fix(shortcut): address review safety notes

internal/app/usage_recording_test.go

@@ -0,0 +1,39 @@
+// Copyright 2026 Alibaba Group
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package app
+
+import "testing"
+
+func TestCloneToolArgsDefensiveCopy(t *testing.T) {
+	args := map[string]any{"page": 1, "query": "keep"}
+	cloned := cloneToolArgs(args)
+	args["page"] = 2
+	args["extra"] = true
+
+	if got := cloned["page"]; got != 1 {
+		t.Fatalf("cloned page = %#v, want 1", got)
+	}
+	if _, ok := cloned["extra"]; ok {
+		t.Fatal("clone changed after source map mutation")
+	}
+}
+
+func TestCloneToolArgsEmpty(t *testing.T) {
+	if got := cloneToolArgs(nil); got != nil {
+		t.Fatalf("nil clone = %#v, want nil", got)
+	}
+	if got := cloneToolArgs(map[string]any{}); got != nil {
+		t.Fatalf("empty clone = %#v, want nil", got)
+	}
+}