feat(system): add laptop power preset module

New `nomarchy.system.laptop.{enable,thermald}` options. `enable`
defaults to `formFactor == "laptop"`, so the installer's existing
formFactor write auto-flips the preset on without installer changes.

The module wires TLP (governors + 75/80 charge thresholds),
force-disables power-profiles-daemon (mutually exclusive with TLP),
enables upower and thermald (x86_64), adds the brightnessctl udev
rule so the existing brightness scripts work without root, and sets
a logind lid-switch policy that resolves to suspend-then-hibernate
when `hibernation.enable` is on, plain suspend otherwise.

Closes the "Form-factor → laptop preset auto-enable" Now item and
the "Laptop preset module" Next item from docs/ROADMAP.md in one
change.

core/system/default.nix

@@ -19,6 +19,7 @@
     ./browser.nix
     # Tier 1 system features (all opt-in via nomarchy.system.*).
     ./snapper.nix
+    ./laptop.nix
     ./hibernate.nix
     ./containers.nix
     ./pam.nix

core/system/laptop.nix

@@ -0,0 +1,42 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.nomarchy.system.laptop;
+  hib = config.nomarchy.system.hibernation;
+  lidAction = if hib.enable then "suspend-then-hibernate" else "suspend";
+in
+{
+  config = lib.mkIf cfg.enable {
+    services.tlp = {
+      enable = lib.mkDefault true;
+      settings = {
+        CPU_SCALING_GOVERNOR_ON_AC = lib.mkDefault "performance";
+        CPU_SCALING_GOVERNOR_ON_BAT = lib.mkDefault "powersave";
+        CPU_BOOST_ON_BAT = lib.mkDefault 0;
+        PLATFORM_PROFILE_ON_AC = lib.mkDefault "balanced";
+        PLATFORM_PROFILE_ON_BAT = lib.mkDefault "low-power";
+        # Charge thresholds only honored on supported hardware (ThinkPad,
+        # some ASUS); a harmless warning is logged elsewhere.
+        START_CHARGE_THRESH_BAT0 = lib.mkDefault 75;
+        STOP_CHARGE_THRESH_BAT0 = lib.mkDefault 80;
+      };
+    };
+
+    # TLP and power-profiles-daemon both arbitrate CPU/EPP — NixOS asserts
+    # mutual exclusion. Opt out of the preset entirely to use PPD instead.
+    services.power-profiles-daemon.enable = lib.mkForce false;
+
+    services.upower.enable = lib.mkDefault true;
+    services.thermald.enable = lib.mkDefault cfg.thermald;
+
+    # Backlight write access for the `video` group, so the existing
+    # nomarchy-brightness-{display,keyboard} scripts run without root.
+    services.udev.packages = [ pkgs.brightnessctl ];
+
+    services.logind.settings.Login = {
+      HandleLidSwitch = lib.mkDefault lidAction;
+      HandleLidSwitchExternalPower = lib.mkDefault "suspend";
+      HandleLidSwitchDocked = lib.mkDefault "ignore";
+    };
+  };
+}

core/system/options.nix

@@ -1,4 +1,4 @@
-{ lib, ... }:
+{ config, lib, pkgs, ... }:
 
 {
   options.nomarchy.system = {
@@ -82,6 +82,32 @@
       };
     };
 
+    laptop = {
+      enable = lib.mkOption {
+        type = lib.types.bool;
+        default = config.nomarchy.system.formFactor == "laptop";
+        defaultText = lib.literalExpression ''config.nomarchy.system.formFactor == "laptop"'';
+        description = ''
+          Laptop power preset: TLP (with sane AC/battery governors),
+          `services.upower`, `services.thermald` (x86_64), a brightnessctl
+          udev rule, and a logind lid-switch policy. Force-disables
+          `services.power-profiles-daemon` (mutually exclusive with TLP).
+          Lid-close defers to `nomarchy.system.hibernation.enable`:
+          suspend-then-hibernate when on, suspend otherwise. Defaults on
+          when `formFactor = "laptop"`.
+        '';
+      };
+      thermald = lib.mkOption {
+        type = lib.types.bool;
+        default = pkgs.stdenv.hostPlatform.isx86_64;
+        defaultText = lib.literalExpression "pkgs.stdenv.hostPlatform.isx86_64";
+        description = ''
+          Enable `services.thermald` (Intel thermal daemon). Default true on
+          x86_64. Harmless no-op on AMD; gated off on aarch64.
+        '';
+      };
+    };
+
     containers = {
       enable = lib.mkEnableOption ''
         Rootless Podman with Docker compatibility (`docker` → `podman`),

docs/OPTIONS.md

@@ -35,9 +35,9 @@ Defined in `core/system/options.nix`; wired in `core/system/network.nix`.
 
 ### `nomarchy.system.formFactor`
 
-`enum [ "laptop" "desktop" ]`, default `"laptop"`. Drives UI affordances and (eventually) lid handling / TLP. The installer auto-detects via `/sys/class/power_supply/BAT*`. The default is `"laptop"` because the battery widget renders empty when no battery is present — safe on a desktop, useful on a laptop.
+`enum [ "laptop" "desktop" ]`, default `"laptop"`. Drives UI affordances and the laptop power preset. The installer auto-detects via `/sys/class/power_supply/BAT*`. The default is `"laptop"` because the battery widget renders empty when no battery is present — safe on a desktop, useful on a laptop.
 
-Wired in `features/desktop/waybar/default.nix` (filters the battery widget out on desktop) and `features/scripts/battery-monitor.nix` (skips the timer on desktop).
+Wired in `features/desktop/waybar/default.nix` (filters the battery widget out on desktop), `features/scripts/battery-monitor.nix` (skips the timer on desktop), and `nomarchy.system.laptop.enable` (defaults true when this is `"laptop"`).
 
 ### `nomarchy.system.theme`
 
@@ -67,6 +67,14 @@ Wired in `features/desktop/waybar/default.nix` (filters the battery widget out o
 
 `int`, default `30`. Idle minutes before suspend-then-hibernate fires.
 
+### `nomarchy.system.laptop.enable`
+
+`bool`, default `nomarchy.system.formFactor == "laptop"`. Laptop power preset: TLP (with sane AC/battery governors and ThinkPad-style 75/80 charge thresholds), `services.upower`, `services.thermald` (gated by `laptop.thermald`), and a brightnessctl udev rule so the existing `nomarchy-brightness-{display,keyboard}` scripts run without root. Force-disables `services.power-profiles-daemon` (mutually exclusive with TLP) — to use PPD instead, set `laptop.enable = false` and wire it yourself. Lid-close action defers to `nomarchy.system.hibernation.enable`: `suspend-then-hibernate` when on, `suspend` otherwise. Charge thresholds are only honored on supported hardware (ThinkPad, some ASUS); harmless warning elsewhere.
+
+### `nomarchy.system.laptop.thermald`
+
+`bool`, default `true` on x86_64. Enables `services.thermald` (Intel thermal daemon). Harmless no-op on AMD; gated off on aarch64.
+
 ### `nomarchy.system.containers.enable`
 
 `bool`, default `false`. Rootless Podman with Docker compatibility (`docker` → `podman`), plus `podman-compose`, `podman-tui`, and `dive`.

docs/ROADMAP.md

@@ -19,11 +19,10 @@ Guardrails (apply when adding anything):
 
 ### Now (ready to pick up)
 
-- **Form-factor → laptop preset auto-enable.** When the installer writes `nomarchy.system.formFactor = "laptop"`, also flip on a yet-to-be-built laptop preset (TLP, brightness keys, lid handling). The option exists; the preset module doesn't.
+- (empty — pick the top of **Next**.)
 
 ### Next (bigger lifts that build on Now)
 
-- **Laptop preset module** (`core/system/laptop.nix`). Gated on `formFactor = "laptop"`. Wires TLP defaults, `services.upower`, `services.thermald` where applicable, brightness key handlers, and a sane logind lid-switch policy that defers to `nomarchy.system.hibernation.enable`.
 - **Desktop preset module.** CPU governor `performance` by default, no battery widget (already done), ZFS-friendly defaults for users who later add a pool.
 - **Accessibility preset.** Larger cursor, slower key-repeat defaults, `services.orca`, screen reader keybinding, high-contrast theme variant.
 - **Gaming preset.** `programs.steam.enable`, `programs.gamemode.enable`, `services.flatpak.enable` with a curated remote, and a Hyprland window-rule to fullscreen Steam-launched apps.
@@ -126,6 +125,7 @@ Each PR description should reference the row(s) in `docs/SCRIPTS.md` it closes,
 
 (Move items here when they land — keep them brief, link the commit/PR.)
 
+- _2026-04-26_ — Laptop preset module (`core/system/laptop.nix`). New `nomarchy.system.laptop.{enable,thermald}` options; `enable` defaults to `formFactor == "laptop"` so the installer's existing `formFactor` write auto-flips it on. Wires TLP (governors + 75/80 charge thresholds), force-disables `power-profiles-daemon`, enables `upower` and `thermald` (x86_64), adds the brightnessctl udev rule for backlight without root, and sets a logind lid-switch policy that defers to `hibernation.enable`. Closes both the Now item and the largest Next item.
 - _2026-04-25_ — Software-profile multi-select in the installer. Users can now pick Dev, Gaming, Office, Media, and CLI Utils profiles during install; logic emits corresponding `home.packages` and system toggles into the generated config.
 - _2026-04-25_ — Pillar 3 Phase B: script & menu audit. Ported/implemented/stubbed ~40 scripts including `nomarchy-version`, `nomarchy-debug`, `nomarchy-reinstall`, `nomarchy-rollback`, `nomarchy-update-firmware`, `nomarchy-pkg-*`, and `nomarchy-theme-*` wrappers. Moved desktop scripts to packaged utility directory.
 - _2026-04-25_ — Docker & fwupd support. Added `nomarchy.system.virtualization.docker.enable` and `nomarchy.hardware.fwupd` options. Wires system services and adds `docker-compose` and `fwupdmgr` to PATH.