feat(keyboard): interactive new-keyboard layout prompt + persist

The runtime-remember complement to nomarchy.keyboard.devices. Set
nomarchy.keyboard.layouts (candidate layouts) and a nomarchy-keyboard-watch
daemon runs (exec-once): it polls hyprctl devices, and when a keyboard
connects after login that isn't declared and hasn't been chosen before, it
pops a rofi layout picker, applies the choice via hyprctl switchxkblayout (an
index into the candidate set carried by input.kb_layout), and remembers it
per-device in ~/.local/state -- re-applied silently on later reconnects. The
boot-time set (incl. the built-in keyboard) is never prompted.

Pure bash + jq/hyprctl/rofi (all in the session PATH); state lives outside
the flake (a stateful runtime piece by design). Eval + bash-syntax verified;
the hotplug behaviour needs an on-hardware test.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

modules/home/hyprland.nix

@@ -54,6 +54,64 @@ let
       ++ lib.optionals (m.vrr != null) [ "vrr" (toString m.vrr) ]
       ++ lib.optional (m.extra != "") m.extra
     );
+
+  # Keyboard layout candidates: the primary nomarchy.keyboard.layout (split on
+  # commas) plus any nomarchy.keyboard.layouts. Drives input.kb_layout so all
+  # of them are switchable, and feeds the watcher's picker.
+  kbLayouts = lib.unique (
+    (lib.splitString "," config.nomarchy.keyboard.layout)
+    ++ config.nomarchy.keyboard.layouts
+  );
+  kbAutoSwitch = config.nomarchy.keyboard.layouts != [ ];
+
+  # On a keyboard that connects after login (not declared in
+  # keyboard.devices, not already remembered), ask for a layout and persist it
+  # per-device, re-applying silently on later reconnects. Stateful runtime
+  # piece — the complement to the declarative keyboard.devices. Reliable
+  # primitives only: poll hyprctl devices, apply via switchxkblayout (an index
+  # into kbLayouts). NOTE: needs an on-hardware test (hotplug isn't verifiable
+  # in CI).
+  keyboardWatch = pkgs.writeShellScriptBin "nomarchy-keyboard-watch" ''
+    set -u
+    layouts="${lib.concatStringsSep " " kbLayouts}"
+    declared="${lib.concatStringsSep " " (builtins.attrNames config.nomarchy.keyboard.devices)}"
+    state="''${XDG_STATE_HOME:-$HOME/.local/state}/nomarchy/keyboard-layouts"
+    mkdir -p "$(dirname "$state")"; [ -f "$state" ] || : > "$state"
+
+    layout_index() { i=0; for l in $layouts; do [ "$l" = "$1" ] && { printf %s "$i"; return; }; i=$((i + 1)); done; printf %s -1; }
+    apply() { idx=$(layout_index "$2"); [ "$idx" -ge 0 ] && hyprctl switchxkblayout "$1" "$idx" >/dev/null 2>&1; }
+    keyboards() { hyprctl devices -j | jq -r '.keyboards[].name'; }
+    is_declared() { case " $declared " in *" $1 "*) return 0 ;; *) return 1 ;; esac; }
+    saved_for() { while IFS='=' read -r k v; do [ "$k" = "$1" ] && { printf '%s' "$v"; return; }; done < "$state"; }
+
+    # Startup: re-apply remembered layouts, never prompt — so the built-in
+    # keyboard just stays on the session default.
+    prev=" "
+    for kb in $(keyboards); do
+      prev="$prev$kb "
+      is_declared "$kb" && continue
+      s=$(saved_for "$kb"); [ -n "$s" ] && apply "$kb" "$s"
+    done
+
+    # Watch for keyboards that connect later.
+    while :; do
+      sleep 3
+      cur=" "
+      for kb in $(keyboards); do
+        cur="$cur$kb "
+        case "$prev" in *" $kb "*) continue ;; esac
+        is_declared "$kb" && continue
+        s=$(saved_for "$kb")
+        if [ -n "$s" ]; then
+          apply "$kb" "$s"
+        else
+          choice=$(printf '%s\n' $layouts | rofi -dmenu -p "Layout · $kb")
+          [ -n "$choice" ] && { printf '%s=%s\n' "$kb" "$choice" >> "$state"; apply "$kb" "$choice"; }
+        fi
+      done
+      prev="$cur"
+    done
+  '';
 in
 {
   wayland.windowManager.hyprland = lib.mkIf config.nomarchy.hyprland.enable {
@@ -88,7 +146,7 @@ in
         # Paint the wallpaper as soon as the session is up (waits for
         # the daemon internally).
         "nomarchy-theme-sync wallpaper"
-      ];
+      ] ++ lib.optional kbAutoSwitch "${keyboardWatch}/bin/nomarchy-keyboard-watch";
 
       # ── Theme-driven look ──────────────────────────────────────────
       # These flow from theme-state.json and stay at NORMAL priority:
@@ -144,7 +202,7 @@ in
       input = {
         # kb_layout/variant come from nomarchy.keyboard.* — set that
         # option (the installer writes it; it also drives tty/LUKS).
-        kb_layout = config.nomarchy.keyboard.layout;
+        kb_layout = lib.concatStringsSep "," kbLayouts;
         kb_variant = config.nomarchy.keyboard.variant;
         follow_mouse = lib.mkDefault 1;
         touchpad.natural_scroll = lib.mkDefault true;

modules/home/options.nix

@@ -96,6 +96,22 @@ in
       description = "XKB variant for the Hyprland session.";
     };
 
+    keyboard.layouts = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [ ];
+      example = [ "de" "fr" ];
+      description = ''
+        Extra candidate layouts offered by the interactive new-keyboard
+        picker. When non-empty, a small watcher runs in the session: when a
+        keyboard connects that isn't covered by nomarchy.keyboard.devices and
+        hasn't been chosen before, it pops a rofi picker (these layouts plus
+        the primary nomarchy.keyboard.layout), applies the choice, and
+        remembers it per-device (~/.local/state) — re-applying automatically
+        on later reconnects. The runtime-remember complement to the
+        declarative keyboard.devices; a stateful runtime piece by design.
+      '';
+    };
+
     keyboard.devices = lib.mkOption {
       type = lib.types.attrsOf (lib.types.submodule {
         options = {

modules/home/waybar.nix

@@ -16,6 +16,7 @@ let
   # is in play — multiple session layouts (comma-separated) or per-device
   # overrides (nomarchy.keyboard.devices) — so single-layout bars stay clean.
   showLanguage = lib.hasInfix "," config.nomarchy.keyboard.layout
+    || config.nomarchy.keyboard.layouts != [ ]
     || config.nomarchy.keyboard.devices != { };
 
   # Power-profile indicator (power-profiles-daemon). Both scripts self-