diff --git a/config/dot/quickshell/settings-system-harness.qml b/config/dot/quickshell/settings-system-harness.qml
index 7c59615..6c563ae 100644
--- a/config/dot/quickshell/settings-system-harness.qml
+++ b/config/dot/quickshell/settings-system-harness.qml
@@ -23,14 +23,16 @@ ShellRoot {
         // Production applyOptions is covered separately by the Hyprland write
         // contract; this seam proves commit/reset routing without changing the
         // desktop that is running the test.
-        SystemSettings.compositorApplyOverride = function(requested) {
-            const batches = root.appliedBatches.slice();
-            batches.push(requested);
-            root.appliedBatches = batches;
-            for (const key in requested)
-                DesktopPreferences.set(key, requested[key]);
-            return true;
-        };
+        if (Quickshell.env("PANAMA_SETTINGS_TEST_ISOLATE_COMPOSITOR") === "1") {
+            SystemSettings.compositorApplyOverride = function(requested) {
+                const batches = root.appliedBatches.slice();
+                batches.push(requested);
+                root.appliedBatches = batches;
+                for (const key in requested)
+                    DesktopPreferences.set(key, requested[key]);
+                return true;
+            };
+        }
         SystemSettings.displayBusy = function() { return false; };
         SystemSettings.readDisplays = function() { return DesktopPreferences.get("displays"); };
         SystemSettings.protectDisplays = function(value) {
diff --git a/tests/quickshell/settings-commit-reset-contract.sh b/tests/quickshell/settings-commit-reset-contract.sh
index 41fdbb8..a1e4352 100755
--- a/tests/quickshell/settings-commit-reset-contract.sh
+++ b/tests/quickshell/settings-commit-reset-contract.sh
@@ -51,7 +51,8 @@ rg -Fq 'property string storedValue:' "$wallpaper_service" \
     || fail 'the shipped wallpaper cannot remain represented by the default empty preference'
 
 qs_for_harness() {
-    XDG_CONFIG_HOME="$config_home" XDG_STATE_HOME="$state_home" qs -p "$harness" "$@"
+    XDG_CONFIG_HOME="$config_home" XDG_STATE_HOME="$state_home" \
+        PANAMA_SETTINGS_TEST_ISOLATE_COMPOSITOR=1 qs -p "$harness" "$@"
 }
 
 restore() {
@@ -60,7 +61,8 @@ restore() {
 }
 trap restore EXIT
 
-XDG_CONFIG_HOME="$config_home" XDG_STATE_HOME="$state_home" qs -p "$harness" --daemonize >/dev/null
+XDG_CONFIG_HOME="$config_home" XDG_STATE_HOME="$state_home" \
+    PANAMA_SETTINGS_TEST_ISOLATE_COMPOSITOR=1 qs -p "$harness" --daemonize >/dev/null
 for _ in $(seq 1 40); do
     qs_for_harness ipc show 2>/dev/null | rg -q '^target settings-system-test$' && break
     sleep 0.1