Serialize display recovery checks

config/dot/quickshell/services/Displays.qml

@@ -85,6 +85,7 @@ Singleton {
             if (!root.awaitingConfirmation)
                 return;
             if (root.revertQueued) {
+                if (!query.running)
                     root.performRevert();
                 return;
             }
@@ -93,6 +94,7 @@ Singleton {
                 return;
             }
             verifyTimer.attempts = 0;
+            verifyTimer.ticks = 0;
             verifyTimer.restart();
         }
     }
@@ -104,17 +106,20 @@ Singleton {
             // success without applying a value, so exact readback decides.
             root.revertVerificationActive = true;
             revertVerifyTimer.attempts = 0;
+            revertVerifyTimer.ticks = 0;
             revertVerifyTimer.restart();
         }
     }
 
     Component.onCompleted: root.refresh()
 
-    function refresh(): void {
+    function refresh(): bool {
         if (!query.running) {
             query.generation = root.operationGeneration;
             query.running = true;
+            return true;
         }
+        return false;
     }
 
     function parse(text: string, generation: int): void {
@@ -411,26 +416,29 @@ Singleton {
     Timer {
         id: verifyTimer
         property int attempts: 0
+        property int ticks: 0
         interval: 120
         repeat: true
         onTriggered: {
-            attempts++;
+            ticks++;
-            if (attempts > 25) {
+            if (ticks > 50) {
                 root.revertWithMessage("The display did not apply that setting, so Panama restored the previous one.");
                 return;
             }
-            root.refresh();
+            if (root.refresh())
+                attempts++;
         }
     }
 
     Timer {
         id: revertVerifyTimer
         property int attempts: 0
+        property int ticks: 0
         interval: 120
         repeat: true
         onTriggered: {
-            attempts++;
+            ticks++;
-            if (attempts > 25) {
+            if (ticks > 50) {
                 stop();
                 root.revertVerificationActive = false;
                 root.revertGeneration = -1;
@@ -439,7 +447,8 @@ Singleton {
                 root.lastError = "The previous display setting could not be verified. Open Displays and restore it manually.";
                 return;
             }
-            root.refresh();
+            if (root.refresh())
+                attempts++;
         }
     }
 

tests/quickshell/displays-contract.sh

@@ -225,8 +225,24 @@ KINDS
 now="$(status)"
 [[ "$(jq -r .scale <<<"$now")" == "$original_scale" ]] || fail 'a refused change still altered the scale'
 
-# ── An unconfirmed change reverts on its own and stores nothing ──────────────
+# An immediate Revert may race both the apply process and its first readback.
+# It must queue until both are clear, then verify the original generation.
 target_scale=$(awk -v s="$original_scale" 'BEGIN { print (s == 1.25) ? 1.5 : 1.25 }')
+[[ "$(run ipc call displays-test applyScale "$target_scale")" == "true" ]] \
+    || fail 'the immediate-revert fixture could not apply'
+run ipc call displays-test revertChange >/dev/null
+immediate_reverted=false
+for _ in $(seq 1 60); do
+    if display_is_restored && [[ "$(status | jq -r .awaiting)" == "false" ]]; then
+        immediate_reverted=true
+        break
+    fi
+    sleep 0.2
+done
+[[ "$immediate_reverted" == true ]] \
+    || fail 'an immediate Revert raced the apply/readback and did not restore the display'
+
+# ── An unconfirmed change reverts on its own and stores nothing ──────────────
 [[ "$(run ipc call displays-test applyScale "$target_scale")" == "true" ]] \
     || fail 'a valid scale change was refused'