fix(billing): merge tax-code Stripe+ID atomically

api/v3/handlers/billingprofiles/convert.go

@@ -69,7 +69,6 @@ var (
 	// goverter:ignore TaxCode
 	ToAPIBillingTaxConfig func(config *productcatalog.TaxConfig) (*api.BillingTaxConfig, error)
 	// goverter:map Stripe Stripe
-	// goverter:ignore TaxCode
 	FromAPIBillingTaxConfig func(config *api.BillingTaxConfig) (*productcatalog.TaxConfig, error)
 )
 

openmeter/app/stripe/appinvoice.go

@@ -571,7 +571,7 @@ func getCreditStripeAddInvoiceItemParams(calculator StripeCalculator, line billi
 	return params
 }
 
-func applyTaxSettingsToInvoiceItem(add *stripe.InvoiceItemParams, taxConfig *productcatalog.TaxConfig) *stripe.InvoiceItemParams {
+func applyTaxSettingsToInvoiceItem(add *stripe.InvoiceItemParams, taxConfig *billing.TaxConfig) *stripe.InvoiceItemParams {
 	if taxConfig != nil && !lo.IsEmpty(taxConfig) {
 		if taxConfig.Behavior != nil {
 			add.TaxBehavior = getStripeTaxBehavior(taxConfig.Behavior)

openmeter/billing/adapter/gatheringlines.go

@@ -221,7 +221,7 @@ func (a *adapter) updateGatheringLines(ctx context.Context, lines billing.Gather
 			}
 
 			if line.TaxConfig != nil {
-				create = create.SetTaxConfig(*line.TaxConfig).
+				create = create.SetNillableTaxConfig(billing.FromProductCatalog(line.TaxConfig)).
 					SetNillableTaxCodeID(line.TaxConfig.TaxCodeID).
 					SetNillableTaxBehavior(line.TaxConfig.Behavior)
 			}
@@ -310,7 +310,7 @@ func (a *adapter) mapGatheringInvoiceLineFromDB(schemaLevel int, dbLine *db.Bill
 			Currency: dbLine.Currency,
 
 			TaxConfig: productcatalog.BackfillTaxConfig(
-				lo.EmptyableToPtr(dbLine.TaxConfig),
+				lo.EmptyableToPtr(dbLine.TaxConfig).ToProductCatalog(),
 				dbLine.TaxBehavior,
 				taxCodeFromInvoiceLineEdge(dbLine),
 			),

openmeter/billing/adapter/stdinvoicelinemapper.go

@@ -318,28 +318,32 @@ func taxCodeFromInvoiceLineEdge(dbLine *db.BillingInvoiceLine) *taxcode.TaxCode
 // TODO[later]: change the billing-facing types to expose TaxCodeSnapshot and TaxCodeReference
 // fields explicitly so it is obvious what is the immutable invoice snapshot and what is the live
 // reference to the tax entity.
-func backfillTaxConfigReferences(snapshottedTaxConfig *productcatalog.TaxConfig, persistedTaxBehavior *productcatalog.TaxBehavior, resolvedTaxCode *taxcode.TaxCode) *productcatalog.TaxConfig {
-	backfilledTaxConfig := productcatalog.BackfillTaxConfig(snapshottedTaxConfig, persistedTaxBehavior, resolvedTaxCode)
+func backfillTaxConfigReferences(snapshottedTaxConfig *billing.TaxConfig, persistedTaxBehavior *productcatalog.TaxBehavior, resolvedTaxCode *taxcode.TaxCode) *billing.TaxConfig {
+	if snapshottedTaxConfig == nil {
+		return billing.FromProductCatalog(productcatalog.BackfillTaxConfig(nil, persistedTaxBehavior, resolvedTaxCode))
+	}
+
+	backfilledTaxConfig := productcatalog.BackfillTaxConfig(snapshottedTaxConfig.ToProductCatalog(), persistedTaxBehavior, resolvedTaxCode)
 
 	if backfilledTaxConfig == nil || resolvedTaxCode == nil {
-		return backfilledTaxConfig
+		return billing.FromProductCatalog(backfilledTaxConfig)
 	}
 
 	if backfilledTaxConfig.TaxCodeID != nil && *backfilledTaxConfig.TaxCodeID != resolvedTaxCode.ID {
-		return backfilledTaxConfig
+		return billing.FromProductCatalog(backfilledTaxConfig)
 	}
 
 	if backfilledTaxConfig.Stripe != nil {
 		mapping, ok := resolvedTaxCode.GetAppMapping(app.AppTypeStripe)
 		if !ok || mapping.TaxCode != backfilledTaxConfig.Stripe.Code {
-			return backfilledTaxConfig
+			return billing.FromProductCatalog(backfilledTaxConfig)
 		}
 	}
 
-	cloned := backfilledTaxConfig.Clone()
-	cloned.TaxCode = resolvedTaxCode
+	result := billing.FromProductCatalog(backfilledTaxConfig)
+	result.TaxCode = resolvedTaxCode
 
-	return &cloned
+	return result
 }
 
 func (a *adapter) mapStandardInvoiceDetailedLineAmountDiscountFromDB(dbDiscount *db.BillingStandardInvoiceDetailedLineAmountDiscount) (billing.AmountLineDiscountManaged, error) {

openmeter/billing/gatheringinvoice.go

@@ -717,9 +717,9 @@ func (g GatheringLine) AsNewStandardLine(invoiceID string) (*StandardLine, error
 		return nil, fmt.Errorf("cloning annotations: %w", err)
 	}
 
-	var taxConfig *productcatalog.TaxConfig
+	var taxConfig *TaxConfig
 	if g.TaxConfig != nil {
-		taxConfig = lo.ToPtr(g.TaxConfig.Clone())
+		taxConfig = FromProductCatalog(lo.ToPtr(g.TaxConfig.Clone()))
 	}
 
 	var subscription *SubscriptionReference

openmeter/billing/httpdriver/invoiceline.go

@@ -160,7 +160,7 @@ func mapCreateLineToEntity(line api.InvoicePendingLineCreate, ns string) (*billi
 			},
 
 			InvoiceAt:         line.InvoiceAt,
-			TaxConfig:         rateCardParsed.TaxConfig,
+			TaxConfig:         billing.FromProductCatalog(rateCardParsed.TaxConfig),
 			RateCardDiscounts: rateCardParsed.Discounts,
 		},
 		UsageBased: &billing.UsageBasedLine{
@@ -324,7 +324,7 @@ func mapInvoiceLineToAPI(line *billing.StandardLine) (api.InvoiceLine, error) {
 		return api.InvoiceLine{}, fmt.Errorf("failed to map price: %w", err)
 	}
 
-	children, err := mapDetailedLinesToAPI(line.DetailedLines, line.InvoiceAt, line.TaxConfig)
+	children, err := mapDetailedLinesToAPI(line.DetailedLines, line.InvoiceAt, line.TaxConfig.ToProductCatalog())
 	if err != nil {
 		return api.InvoiceLine{}, fmt.Errorf("failed to map children: %w", err)
 	}
@@ -362,7 +362,7 @@ func mapInvoiceLineToAPI(line *billing.StandardLine) (api.InvoiceLine, error) {
 			To:   line.Period.To,
 		},
 
-		TaxConfig: mapTaxConfigToAPI(line.TaxConfig),
+		TaxConfig: mapTaxConfigToAPI(line.TaxConfig.ToProductCatalog()),
 
 		FeatureKey:                   lo.EmptyableToPtr(line.UsageBased.FeatureKey),
 		MeteredQuantity:              decimalPtrToStringPtrIfNotEqual(line.UsageBased.MeteredQuantity, line.UsageBased.Quantity),
@@ -373,7 +373,7 @@ func mapInvoiceLineToAPI(line *billing.StandardLine) (api.InvoiceLine, error) {
 		Price: lo.ToPtr(price),
 
 		RateCard: &api.InvoiceUsageBasedRateCard{
-			TaxConfig:  mapTaxConfigToAPI(line.TaxConfig),
+			TaxConfig:  mapTaxConfigToAPI(line.TaxConfig.ToProductCatalog()),
 			Price:      lo.ToPtr(price),
 			FeatureKey: lo.EmptyableToPtr(line.UsageBased.FeatureKey),
 		},
@@ -634,7 +634,7 @@ func mapSimulationLineToEntity(line api.InvoiceSimulationLine) (*billing.Standar
 			},
 
 			InvoiceAt:         line.InvoiceAt.Truncate(streaming.MinimumWindowSizeDuration),
-			TaxConfig:         rateCardParsed.TaxConfig,
+			TaxConfig:         billing.FromProductCatalog(rateCardParsed.TaxConfig),
 			RateCardDiscounts: rateCardParsed.Discounts,
 		},
 		UsageBased: &billing.UsageBasedLine{
@@ -679,7 +679,7 @@ func standardLineFromInvoiceLineReplaceUpdate(line api.InvoiceLineReplaceUpdate,
 			},
 			InvoiceAt: line.InvoiceAt.Truncate(streaming.MinimumWindowSizeDuration),
 
-			TaxConfig:         rateCardParsed.TaxConfig,
+			TaxConfig:         billing.FromProductCatalog(rateCardParsed.TaxConfig),
 			RateCardDiscounts: rateCardParsed.Discounts,
 		},
 		UsageBased: &billing.UsageBasedLine{
@@ -760,7 +760,7 @@ func mergeStandardLineFromInvoiceLineReplaceUpdate(existing *billing.StandardLin
 	existing.Period.To = line.Period.To.Truncate(streaming.MinimumWindowSizeDuration)
 	existing.InvoiceAt = line.InvoiceAt.Truncate(streaming.MinimumWindowSizeDuration)
 
-	existing.TaxConfig = rateCardParsed.TaxConfig
+	existing.TaxConfig = billing.FromProductCatalog(rateCardParsed.TaxConfig)
 	existing.UsageBased.Price = rateCardParsed.Price
 	existing.UsageBased.FeatureKey = rateCardParsed.FeatureKey
 

openmeter/billing/service/invoicecalc/taxconfig.go

@@ -4,7 +4,6 @@ import (
 	"github.com/samber/lo"
 
 	"github.com/openmeterio/openmeter/openmeter/billing"
-	"github.com/openmeterio/openmeter/openmeter/productcatalog"
 )
 
 // SnapshotTaxConfigIntoLines merges the invoice's DefaultTaxConfig into each line and
@@ -16,7 +15,7 @@ func SnapshotTaxConfigIntoLines(invoice *billing.StandardInvoice, deps StandardI
 	}
 
 	for _, line := range invoice.Lines.OrEmpty() {
-		line.TaxConfig = productcatalog.MergeTaxConfigs(invoice.Workflow.Config.Invoicing.DefaultTaxConfig, line.TaxConfig)
+		line.TaxConfig = billing.MergeTaxConfigs(billing.FromProductCatalog(invoice.Workflow.Config.Invoicing.DefaultTaxConfig), line.TaxConfig)
 
 		if line.TaxConfig == nil || line.TaxConfig.Stripe == nil {
 			continue

openmeter/billing/service/invoicecalc/taxconfig_test.go

@@ -14,6 +14,71 @@ import (
 	"github.com/openmeterio/openmeter/pkg/models"
 )
 
+// TaxConfigEqualDetectsTaxCode is the regression guard for the fix: billing.TaxConfig.Equal
+// now includes the resolved TaxCode entity. Two configs that are identical except for TaxCode
+// (one nil, one stamped) must compare as NOT equal, so the adapter diff guard re-upserts the line
+// and the snapshot is persisted to the tax_config JSONB column.
+func TestTaxConfigEqualDetectsTaxCode(t *testing.T) {
+	tc1 := taxcode.TaxCode{
+		NamespacedID: models.NamespacedID{Namespace: "ns", ID: "tc-1"},
+		AppMappings: taxcode.TaxCodeAppMappings{
+			{AppType: app.AppTypeStripe, TaxCode: "txcd_10000000"},
+		},
+	}
+
+	// Persisted state: TaxCodeID set, but the TaxCode entity snapshot is absent.
+	persistedState := &billing.TaxConfig{
+		TaxConfig: productcatalog.TaxConfig{
+			Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
+			Behavior:  lo.ToPtr(productcatalog.ExclusiveTaxBehavior),
+			TaxCodeID: lo.ToPtr("tc-1"),
+		},
+		TaxCode: nil,
+	}
+
+	// In-memory state after SnapshotTaxConfigIntoLines stamps the entity. Identical except TaxCode.
+	expectedState := &billing.TaxConfig{
+		TaxConfig: productcatalog.TaxConfig{
+			Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
+			Behavior:  lo.ToPtr(productcatalog.ExclusiveTaxBehavior),
+			TaxCodeID: lo.ToPtr("tc-1"),
+		},
+		TaxCode: &tc1,
+	}
+
+	assert.False(t, persistedState.Equal(expectedState),
+		"Equal must detect the stamped TaxCode so the line is re-upserted and the snapshot persisted")
+
+	// Same-ID sub-case: two configs whose TaxCode shares the same ID but differs in other fields
+	// (e.g. AppMappings) must compare as equal — equality is ID-only.
+	tc2 := taxcode.TaxCode{
+		NamespacedID: models.NamespacedID{Namespace: "ns", ID: "tc-1"},
+		AppMappings: taxcode.TaxCodeAppMappings{
+			{AppType: app.AppTypeStripe, TaxCode: "txcd_20000000"},
+		},
+	}
+
+	leftConfig := &billing.TaxConfig{
+		TaxConfig: productcatalog.TaxConfig{
+			Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
+			Behavior:  lo.ToPtr(productcatalog.ExclusiveTaxBehavior),
+			TaxCodeID: lo.ToPtr("tc-1"),
+		},
+		TaxCode: &tc1,
+	}
+	rightConfig := &billing.TaxConfig{
+		TaxConfig: productcatalog.TaxConfig{
+			Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
+			Behavior:  lo.ToPtr(productcatalog.ExclusiveTaxBehavior),
+			TaxCodeID: lo.ToPtr("tc-1"),
+		},
+		TaxCode: &tc2,
+	}
+
+	assert.True(t, leftConfig.Equal(rightConfig),
+		"Equal uses ID-only comparison: same TaxCode.ID means equal regardless of other TaxCode fields")
+}
+
 func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 	tc1 := taxcode.TaxCode{
 		NamespacedID: models.NamespacedID{Namespace: "ns", ID: "tc-1"},
@@ -47,7 +112,7 @@ func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 	newLine := func(tc *productcatalog.TaxConfig) *billing.StandardLine {
 		return &billing.StandardLine{
 			StandardLineBase: billing.StandardLineBase{
-				TaxConfig: tc,
+				TaxConfig: billing.FromProductCatalog(tc),
 			},
 		}
 	}
@@ -56,7 +121,7 @@ func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 		name      string
 		invoice   billing.StandardInvoice
 		deps      StandardInvoiceCalculatorDependencies
-		wantTC    *productcatalog.TaxConfig
+		wantTC    *billing.TaxConfig
 		wantNoErr bool
 	}{
 		{
@@ -69,7 +134,7 @@ func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 				}),
 			),
 			deps:      StandardInvoiceCalculatorDependencies{TaxCodes: TaxCodes{"txcd_10000000": tc1}},
-			wantTC:    &productcatalog.TaxConfig{Stripe: &productcatalog.StripeTaxConfig{Code: "txcd_10000000"}},
+			wantTC:    &billing.TaxConfig{TaxConfig: productcatalog.TaxConfig{Stripe: &productcatalog.StripeTaxConfig{Code: "txcd_10000000"}}},
 			wantNoErr: true,
 		},
 		{
@@ -82,10 +147,12 @@ func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 				}),
 			),
 			deps: StandardInvoiceCalculatorDependencies{TaxCodes: TaxCodes{"txcd_10000000": tc1}},
-			wantTC: &productcatalog.TaxConfig{
-				Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
-				TaxCodeID: lo.ToPtr("tc-1"),
-				TaxCode:   &tc1,
+			wantTC: &billing.TaxConfig{
+				TaxConfig: productcatalog.TaxConfig{
+					Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
+					TaxCodeID: lo.ToPtr("tc-1"),
+				},
+				TaxCode: &tc1,
 			},
 			wantNoErr: true,
 		},
@@ -100,10 +167,12 @@ func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 				}),
 			),
 			deps: StandardInvoiceCalculatorDependencies{TaxCodes: TaxCodes{"txcd_10000000": tc1}},
-			wantTC: &productcatalog.TaxConfig{
-				Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
-				TaxCodeID: lo.ToPtr("already-set"),
-				TaxCode:   &tc1,
+			wantTC: &billing.TaxConfig{
+				TaxConfig: productcatalog.TaxConfig{
+					Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
+					TaxCodeID: lo.ToPtr("already-set"),
+				},
+				TaxCode: &tc1,
 			},
 			wantNoErr: true,
 		},
@@ -117,8 +186,10 @@ func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 				}),
 			),
 			deps: StandardInvoiceCalculatorDependencies{TaxCodes: TaxCodes{}},
-			wantTC: &productcatalog.TaxConfig{
-				Stripe: &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
+			wantTC: &billing.TaxConfig{
+				TaxConfig: productcatalog.TaxConfig{
+					Stripe: &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
+				},
 			},
 			wantNoErr: true,
 		},
@@ -133,11 +204,13 @@ func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 				newLine(nil),
 			),
 			deps: StandardInvoiceCalculatorDependencies{TaxCodes: TaxCodes{"txcd_10000000": tc1}},
-			wantTC: &productcatalog.TaxConfig{
-				Behavior:  lo.ToPtr(productcatalog.InclusiveTaxBehavior),
-				Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
-				TaxCodeID: lo.ToPtr("tc-1"),
-				TaxCode:   &tc1,
+			wantTC: &billing.TaxConfig{
+				TaxConfig: productcatalog.TaxConfig{
+					Behavior:  lo.ToPtr(productcatalog.InclusiveTaxBehavior),
+					Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_10000000"},
+					TaxCodeID: lo.ToPtr("tc-1"),
+				},
+				TaxCode: &tc1,
 			},
 			wantNoErr: true,
 		},
@@ -156,10 +229,12 @@ func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 				"txcd_10000000": tc1,
 				"txcd_20000000": tc2,
 			}},
-			wantTC: &productcatalog.TaxConfig{
-				Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_20000000"},
-				TaxCodeID: lo.ToPtr("tc-2"),
-				TaxCode:   &tc2,
+			wantTC: &billing.TaxConfig{
+				TaxConfig: productcatalog.TaxConfig{
+					Stripe:    &productcatalog.StripeTaxConfig{Code: "txcd_20000000"},
+					TaxCodeID: lo.ToPtr("tc-2"),
+				},
+				TaxCode: &tc2,
 			},
 			wantNoErr: true,
 		},
@@ -173,8 +248,10 @@ func TestSnapshotTaxConfigIntoLines(t *testing.T) {
 				}),
 			),
 			deps: StandardInvoiceCalculatorDependencies{TaxCodes: TaxCodes{"txcd_10000000": tc1}},
-			wantTC: &productcatalog.TaxConfig{
-				Behavior: lo.ToPtr(productcatalog.ExclusiveTaxBehavior),
+			wantTC: &billing.TaxConfig{
+				TaxConfig: productcatalog.TaxConfig{
+					Behavior: lo.ToPtr(productcatalog.ExclusiveTaxBehavior),
+				},
 			},
 			wantNoErr: true,
 		},

openmeter/billing/stdinvoice.go

@@ -13,7 +13,6 @@ import (
 	"github.com/openmeterio/openmeter/openmeter/billing/models/externalid"
 	"github.com/openmeterio/openmeter/openmeter/billing/models/totals"
 	"github.com/openmeterio/openmeter/openmeter/customer"
-	"github.com/openmeterio/openmeter/openmeter/productcatalog"
 	"github.com/openmeterio/openmeter/openmeter/streaming"
 	"github.com/openmeterio/openmeter/pkg/currencyx"
 	"github.com/openmeterio/openmeter/pkg/expand"
@@ -450,7 +449,7 @@ func (i *StandardInvoice) getLeafLines() DetailedLines {
 
 type DetailedLineWithResolvedTaxConfig struct {
 	DetailedLine
-	TaxConfig *productcatalog.TaxConfig
+	TaxConfig *TaxConfig
 }
 
 // GetLeafLinesWithResolvedTaxConfig returns invoice leaf lines together with the effective tax
@@ -459,7 +458,7 @@ func (i *StandardInvoice) GetLeafLinesWithResolvedTaxConfig() []DetailedLineWith
 	out := make([]DetailedLineWithResolvedTaxConfig, 0)
 
 	for _, parentLine := range i.Lines.OrEmpty() {
-		taxConfig := productcatalog.MergeTaxConfigs(i.Workflow.Config.Invoicing.DefaultTaxConfig, parentLine.TaxConfig)
+		taxConfig := MergeTaxConfigs(FromProductCatalog(i.Workflow.Config.Invoicing.DefaultTaxConfig), parentLine.TaxConfig)
 		for _, line := range parentLine.DetailedLines {
 			out = append(out, DetailedLineWithResolvedTaxConfig{
 				DetailedLine: line,