feat(logger): WithSource/Scoped 日志来源标注；AGENTS 追加日志标来源+客户端API契约红线

internal/logger/logger_test.go

@@ -91,3 +91,28 @@ func TestNew_DefaultsToErrAndText(t *testing.T) {
 		t.Fatal("New(Options{}) returned nil logger")
 	}
 }
+
+func TestWithSource_TagsRecords(t *testing.T) {
+	t.Parallel()
+
+	var buf bytes.Buffer
+	base := New(Options{Level: "debug", Format: "json", Out: &buf})
+	log := WithSource(base, "runtime/loop")
+	log.Info("hello")
+	if !strings.Contains(buf.String(), `"source":"runtime/loop"`) {
+		t.Fatalf("missing source field, got %q", buf.String())
+	}
+}
+
+func TestScoped_TagsModuleAndSub(t *testing.T) {
+	t.Parallel()
+
+	var buf bytes.Buffer
+	base := New(Options{Level: "debug", Format: "json", Out: &buf})
+	log := Scoped(base, "channel", "adapter")
+	log.Info("hello")
+	got := buf.String()
+	if !strings.Contains(got, `"module":"channel"`) || !strings.Contains(got, `"sub":"adapter"`) {
+		t.Fatalf("missing module/sub fields, got %q", got)
+	}
+}