Finish the wonderland: System told truthfully, in eight tabs instead of ten

Claude-Session: https://claude.ai/code/session_01Ms2FbjQy31TVf3CEvQhGM8

config/dot/quickshell/settings-backup-harness.qml

@@ -141,6 +141,25 @@ ShellRoot {
             return SettingsBackup.handleRestoreOutput(output);
         }
 
+        // The two pure functions behind a display restore, exposed directly.
+        // Everything else here is exercised through handleRestoreOutput, but
+        // the colour half of a layout is invisible from there: a snapshot
+        // whose colour fields were dropped restores geometry perfectly and
+        // reports success, which is exactly why nothing caught it for as long
+        // as it did.
+        function layoutFor(storedJson: string): string {
+            return JSON.stringify(
+                SettingsBackup.layoutFromStoredDisplays(JSON.parse(storedJson)));
+        }
+
+        // Both layouts in one object rather than two arguments: the IPC client
+        // flattens a top-level JSON array into one argument per element, so a
+        // pair of two-monitor layouts arrives as four arguments.
+        function layoutsMatch(pairJson: string): bool {
+            const pair = JSON.parse(pairJson);
+            return SettingsBackup.layoutsEqual(pair.left, pair.right);
+        }
+
         function status(): string {
             return JSON.stringify({
                 calls: root.calls,