diff --git a/dwds/debug_extension_mv3/web/background.dart b/dwds/debug_extension_mv3/web/background.dart
index 552a5f571..9de0c0f60 100644
--- a/dwds/debug_extension_mv3/web/background.dart
+++ b/dwds/debug_extension_mv3/web/background.dart
@@ -29,6 +29,16 @@ void _registerListeners() {
   chrome.runtime.onMessage.addListener(allowInterop(_handleRuntimeMessages));
   chrome.tabs.onRemoved
       .addListener(allowInterop((tabId, _) => maybeRemoveLifelinePort(tabId)));
+  // Update the extension icon on tab navigation:
+  chrome.tabs.onActivated.addListener(allowInterop((ActiveInfo info) {
+    _updateIcon(info.tabId);
+  }));
+  chrome.windows.onFocusChanged.addListener(allowInterop((_) async {
+    final currentTab = await _getTab();
+    if (currentTab?.id != null) {
+      _updateIcon(currentTab!.id);
+    }
+  }));
 
   // Detect clicks on the Dart Debug Extension icon.
   chrome.action.onClicked.addListener(allowInterop(_startDebugSession));
@@ -86,27 +96,39 @@ void _handleRuntimeMessages(
       expectedSender: Script.detector,
       expectedRecipient: Script.background,
       messageHandler: (DebugInfo debugInfo) async {
-        final currentTab = await _getTab();
-        final currentUrl = currentTab?.url ?? '';
-        final appUrl = debugInfo.appUrl ?? '';
-        if (currentTab == null ||
-            currentUrl.isEmpty ||
-            appUrl.isEmpty ||
-            currentUrl != appUrl) {
-          console.warn(
-              'Dart app detected at $appUrl but current tab is $currentUrl.');
+        final dartTab = sender.tab;
+        if (dartTab == null) {
+          console.warn('Received debug info but tab is missing.');
           return;
         }
         // Save the debug info for the Dart app in storage:
         await setStorageObject<DebugInfo>(
-            type: StorageObject.debugInfo,
-            value: debugInfo,
-            tabId: currentTab.id);
+            type: StorageObject.debugInfo, value: debugInfo, tabId: dartTab.id);
         // Update the icon to show that a Dart app has been detected:
-        chrome.action.setIcon(IconInfo(path: 'dart.png'), /*callback*/ null);
+        final currentTab = await _getTab();
+        if (currentTab?.id == dartTab.id) {
+          _setDebuggableIcon();
+        }
       });
 }
 
+void _updateIcon(int activeTabId) async {
+  final debugInfo = await _fetchDebugInfo(activeTabId);
+  if (debugInfo != null) {
+    _setDebuggableIcon();
+  } else {
+    _setDefaultIcon();
+  }
+}
+
+void _setDebuggableIcon() {
+  chrome.action.setIcon(IconInfo(path: 'dart.png'), /*callback*/ null);
+}
+
+void _setDefaultIcon() {
+  chrome.action.setIcon(IconInfo(path: 'dart_grey.png'), /*callback*/ null);
+}
+
 Future<DebugInfo?> _fetchDebugInfo(int tabId) {
   return fetchStorageObject<DebugInfo>(
     type: StorageObject.debugInfo,
diff --git a/dwds/debug_extension_mv3/web/chrome_api.dart b/dwds/debug_extension_mv3/web/chrome_api.dart
index 05ccbfedc..14d4c368f 100644
--- a/dwds/debug_extension_mv3/web/chrome_api.dart
+++ b/dwds/debug_extension_mv3/web/chrome_api.dart
@@ -177,15 +177,29 @@ class Tabs {
 
   external Object create(TabInfo tabInfo);
 
+  external OnActivatedHandler get onActivated;
+
   external OnRemovedHandler get onRemoved;
 }
 
+@JS()
+@anonymous
+class OnActivatedHandler {
+  external void addListener(void Function(ActiveInfo activeInfo) callback);
+}
+
 @JS()
 @anonymous
 class OnRemovedHandler {
   external void addListener(void Function(int tabId, dynamic info) callback);
 }
 
+@JS()
+@anonymous
+class ActiveInfo {
+  external int get tabId;
+}
+
 @JS()
 @anonymous
 class TabInfo {
@@ -218,6 +232,14 @@ class Tab {
 @anonymous
 class Windows {
   external Object create(WindowInfo? createData);
+
+  external OnFocusChangedHandler get onFocusChanged;
+}
+
+@JS()
+@anonymous
+class OnFocusChangedHandler {
+  external void addListener(void Function(int windowId) callback);
 }
 
 @JS()
diff --git a/dwds/debug_extension_mv3/web/dart_grey.png b/dwds/debug_extension_mv3/web/dart_grey.png
new file mode 100644
index 000000000..3afba3fbe
Binary files /dev/null and b/dwds/debug_extension_mv3/web/dart_grey.png differ