Add Steam Deck (nix-deck) configuration with Jovian-NixOS and remote building

- Add Jovian-NixOS integration for Steam Deck hardware support
- Create nix-deck machine configuration with SteamOS role
- Add jovian-compat.nix for NixOS 25.05 compatibility (remove in 25.11+)
- Create remote-build role for distributed builds
- Configure zix790prors as build host
- Configure nix-book and nix-deck to use remote builder with fallback
- Add comprehensive setup documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

STEAM_DECK_JOVIAN_SETUP.md

@@ -0,0 +1,280 @@
+# Steam Deck (nix-deck) Jovian-NixOS Setup Guide
+
+This document describes the setup for installing and maintaining NixOS with Jovian-NixOS on a Steam Deck.
+
+## Overview
+
+The `nix-deck` configuration provides:
+- **Jovian-NixOS integration** for Steam Deck hardware support
+- **Remote building** using `zix790prors` as the build host
+- **SteamOS role** for easy Steam Deck UI configuration
+- **Compatibility shim** for using Jovian on NixOS 25.05 stable
+
+## Architecture
+
+### Remote Building
+
+The setup uses distributed builds to avoid slow compilation on the Steam Deck:
+
+- **Build Host**: `zix790prors` (powerful desktop)
+  - Runs as a dedicated `nix-builder` user (not root)
+  - Accepts SSH connections from client machines
+  - Performs all heavy compilation work
+
+- **Build Clients**: `nix-book` and `nix-deck`
+  - Automatically offload builds to `zix790prors`
+  - Fall back to local building if remote builder is unavailable
+  - Steam Deck heavily prefers remote (speedFactor=4)
+
+### Jovian-NixOS Integration
+
+- **Jovian module**: Provides Steam Deck hardware support, drivers, and Steam UI
+- **Compatibility layer**: `roles/jovian-compat.nix` provides `services.logind.settings` for NixOS 25.05
+  - **IMPORTANT**: Remove this when upgrading to NixOS 25.11+
+  - An assertion will fail the build if used on 25.11+
+
+- **SteamOS role**: `roles.desktop.steamos` abstracts Jovian configuration
+  ```nix
+  roles.desktop.steamos = {
+    enable = true;
+    autoStart = false;  # Set to true to boot directly to Steam UI
+    desktopSession = "plasmawayland";
+  };
+  ```
+
+## Initial Installation
+
+### Prerequisites
+
+1. Steam Deck in recovery mode or booted to a live Linux environment
+2. SSH access enabled on the Steam Deck
+3. SSH key set up for passwordless authentication
+
+### Option 1: Using nixos-anywhere (Initial Install Only)
+
+```bash
+# From your main machine
+nix run github:nix-community/nixos-anywhere -- \
+  --flake .#nix-deck \
+  root@<steam-deck-ip>
+```
+
+**Note**: This is only for the initial install. For updates, see below.
+
+### Option 2: Manual Installation
+
+1. Boot Steam Deck from NixOS installer USB
+2. Partition and format the disk
+3. Mount filesystems
+4. Clone this repository
+5. Generate hardware config:
+   ```bash
+   nixos-generate-config --show-hardware-config > /tmp/hw.nix
+   ```
+6. Copy the hardware config content to `machines/nix-deck/hardware-configuration.nix`
+7. Keep the `jovian.devices.steamdeck` settings in the file
+8. Install:
+   ```bash
+   nixos-install --flake .#nix-deck
+   ```
+
+## Updates and Rebuilds
+
+### Method 1: Remote Build and Deploy (Recommended)
+
+Build on your main machine, deploy to Steam Deck:
+
+```bash
+# From nix-book or zix790prors
+nixos-rebuild switch \
+  --flake .#nix-deck \
+  --target-host root@nix-deck \
+  --build-host localhost
+```
+
+### Method 2: On-Device Rebuild (Uses Remote Builder)
+
+The Steam Deck is configured to automatically use `zix790prors` as a remote builder:
+
+```bash
+# SSH into the Steam Deck
+ssh root@nix-deck
+
+# This will automatically build on zix790prors
+nixos-rebuild switch --flake /path/to/nixos-configs#nix-deck
+```
+
+The build will automatically happen on `zix790prors` and be deployed locally.
+
+## Remote Builder Setup
+
+### On the Build Host (zix790prors)
+
+The configuration creates a `nix-builder` user that client machines connect to:
+
+```nix
+roles.remote-build.enableBuilder = true;
+```
+
+### On Client Machines (nix-book, nix-deck)
+
+Configure the remote builder:
+
+```nix
+roles.remote-build.builders = [{
+  hostName = "zix790prors";
+  maxJobs = 16;
+  speedFactor = 4;  # Higher = prefer remote more
+}];
+```
+
+### SSH Key Setup
+
+1. Generate SSH key on the builder host for the `nix-builder` user:
+   ```bash
+   sudo -u nix-builder ssh-keygen -t ed25519 -f /var/lib/nix-builder/.ssh/id_ed25519
+   ```
+
+2. Copy the public key to client machines:
+   ```bash
+   # Add to /var/lib/nix-builder/.ssh/authorized_keys on zix790prors
+   ```
+
+3. On client machines, ensure you can connect:
+   ```bash
+   ssh nix-builder@zix790prors
+   ```
+
+## Configuration Files
+
+### Key Files Created/Modified
+
+- `flake.nix` - Added Jovian input and nix-deck configuration
+- `roles/jovian-compat.nix` - Compatibility shim (remove in 25.11+)
+- `roles/desktop/steamos.nix` - SteamOS/Jovian role abstraction
+- `roles/remote-build/default.nix` - Remote builder role
+- `machines/nix-deck/configuration.nix` - Steam Deck system config
+- `machines/nix-deck/hardware-configuration.nix` - Hardware config (placeholder)
+
+### Example Configuration
+
+```nix
+# machines/nix-deck/configuration.nix
+{
+  roles = {
+    desktop = {
+      enable = true;
+      wayland = true;
+      gaming.enable = true;
+      kde = true;
+      sddm = true;
+      steamos = {
+        enable = true;
+        autoStart = false;  # or true to boot to Steam UI
+        desktopSession = "plasmawayland";
+      };
+    };
+    remote-build.builders = [{
+      hostName = "zix790prors";
+      maxJobs = 16;
+      speedFactor = 4;
+    }];
+  };
+}
+```
+
+## Jovian Features
+
+### Enabled by Default
+
+- Steam Deck hardware support (`jovian.devices.steamdeck.enable`)
+- Steam UI (`jovian.steam.enable`)
+- Decky Loader plugin system (`jovian.decky-loader.enable`)
+
+### Optional Features
+
+Set in the hardware-configuration.nix:
+
+```nix
+jovian.devices.steamdeck = {
+  enable = true;
+  autoUpdate = false;  # Auto-update BIOS/controller firmware
+};
+```
+
+### Manual Firmware Updates
+
+```bash
+# BIOS update
+sudo jupiter-biosupdate
+
+# Controller update
+sudo jupiter-controller-update
+
+# Docking station (connect via USB-C first)
+jupiter-dock-updater
+```
+
+## Troubleshooting
+
+### Remote Builds Not Working
+
+1. Check SSH connectivity:
+   ```bash
+   ssh nix-builder@zix790prors
+   ```
+
+2. Verify builder is trusted:
+   ```bash
+   # On zix790prors
+   nix show-config | grep trusted-users
+   ```
+
+3. Check build logs:
+   ```bash
+   journalctl -u nix-daemon -f
+   ```
+
+### Jovian Not Working
+
+1. Ensure you're on NixOS 25.05 or the compatibility layer is removed for 25.11+
+2. Check Jovian is imported in flake.nix
+3. Verify hardware config has `jovian.devices.steamdeck.enable = true`
+
+### Compatibility Layer Issues
+
+If you see an error about `jovian-compat.nix` being incompatible:
+
+1. You're running NixOS 25.11 or later
+2. Remove `./roles/jovian-compat.nix` from `flake.nix`
+3. Jovian should work natively on 25.11+
+
+## Future Upgrades
+
+### Upgrading to NixOS 25.11
+
+1. Update `nixpkgs` input in flake.nix to 25.11
+2. Remove `./roles/jovian-compat.nix` from flake.nix imports
+3. The assertion in jovian-compat.nix will prevent accidental use
+4. Test the build
+5. Deploy
+
+### Switching to Unstable
+
+If you need Jovian to follow unstable nixpkgs:
+
+1. Edit `flake.nix`:
+   ```nix
+   jovian = {
+     url = "github:Jovian-Experiments/Jovian-NixOS";
+     inputs.nixpkgs.follows = "nixpkgs-unstable";
+   };
+   ```
+
+2. This only affects Jovian packages, not your base system
+
+## Additional Resources
+
+- [Jovian-NixOS Documentation](https://jovian-experiments.github.io/Jovian-NixOS/)
+- [Jovian Steam Deck Guide](https://jovian-experiments.github.io/Jovian-NixOS/devices/valve-steam-deck/)
+- [NixOS Remote Builds](https://nixos.org/manual/nix/stable/advanced-topics/distributed-builds.html)

flake.lock

@@ -57,6 +57,27 @@
         "type": "github"
       }
     },
+    "jovian": {
+      "inputs": {
+        "nix-github-actions": "nix-github-actions",
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1763223001,
+        "narHash": "sha256-Hi6XxTJJjKsDrO+D0fYXS88ehCYzQkZlp9qxX1zoM1s=",
+        "owner": "Jovian-Experiments",
+        "repo": "Jovian-NixOS",
+        "rev": "68a1bcc019378272e601558719f82005a80ddab0",
+        "type": "github"
+      },
+      "original": {
+        "owner": "Jovian-Experiments",
+        "repo": "Jovian-NixOS",
+        "type": "github"
+      }
+    },
     "nix-darwin": {
       "inputs": {
         "nixpkgs": [
@@ -78,6 +99,28 @@
         "type": "github"
       }
     },
+    "nix-github-actions": {
+      "inputs": {
+        "nixpkgs": [
+          "jovian",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1729697500,
+        "narHash": "sha256-VFTWrbzDlZyFHHb1AlKRiD/qqCJIripXKiCSFS8fAOY=",
+        "owner": "zhaofengli",
+        "repo": "nix-github-actions",
+        "rev": "e418aeb728b6aa5ca8c5c71974e7159c2df1d8cf",
+        "type": "github"
+      },
+      "original": {
+        "owner": "zhaofengli",
+        "ref": "matrix-name",
+        "repo": "nix-github-actions",
+        "type": "github"
+      }
+    },
     "nixos-wsl": {
       "inputs": {
         "flake-compat": "flake-compat",
@@ -173,6 +216,7 @@
       "inputs": {
         "google-cookie-retrieval": "google-cookie-retrieval",
         "home-manager": "home-manager",
+        "jovian": "jovian",
         "nix-darwin": "nix-darwin",
         "nixos-wsl": "nixos-wsl",
         "nixpkgs": "nixpkgs_2",

flake.nix

@@ -26,6 +26,11 @@
       url = "git+https://git.johnogle.info/johno/google-cookie-retrieval.git";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+
+    jovian = {
+      url = "github:Jovian-Experiments/Jovian-NixOS";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs = { self, nixpkgs, nixpkgs-unstable, nixos-wsl, ... } @ inputs: let
@@ -33,6 +38,8 @@
       ./roles
     ] ++ [
       inputs.home-manager.nixosModules.home-manager
+      ./roles/jovian-compat.nix  # Compatibility shim for Jovian on stable NixOS
+      inputs.jovian.nixosModules.jovian
       {
         nixpkgs.overlays = [
           (final: prev: {
@@ -142,6 +149,18 @@
       ];
     };
 
+    # Steam Deck configuration
+    nixosConfigurations.nix-deck = nixpkgs.lib.nixosSystem rec {
+      system = "x86_64-linux";
+      modules = nixosModules ++ [
+        ./machines/nix-deck/configuration.nix
+        {
+          home-manager.users.johno = import ./home/home-desktop.nix;
+          home-manager.extraSpecialArgs = { inherit system; };
+        }
+      ];
+    };
+
     # Darwin/macOS configurations
     darwinConfigurations."blkfv4yf49kt7" = inputs.nix-darwin.lib.darwinSystem rec {
       system = "aarch64-darwin";

machines/nix-book/configuration.nix

@@ -21,6 +21,11 @@
     };
     nfs-mounts.enable = true;
     printing.enable = true;
+    remote-build.builders = [{
+      hostName = "zix790prors";
+      maxJobs = 16;
+      speedFactor = 3;
+    }];
     spotifyd.enable = true;
     users = {
       enable = true;

machines/nix-deck/configuration.nix

@@ -0,0 +1,41 @@
+{ pkgs, ... }:
+{
+  imports = [
+    ./hardware-configuration.nix
+  ];
+
+  roles = {
+    audio.enable = true;
+    bluetooth.enable = true;
+    desktop = {
+      enable = true;
+      wayland = true;
+      gaming.enable = true;
+      kde = true;
+      sddm = true;
+      steamos = {
+        enable = true;
+        autoStart = false;
+        desktopSession = "plasmawayland";
+      };
+    };
+    remote-build.builders = [{
+      hostName = "zix790prors";
+      maxJobs = 16;
+      speedFactor = 4;  # Prefer remote heavily on Steam Deck
+    }];
+    users = {
+      enable = true;
+      extraGroups = [ "video" ];
+    };
+  };
+
+  # Bootloader
+  boot.loader.systemd-boot.enable = true;
+  boot.loader.efi.canTouchEfiVariables = true;
+
+  networking.hostName = "nix-deck";
+  networking.networkmanager.enable = true;
+
+  system.stateVersion = "25.05";
+}

machines/nix-deck/hardware-configuration.nix

@@ -0,0 +1,37 @@
+# This is a placeholder hardware configuration for the Steam Deck.
+# Run `nixos-generate-config --show-hardware-config` on the actual device
+# to generate the real hardware configuration, then merge the jovian settings below.
+
+{ config, lib, pkgs, modulesPath, ... }:
+
+{
+  imports = [ ];
+
+  # Steam Deck specific hardware configuration
+  jovian.devices.steamdeck = {
+    enable = true;
+    autoUpdate = false;  # Set to true if you want automatic firmware updates
+  };
+
+  # TODO: Replace this with actual hardware configuration from the Steam Deck
+  # Run `nixos-generate-config --show-hardware-config` on the device and merge it here
+
+  # Minimal placeholder configuration to allow flake to build
+  boot.initrd.availableKernelModules = [ ];
+  boot.initrd.kernelModules = [ ];
+  boot.kernelModules = [ ];
+
+  fileSystems."/" = {
+    device = "/dev/disk/by-label/nixos";
+    fsType = "ext4";
+  };
+
+  fileSystems."/boot" = {
+    device = "/dev/disk/by-label/boot";
+    fsType = "vfat";
+  };
+
+  swapDevices = [ ];
+
+  nixpkgs.hostPlatform = lib.mkDefault "x86_64-linux";
+}

machines/zix790prors/configuration.nix

@@ -29,6 +29,7 @@ with lib;
     nfs-mounts.enable = true;
     nvidia.enable = true;
     printing.enable = true;
+    remote-build.enableBuilder = true;
     users.enable = true;
     virtualisation.enable = true;
   };

roles/default.nix

@@ -12,6 +12,7 @@ with lib;
     ./nfs-mounts
     ./nvidia
     ./printing
+    ./remote-build
     ./spotifyd
     ./users
     ./virtualisation

roles/desktop/default.nix

@@ -23,5 +23,6 @@ with lib;
     ./kde.nix
     ./programs.nix
     ./sddm.nix
+    ./steamos.nix
   ];
 }

roles/desktop/steamos.nix

@@ -0,0 +1,47 @@
+{ lib, config, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.roles.desktop;
+in
+{
+  options.roles.desktop.steamos = {
+    enable = mkEnableOption "SteamOS (Jovian) configuration";
+
+    autoStart = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Automatically start Steam Deck UI on boot";
+    };
+
+    user = mkOption {
+      type = types.str;
+      default = "johno";
+      description = "User to run Steam as";
+    };
+
+    desktopSession = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = "Desktop session to launch when switching to Desktop Mode";
+    };
+
+    enableDeckyLoader = mkOption {
+      type = types.bool;
+      default = true;
+      description = "Enable Decky Loader plugin system";
+    };
+  };
+
+  config = mkIf (cfg.enable && cfg.steamos.enable) {
+    jovian.steam = {
+      enable = true;
+      autoStart = cfg.steamos.autoStart;
+      user = cfg.steamos.user;
+      desktopSession = cfg.steamos.desktopSession;
+    };
+
+    jovian.decky-loader.enable = cfg.steamos.enableDeckyLoader;
+  };
+}

roles/jovian-compat.nix

@@ -0,0 +1,43 @@
+{ lib, config, ... }:
+
+# Compatibility shim to provide services.logind.settings for NixOS 25.05
+# This allows Jovian-NixOS to work with stable NixOS
+# REMOVE THIS FILE when upgrading to NixOS 25.11 or later
+
+with lib;
+
+let
+  nixosVersion = config.system.nixos.release;
+  isCompatibleVersion = versionOlder nixosVersion "25.11";
+in
+{
+  options.services.logind.settings = mkOption {
+    type = types.attrsOf (types.attrsOf types.anything);
+    default = {};
+    description = "systemd-logind configuration. See logind.conf(5) for available options.";
+  };
+
+  config = mkMerge [
+    {
+      assertions = [
+        {
+          assertion = isCompatibleVersion;
+          message = ''
+            The Jovian compatibility shim (roles/jovian-compat.nix) is only needed for NixOS 25.05 and earlier.
+            You are running NixOS ${nixosVersion}.
+            Please remove 'roles/jovian-compat.nix' from your flake.nix imports.
+          '';
+        }
+      ];
+    }
+    (mkIf (config.services.logind.settings != {}) {
+      # Convert the settings to extraConfig format for older NixOS
+      services.logind.extraConfig = let
+        mkSection = section: settings:
+          "[${section}]\n" +
+          (concatStringsSep "\n" (mapAttrsToList (k: v: "${k}=${toString v}") settings));
+      in
+        concatStringsSep "\n\n" (mapAttrsToList mkSection config.services.logind.settings);
+    })
+  ];
+}

roles/remote-build/default.nix

@@ -0,0 +1,127 @@
+{ lib, config, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.roles.remote-build;
+in
+{
+  options.roles.remote-build = {
+    enableBuilder = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Enable this machine as a remote build host for other machines";
+    };
+
+    builderUser = mkOption {
+      type = types.str;
+      default = "nix-builder";
+      description = "User account for remote builders to connect as";
+    };
+
+    builders = mkOption {
+      type = types.listOf (types.submodule {
+        options = {
+          hostName = mkOption {
+            type = types.str;
+            description = "Hostname or IP address of the build machine";
+          };
+
+          systems = mkOption {
+            type = types.listOf types.str;
+            default = [ "x86_64-linux" ];
+            description = "Supported systems";
+          };
+
+          maxJobs = mkOption {
+            type = types.int;
+            default = 8;
+            description = "Maximum number of parallel build jobs";
+          };
+
+          speedFactor = mkOption {
+            type = types.int;
+            default = 2;
+            description = "Speed factor compared to local building (higher = prefer remote)";
+          };
+
+          supportedFeatures = mkOption {
+            type = types.listOf types.str;
+            default = [ "nixos-test" "benchmark" "big-parallel" "kvm" ];
+            description = "Supported build features";
+          };
+
+          sshUser = mkOption {
+            type = types.str;
+            default = "nix-builder";
+            description = "SSH user for connecting to the builder";
+          };
+
+          sshKey = mkOption {
+            type = types.nullOr types.path;
+            default = null;
+            description = "Path to SSH private key for authentication";
+          };
+        };
+      });
+      default = [];
+      description = "List of remote build machines to use";
+    };
+
+    fallbackToLocalBuild = mkOption {
+      type = types.bool;
+      default = true;
+      description = "Fallback to local building if remote builders are unavailable";
+    };
+  };
+
+  config = mkMerge [
+    # Builder host configuration
+    (mkIf cfg.enableBuilder {
+      # Create dedicated builder user
+      users.users.${cfg.builderUser} = {
+        isSystemUser = true;
+        group = cfg.builderUser;
+        description = "Nix remote build user";
+        home = "/var/lib/${cfg.builderUser}";
+        createHome = true;
+        shell = pkgs.bashInteractive;
+        openssh.authorizedKeys.keyFiles = [];  # Will be populated by client machines
+      };
+
+      users.groups.${cfg.builderUser} = {};
+
+      # Allow builder user to perform builds
+      nix.settings.trusted-users = [ cfg.builderUser ];
+
+      # Allow remote builds
+      services.openssh.enable = true;
+
+      # Ensure nix-daemon is accessible
+      nix.settings.allowed-users = [ "*" ];
+    })
+
+    # Client configuration (machines using remote builders)
+    (mkIf (cfg.builders != []) {
+      nix.buildMachines = map (builder: {
+        hostName = builder.hostName;
+        systems = builder.systems;
+        maxJobs = builder.maxJobs;
+        speedFactor = builder.speedFactor;
+        supportedFeatures = builder.supportedFeatures;
+        sshUser = builder.sshUser;
+        sshKey = builder.sshKey;
+      }) cfg.builders;
+
+      nix.distributedBuilds = true;
+
+      # Use substitutes from remote builders
+      nix.extraOptions = ''
+        builders-use-substitutes = true
+      '';
+
+      # Fallback to local build if remote unavailable
+      nix.settings.fallback = cfg.fallbackToLocalBuild;
+    })
+  ];
+}