feat(mibook): boot to terminal, launch KDE on demand

Add my.profiles.kde-desktop.startOnBoot (default true, no change for
existing consumers). When false, boot to multi-user.target, keep SDDM
out of any boot target's wants, and provide a 'desktop' command that
starts the display manager on demand. Enable this on mibook.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CfozKLQdUh5TzqyjSigLUx

docs/superpowers/specs/2026-07-27-mibook-boot-desktop-choice-design.md

@@ -0,0 +1,61 @@
+# mibook: choose terminal-only vs desktop at boot
+
+## Goal
+
+Let mibook boot to a text console by default, with KDE fully installed and
+launchable on demand. The user decides after boot whether they need the
+graphical desktop, without rebuilding the system.
+
+## Behavior
+
+- mibook boots to a text console (`multi-user.target`). SDDM and Plasma do
+  **not** start automatically.
+- KDE (SDDM + Plasma 6) remains fully installed.
+- Running `desktop` in the terminal starts the SDDM display manager, which
+  presents the graphical login screen; logging in there enters a Plasma 6
+  session.
+- No reverse command. To return to a text console, stop the display manager
+  (`sudo systemctl stop display-manager`) or reboot.
+- Other machines that enable the `kde-desktop` profile are unaffected; their
+  desktop still starts on boot.
+
+## Implementation
+
+### `modules/environments/kde-desktop/default.nix`
+
+Add an opt-out option to the existing profile:
+
+- New option `my.profiles.kde-desktop.startOnBoot`, a boolean defaulting to
+  `true`. The default preserves the current behavior for every consumer.
+- The existing `config` block (SDDM, Plasma 6, user packages) stays enabled
+  whenever the profile is enabled, regardless of `startOnBoot`.
+- When `startOnBoot = false`, additionally apply:
+  - `systemd.services.display-manager.wantedBy = lib.mkForce [ ];` so SDDM is
+    defined but not pulled in by any boot target.
+  - `systemd.defaultUnit = "multi-user.target";` so the boot target is the
+    text console.
+  - A `desktop` command provided via
+    `pkgs.writeShellScriptBin "desktop" "exec sudo systemctl start display-manager.service"`,
+    added to `environment.systemPackages`.
+
+### `machines/mibook/environments.nix`
+
+Set `kde-desktop.startOnBoot = false;` alongside the existing
+`kde-desktop.enable = true;`.
+
+## Testing / verification
+
+- `nix build '.#nixosConfigurations.mibook.config.system.build.toplevel'`
+  builds without error.
+- After `nixos-rebuild switch` on mibook: system boots to a TTY, no SDDM;
+  running `desktop` brings up the SDDM login and a working Plasma session.
+- Confirm jupiter (or any non-mibook consumer) is unchanged: its evaluated
+  `systemd.defaultUnit` / display-manager wantedBy are not altered.
+
+## Trade-offs
+
+- `desktop` relies on `sudo`; the user has sudo access, so no extra
+  configuration is required.
+- Chose "boot to terminal, launch on demand" over a GRUB boot-menu entry
+  because it is more robust across NixOS generations and needs no fragile
+  static kernel entries.

flake.lock

@@ -21,11 +21,11 @@
         "nixpkgs-lib": "nixpkgs-lib"
       },
       "locked": {
-        "lastModified": 1778716662,
-        "narHash": "sha256-m1Yf0wZ8j1OHjTc2UwHwyQRSnNeSgLJOd7q5Y45hzi4=",
+        "lastModified": 1782949081,
+        "narHash": "sha256-vp6Y/Grm98ESt6ceOkWiHWyZRDV3J1RID4w+6NWK9yA=",
         "owner": "hercules-ci",
         "repo": "flake-parts",
-        "rev": "f7c1a2d347e4c52d5fb8d10cb4d94b5884e546fb",
+        "rev": "17c9d6cdfc60c64f4ee8d306f9bc0b4ccb51481e",
         "type": "github"
       },
       "original": {
@@ -42,11 +42,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1778716662,
-        "narHash": "sha256-m1Yf0wZ8j1OHjTc2UwHwyQRSnNeSgLJOd7q5Y45hzi4=",
+        "lastModified": 1782949081,
+        "narHash": "sha256-vp6Y/Grm98ESt6ceOkWiHWyZRDV3J1RID4w+6NWK9yA=",
         "owner": "hercules-ci",
         "repo": "flake-parts",
-        "rev": "f7c1a2d347e4c52d5fb8d10cb4d94b5884e546fb",
+        "rev": "17c9d6cdfc60c64f4ee8d306f9bc0b4ccb51481e",
         "type": "github"
       },
       "original": {
@@ -60,20 +60,17 @@
         "flake-compat": [
           "nix"
         ],
-        "gitignore": [
-          "nix"
-        ],
         "nixpkgs": [
           "nix",
           "nixpkgs"
         ]
       },
       "locked": {
-        "lastModified": 1781733627,
-        "narHash": "sha256-U3yTuGBnmXvXoQI3qkpfEDsn9RovQPAjN7ndRco+3u0=",
+        "lastModified": 1783008725,
+        "narHash": "sha256-jGiy6+sxjNWXSjp25uoJuNfyH9zBK1PEDY0lVoL4ibQ=",
         "owner": "cachix",
         "repo": "git-hooks.nix",
-        "rev": "3bbec39bc90eadfa031e6f3b77272f3f60803e39",
+        "rev": "bca82caa46d5ec0f5d422c61fb1e30bc51313cbe",
         "type": "github"
       },
       "original": {
@@ -92,11 +89,11 @@
         "nixpkgs-regression": "nixpkgs-regression"
       },
       "locked": {
-        "lastModified": 1782337899,
-        "narHash": "sha256-Imevyelg3r2N5iDonnGdOKGRiB56m3HgVFAljTB3CLU=",
+        "lastModified": 1784762557,
+        "narHash": "sha256-R/r6jRnANV50c8F5Fz5+1Q1moab0IGWRk+cg5ME2nMY=",
         "owner": "NixOS",
         "repo": "nix",
-        "rev": "3887a906b178836818a62e8eba666ad652e8a388",
+        "rev": "d10c84cd0cc0efdcb29cf2611caf5fbcd10fa071",
         "type": "github"
       },
       "original": {
@@ -146,11 +143,11 @@
         "nixpkgs": "nixpkgs_2"
       },
       "locked": {
-        "lastModified": 1782379505,
-        "narHash": "sha256-zPvPiU+a7pqtH47xrtZLNRABJKpOjfZQclDbcvNtH+I=",
+        "lastModified": 1784723954,
+        "narHash": "sha256-1CfD8ZUjCkTgjsneLZ/lxCHhgDfqxxE7/GX0MmsgiqA=",
         "owner": "NixOS",
         "repo": "nixos-hardware",
-        "rev": "603d3afd1b6145bd66e97ae38a34d91c95df70cf",
+        "rev": "a017f5b72210026af5b3ac5949f08d94380a6fbd",
         "type": "github"
       },
       "original": {
@@ -161,11 +158,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1780902259,
-        "narHash": "sha256-YMnBf9lk/LYgvqfmSSJuOGigtRs5Lsy26pJHVlR9yMY=",
-        "rev": "bd0ff2d3eac24699c3664d5966b9ef36f388e2ca",
+        "lastModified": 1783148766,
+        "narHash": "sha256-H9+N+GFtsbVC8ZniHliChM7ndizxtqVZs6bnGOLM3WQ=",
+        "rev": "a50de1b7d8a586adc18d2395c19de7d6058e6030",
         "type": "tarball",
-        "url": "https://releases.nixos.org/nixos/26.05/nixos-26.05.1550.bd0ff2d3eac2/nixexprs.tar.xz"
+        "url": "https://releases.nixos.org/nixos/26.05/nixos-26.05.4193.a50de1b7d8a5/nixexprs.tar.xz"
       },
       "original": {
         "type": "tarball",
@@ -190,11 +187,11 @@
     },
     "nixpkgs-lib": {
       "locked": {
-        "lastModified": 1777168982,
-        "narHash": "sha256-GOkGPcboWE9BmGCRMLX3worL4EMnsnG8MyKmXNeYuhQ=",
+        "lastModified": 1782614948,
+        "narHash": "sha256-ePjCwr1sNm9NYUqywL7QfK3JnlS015msC+eBu2zKlp8=",
         "owner": "nix-community",
         "repo": "nixpkgs.lib",
-        "rev": "f5901329dade4a6ea039af1433fb087bd9c1fe14",
+        "rev": "db3f255737b94216eb71cce308e2912cf6bc2d7c",
         "type": "github"
       },
       "original": {
@@ -221,11 +218,11 @@
     },
     "nixpkgs-unstable": {
       "locked": {
-        "lastModified": 1782467914,
-        "narHash": "sha256-inDx/w70OSJoJPqtKh0BrzAsbZZhpya7YgS43jHnhwg=",
-        "rev": "e73de5be04e0eff4190a1432b946d469c794e7b4",
+        "lastModified": 1784796856,
+        "narHash": "sha256-vwxWgF+Gj276WznzGb1LxGsK/39HaQwgQXiU3EkC844=",
+        "rev": "e2587caef70cea85dd97d7daab492899902dbf5d",
         "type": "tarball",
-        "url": "https://releases.nixos.org/nixos/unstable/nixos-26.11pre1022855.e73de5be04e0/nixexprs.tar.xz"
+        "url": "https://releases.nixos.org/nixos/unstable/nixos-26.11pre1040357.e2587caef70c/nixexprs.tar.xz"
       },
       "original": {
         "id": "nixpkgs",
@@ -248,11 +245,11 @@
     },
     "nixpkgs_3": {
       "locked": {
-        "lastModified": 1782375420,
-        "narHash": "sha256-f+/IH5ng5P91VHrhcNxqpW2RYDySD68V1fcX00COQy4=",
-        "rev": "4062d36ebeae843c750011eef6b61ec9a9dbc9a9",
+        "lastModified": 1784707089,
+        "narHash": "sha256-DUedXhD2Rg8q4Xyd07Sb90eZGy4gg6W+Vl/WbLNwAZo=",
+        "rev": "b3fe9581c9061c749abef42b6d4ee7b7c05c33fa",
         "type": "tarball",
-        "url": "https://releases.nixos.org/nixos/26.05/nixos-26.05.3250.4062d36ebeae/nixexprs.tar.xz"
+        "url": "https://releases.nixos.org/nixos/26.05/nixos-26.05.5845.b3fe9581c906/nixexprs.tar.xz"
       },
       "original": {
         "id": "nixpkgs",

machines/mibook/configuration.nix

@@ -44,6 +44,14 @@
 
   services.openssh.enable = true;
 
+  # KDE (PowerDevil) power settings: do nothing on lid close while on AC power.
+  # Shipped as a system-wide default; KConfig cascades so a user's own
+  # ~/.config/powerdevilrc will override this if present.
+  environment.etc."xdg/powerdevilrc".text = ''
+    [AC][SuspendAndShutdown]
+    LidAction=0
+  '';
+
   system = {
     stateVersion = "23.05";
     autoUpgrade.enable = true;

machines/mibook/environments.nix

@@ -6,6 +6,7 @@ in
 {
   my.profiles = {
     kde-desktop.enable = true;
+    kde-desktop.startOnBoot = false;
     zsh.enable = true;
     apps = {
       desktop_apps = true;

modules/environments/kde-desktop/default.nix

@@ -11,9 +11,19 @@ in
 {
   options.my.profiles.kde-desktop = with lib; {
     enable = mkEnableOption "KDE Desktop Environment";
+    startOnBoot = mkOption {
+      type = types.bool;
+      default = true;
+      description = ''
+        Whether the display manager (SDDM) starts automatically at boot.
+        When false, the system boots to a text console and KDE can be
+        launched on demand with the `desktop` command.
+      '';
+    };
   };
 
-  config = lib.mkIf cfg.enable {
+  config = lib.mkIf cfg.enable (lib.mkMerge [
+    {
       services = {
         displayManager.sddm.enable = true;
         displayManager.sddm.wayland.enable = true;
@@ -23,5 +33,15 @@ in
         # Programms can be added here...
         numix-icon-theme
       ];
-  };
+    }
+    (lib.mkIf (!cfg.startOnBoot) {
+      # Boot to a text console; SDDM stays installed but is not pulled in
+      # by any boot target. Launch KDE on demand with `desktop`.
+      systemd.services.display-manager.wantedBy = lib.mkForce [ ];
+      systemd.defaultUnit = lib.mkForce "multi-user.target";
+      environment.systemPackages = [
+        (pkgs.writeShellScriptBin "desktop" "exec sudo systemctl start display-manager.service")
+      ];
+    })
+  ]);
 }