Hide context menus on form and list pages to prevent exploits

The right-click context menus on form headers and list rows provided
options that could be used to modify fields/data outside the task scope.
This adds MutationObservers that remove context menus as soon as they
appear, preventing agents from using this mechanism to bypass restrictions.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: aldro61

src/browsergym/workarena/tasks/form.py

@@ -395,6 +395,30 @@ def get_init_scripts(self) -> List[str]:
 
                 runInGsftMainOnlyAndProtectByURL(removeAdditionalActionsButton, '{url_suffix}');
             """,
+            f"""
+                function removeContextMenus() {{
+                    waLog('Setting up context menu removal observer...', 'removeContextMenus');
+                    // Remove any existing context menus
+                    document.querySelectorAll('.context_menu').forEach((menu) => {{
+                        menu.remove();
+                    }});
+                    // Observe for new context menus being added
+                    const observer = new MutationObserver((mutations) => {{
+                        mutations.forEach((mutation) => {{
+                            mutation.addedNodes.forEach((node) => {{
+                                if (node.nodeType === 1 && node.classList && node.classList.contains('context_menu')) {{
+                                    node.remove();
+                                    waLog('Removed dynamically added context menu', 'removeContextMenus');
+                                }}
+                            }});
+                        }});
+                    }});
+                    observer.observe(document.body, {{ childList: true, subtree: true }});
+                    waLog('Context menu observer active', 'removeContextMenus');
+                }}
+
+                runInGsftMainOnlyAndProtectByURL(removeContextMenus, '{url_suffix}');
+            """,
         ]
 
     def start(self, page: Page) -> None:

src/browsergym/workarena/tasks/list.py

@@ -116,6 +116,7 @@ def get_init_scripts(self) -> List[str]:
         return super().get_init_scripts() + [
             "registerGsftMainLoaded();",
             self._get_remove_personalize_list_button_script(),
+            self._get_remove_context_menus_script(),
         ]
 
     def _get_remove_personalize_list_button_script(self):
@@ -136,6 +137,37 @@ def _get_remove_personalize_list_button_script(self):
         """
         return script
 
+    def _get_remove_context_menus_script(self):
+        """
+        Removes context menus that appear on right-click in list views.
+        These menus provide options that could be used to modify list data outside the task scope.
+        """
+        script = """
+            function removeContextMenus() {
+                waLog('Setting up context menu removal observer...', 'removeContextMenus');
+                // Remove any existing context menus
+                document.querySelectorAll('.context_menu').forEach((menu) => {
+                    menu.remove();
+                });
+                // Observe for new context menus being added
+                const observer = new MutationObserver((mutations) => {
+                    mutations.forEach((mutation) => {
+                        mutation.addedNodes.forEach((node) => {
+                            if (node.nodeType === 1 && node.classList && node.classList.contains('context_menu')) {
+                                node.remove();
+                                waLog('Removed dynamically added context menu', 'removeContextMenus');
+                            }
+                        });
+                    });
+                });
+                observer.observe(document.body, { childList: true, subtree: true });
+                waLog('Context menu observer active', 'removeContextMenus');
+            }
+
+            runInGsftMainOnlyAndProtectByURL(removeContextMenus, '_list.do');
+        """
+        return script
+
     def _get_visible_list(self, page: Page):
         self._wait_for_ready(page)