing a centralized way to manage global configuration parameters.

```nix
# modules/meta.nix
{
  meta.username = "iam";
}

```

--------------------------------

### Exposing NixOS Configurations with flake-parts

Source: https://context7.com/vic/dendritic/llms.txt

This Nix code uses `flake-parts` to expose configurations as flake outputs. Each configuration imports a single top-level module, adhering to the recommendation of modularity and simplifying NixOS system definitions.

```nix
# modules/configurations.nix
{
  flake.nixosConfigurations.my-laptop = lib.nixosSystem {
    # recommendation is for nixos to include only a single module
    # and make that module import others as needed.
    modules = [ self.modules.nixos.my-laptop ];
  };

  # instantiate other kinds of configurations like darwinConfigurations, nixDroid, etc.
}

```

--------------------------------

### Host-Specific Configuration Module in Nix

Source: https://context7.com/vic/dendritic/llms.txt

This Nix module defines a host-specific configuration. It imports relevant concern modules (like admin and shell) and sets host-specific options, allowing for tailored configurations per machine.

```nix
# modules/my-laptop.nix
{
  flake.modules.nixos.my-laptop = {
    imports = with self.modules.nixos;
      [ admin shell no-boot # any other usability concerns for my-laptop
      ];

    nixpkgs.hostPlatform = "x86_64-linux";
  };
}

```

--------------------------------

### Defining Supported Systems in Nix Flake

Source: https://context7.com/vic/dendritic/llms.txt

This Nix code snippet specifies the systems supported by the flake. This is crucial for generating per-system outputs and ensuring compatibility across different architectures and operating systems.

```nix
# modules/systems.nix
{
  systems = [
    "x86_64-linux"
    "aarch64-linux"
  ];
}

```

--------------------------------

### Defining Custom Top-Level Options in Nix

Source: https://context7.com/vic/dendritic/llms.txt

This Nix code defines custom options at the top level of a configuration. These options can be accessed by any module through `config`, effectively replacing the `specialArgs` anti-pattern and promoting cleaner configuration management.

```nix
# modules/options/meta.nix
{
  options.meta.username = lib.mkOption {
    description = "Principal User's username";
    type = lib.types.str;
  };
}

```

--------------------------------

### Enabling flake-parts Modules System

Source: https://context7.com/vic/dendritic/llms.txt

This Nix code snippet enables the flake-parts modules system, which is used to store and manage lower-level NixOS, Darwin, and other configuration modules within a Dendritic project.

```nix
# modules/options/flakeparts-modules.nix
{
  imports = [ inputs.flake-parts.flakeModules.modules ];
}

```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.