feat(displays): display profiles — docked/undocked switching (item 15a)

nomarchy.displayProfiles: named layouts for the same outputs, each a
list of nomarchy.monitors-style entries. The active profile lives in
the in-flake state (settings.displayProfile) on the night-light
pattern: nomarchy-display-profile apply <name> fires the baked hyprctl
rules instantly and writes the state with --no-switch; the next rebuild
bakes the profile's entries over nomarchy.monitors whole-by-name.
Monitor-rule composition is extracted to pure monitor-rules.nix
(renderer + 3-layer resolve, incl. a disable-guard so a stale menu
resolution pick can't resurrect a profile-disabled panel, and junk
state degrading to base config instead of an eval error) — because a
writeText/toFile state fixture is unreadable at flake-check eval time,
the new checks.display-profiles unit-tests the pure function directly.
Menu: System › Display gains a self-gated "Profiles ›" row (●/○ active
mark, Base layout to clear); commented template example + README row.

Verified: V0 (flake check, forcing the new check's asserts); V1 — a
scratch downstream through lib.mkFlake builds: the generated tool
passes bash -n with correct rules (disable/vrr/float scale), the baked
hyprland.conf shows the exact expected overlay, the menu renders, and
list/usage smoke-test clean. Remains: V3 live switching on a dock
(HARDWARE-QUEUE). Slices b (hotplug auto-switch) + c (workspace
binding) stay in item 15.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

modules/home/hyprland.nix

@@ -46,44 +46,59 @@ let
   keybinds = import ./keybinds.nix;
   mkBind = b: "${b.mods}, ${b.key}, ${b.action}";
 
-  # A nomarchy.monitors entry -> a Hyprland `monitor` rule. Unset optional
-  # fields are omitted; `resolution = "disable"` collapses to the short form.
-  monitorRule = m:
-    if m.resolution == "disable" then "${m.name}, disable"
-    else lib.concatStringsSep ", " (
-      [ m.name m.resolution (toString m.position) (toString m.scale) ]
-      ++ lib.optionals (m.transform != null) [ "transform" (toString m.transform) ]
-      ++ lib.optionals (m.mirror != null) [ "mirror" m.mirror ]
-      ++ lib.optionals (m.bitdepth != null) [ "bitdepth" (toString m.bitdepth) ]
-      ++ lib.optionals (m.vrr != null) [ "vrr" (toString m.vrr) ]
-      ++ lib.optional (m.extra != "") m.extra
-    );
+  # Monitor-rule composition (rendering + the display-profile/resolution
+  # overlays) lives in ./monitor-rules.nix — pure, so
+  # checks.display-profiles unit-tests the overlay semantics directly.
+  # The layering story (profiles replace whole-by-name, menu resolution
+  # picks apply field-level, disable-guard) is documented there.
+  monitorLib = import ./monitor-rules.nix { inherit lib; };
+  monitorRule = monitorLib.rule;
 
-  # Menu-remembered per-output resolutions (settings.monitors: output-name ->
-  # "WxH@R", written instantly by the Display menu — see rofi.nix) overlaid onto
-  # the declarative nomarchy.monitors by name: a declared output keeps its
-  # position/scale/etc and only its resolution changes; an output covered solely
-  # by the `,preferred,auto,1` wildcard (e.g. the laptop's built-in panel)
-  # becomes a new rule with default position/scale. The menu writes the in-flake
-  # state with --no-switch (no rebuild) and applies the mode live via hyprctl;
-  # this bakes the same choice on the next rebuild — the monitor twin of the
-  # keyboard graduation. The menu pick wins over a hand-set resolution (it's the
-  # explicit live action); other declared fields are untouched.
-  resOverrides = config.nomarchy.settings.monitors;
-  # Skeleton for an output that's only menu-set (mirrors the monitorType defaults).
-  monitorDefaults = {
-    resolution = "preferred"; position = "auto"; scale = 1;
-    transform = null; mirror = null; bitdepth = null; vrr = null; extra = "";
+  # The night-light pattern: nomarchy-display-profile applies rules live
+  # via hyprctl and writes settings.displayProfile with --no-switch;
+  # resolve bakes the same choice here at the next rebuild.
+  profiles = config.nomarchy.displayProfiles;
+  resolvedMonitors = monitorLib.resolve {
+    base = config.nomarchy.monitors;
+    inherit profiles;
+    active = config.nomarchy.settings.displayProfile or "";
+    resOverrides = config.nomarchy.settings.monitors;
   };
-  declaredNames = map (m: m.name) config.nomarchy.monitors;
-  resolvedMonitors =
-    map (m: if resOverrides ? ${m.name}
-            then m // { resolution = resOverrides.${m.name}; }
-            else m)
-        config.nomarchy.monitors
-    ++ lib.mapAttrsToList
-         (name: res: monitorDefaults // { inherit name; resolution = res; })
-         (lib.filterAttrs (name: _: ! lib.elem name declaredNames) resOverrides);
+
+  # Profile applier — on PATH only when profiles are declared (the menu
+  # row self-gates on it). apply: the profile's rules live via hyprctl +
+  # the in-flake state write; base: clear the state, then hyprctl reload
+  # re-applies the generated config's rules.
+  displayProfileTool = pkgs.writeShellScriptBin "nomarchy-display-profile" ''
+    case "''${1:-}" in
+      list)
+${lib.concatMapStringsSep "\n" (n: "        echo ${lib.escapeShellArg n}") (lib.attrNames profiles)} ;;
+      active)
+        cur=$(${sync} get settings.displayProfile 2>/dev/null) || cur=
+        echo "''${cur:-none}" ;;
+      apply)
+        case "''${2:-}" in
+${lib.concatStringsSep "\n" (lib.mapAttrsToList
+  (name: entries:
+    "          ${lib.escapeShellArg name})\n"
+    + lib.concatMapStringsSep "\n"
+        (m: "            hyprctl keyword monitor ${lib.escapeShellArg (monitorRule m)} >/dev/null 2>&1")
+        entries
+    + " ;;")
+  profiles)}
+          *) echo "unknown profile '$2' — try: nomarchy-display-profile list" >&2; exit 64 ;;
+        esac
+        ${sync} --quiet set settings.displayProfile "$2" --no-switch
+        notify-send "Display profile" "Applied: $2" ;;
+      base)
+        ${sync} --quiet set settings.displayProfile "" --no-switch
+        hyprctl reload >/dev/null 2>&1
+        notify-send "Display profile" "Base layout restored." ;;
+      *)
+        echo "usage: nomarchy-display-profile [list|active|apply <name>|base]" >&2
+        exit 64 ;;
+    esac
+  '';
 
   # Candidate layouts offered by the new-keyboard picker: the session
   # layout(s) (nomarchy.keyboard.layout, comma-split for a multi-layout
@@ -359,5 +374,7 @@ in
       [ pkgs.nwg-displays ]
     # The new-keyboard watcher on PATH (when enabled) so it's discoverable and
     # runnable by name for debugging — Hyprland still exec-once's it by store path.
-    ++ lib.optional (config.nomarchy.hyprland.enable && kbAutoSwitch) keyboardWatch;
+    ++ lib.optional (config.nomarchy.hyprland.enable && kbAutoSwitch) keyboardWatch
+    # The display-profile switcher (the menu's Profiles row gates on it).
+    ++ lib.optional (config.nomarchy.hyprland.enable && profiles != { }) displayProfileTool;
 }