system: replace host detection with capabilities module

Replace scattered osConfig.system.name comparisons with a declarative
host.capabilities module. This improves maintainability and semantic
clarity by expressing what capabilities a host has rather than checking
its name.

Changes:
- Add system/host-capabilities.nix with options for hardware, form factor,
  UI behavior, services, and backup configuration
- Configure capabilities in hosts/gunter and hosts/magicman
- Migrate 6 files to use capabilities: packages, waybar, ssh, backup-home
- Remove redundant host name check for pciutils in gunter config
- Make backup-home service conditionally enabled based on capabilities

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

home/hyprland/waybar/default.nix

@@ -14,8 +14,9 @@ let
     dontUnpack = true;
     installPhase = "install -Dm755 ${./arrhist.py} $out/bin/arrhist";
   };
-  withArrhist = if (osConfig.system.name == "gunter") then true else false;
+  cfg = osConfig.host.capabilities;
-  withBattery = if (osConfig.system.name == "magicman") then true else false;
+  withArrhist = cfg.enableArrhist;
+  withBattery = cfg.hasBattery;
 in
 {
   sops.secrets."sonarr_base_url" = { };
@@ -153,7 +154,7 @@ in
     settings = [
       (
         let
-          volInterval = if (osConfig.system.name == "gunter") then "5" else "1";
+          volInterval = toString cfg.volumeScrollStep;
         in
         {
           "layer" = "top";

home/packages/default.nix

@@ -1,6 +1,6 @@
 { pkgs, osConfig, ... }:
 let
-  withCuda = if (osConfig.system.name == "gunter") then true else false;
+  withCuda = osConfig.host.capabilities.hasCuda;
 in
 {
   imports = [

home/services/backup-home.nix

@@ -1,5 +1,14 @@
-{ pkgs, config, ... }:
+{
+  pkgs,
+  config,
+  lib,
+  osConfig,
+  ...
+}:
 let
+  cfg = osConfig.host.capabilities;
+  backupEnabled = cfg.backupRepository != null && cfg.backupPassword != null;
+
   # Backup home script
   backup-home = pkgs.writeShellApplication {
     name = "backup-home";
@@ -12,8 +21,8 @@ let
     ];
     text = ''
       echo "========== BACKUP HOME STARTING =========="
-      export RESTIC_PASSWORD="gunter.home.2rjus.net"
+      export RESTIC_PASSWORD="${cfg.backupPassword}"
-      export RESTIC_REPOSITORY="rest:http://10.69.12.52:8000/gunter.home.2rjus.net"
+      export RESTIC_REPOSITORY="${cfg.backupRepository}"
       SECRET_PATH="$XDG_CONFIG_HOME/sops-nix/secrets/gotify_backup_home"
 
       if ! [ -f "$SECRET_PATH" ]; then
@@ -53,7 +62,7 @@ let
           retval=$?
           if [ $retval -ne 0 ]; then
             curl "https://gotify.t-juice.club/message?token=$GOTIFY_TOKEN" \
-              -F "title=Backup of home@gunter failed!" \
+              -F "title=Backup of home@${osConfig.networking.hostName} failed!" \
               -F "message=Please check status of backup-home service"
           fi
       fi
@@ -92,9 +101,9 @@ let
   };
 in
 {
-  sops.secrets."gotify_backup_home" = { };
+  sops.secrets."gotify_backup_home" = lib.mkIf backupEnabled { };
 
-  systemd.user.services.backup-home = {
+  systemd.user.services.backup-home = lib.mkIf backupEnabled {
     Unit = {
       Description = "Backup home directory";
       After = [
@@ -107,7 +116,7 @@ in
       ExecStart = "${backup-home}/bin/backup-home";
     };
   };
-  systemd.user.timers.backup-home = {
+  systemd.user.timers.backup-home = lib.mkIf backupEnabled {
     Unit = {
       Description = "Backup home directory";
       After = [ "network.target" ];

home/ssh/config.nix

@@ -22,7 +22,7 @@ in
 
     matchBlocks = {
       "bmo.uio.no-on-eduroam" = (
-        lib.mkIf (osConfig.system.name == "magicman") (
+        lib.mkIf (osConfig.host.capabilities.hasEduroamAccess) (
           lib.hm.dag.entryBefore [ "bmo.uio.no" "*" ] {
             match = "host bmo.uio.no exec \"nmcli -g GENERAL.STATE c s eduroam|grep -q -E '\\bactiv'\"";
             hostname = "bmo.uio.no";

hosts/gunter/configuration.nix

@@ -113,6 +113,19 @@
   # ];
   services.xserver.videoDrivers = [ "nvidia" ];
 
+  # Host capabilities
+  host.capabilities = {
+    hasCuda = true;
+    hasNvidia = true;
+    hasBattery = false;
+    formFactor = "desktop";
+    volumeScrollStep = 5;
+    enableArrhist = true;
+    hasEduroamAccess = false;
+    backupRepository = "rest:http://10.69.12.52:8000/gunter.home.2rjus.net";
+    backupPassword = "gunter.home.2rjus.net";
+  };
+
   # Install system-wide packages
   environment.systemPackages = with pkgs; [
     curl
@@ -123,7 +136,7 @@
     wget
     v4l-utils
     nmap
-    (lib.mkIf (config.system.name == "gunter") pciutils)
+    pciutils
 
     # X shit
     # xorg.xorgserver

hosts/magicman/configuration.nix

@@ -44,6 +44,19 @@
     };
   };
 
+  # Host capabilities
+  host.capabilities = {
+    hasCuda = false;
+    hasNvidia = false;
+    hasBattery = true;
+    formFactor = "laptop";
+    volumeScrollStep = 1;
+    enableArrhist = false;
+    hasEduroamAccess = true;
+    backupRepository = null;
+    backupPassword = null;
+  };
+
   # Bluetooth stuff
   services.blueman.enable = true;
   hardware.bluetooth.enable = true;

system/default.nix

@@ -5,6 +5,7 @@
     ./fwupd.nix
     ./git.nix
     ./greetd.nix
+    ./host-capabilities.nix
     ./hyprland.nix
     ./label.nix
     ./libvirt.nix

system/host-capabilities.nix

@@ -0,0 +1,70 @@
+{ lib, ... }:
+with lib;
+{
+  options.host.capabilities = {
+    # Hardware capabilities
+    hasCuda = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Whether the host has CUDA-capable GPU (for btop, OBS, etc.)";
+    };
+
+    hasNvidia = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Whether the host has NVIDIA GPU";
+    };
+
+    hasBattery = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Whether the host has a battery (laptop)";
+    };
+
+    # Form factor
+    formFactor = mkOption {
+      type = types.enum [
+        "desktop"
+        "laptop"
+      ];
+      default = "desktop";
+      description = "Physical form factor of the host";
+    };
+
+    # UI behavior customizations
+    volumeScrollStep = mkOption {
+      type = types.int;
+      default = 5;
+      description = "Volume adjustment step percentage for scroll wheel";
+    };
+
+    # Service-specific features
+    enableArrhist = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Enable Sonarr/Radarr monitoring widget (arrhist)";
+    };
+
+    # Network environment features
+    hasEduroamAccess = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Whether this host can connect to eduroam (for SSH config)";
+    };
+
+    # Backup configuration
+    backupRepository = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = "Restic backup repository URL for this host";
+      example = "rest:http://10.69.12.52:8000/gunter.home.2rjus.net";
+    };
+
+    backupPassword = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = "Restic backup password identifier for this host";
+      example = "gunter.home.2rjus.net";
+    };
+  };
+}