feat(appearance): wallpaper picker and scheme switcher

One drawer for how the desktop looks, on SUPER+Return, replacing the
qarma file dialog that key used to open. wallp is untouched and still
does the work: the panel calls it with H= and V= and it still runs from
a terminal.

Clicking a thumbnail stages it rather than setting it, so both screens
can be composed before anything changes and Apply is a single wallp
call. The mock screens show the result: the staged pick where there is
one, what is set where there is not, and the hovered thumbnail on the
targeted screen. They are drawn at the real proportions from hyprctl
monitors, DP-3 upright because it has transform=1, centred against each
other as Hyprland has them.

The scheme tab reads the palette pair unified-desktop-theme keeps for
each scheme, so the swatches are that scheme's real colours and the list
needs no edit when a scheme is added. Applying writes roles.conf and
runs install.sh, and reloads nothing, because install.sh reloads
nothing: the panel says what is still showing the old scheme rather than
pretending the switch is done.

Two QML traps are documented in AGENTS.md because neither announces
itself: there is no String.matchAll, which threw inside a try and left
every swatch empty, and assigning running = true to an already-running
Process does nothing, which stopped the scheme loader after the first
file.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01G7NRsGyF9jGfPYS4zPqpN7

1 files changed, 66 insertions, 0 deletions

diff --git a/appearance/Theme.qml b/appearance/Theme.qml
new file mode 100644
index 0000000..423dd49
--- /dev/null
+++ b/appearance/Theme.qml
@@ -0,0 +1,66 @@
+// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+pragma Singleton
+
+import Quickshell
+import Quickshell.Io
+import QtQuick
+
+// The palette comes from unified-desktop-theme: udt-accent writes
+// ~/.cache/wal/udt-palette.qml on every wallpaper change, holding the
+// Macchiato colours from its palette.rasi plus the accent snapped from the
+// wallpaper. Watching that file is what makes a theme edit show up here.
+//
+// The defaults below are only what renders before the file is read, or on a
+// machine where unified-desktop-theme is not installed.
+Singleton {
+    id: root
+
+    property color base: "#24273a"
+    property color surface: "#363a4f"
+    property color text: "#cad3f5"
+    property color subtext: "#a5adcb"
+    property color red: "#ed8796"
+    property color green: "#a6da95"
+    property color yellow: "#eed49f"
+    property color surfaceAlt: "#494d64"
+    property color overlay: "#6e738d"
+    property color accent: "#b7bdf8"
+
+    readonly property string fontFamily: "Noto Sans"
+    readonly property int fontSize: 16
+
+    // Parsed rather than imported: a generated file cannot be a QML import
+    // without a qmldir next to it, and the cache directory has no reason to
+    // carry one. The format is fixed and machine-written, so a regex is enough.
+    FileView {
+        path: `${Quickshell.env("HOME")}/.cache/wal/udt-palette.qml`
+        watchChanges: true
+        onFileChanged: reload()
+        onLoaded: {
+            const pick = key => {
+                const m = text().match(new RegExp(`property color ${key}: "(#[0-9a-fA-F]{6})"`));
+                return m ? m[1] : null;
+            };
+            root.base    = pick("base")     ?? root.base;
+            root.surface = pick("surface0") ?? root.surface;
+            root.text    = pick("text")     ?? root.text;
+            root.subtext = pick("subtext0") ?? root.subtext;
+            root.red     = pick("red")      ?? root.red;
+            root.green = pick("green") ?? root.green;
+            root.yellow = pick("yellow") ?? root.yellow;
+            root.surfaceAlt = pick("surface1") ?? root.surfaceAlt;
+            root.overlay = pick("overlay0") ?? root.overlay;
+            root.accent  = pick("accent")   ?? root.accent;
+        }
+    }
+}