wallpaper: one run() for Apply and the engine, with a finished signal

The engine's timer must set wallpapers the same way Apply does so the
burn plays. run() is that one path; applied stays Apply's alone (save bar,
window close) while finished marks every run's end, which is what the
spread overlay now hides on.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2 files changed, 39 insertions, 11 deletions

diff --git a/desktop/modules/appearance/WallpaperSpread.qml b/desktop/modules/appearance/WallpaperSpread.qml
index c133343..d1c383d 100644
--- a/desktop/modules/appearance/WallpaperSpread.qml
+++ b/desktop/modules/appearance/WallpaperSpread.qml
@@ -59,9 +59,10 @@ Scope {
                     newImg.source = to;
                     win.running = true;
                 }
-                // A failed set may have left either picture underneath, so
-                // the cover goes at once rather than claiming the new one.
-                function onApplied(ok) {
+                // Any run's end, Apply's or the engine's. A failed set may
+                // have left either picture underneath, so the cover goes at
+                // once rather than claiming the new one.
+                function onFinished(ok) {
                     win.done = true;
                     if (!ok) win.running = false;
                     else if (!anim.running) win.running = false;
diff --git a/desktop/modules/appearance/Wallpapers.qml b/desktop/modules/appearance/Wallpapers.qml
index 9e9d4ad..5507476 100644
--- a/desktop/modules/appearance/Wallpapers.qml
+++ b/desktop/modules/appearance/Wallpapers.qml
@@ -60,6 +60,11 @@ Singleton {
     // Sent before wallp runs, while current still names the old picture, so
     // WallpaperSpread can cover the swap with it.
     signal swapping(string which, string from, string to)
+    // Every run's end, Apply's or the engine's. applied is Apply's alone: it
+    // reports to the save bar and closes the window.
+    signal finished(bool ok)
+    // A successful Apply, with what it set ("" for a screen it left).
+    signal manualApplied(string h, string v)
 
     // Sorted by most recent first: the wallpaper wanted now is usually one
     // added recently. -maxdepth keeps a stray git checkout from being walked.
@@ -226,24 +231,46 @@ Singleton {
     // 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;
+        if (dirty) run(pendingH, pendingV, "manual");
+    }
+
+    // What started the run in flight: "manual" (Apply), "tick" (the engine's
+    // timer) or "home" (the engine switched off). A tick is the light run,
+    // UDT_ROTATION, which udt-accent reads; the others are full.
+    property string kind: ""
+
+    // false when nothing was started: a run in flight, or nothing to set.
+    function run(h, v, kind) {
+        if (applying || (h === "" && v === "")) return false;
         applying = true;
-        if (pendingH !== "" && currentH !== "") swapping("H", currentH, pendingH);
-        if (pendingV !== "" && currentV !== "") swapping("V", currentV, pendingV);
+        root.kind = kind;
+        if (h !== "" && currentH !== "" && h !== currentH) swapping("H", currentH, h);
+        if (v !== "" && currentV !== "" && v !== currentV) swapping("V", currentV, v);
         const args = [];
-        if (pendingH !== "") args.push(`H=${JSON.stringify(pendingH)}`);
-        if (pendingV !== "") args.push(`V=${JSON.stringify(pendingV)}`);
-        applyProc.command = ["sh", "-c", `wallp --set ${args.join(" ")} >/dev/null 2>&1`];
+        if (h !== "") args.push(`H=${JSON.stringify(h)}`);
+        if (v !== "") args.push(`V=${JSON.stringify(v)}`);
+        const env = kind === "tick" ? "UDT_ROTATION=1 " : "";
+        applyProc.command = ["sh", "-c", `${env}wallp --set ${args.join(" ")} >/dev/null 2>&1`];
         applyProc.running = true;
+        return true;
     }
 
     Process {
         id: applyProc
         stderr: StdioCollector { id: applyErr }
         onExited: code => {
+            const ok = code === 0;
             root.applying = false;
-            if (code === 0) root.clearPending();
-            root.applied(code === 0, code === 0 ? "" : (applyErr.text.trim() || `wallp exited ${code}`));
+            if (root.kind === "manual") {
+                if (ok) {
+                    root.manualApplied(root.pendingH, root.pendingV);
+                    root.clearPending();
+                }
+                root.applied(ok, ok ? "" : (applyErr.text.trim() || `wallp exited ${code}`));
+            } else if (!ok) {
+                console.warn(`Wallpapers: the engine's ${root.kind} set failed, wallp exited ${code}`);
+            }
+            root.finished(ok);
         }
     }
 }