fix: avoid replaying delegated sharing conflicts

Author: shepilov

model/sharing/member.go

@@ -390,7 +390,7 @@ func (s *Sharing) SendDelegated(inst *instance.Instance, api *APIDelegateAddCont
 	}
 	res, err := request.Req(opts)
 	preRefreshRes, preRefreshErr := res, err
-	if res != nil && res.StatusCode/100 == 4 {
+	if shouldRetryDelegatedRequest(res) {
 		res, err = RefreshToken(inst, res, err, s, &s.Members[0], c, opts, body)
 	}
 	if err != nil {
@@ -449,6 +449,20 @@ func (s *Sharing) SendDelegated(inst *instance.Instance, api *APIDelegateAddCont
 	return s.SendInvitationsToMembers(inst, api.members, states)
 }
 
+// shouldRetryDelegatedRequest restricts replay to authentication and instance
+// relocation responses. Retrying other client errors can duplicate invitations.
+func shouldRetryDelegatedRequest(res *http.Response) bool {
+	if res == nil {
+		return false
+	}
+	switch res.StatusCode {
+	case http.StatusUnauthorized, http.StatusForbidden, http.StatusGone:
+		return true
+	default:
+		return false
+	}
+}
+
 func preserveDelegatedResponseError(
 	res *http.Response,
 	err error,

model/sharing/member_test.go

@@ -20,6 +20,28 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestShouldRetryDelegatedRequest(t *testing.T) {
+	tests := []struct {
+		name     string
+		response *http.Response
+		expected bool
+	}{
+		{name: "missing response"},
+		{name: "unauthorized", response: &http.Response{StatusCode: http.StatusUnauthorized}, expected: true},
+		{name: "forbidden", response: &http.Response{StatusCode: http.StatusForbidden}, expected: true},
+		{name: "moved", response: &http.Response{StatusCode: http.StatusGone}, expected: true},
+		{name: "bad request", response: &http.Response{StatusCode: http.StatusBadRequest}},
+		{name: "conflict", response: &http.Response{StatusCode: http.StatusConflict}},
+		{name: "not found", response: &http.Response{StatusCode: http.StatusNotFound}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.Equal(t, tt.expected, shouldRetryDelegatedRequest(tt.response))
+		})
+	}
+}
+
 func TestPreserveDelegatedResponseError(t *testing.T) {
 	t.Run("prefers the response returned after token refresh", func(t *testing.T) {
 		preRefreshRes := &http.Response{StatusCode: http.StatusUnauthorized}