# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## What This Is

Personal NixOS system configuration for host `cesium` — a QEMU/KVM-virtualized x86_64 desktop workstation. Uses NixOS with Home Manager (channel-based, no Flakes). NixOS version is locked to 25.11.

## Commands

```bash
# Rebuild and apply configuration (aliased as 'rebuild')
sudo nixos-rebuild switch

# Rebuild with package upgrades (aliased as 'update')
sudo nixos-rebuild switch --upgrade

# Test configuration without persisting (loads into current session only)
sudo nixos-rebuild test

# Build without applying (useful to check for errors)
sudo nixos-rebuild build

# Optimize store and garbage collect (aliased as 'ngc')
sudo nix-store --optimise && sudo nix-collect-garbage -d

# After first install: setup SMB credentials
sudo /etc/nixos/setup-smb-credentials.sh
```

## Architecture

Entry point is `config/configuration.nix`, which imports all other modules:

```
config/configuration.nix          # Top-level: imports all modules, enables Home Manager
├── hardware-configuration.nix    # Auto-generated (gitignored), QEMU guest hardware
├── common.nix                    # System-wide: bootloader, locale, GNOME, PipeWire, packages
├── mounts.nix                    # CIFS/SMB mounts to TrueNAS (automount with systemd)
├── services.nix                  # Docker (custom data root /home/docker), ddev
├── users/sebastian.nix           # User account, groups, SSH askpass
│   └── imports home.nix          # Home Manager config for this user
├── home.nix                      # User environment: apps, shell, git, scripts, Flatpak
├── scripts.nix                   # Custom shell scripts (composer, lazydocker, gclb)
├── vm-guest.nix                  # Optional: SPICE agent for VM clipboard/file sharing
└── vm-host.nix                   # Optional: KVM/QEMU host with libvirtd, virt-manager
```

Key design patterns:
- `common.nix` handles all system-level config (boot, locale, desktop, audio, auto-updates, garbage collection)
- `home.nix` handles all user-level config via Home Manager (applications, shell aliases, git, vim, GTK theme, GNOME extensions, Flatpak activation scripts)
- `scripts.nix` defines Docker-wrapped CLI tools (composer, lazydocker) and git helpers using `writeShellScriptBin`
- `mounts.nix` uses systemd automount with 60s idle timeout for TrueNAS SMB shares
- `vm-guest.nix` and `vm-host.nix` are optional modules (not imported by default in configuration.nix)

## Conventions

- **Commit messages** use `[TASK]` prefix (e.g., `[TASK] Add filemounts`)
- **Formatting**: 2-space indentation for `.nix` files, 4-space for everything else (see `.editorconfig`)
- **Unfree packages** are allowed (`nixpkgs.config.allowUnfree = true`)
- `hardware-configuration.nix` is gitignored — it's auto-generated per machine