fix(consent): store no consent on a flow that can never record one

core/authenticate/service.go

@@ -220,7 +220,8 @@ func (s Service) StartFlow(ctx context.Context, request RegistrationStartRequest
 		return nil, ErrUnsupportedMethod
 	}
 	// the gate runs before anything is sent or redirected
-	if err := s.gateFlowConsent(request.Intent, request.AcceptedDocumentIDs); err != nil {
+	consented, err := s.gateFlowConsent(request.Intent, request.AcceptedDocumentIDs)
+	if err != nil {
 		return nil, err
 	}
 	// both mail strategies know the address before anything is sent, and share
@@ -246,7 +247,7 @@ func (s Service) StartFlow(ctx context.Context, request RegistrationStartRequest
 	if request.Intent != FlowIntentUnspecified {
 		flow.Metadata[flowIntentKey] = request.Intent.String()
 	}
-	if len(request.AcceptedDocumentIDs) > 0 {
+	if len(consented) > 0 {
 		flow.Metadata[flowConsentKey] = map[string]any{
 			consentDocumentIDsKey: request.AcceptedDocumentIDs,
 			consentIPAddressKey:   request.IPAddress,
@@ -455,21 +456,22 @@ func (s Service) gateFlowStart(ctx context.Context, intent FlowIntent, email str
 // decides which rule applies, because without one a signup and a login look
 // identical: a signup has to be complete here, an unset intent only has to
 // name known ids, and a login checks nothing because it writes no record.
-func (s Service) gateFlowConsent(intent FlowIntent, ids []string) error {
+func (s Service) gateFlowConsent(intent FlowIntent, ids []string) ([]consent.Document, error) {
 	if s.consentService == nil || intent == FlowIntentLogin {
-		return nil
+		return nil, nil
 	}
 
+	var documents []consent.Document
 	var err error
 	if intent == FlowIntentSignup {
-		_, err = s.consentService.ResolveAll(ids)
+		documents, err = s.consentService.ResolveAll(ids)
 	} else {
-		_, err = s.consentService.Resolve(ids)
+		documents, err = s.consentService.Resolve(ids)
 	}
 	if err != nil {
-		return fmt.Errorf("%w: %w", ErrConsentRequired, err)
+		return nil, fmt.Errorf("%w: %w", ErrConsentRequired, err)
 	}
-	return nil
+	return documents, nil
 }
 
 // applyMailOTP actions when user submitted otp from the email

core/authenticate/service_test.go

@@ -1298,10 +1298,16 @@ func TestService_StartFlow_WritesIntentAndConsent(t *testing.T) {
 			storedFlow = flow
 		}).Return(nil)
 
+		enabled := consent.NewService(slog.New(slog.NewTextHandler(io.Discard, nil)),
+			consent.Config{Enabled: true, Documents: map[string]consent.DocumentConfig{
+				"terms_of_service": {Title: "Terms & Conditions", Version: "v2", URL: "https://example.org/t"},
+				"privacy_policy":   {Title: "Privacy Policy", Version: "v1", URL: "https://example.org/p"},
+			}}, nil)
+
 		srv := authenticate.NewService(nil, authenticate.Config{
 			MailOTP:   authenticate.MailOTPConfig{Validity: 10 * time.Minute},
 			TestUsers: testusers.Config{Enabled: true, OTP: "111111", Domain: "example.com"},
-		}, mockFlowRepo, mailer.NewMockDialer(), nil, nil, mockUserService, nil, nil, nil, nil)
+		}, mockFlowRepo, mailer.NewMockDialer(), nil, nil, mockUserService, nil, nil, nil, enabled)
 		srv.Now = func() time.Time { return timeNow }
 
 		_, err := srv.StartFlow(ctx, request)
@@ -1453,25 +1459,35 @@ func TestService_StartFlow_Consent(t *testing.T) {
 		assert.ErrorIs(t, err, consent.ErrUnknownDocuments)
 	})
 
-	t.Run("a login checks nothing, because it writes no record", func(t *testing.T) {
+	t.Run("a login checks nothing, and persists nothing, because it writes no record", func(t *testing.T) {
 		mockConsent := mocks.NewConsentService(t)
 
 		mockFlowRepo, mockUserService, _, _, _ := createMocks(t)
 		ctx := context.Background()
 		mockUserService.EXPECT().GetByID(ctx, email).Return(user.User{ID: "user-id", Email: email}, nil)
-		mockFlowRepo.EXPECT().Set(ctx, mock.Anything).Return(nil)
+
+		var storedFlow *authenticate.Flow
+		mockFlowRepo.EXPECT().Set(ctx, mock.Anything).Run(func(_ context.Context, flow *authenticate.Flow) {
+			storedFlow = flow
+		}).Return(nil)
 
 		srv := authenticate.NewService(nil, authenticate.Config{
 			MailOTP:   authenticate.MailOTPConfig{Validity: 10 * time.Minute},
 			TestUsers: testusers.Config{Enabled: true, OTP: "111111", Domain: "example.com"},
 		}, mockFlowRepo, mailer.NewMockDialer(), nil, nil, mockUserService, nil, nil, nil, mockConsent)
 
 		_, err := srv.StartFlow(ctx, authenticate.RegistrationStartRequest{
-			Method: authenticate.MailOTPAuthMethod.String(),
-			Email:  email,
-			Intent: authenticate.FlowIntentLogin,
+			Method:              authenticate.MailOTPAuthMethod.String(),
+			Email:               email,
+			Intent:              authenticate.FlowIntentLogin,
+			AcceptedDocumentIDs: acceptedIDs,
+			IPAddress:           "10.0.0.1",
 		})
 		require.NoError(t, err)
+		require.NotNil(t, storedFlow)
+
+		_, ok := storedFlow.Consent()
+		assert.False(t, ok, "a login must persist no consent block")
 	})
 
 	t.Run("a deployment with consent disabled ignores the ids rather than rejecting them", func(t *testing.T) {
@@ -1487,6 +1503,40 @@ func TestService_StartFlow_Consent(t *testing.T) {
 		require.NoError(t, err)
 		require.NotNil(t, got)
 	})
+
+	t.Run("a deployment with consent disabled persists no consent onto the flow", func(t *testing.T) {
+		disabled := consent.NewService(slog.New(slog.NewTextHandler(io.Discard, nil)),
+			consent.Config{Enabled: false}, nil)
+
+		ctx := context.Background()
+		mockFlowRepo, mockUserService, _, _, _ := createMocks(t)
+		mockUserService.EXPECT().GetByID(ctx, email).
+			Return(user.User{}, errors.New("user not found")).Maybe()
+
+		var storedFlow *authenticate.Flow
+		mockFlowRepo.EXPECT().Set(ctx, mock.Anything).Run(func(_ context.Context, flow *authenticate.Flow) {
+			storedFlow = flow
+		}).Return(nil)
+
+		srv := authenticate.NewService(nil, authenticate.Config{
+			MailOTP:   authenticate.MailOTPConfig{Validity: 10 * time.Minute},
+			TestUsers: testusers.Config{Enabled: true, OTP: "111111", Domain: "example.com"},
+		}, mockFlowRepo, mailer.NewMockDialer(), nil, nil, mockUserService, nil, nil, nil, disabled)
+
+		_, err := srv.StartFlow(ctx, authenticate.RegistrationStartRequest{
+			Method:              authenticate.MailOTPAuthMethod.String(),
+			Email:               email,
+			Intent:              authenticate.FlowIntentSignup,
+			AcceptedDocumentIDs: acceptedIDs,
+			IPAddress:           "10.0.0.1",
+		})
+		require.NoError(t, err)
+		require.NotNil(t, storedFlow)
+
+		_, ok := storedFlow.Consent()
+		assert.False(t, ok, "a disabled deployment must persist no consent block")
+		assert.Equal(t, authenticate.FlowIntentSignup, storedFlow.Intent())
+	})
 }
 
 // TestFlow_IntentAndConsent covers the accessors directly: the JSON round trip