diff --git a/.omni/e42f8a19-untitled/memory.md b/.omni/e42f8a19-untitled/memory.md
index ef4f66c..1760ebe 100644
--- a/.omni/e42f8a19-untitled/memory.md
+++ b/.omni/e42f8a19-untitled/memory.md
@@ -18,6 +18,7 @@
 ## Key Discoveries
 
 - Selection capture is coordinated in `src/background/service-worker.ts`: popup sends `CAPTURE_SCREENSHOT`, service worker injects the selection overlay, then receives `SELECTION_COMPLETE` and crops via the offscreen document.
+- Popup runtime message listeners must ignore unrelated messages synchronously; an async listener can interfere with offscreen `ADD_WATERMARK` responses while the popup is open.
 
 ---
-_Last system refresh: 2026-05-06 06:33 UTC_
+_Last system refresh: 2026-05-06 07:09 UTC_
diff --git a/src/popup/popup.tsx b/src/popup/popup.tsx
index 8a7bfab..be5a9f1 100644
--- a/src/popup/popup.tsx
+++ b/src/popup/popup.tsx
@@ -271,8 +271,12 @@ function PopupApp() {
 
   // Listen for upload progress updates
   useEffect(() => {
-    const handleMessage = async (message: any) => {
-      if (message.type === 'UPLOAD_PROGRESS') {
+    const handleMessage = (message: any) => {
+      if (message.type !== 'UPLOAD_PROGRESS') {
+        return false;
+      }
+
+      void (async () => {
         const payload = message.payload;
 
         // Reload assets to show updated progress
@@ -291,7 +295,9 @@ function PopupApp() {
             metadata: { nid: payload.nid },
           } as any);
         }
-      }
+      })();
+
+      return false;
     };
 
     chrome.runtime.onMessage.addListener(handleMessage);