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, 115 insertions, 0 deletions

diff --git a/appearance/Wallpapers.qml b/appearance/Wallpapers.qml
new file mode 100644
index 0000000..0d61f90
--- /dev/null
+++ b/appearance/Wallpapers.qml
@@ -0,0 +1,115 @@
+// 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 wallpaper side. Setting one is `wallp`'s job: it knows about the two
+// outputs, the saved state and the accent run, and none of that is worth
+// reimplementing here.
+Singleton {
+    id: root
+
+    readonly property string home: Quickshell.env("HOME")
+    readonly property string dir: `${home}/Pictures/wallpapers`
+
+    // Which screen a pick applies to. wallp calls them H and V.
+    property string target: "H"
+
+    // Staged picks, empty until something is chosen. Selecting does not set
+    // anything: both screens can be composed and applied together, which is
+    // also a single wallp call rather than two.
+    property string pendingH: ""
+    property string pendingV: ""
+    readonly property bool dirty: pendingH !== "" || pendingV !== ""
+
+    function pick(path) {
+        if (target === "V") pendingV = path;
+        else pendingH = path;
+    }
+
+    function clearPending() { pendingH = ""; pendingV = ""; }
+
+    // What a screen should show: the staged pick if there is one, else what
+    // is actually set.
+    function shown(which) {
+        if (which === "V") return pendingV !== "" ? pendingV : currentV;
+        return pendingH !== "" ? pendingH : currentH;
+    }
+
+    property list<string> files: []
+    property bool scanning: true
+    property bool applying: false
+    signal applied(bool ok, string message)
+
+    // Sorted by most recent first: the wallpaper wanted now is usually one
+    // added recently. -maxdepth keeps a stray git checkout from being walked.
+    Process {
+        running: true
+        command: ["sh", "-c",
+            `find ${JSON.stringify(root.dir)} -maxdepth 2 -type f ` +
+            `\\( -iname '*.png' -o -iname '*.jpg' -o -iname '*.jpeg' -o -iname '*.webp' \\) ` +
+            `-not -path '*/.*' -printf '%T@ %p\\n' 2>/dev/null | sort -rn | cut -d' ' -f2-`]
+        stdout: StdioCollector {
+            onStreamFinished: {
+                root.files = text.trim().split("\n").filter(s => s.length);
+                root.scanning = false;
+            }
+        }
+    }
+
+    function basename(path) { return path.slice(path.lastIndexOf("/") + 1); }
+
+    // What is on each screen now. wallp writes these on every set, so
+    // watching them keeps the mock honest even when set from a terminal.
+    property string currentH: ""
+    property string currentV: ""
+
+    FileView {
+        path: `${root.home}/.config/wallp/wall_h`
+        watchChanges: true
+        onFileChanged: reload()
+        onLoaded: root.currentH = text().trim()
+    }
+
+    FileView {
+        path: `${root.home}/.config/wallp/wall_v`
+        watchChanges: true
+        onFileChanged: reload()
+        onLoaded: root.currentV = text().trim()
+    }
+
+    // wallp does the work, including running udt-accent, so the accent follows
+    // the new wallpaper exactly as it does from the command line. Both screens
+    // go in one call: wallp accepts H= and V= together.
+    function apply() {
+        if (applying || !dirty) return;
+        applying = true;
+        const args = [];
+        if (pendingH !== "") args.push(`H=${JSON.stringify(pendingH)}`);
+        if (pendingV !== "") args.push(`V=${JSON.stringify(pendingV)}`);
+        applyProc.command = ["sh", "-c", `wallp --set ${args.join(" ")} >/dev/null 2>&1`];
+        applyProc.running = true;
+    }
+
+    Process {
+        id: applyProc
+        stderr: StdioCollector { id: applyErr }
+        onExited: code => {
+            root.applying = false;
+            if (code === 0) root.clearPending();
+            root.applied(code === 0, code === 0 ? "" : (applyErr.text.trim() || `wallp exited ${code}`));
+        }
+    }
+}