diff --git a/src/lib.rs b/src/lib.rs
index 77dcf80..17d9e8d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7016,6 +7016,20 @@ multiline-compatible = """4.5.6"""
         assert!(args.iter().any(|arg| arg == "--use-mock-keychain"));
     }
 
+    #[test]
+    fn chromium_keychain_defaults_honor_user_override_filtering() {
+        let ignored = vec![
+            "--password-store".to_string(),
+            "--use-mock-keychain".to_string(),
+        ];
+
+        assert!(launch_default_arg_ignored(
+            "--password-store=basic",
+            &ignored
+        ));
+        assert!(launch_default_arg_ignored("--use-mock-keychain", &ignored));
+    }
+
     #[test]
     fn chromium_launch_failure_message_includes_stderr_tail() {
         let stderr = NamedTempFile::new().unwrap();
diff --git a/tests/test_mind2web_benchmark.py b/tests/test_mind2web_benchmark.py
index 3bf3786..148247f 100644
--- a/tests/test_mind2web_benchmark.py
+++ b/tests/test_mind2web_benchmark.py
@@ -21,6 +21,19 @@ def load_tool(name: str, path: str):
 run_mind2web_benchmark = load_tool("run_mind2web_benchmark", "tools/run_mind2web_benchmark.py")
 
 
+def test_raw_cdp_adapter_spawn_uses_mock_keychain():
+    source = run_mind2web_benchmark.node_raw_cdp_adapter_code()
+    spawn_argv = source.split("const browser = spawn(executable, [", 1)[1].split(
+        "], { stdio: 'ignore' });", 1
+    )[0]
+
+    password_store = spawn_argv.index("'--password-store=basic',")
+    mock_keychain = spawn_argv.index("'--use-mock-keychain',")
+    about_blank = spawn_argv.index("'about:blank',")
+    assert password_store < about_blank
+    assert mock_keychain < about_blank
+
+
 def test_manifest_task_can_include_executable_action_fixture(tmp_path):
     source = tmp_path / "mind2web.json"
     source.write_text("[]", encoding="utf-8")