chore: import upstream snapshot with attribution

internal/cmdutil/secheader_sidecar_test.go

@@ -0,0 +1,34 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+//go:build authsidecar
+
+package cmdutil
+
+import (
+	"testing"
+
+	sidecarcred "github.com/larksuite/cli/extension/credential/sidecar"
+	sidecartrans "github.com/larksuite/cli/extension/transport/sidecar"
+)
+
+// TestIsBuiltinProvider_SidecarProviders locks the classification for the
+// sidecar-mode providers enumerated in design doc §3.3.2 as "官方自带". These
+// types only compile when the `authsidecar` build tag is active, so the test
+// is guarded by the same tag.
+func TestIsBuiltinProvider_SidecarProviders(t *testing.T) {
+	cases := []struct {
+		name     string
+		provider any
+	}{
+		{"sidecar credential provider", &sidecarcred.Provider{}},
+		{"sidecar transport provider", &sidecartrans.Provider{}},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			if !isBuiltinProvider(tc.provider) {
+				t.Fatalf("%T must be classified as builtin (PkgPath under %s)", tc.provider, officialModulePath)
+			}
+		})
+	}
+}