# NixOS Configuration

A modular NixOS flake configuration for managing multiple machines (kronos, herra, mystra) with a layered architecture and swappable desktop rices.

## Quick Start

```bash
# Apply configuration
sudo nixos-rebuild switch

# Build for specific host
sudo nixos-rebuild switch --flake .#kronos
sudo nixos-rebuild switch --flake .#herra
sudo nixos-rebuild switch --flake .#mystra

# Test without applying
sudo nixos-rebuild test

# Validate syntax
nix flake check

# Preview changes
sudo nixos-rebuild dry-run

# Update flake inputs
nix flake update
```

## Architecture

```
flake.nix                          # Entry point - assigns rices to hosts
  ↓
hosts/{kronos,herra,mystra}/       # Per-machine configs
  ├─ configuration.nix             # Machine identity + overrides
  └─ hardware-configuration.nix    # Hardware (autogenerated)

system/                            # System-wide base config
  └─ default.nix                   # Orchestrator (base modules only)
      ├─ boot.nix, audio.nix, bluetooth.nix
      ├─ networking.nix, graphics.nix
      ├─ packages.nix, programs.nix, services.nix
      └─ users.nix, nix.nix

home/rices/{rice}/system.nix       # Rice system config
  ├─ Desktop (X11 + i3wm)
  └─ Stylix (theming)

home/mun/                          # User "mun" config
  └─ default.nix                   # User orchestrator
      ├─ programs/                 # git, ssh, zsh
      └─ (imports rice via specialArgs)

home/rices/                        # Desktop rices (home-manager)
  ├─ nord-blue/                    # Complete rice
  ├─ original/                     # Complete rice
  └─ cosmic/                       # WIP rice
```

## Directory Structure

```
.
├── flake.nix                      # Flake inputs/outputs
├── flake.lock                     # Reproducibility lock
│
├── hosts/
│   ├── kronos/                    # Machine 1
│   │   ├── configuration.nix
│   │   └── hardware-configuration.nix
│   ├── herra/                     # Machine 2 (desktop, dual-boot, Zen kernel)
│   │   ├── configuration.nix
│   │   ├── hardware-configuration.nix
│   │   ├── packages.nix
│   │   ├── audio.nix
│   │   └── drivers.nix
│   └── mystra/                    # Machine 3
│       ├── configuration.nix
│       └── hardware-configuration.nix
│
├── system/                        # System-wide base modules
│   ├── default.nix                # Imports all base system modules
│   ├── nix.nix                    # Nix settings, flakes
│   ├── boot.nix                   # Bootloader, kernel
│   ├── audio.nix                  # Pipewire
│   ├── bluetooth.nix              # Bluetooth
│   ├── networking.nix             # NetworkManager
│   ├── graphics.nix               # GPU drivers
│   ├── packages.nix               # System packages
│   ├── programs.nix               # System programs
│   ├── services.nix               # System services
│   └── users.nix                  # User accounts
│
└── home/
    ├── mun/                       # User "mun"
    │   ├── default.nix            # User orchestrator
    │   └── programs/
    │       ├── git.nix
    │       ├── ssh.nix
    │       └── zsh.nix
    │
    └── rices/                     # Desktop themes
        ├── nord-blue/             # Complete rice
        │   ├── system.nix         # Desktop + stylix config
        │   ├── default.nix        # Home-manager modules
        │   ├── i3.nix
        │   ├── alacritty.nix
        │   ├── nvim.nix
        │   ├── helix.nix
        │   ├── picom.nix
        │   └── fastfetch.nix
        │
        ├── original/              # Complete rice
        │   ├── system.nix         # Desktop + stylix config
        │   ├── default.nix        # Home-manager modules
        │   ├── variables.nix      # Color definitions
        │   ├── i3.nix
        │   ├── kitty.nix
        │   ├── polybar.nix
        │   ├── rofi.nix
        │   ├── dunst.nix
        │   ├── neovim.nix
        │   ├── nnn.nix
        │   ├── picom.nix
        │   ├── scripts.nix
        │   └── xdg.nix
        │
        └── cosmic/                # WIP rice
            ├── system.nix         # Desktop + stylix config
            ├── default.nix        # Home-manager modules
            └── fluxbox.nix
```

## Configuration Layers

### 1. System Layer (`system/`)
Base system config applied to all machines: boot, networking, audio, graphics, packages, services, users. Does NOT include desktop or stylix (moved to rice layer).

### 2. Machine Layer (`hosts/`)
Per-machine identity (hostname), hardware configuration, and optional machine-specific overrides (e.g., herra uses Zen kernel).

### 3. Rice System Layer (`home/rices/*/system.nix`)
Desktop environment (X11 + i3wm) and stylix theming (colors, fonts, cursor). Imported at system level in flake.

### 4. User Layer (`home/mun/`)
User-specific programs: git, ssh, zsh config. Imports the active rice via specialArgs.

### 5. Rice Home Layer (`home/rices/*/`)
Desktop application configs: window manager, terminal, editor, compositor. Imported at home-manager level.

## Adding Configurations

**New system package:**
```nix
# system/packages.nix
environment.systemPackages = with pkgs; [
  # add here
];
```

**New system module:**
1. Create `system/mymodule.nix`
2. Add to `system/default.nix` imports

**New user program:**
1. Create `home/mun/programs/myprogram.nix`
2. Add to `home/mun/default.nix` imports

**New rice module:**
1. Create file in target rice directory (e.g., `home/rices/nord-blue/mymodule.nix`)
2. Add to that rice's `default.nix` imports

## Switching Rices

Rices are assigned per-host in `flake.nix`. Edit the `nixosConfigurations` section:

```nix
nixosConfigurations = {
  kronos = mkSystem "kronos" "nord-blue";    # Laptop uses nord-blue
  herra = mkSystem "herra" "cosmic";         # Desktop uses cosmic
  mystra = mkSystem "mystra" "nord-blue";    # Another machine uses nord-blue
};
```

Then rebuild: `sudo nixos-rebuild switch`

Each rice is imported twice:
1. **System-level**: `home/rices/${rice}/system.nix` (desktop + stylix)
2. **Home-level**: `home/rices/${rice}` (app configs via specialArgs)

## Creating a New Rice

1. Create directory: `home/rices/my-rice/`
2. Create `system.nix` with desktop environment and stylix config
3. Create `default.nix` orchestrator (imports home-manager modules)
4. Add application configs (i3.nix, terminal, editor, etc.)
5. Optional: Create `variables.nix` for shared color variables
6. Assign to host in `flake.nix`: `myhost = mkSystem "myhost" "my-rice";`

## Machine-Specific Config

Each host has minimal configuration - hostname, hardware, and optional overrides:

```nix
# hosts/kronos/configuration.nix (minimal)
{
  imports = [ ./hardware-configuration.nix ];
  networking.hostName = "kronos";
}

# hosts/herra/configuration.nix (with overrides)
{
  imports = [
    ./hardware-configuration.nix
    ./packages.nix
    ./audio.nix
    ./drivers.nix
  ];
  networking.hostName = "herra";
  boot.loader.grub.useOSProber = true;  # Dual-boot with Windows
  boot.kernelPackages = lib.mkForce pkgs.linuxPackages_zen;  # Gaming kernel
}
```

All shared config lives in `system/` and `home/`.

## Flake Inputs

- `nixpkgs` - NixOS 25.11 (stable)
- `nixpkgs-unstable` - Rolling release, accessible via `pkgs.unstable.*`
- `home-manager` - 25.11 (user environment manager)
- `stylix` - System-wide theming framework (base16 colors, fonts, cursor)
- `fenix` - Rust toolchain manager (provides latest stable/nightly Rust)
- `crane` - Nix build system for Rust projects
- `nixowos` - NixOS branding and theming (os-release customization)