diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..d525137
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,61 @@
+# 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
\ No newline at end of file
diff --git a/README.md b/README.md
index 11e08eb..f837b41 100644
--- a/README.md
+++ b/README.md
@@ -24,11 +24,15 @@ loadkeys de
 curl -L https://www.fischer.im/nixos/minimal-install --output install.sh
 chmod 744 ./install.sh
 ./install.sh
+
+reboot
 ```
 
+If you don't use the installation script, you need to follow the steps 2-8
+
 ### 2. Partitionierung
 
-Das folgende Schema erstellt fuenf Partitionen auf `/dev/sda`:
+Das folgende Schema erstellt view Partitionen auf `/dev/sda`:
 
 | Partition   | Typ            | Groesse           | Mountpoint |
 |-------------|----------------|-------------------|------------|
@@ -121,23 +125,39 @@ boot.loader = {
 
 ```bash
 nixos-install
-```
 
-Nach der Installation wird ein Root-Passwort abgefragt. Danach:
+# After the installation the script sets your root password. (Test1)
 
-```bash
 reboot
 ```
 
 ### 9. Nach dem ersten Start
 
 ```bash
+curl --output release.tar.gz https://gitea.fischer.im/sebastian/nixos-cesium/archive/[0.0.2].tar.gz
+tar xzf release.tar.gz
+chmod 744 nixos-cesium/script/post-install.sh
+./nixos-cesium/script/post-install.sh
+```
+If you don't use the post-installation script, follow the next step
+
+```bash
+cp -r ~/nixos-cesium/config/* /etc/nixos/
+
+# Remember to activate vm-guest.nix or vm-host.nix in configuration.nix
+
 nix-channel --add https://github.com/nix-community/home-manager/archive/release-25.11.tar.gz home-manager
 nix-channel --update
 
 # Konfiguration anwenden
-sudo nixos-rebuild switch
+nixos-rebuild switch
 
+reboot
+```
+
+### 10. Post Installation
+
+```bash
 # SMB-Zugangsdaten einrichten (falls Netzlaufwerke genutzt werden)
 sudo /etc/nixos/setup-smb-credentials.sh
 ```
diff --git a/scripts/minimal-install.sh b/scripts/minimal-install.sh
old mode 100644
new mode 100755
index a45065a..0dd68f0
--- a/scripts/minimal-install.sh
+++ b/scripts/minimal-install.sh
@@ -61,6 +61,7 @@ swapon /dev/disk/by-label/swap
 
 
 nixos-generate-config --root /mnt
+nixos-install
 
 
 # If root password wasn't set because the installation needed to be restarted.
diff --git a/scripts/post-install.sh b/scripts/post-install.sh
new file mode 100755
index 0000000..9d354ef
--- /dev/null
+++ b/scripts/post-install.sh
@@ -0,0 +1,10 @@
+#!/usr/bin/env sh
+
+sudo -i
+
+cp -r ~/nixos-cesium/config/* /etc/nixos/
+
+nix-channel --add https://github.com/nix-community/home-manager/archive/release-25.11.tar.gz home-manager
+nix-channel --update
+
+nixos-rebuild switch