# NixOS Configuration Repository - AI Agent Guide

This guide provides everything you need to know to work efficiently with this NixOS configuration repository. Keep this file handy when making changes.

## Repository Overview

This repository manages NixOS configurations for multiple systems using flakes and Home Manager. All systems are defined declaratively in Nix expressions.

### Managed Systems

| Hostname | Type | Hardware | Special Notes |
|----------|------|----------|---------------|
| `framework` | Desktop/Laptop | Framework AMD AI 300 series | User: jsutter, Uses nixos-hardware module |
| `aurora` | Desktop | Custom | Users: jsutter, isutter, aksutter |
| `labrizor` | Desktop | Custom | User: jsutter |
| `skip01` | Server (WIP) | Custom | Headless configuration |

### Core Technologies

- **NixOS**: 25.11 (stable channel)
- **Nixpkgs Unstable**: For packages requiring latest versions
- **Home Manager**: Release 25.11
- **Plasma Manager**: KDE Plasma configuration management
- **Flakes**: For reproducible, declarative system definitions

## Project Structure

```
nixos/
├── appflakes/           # Local flake inputs
│   └── octofriend/      # Custom application flake
├── desktop/             # Desktop environment configurations
│   ├── plasma.nix       # KDE Plasma + Plasma Manager
│   ├── dev.nix          # Development tools and languages
│   ├── office.nix       # Office applications
│   ├── gaming.nix       # Games and gaming platforms
│   ├── media.nix        # Audio/video software
│   ├── virtualization.nix  # VMs and containers
│   ├── tailscale.nix    # VPN configuration
│   ├── 2dprinting.nix   # Printer setup
│   ├── 3dprinting.nix   # 3D printer tools
│   ├── dnm.nix          # Framework-specific config
│   └── stp-elc-udmshare.nix  # Specific mount/share config
├── docs/                # Documentation
│   └── agents.md        # This file
├── servers/             # Server configurations (future use)
├── systems/             # Hardware-specific configurations
│   ├── common.nix       # Shared system settings (bootloader, nix config, etc.)
│   ├── common-headless.nix  # Common settings for headless systems
│   ├── framework.nix    # Framework laptop hardware config
│   ├── aurora.nix       # Aurora desktop hardware config
│   ├── labrizor.nix     # Labrizor desktop hardware config
│   └── skip01.nix       # Skip01 server config
├── users/               # User configurations with Home Manager
│   ├── common-home.nix  # Shared user packages and settings
│   ├── jsutter.nix      # Primary user configuration
│   ├── isutter.nix      # Secondary user configuration
│   └── aksutter.nix     # Secondary user configuration
└── flake.nix            # Top-level flake definition
```

## Core Principles

### 1. Declarative Configuration
- All system state must be defined in Nix expressions
- Never use imperative commands for permanent changes
- Every configuration change should be reproducible

### 2. Modular Architecture
- Maintain separation between hardware, software, and user configurations
- Use existing modules before creating new ones
- Follow the established directory structure strictly

### 3. Security First
- Never expose sensitive data (passwords, private keys, API tokens)
- Use proper user privilege separation
- Validate all external inputs and configurations

## Configuration Patterns

### Function Parameters

Always include the appropriate parameters based on what the module needs:

```nix
# For modules using unstable packages
{ config, pkgs, pkgs-unstable, lib, ... }:

# For stable-only modules
{ config, pkgs, lib, ... }:

# For modules using special args from flake
{ config, pkgs, pkgs-unstable, lib, octofriend, ... }:

# For Home Manager modules
{ pkgs, ... }:
```

### System Configuration Pattern

```nix
{ config, lib, pkgs, ... }:
{
  # Always include hostname first
  networking.hostName = "system-name";
  
  # Hardware configuration
  fileSystems."/" = { 
    device = "/dev/disk/by-partlabel/primary";
    fsType = "ext4";
  };
  fileSystems."/boot" = {
    device = "/dev/disk/by-partlabel/ESP";
    fsType = "vfat";
  };

  # System-specific settings
  # Group related configurations together
}
```

### User Configuration Pattern

```nix
{ config, pkgs, pkgs-unstable, home-manager, ... }:
{
  # System user definition
  users.users.username = {
    shell = pkgs.zsh;
    isNormalUser = true;
    description = "User Description";
    extraGroups = [ "networkmanager" "wheel" ];  # Only essential groups
  };

  # Home Manager configuration
  home-manager.users.username = {
    home.username = "username";
    home.homeDirectory = "/home/username";
    home.stateVersion = "25.05";

    # User configurations
  };
}
```

### Desktop Module Pattern

```nix
{ config, pkgs, pkgs-unstable, lib, ... }:
{
  # System packages for this category
  environment.systemPackages = with pkgs; [
    package1
    package2
  ];

  # Configuration options
  services.service-name.enable = true;

  # Home Manager integrations (if applicable)
}
```

## Package Management Guidelines

### Stable vs Unstable Packages

```nix
# PREFERRED: Use stable packages by default
environment.systemPackages = with pkgs; [
  firefox
  git
  vim
];

# ACCEPTABLE: Use unstable when necessary
# Add comments explaining why unstable is needed
environment.systemPackages = with pkgs; [
  firefox
  pkgs-unstable.windsurf  # Latest features not in stable
];
```

### Package Selection Criteria

1. **Use stable unless**: Package doesn't exist OR needs newer version
2. **Document reasons**: Always comment why unstable is used
3. **Test thoroughly**: Unstable packages may have issues
4. **Review regularly**: Check if unstable packages can move to stable

### Common Package Sets by Module

- `dev.nix`: IDEs, languages, development tools
- `office.nix`: LibreOffice, productivity apps
- `gaming.nix`: Steam, Lutris, game launchers
- `media.nix`: Audio/video players, editors
- `virtualization.nix`: VirtualBox, Docker, other virt tools
- `plasma.nix`: KDE Plasma applications and themes

## System-Specific Information

### Framework (`framework.nix`)
- Uses `nixos-hardware` module: `framework-amd-ai-300-series`
- Additional modules: `dnm.nix`, `stp-elc-udmshare.nix`
- Single user: jsutter

### Aurora (`aurora.nix`)
- Multi-user system: jsutter, isutter, aksutter
- Additional modules: `3dprinting.nix`, `2dprinting.nix`
- No specialized hardware module

### Labrizor (`labrizor.nix`)
- Single user: jsutter
- Additional modules: `3dprinting.nix`
- No specialized hardware module

### Common Settings (`systems/common.nix`)
Includes:
- Hardware firmware and fwupd
- NetworkManager with VPN plugins (OpenVPN, OpenConnect)
- Systemd-boot EFI bootloader
- Latest kernel
- Nix settings with experimental features (flakes, nix-command)
- Weekly garbage collection (7-day retention)
- Auto-optimized Nix store
- Trusted users: root, jsutter
- Timezone: America/Los_Angeles
- Locale: en_US.UTF-8
- PipeWire audio stack
- SSH service enabled
- Zsh shell enabled
- Passwordless sudo for wheel group
- Flatpak enabled
- USB plugdev group rules

## File Naming Conventions

- Use lowercase with hyphens: `vpn-config.nix`, `development-tools.nix`
- System configurations must match hostname: `framework.nix`, `aurora.nix`
- User configurations must match username: `jsutter.nix`, `isutter.nix`
- Common configurations: `common.nix`, `common-home.nix`

## Code Style

- Use 2-space indentation
- Align attribute lists consistently
- Add comments for non-obvious configurations
- Group related configurations together

Example:
```nix
{
  # Audio configuration
  sound.enable = true;
  hardware.pulseaudio.enable = false;
  security.rtkit.enable = true;
  services.pipewire = {
    enable = true;
    alsa.enable = true;
    alsa.support32Bit = true;
    pulse.enable = true;
  };
}
```

## Common Workflows

### Adding a New Package

1. Determine appropriate module (desktop/, systems/, users/)
2. Check if package exists in stable channel: `nix search nixpkgs package-name`
3. Use unstable only if necessary with documentation
4. Add to appropriate environment.systemPackages or home.packages
5. Run dry-run before applying
6. Update relevant documentation if it affects multiple systems

Example:
```nix
# In desktop/dev.nix
environment.systemPackages = with pkgs; [
  # Added for Python development
  python312
  python312Packages.pip
  pkgs-unstable.windsurf  # Latest AI features not in stable
];
```

### Creating a New Desktop Module

1. Create file in `desktop/` with descriptive name
2. Include proper function parameters
3. Add packages, services, and configurations
4. Test module independently
5. Add to `commonDesktopModules` in flake.nix if for all desktops
6. Add to specific system in flake.nix if selective

### Adding a New System

1. Create `systems/<hostname>.nix` following existing patterns
2. Set `networking.hostName = "<hostname>"`
3. Configure hardware (fileSystems, hardware-specific settings)
4. Add system entry to `flake.nix`:
```nix
new-system = mkSystem {
  modules = commonDesktopModules ++ [
    ./systems/new-system.nix
    ./users/username.nix
  ];
};
```
5. Test with dry-run and build

### Modifying User Configuration

1. Edit appropriate file in `users/`
2. For shared changes: modify `common-home.nix`
3. For user-specific changes: modify `<username>.nix`
4. Home Manager configuration goes in `home-manager.users.<username>`

## Testing and Validation

### Pre-commit Testing

ALWAYS run these commands before submitting changes:

```bash
# 1. Syntax check
nix flake check

# 2. Dry run for affected systems (run for ALL affected)
sudo nixos-rebuild dry-run --flake .#framework
sudo nixos-rebuild dry-run --flake .#aurora
sudo nixos-rebuild dry-run --flake .#labrizor

# 3. Check flake outputs
nix flake show
```

### Applying Changes

```bash
# Build and switch (active system only)
sudo nixos-rebuild switch --flake .#hostname

# Build only (test without switching)
sudo nixos-rebuild build --flake .#hostname

# Build and boot (adds to GRUB menu)
sudo nixos-rebuild boot --flake .#hostname
```

### Build Verification

- Test on at least one system before merging
- Verify all services start correctly: `systemctl status`
- Check for package conflicts
- Validate hardware-specific configurations

### Updating Packages

```bash
# Update flake inputs
nix flake update

# Check what changed
nix flake diff

# Rebuild after update
sudo nixos-rebuild switch --flake .#hostname
```

## Security Rules

### Sensitive Data Handling

- **NEVER** commit plaintext passwords
- **NEVER** commit private SSH keys
- **NEVER** commit API tokens or secrets
- **ALWAYS** use hashed passwords: `hashedPassword = "$6$..."`
- **CONSIDER** using sops-nix for advanced secret management

### User Privilege Management

```nix
# GOOD: Minimal necessary groups
extraGroups = [ "networkmanager" "wheel" "audio" ];

# BAD: Over-privileged users
extraGroups = [ "networkmanager" "wheel" "audio" "video" "input" "disk" "lp" "scanner" ];
```

### SSH Key Management

```nix
# GOOD: Use authorizedKeys for SSH access
openssh.authorizedKeys.keys = [
  "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIBNVUh+RrcOSMRV6qysnsdPs5AyK8dSm4QhhnwgpikyI user@domain"
];

# FORBIDDEN: Never include private keys
```

## Rollback Procedures

### Configuration Rollback

```bash
# List available generations
sudo nix-env --list-generations --profile /nix/var/nix/profiles/system

# Rollback to previous working generation
sudo nixos-rebuild switch --profile-name generation-123

# Or use rollback shortcut
sudo nixos-rebuild switch --rollback

# Rollback specific system
sudo nixos-rebuild switch --rollback --flake .#hostname
```

### Emergency System Recovery

If a system fails to boot after changes:

1. Boot from installation media
2. Mount root filesystem: `mount /dev/disk/by-partlabel/primary /mnt`
3. Roll back: `sudo nixos-rebuild switch --rollback --install-bootloader /mnt`
4. Identify and fix configuration issues
5. Test before rebooting

### Booting into Previous Generations

At boot time (GRUB menu):
1. Hold Shift during boot to see GRUB menu
2. Select "Advanced options for NixOS"
3. Choose previous generation

## NixOS Installation (New System)

```bash
# Partition disk (example for NVMe)
sudo parted /dev/nvme0n1 -- mklabel gpt
sudo parted /dev/nvme0n1 -- mkpart primary ext4 512MB 100%
sudo parted /dev/nvme0n1 -- mkpart ESP fat32 1MB 512MB
sudo parted /dev/nvme0n1 -- set 2 esp on
sudo mkfs.ext4 /dev/disk/by-partlabel/primary
sudo mkfs.vfat /dev/disk/by-partlabel/ESP

# Mount filesystems
sudo mount -o rw /dev/disk/by-partlabel/primary /mnt/
sudo mkdir /mnt/boot
sudo mount -o rw /dev/disk/by-partlabel/ESP /mnt/boot/
sudo mkdir /mnt/root
sudo git clone https://git.symbiotrip.com/jsutter/nixos /mnt/root/nixos

# Install (no root password, impure for git access)
sudo -i
cd /mnt/root/nixos
nixos-install --flake .#<name> --no-root-password --impure

# Set password after install
nixos-enter --root '/mnt'
passwd jsutter
```

## Module Dependencies

### Known Dependencies

- `plasma.nix` depends on: `common.nix`, `home-manager`
- `dev.nix` is included in all desktop systems
- All desktop systems include: `common.nix`, `plasma.nix`, `dev.nix`, `office.nix`, `gaming.nix`, `media.nix`, `virtualization.nix`, `tailscale.nix`
- User files include Home Manager configuration

### Avoiding Circular Dependencies

- Don't import system modules into user modules
- Use `common.nix` for shared system settings only
- Use `common-home.nix` for shared user settings only
- Hardware-specific modules should not depend on desktop modules

## Emergency Tools

### Useful Commands

```bash
# Check what packages provide a command
nix-locate bin/commandname

# Search for packages
nix search nixpkgs package-name
nix search nixpkgs-unstable package-name

# Check Nix store size
du -sh /nix/store

# Garbage collect manually
sudo nix-collect-garbage -d

# Profile Nix operations
sudo nix-env --profile /nix/var/nix/profiles/system --list-generations

# Check hardware info
lshw
lspci
lsusb
lsblk
hwinfo
```

## Troubleshooting Common Issues

### Build Errors

1. Read the error message carefully
2. Check for syntax errors in the modified file
3. Verify all attributes are closed properly
4. Run `nix flake check` to validate syntax

### Service Failures

```bash
# Check service status
systemctl status service-name

# View service logs
journalctl -u service-name -e

# Restart service
systemctl restart service-name
```

### Package Conflicts

- If two modules try to enable the same service with different settings
- Use `lib.mkForce` to override settings if necessary
- Or consolidate the configuration in one place

## Flakes Reference

### Input Structure

```nix
inputs = {
  nixpkgs.url = "nixpkgs/nixos-25.11";              # Stable
  nixpkgs-unstable.url = "nixpkgs/nixos-unstable";  # Unstable
  nixos-hardware.url = "github:NixOS/nixos-hardware/master";
  home-manager.url = "github:nix-community/home-manager/release-25.11";
  plasma-manager.url = "github:nix-community/plasma-manager";
  octofriend.url = "path:./appflakes/octofriend";   # Local flake
};
```

### Special Args

Available in all modules:
- `pkgs`: Stable Nix packages
- `pkgs-unstable`: Unstable Nix packages
- `octofriend`: Local octofriend flake

### Output Structure

```nix
outputs = {
  self,                             # Self reference
  nixpkgs,                          # Stable packages
  nixpkgs-unstable,                 # Unstable packages
  nixos-hardware,                   # Hardware modules
  home-manager,                     # Home Manager
  plasma-manager,                   # Plasma Manager
  octofriend                        # Custom app flake
}: {
  nixosConfigurations = {
    framework = { ... };  # Define each system
    aurora = { ... };
    labrizor = { ... };
  };
};
```

## Documentation Requirements

### Code Comments

- Explain non-obvious configurations
- Document reasons for unstable package usage
- Note hardware-specific requirements
- Reference external dependencies

Example:
```nix
# Use unstable neovim for LuaLS integration not in stable
pkgs-unstable.neovim  # Latest features needed for Lua development
```

### Commit Messages

Use clear, descriptive commit messages:
- Reference affected systems/modules
- Explain reasoning for significant changes
- Include testing steps when applicable

Example:
```
feat(framework): Add 3D printing support for Prusa printers

- Added 3dprinting.nix module with PrusaSlicer and Cura
- Installed USB rules for Prusa devices
- Added to framework system configuration

Tested: Prusa MK4 recognized and can start print via USB
```

## Performance Considerations

### Nix Settings

The repository uses optimized Nix settings:
- `auto-optimise-store`: Auto-optimizes the Nix store
- `keep-outputs = true`: Keeps build outputs
- `keep-derivations = true`: Keeps derivations for evaluation
- `download-buffer-size`: 512MB for faster downloads

### Garbage Collection

Automatically runs weekly:
- Deletes builds older than 7 days
- Run manually: `sudo nix-collect-garbage -d`

### Build Caching

Consider using `nix-serve` or Cachix for:
- Faster rebuilds
- Shared cache across systems
- CI/CD integration

## Resources

### Official Documentation
- [NixOS Manual](https://nixos.org/manual/nixos/stable/)
- [Home Manager Manual](https://nix-community.github.io/home-manager/)
- [Nix Pills](https://nixos.org/guides/nix-pills/)
- [NixOS Wiki](https://nixos.wiki/)

### Community Resources
- [NixOS Discourse](https://discourse.nixos.org/)
- [NixOS subreddit](https://reddit.com/r/NixOS/)
- [NixOS Matrix](https://matrix.to/#/#nixos:nixos.org)

### Package Search
- [search.nixos.org](https://search.nixos.org/packages)
- Command line: `nix search nixpkgs package-name`

## Quick Reference

### Essential Commands

| Action | Command |
|--------|---------|
| Update system | `sudo nixos-rebuild switch --flake .#hostname` |
| Dry run | `sudo nixos-rebuild dry-run --flake .#hostname` |
| Rollback | `sudo nixos-rebuild switch --rollback` |
| Update flakes | `nix flake update` |
| Check flakes | `nix flake check` |
| Search packages | `nix search nixpkgs name` |
| Garbage collect | `sudo nix-collect-garbage -d` |

### File Paths Reference

| Type | Location |
|------|----------|
| Common system settings | `systems/common.nix` |
| System hardware config | `systems/<hostname>.nix` |
| Common user settings | `users/common-home.nix` |
| User config | `users/<username>.nix` |
| Desktop apps | `desktop/<category>.nix` |
| Flake definition | `flake.nix` |

## Maintenance & Changelog

This section tracks changes to the repository structure and when this document was updated. Keep this in sync!

### Current Repository State
- **Last Updated**: February 2026
- **NixOS Version**: 25.11
- **Managed Systems**: 3 (framework, aurora, labrizor)
- **Users**: jsutter (primary), isutter, aksutter

### Repository Change Log

| Date | Change | Updated Sections |
|------|--------|------------------|
| 2026-02 - Created | Created `agents.md` with comprehensive guide | All sections |
| 2026-02 - Removed | Removed .clinerules file, consolidated into agents.md | Maintenance section |
| 2026-02 - Cleanup | Removed unused gnome.nix module, common-headless.nix; removed allowBroken setting | System structure |
| 2026-02 - Cleanup | Removed commented packages across multiple files; fixed trailing whitespace | Code quality |
| 2026-02 - Cleanup | Removed .clinerules file; deleted gnome.nix (unused); common-headless.nix (duplicated) | File structure |
| 2026-02 - Improvement | Added result, *.swp, *~ to .gitignore | Maintenance |

### When to Update This Document

Update `agents.md` when any of the following occur:

- **Structural Changes**:
  - New system added to `flake.nix`
  - New user configuration added
  - New or renamed desktop module
  - Directory restructuring

- **Configuration Changes**:
  - New shared settings in `systems/common.nix`
  - New shared user settings in `users/common-home.nix`
  - Changes to module pattern or function parameters
  - New package categories or organizational changes

- **Technology Updates**:
  - NixOS version changes
  - Channel updates (stable/unstable)
  - New major inputs added to flake
  - Significant Nix configuration changes

- **Procedure Changes**:
  - New testing workflow
  - Changed emergency procedures
  - Updated installation steps
  - New common commands

### Update Template

When making changes, add an entry using this format:

```
| YYYY-MM - One-line description | More detail if needed | Section(s) affected |
| --- | --- | --- |
```

### Version History for agents.md

- **v1.0** (2025-01): Initial creation with full repository documentation

## Getting Help

When unsure about something:
1. Check this documentation first
2. Review existing similar configurations
3. Search NixOS manual and wiki
4. Test changes with dry-run before applying

---

**Remember**: This repository values declarative, reproducible configurations. When in doubt, prefer explicit configuration over implicit behavior. Test thoroughly, document changes, and never skip the dry-run step!