Adjust Linux wallpaper test mode

dist/main/system_handlers.js

@@ -221,18 +221,41 @@ function registerSystemHandlers() {
             }
         }
         if (os.platform() === 'linux') {
-            let img_path = imagePath ? (0, file_utils_1.expandPath)(imagePath) : null;
-            if (!img_path && url) {
-                const result = await download_wallpaper_image(url, 'wallpaper_primary');
-                if (!result.success || !result.path)
-                    return { success: false, error: result.error };
-                img_path = result.path;
-            }
-            if (!img_path)
+            // Dev test mode: never touch the desktop on Linux. Running gsettings during
+            // development would reset the dev workstation monitors on every test cycle.
+            // Return what would have run so the Svelte side can show a debug popup.
+            const would_run = [];
+            const cache_dir = wallpaper_cache_dir;
+            if (!imagePath && !url && !url_external) {
                 return { success: false, error: 'No image source provided' };
-            if (!fs.existsSync(img_path))
-                return { success: false, error: 'Image file not found' };
-            return await runExec(`gsettings set org.gnome.desktop.background picture-uri "file://${img_path}"`);
+            }
+            if (imagePath) {
+                const clean = (0, file_utils_1.expandPath)(imagePath);
+                if (!fs.existsSync(clean))
+                    return { success: false, error: 'Image file not found' };
+            }
+            if (url)
+                would_run.push(`download: ${url}\n  → ${path.join(cache_dir, 'wallpaper_primary.jpg')}`);
+            if (url_external)
+                would_run.push(`download: ${url_external}\n  → ${path.join(cache_dir, 'wallpaper_external.jpg')}`);
+            if (imagePath) {
+                would_run.push(`gsettings set org.gnome.desktop.background picture-uri "file://${(0, file_utils_1.expandPath)(imagePath)}"`);
+            }
+            else if (url) {
+                would_run.push(`gsettings set org.gnome.desktop.background picture-uri "file://${path.join(cache_dir, 'wallpaper_primary.jpg')}"`);
+            }
+            if (url_external) {
+                would_run.push(`(external display: gsettings has no per-display wallpaper support)`);
+            }
+            return {
+                success: true,
+                linux_test_mode: true,
+                platform: 'linux',
+                display,
+                url: url ?? null,
+                url_external: url_external ?? null,
+                would_run
+            };
         }
         return { success: false, error: 'Platform not supported' };
     });