feat(taxcode): prevent deletion of add-on-referenced tax codes

app/common/productcatalog.go

@@ -25,6 +25,7 @@ import (
 	"github.com/openmeterio/openmeter/openmeter/productcatalog/planaddon"
 	planaddonadapter "github.com/openmeterio/openmeter/openmeter/productcatalog/planaddon/adapter"
 	planaddonservice "github.com/openmeterio/openmeter/openmeter/productcatalog/planaddon/service"
+	"github.com/openmeterio/openmeter/openmeter/productcatalog/taxcoderesolver"
 	"github.com/openmeterio/openmeter/openmeter/streaming"
 	"github.com/openmeterio/openmeter/openmeter/taxcode"
 	"github.com/openmeterio/openmeter/openmeter/watermill/eventbus"
@@ -49,6 +50,7 @@ var Cost = wire.NewSet(
 
 var Plan = wire.NewSet(
 	NewPlanService,
+	NewTaxCodeResolver,
 )
 
 var Addon = wire.NewSet(
@@ -71,6 +73,8 @@ func NewFeatureConnector(
 
 var NewFeatureResolver = featureresolver.New
 
+var NewTaxCodeResolver = taxcoderesolver.New
+
 func NewCostService(
 	featureConnector feature.FeatureConnector,
 	meterService meter.Service,
@@ -88,6 +92,7 @@ func NewPlanService(
 	logger *slog.Logger,
 	db *entdb.Client,
 	featureResolver productcatalog.FeatureResolver,
+	taxCodeResolver productcatalog.TaxCodeResolver,
 	taxCodeService taxcode.Service,
 	publisher eventbus.Publisher,
 ) (plan.Service, error) {
@@ -102,6 +107,7 @@ func NewPlanService(
 	return planservice.New(planservice.Config{
 		Adapter:         adapter,
 		FeatureResolver: featureResolver,
+		TaxCodeResolver: taxCodeResolver,
 		TaxCode:         taxCodeService,
 		Logger:          logger.With("subsystem", "productcatalog.plan"),
 		Publisher:       publisher,
@@ -112,6 +118,7 @@ func NewAddonService(
 	logger *slog.Logger,
 	db *entdb.Client,
 	featureResolver productcatalog.FeatureResolver,
+	taxCodeResolver productcatalog.TaxCodeResolver,
 	taxCodeService taxcode.Service,
 	publisher eventbus.Publisher,
 ) (addon.Service, error) {
@@ -126,6 +133,7 @@ func NewAddonService(
 	return addonservice.New(addonservice.Config{
 		Adapter:         adapter,
 		FeatureResolver: featureResolver,
+		TaxCodeResolver: taxCodeResolver,
 		TaxCode:         taxCodeService,
 		Logger:          logger.With("subsystem", "productcatalog.addon"),
 		Publisher:       publisher,

app/common/taxcode.go

@@ -11,6 +11,7 @@ import (
 	"github.com/openmeterio/openmeter/app/config"
 	"github.com/openmeterio/openmeter/openmeter/app"
 	entdb "github.com/openmeterio/openmeter/openmeter/ent/db"
+	"github.com/openmeterio/openmeter/openmeter/productcatalog/addon"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog/plan"
 	"github.com/openmeterio/openmeter/openmeter/taxcode"
 	taxcodeadapter "github.com/openmeterio/openmeter/openmeter/taxcode/adapter"
@@ -67,6 +68,28 @@ func NewTaxCodePlanServiceHook(
 	return h, nil
 }
 
+// TaxCodeAddonHook prevents deleting tax codes that are still referenced by add-ons.
+type TaxCodeAddonHook taxcodehooks.AddonHook
+
+// NewTaxCodeAddonServiceHook builds the add-on-reference hook and registers it
+// on the tax code service. It depends on both the add-on and tax code services so wire constructs
+// it only after both exist, avoiding a construction cycle (add-on already depends on tax code).
+func NewTaxCodeAddonServiceHook(
+	addonService addon.Service,
+	taxCodeService taxcode.Service,
+) (TaxCodeAddonHook, error) {
+	h, err := taxcodehooks.NewAddonHook(taxcodehooks.AddonHookConfig{
+		AddonService: addonService,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to create tax code add-on hook: %w", err)
+	}
+
+	taxCodeService.RegisterHooks(h)
+
+	return h, nil
+}
+
 func NewTaxCodeNamespaceHandler(
 	logger *slog.Logger,
 	service taxcode.Service,

cmd/server/wire.go

@@ -100,6 +100,7 @@ type Application struct {
 	TaxCodeNamespaceHandler          *taxcode.NamespaceHandler
 	TaxCodeService                   taxcode.Service
 	TaxCodePlanHook                  common.TaxCodePlanHook
+	TaxCodeAddonHook                 common.TaxCodeAddonHook
 	TelemetryServer                  common.TelemetryServer
 	TerminationChecker               *common.TerminationChecker
 	RuntimeMetricsCollector          common.RuntimeMetricsCollector
@@ -150,6 +151,7 @@ func initializeApplication(ctx context.Context, conf config.Configuration) (Appl
 		common.TaxCode,
 		common.TaxCodeNamespaceHandler,
 		common.NewTaxCodePlanServiceHook,
+		common.NewTaxCodeAddonServiceHook,
 		common.Subscription,
 		common.Lockr,
 		common.Secret,

openmeter/productcatalog/addon.go

@@ -332,3 +332,9 @@ func ValidateAddonWithFeatures(ctx context.Context, resolver NamespacedFeatureRe
 		return ValidateRateCardsWithFeatures(ctx, resolver)(a.RateCards)
 	}
 }
+
+func ValidateAddonWithTaxCodes(ctx context.Context, resolver NamespacedTaxCodeResolver) models.ValidatorFunc[Addon] {
+	return func(a Addon) error {
+		return ValidateRateCardsWithTaxCodes(ctx, resolver)(a.RateCards)
+	}
+}

openmeter/productcatalog/addon/adapter/adapter_test.go

@@ -10,11 +10,14 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	"github.com/openmeterio/openmeter/openmeter/app"
 	"github.com/openmeterio/openmeter/openmeter/meter"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog/addon"
 	"github.com/openmeterio/openmeter/openmeter/productcatalog/feature"
 	pctestutils "github.com/openmeterio/openmeter/openmeter/productcatalog/testutils"
+	"github.com/openmeterio/openmeter/openmeter/taxcode"
+	tctestutils "github.com/openmeterio/openmeter/openmeter/taxcode/testutils"
 	"github.com/openmeterio/openmeter/openmeter/testutils"
 	"github.com/openmeterio/openmeter/pkg/clock"
 	"github.com/openmeterio/openmeter/pkg/datetime"
@@ -438,5 +441,108 @@ func TestPostgresAdapter(t *testing.T) {
 				})
 			}
 		})
+
+		t.Run("ListTaxCodeFilter", func(t *testing.T) {
+			testListAddonTaxCodeFilter(t, env)
+		})
+	})
+}
+
+func testListAddonTaxCodeFilter(t *testing.T, env *pctestutils.TestEnv) {
+	t.Helper()
+
+	ns := pctestutils.NewTestNamespace(t)
+
+	// Create two tax codes with distinct Stripe app mappings so the add-on service
+	// can resolve them and populate the rate-card tax_code_id FK.
+	tcEnv := tctestutils.NewTestEnvFromClient(t, env.Client, env.Logger)
+
+	taxA := tcEnv.CreateTaxCode(t, ns, taxcode.CreateTaxCodeInput{
+		Key:  "tax-a",
+		Name: "Tax A",
+		AppMappings: taxcode.TaxCodeAppMappings{
+			{AppType: app.AppTypeStripe, TaxCode: "txcd_20000001"},
+		},
+	})
+
+	taxB := tcEnv.CreateTaxCode(t, ns, taxcode.CreateTaxCodeInput{
+		Key:  "tax-b",
+		Name: "Tax B",
+		AppMappings: taxcode.TaxCodeAppMappings{
+			{AppType: app.AppTypeStripe, TaxCode: "txcd_20000002"},
+		},
+	})
+
+	// Helper: build a minimal add-on input with a FlatFeeRateCard referencing the given taxCodeID.
+	makeAddonInput := func(key string, taxCodeID string) addon.CreateAddonInput {
+		input := pctestutils.NewTestAddon(t, ns,
+			&productcatalog.FlatFeeRateCard{
+				RateCardMeta: productcatalog.RateCardMeta{
+					Key:  "rc-1",
+					Name: "RC 1",
+					TaxConfig: &productcatalog.TaxConfig{
+						TaxCodeID: lo.ToPtr(taxCodeID),
+					},
+				},
+			},
+		)
+		input.Addon.AddonMeta.Key = key
+		return input
+	}
+
+	// given: two add-ons each referencing a different tax code
+	addonA, err := env.Addon.CreateAddon(t.Context(), makeAddonInput("addon-a", taxA.ID))
+	require.NoError(t, err, "creating addonA must not fail")
+
+	addonB, err := env.Addon.CreateAddon(t.Context(), makeAddonInput("addon-b", taxB.ID))
+	require.NoError(t, err, "creating addonB must not fail")
+
+	t.Run("filter by taxA returns only addonA", func(t *testing.T) {
+		// when: listing add-ons filtered by taxA
+		result, err := env.AddonRepository.ListAddons(t.Context(), addon.ListAddonsInput{
+			Namespaces: []string{ns},
+			TaxCodes:   &filter.FilterString{In: lo.ToPtr([]string{taxA.ID})},
+			Page:       pagination.Page{PageSize: 100, PageNumber: 1},
+		})
+
+		// then: only addonA is returned
+		require.NoError(t, err)
+		ids := addonIDs(result)
+		require.ElementsMatch(t, []string{addonA.ID}, ids)
+	})
+
+	t.Run("filter by taxB returns only addonB", func(t *testing.T) {
+		// when: listing add-ons filtered by taxB
+		result, err := env.AddonRepository.ListAddons(t.Context(), addon.ListAddonsInput{
+			Namespaces: []string{ns},
+			TaxCodes:   &filter.FilterString{In: lo.ToPtr([]string{taxB.ID})},
+			Page:       pagination.Page{PageSize: 100, PageNumber: 1},
+		})
+
+		// then: only addonB is returned
+		require.NoError(t, err)
+		ids := addonIDs(result)
+		require.ElementsMatch(t, []string{addonB.ID}, ids)
 	})
+
+	t.Run("filter by nonexistent tax code returns empty", func(t *testing.T) {
+		// when: listing add-ons filtered by a tax code id that doesn't exist
+		result, err := env.AddonRepository.ListAddons(t.Context(), addon.ListAddonsInput{
+			Namespaces: []string{ns},
+			TaxCodes:   &filter.FilterString{In: lo.ToPtr([]string{"01000000000000000000000000"})},
+			Page:       pagination.Page{PageSize: 100, PageNumber: 1},
+		})
+
+		// then: no add-ons are returned
+		require.NoError(t, err)
+		require.Empty(t, result.Items)
+	})
+}
+
+func addonIDs(result pagination.Result[addon.Addon]) []string {
+	ids := make([]string, 0, len(result.Items))
+	for _, a := range result.Items {
+		ids = append(ids, a.ID)
+	}
+	return ids
 }