Persist unit config - OM-395

openmeter/billing/charges/usagebased/adapter/charge.go

@@ -49,6 +49,12 @@ func (a *adapter) UpdateCharge(ctx context.Context, charge usagebased.ChargeBase
 			SetStatusDetailed(charge.Status).
 			SetOrClearCurrentRealizationRunID(charge.State.CurrentRealizationRunID)
 
+		if baseIntent.UnitConfig != nil {
+			update = update.SetUnitConfig(baseIntent.UnitConfig)
+		} else {
+			update = update.ClearUnitConfig()
+		}
+
 		update, err = chargemeta.Update(update, chargemeta.UpdateInput{
 			ManagedResource:     charge.ManagedResource,
 			IntentMutableFields: baseIntent.IntentMutableFields.IntentMutableFields,
@@ -311,6 +317,10 @@ func (a *adapter) buildCreateUsageBasedCharge(ctx context.Context, ns string, in
 		SetInvoiceAt(meta.NormalizeTimestamp(baseIntent.InvoiceAt).In(time.UTC)).
 		SetSettlementMode(baseIntent.SettlementMode)
 
+	if baseIntent.UnitConfig != nil {
+		create = create.SetUnitConfig(baseIntent.UnitConfig)
+	}
+
 	create, err := chargemeta.Create[*db.ChargeUsageBasedCreate](create, chargemeta.CreateInput{
 		Namespace:           ns,
 		Intent:              baseIntent.Intent,

openmeter/billing/charges/usagebased/adapter/intentoverride.go

@@ -42,6 +42,7 @@ func mapIntentOverrideFromDB(dbOverride *entdb.ChargeUsageBasedOverride) *usageb
 		FeatureKey:      dbOverride.FeatureKey,
 		Price:           lo.FromPtr(dbOverride.Price),
 		Discounts:       lo.FromPtr(dbOverride.Discounts),
+		UnitConfig:      dbOverride.UnitConfig,
 	}
 }
 
@@ -155,6 +156,9 @@ func (a *adapter) createIntentOverride(ctx context.Context, chargeID meta.Charge
 		SetFeatureKey(normalized.FeatureKey).
 		SetPrice(&normalized.Price).
 		SetDiscounts(&normalized.Discounts)
+	if normalized.UnitConfig != nil {
+		create = create.SetUnitConfig(normalized.UnitConfig)
+	}
 	if normalized.Metadata != nil {
 		create = create.SetMetadata(&normalized.Metadata)
 	}
@@ -190,6 +194,11 @@ func (a *adapter) updateIntentOverride(ctx context.Context, chargeID meta.Charge
 		SetFeatureKey(normalized.FeatureKey).
 		SetPrice(&normalized.Price).
 		SetDiscounts(&normalized.Discounts)
+	if normalized.UnitConfig != nil {
+		update = update.SetUnitConfig(normalized.UnitConfig)
+	} else {
+		update = update.ClearUnitConfig()
+	}
 	if normalized.Metadata == nil {
 		update = update.ClearMetadata()
 	} else {

openmeter/billing/charges/usagebased/adapter/intentoverride_test.go

@@ -265,6 +265,108 @@ func (s *UsageBasedIntentOverrideAdapterSuite) TestDeleteChargeWithIntentOverrid
 	s.Equal(deletedAt, *fetched.DeletedAt)
 }
 
+// newTestUnitConfig builds a deterministic unit config for round-trip assertions.
+func newTestUnitConfig(factor int64, displayUnit string) *productcatalog.UnitConfig {
+	return &productcatalog.UnitConfig{
+		Operation:        productcatalog.UnitConfigOperationDivide,
+		ConversionFactor: alpacadecimal.NewFromInt(factor),
+		Rounding:         productcatalog.UnitConfigRoundingModeCeiling,
+		Precision:        0,
+		DisplayUnit:      lo.ToPtr(displayUnit),
+	}
+}
+
+// TestUnitConfigRoundTrip verifies unit_config persists through the charge write
+// sites. unit_config is a mutable field in IntentMutableFields (alongside price),
+// so it round-trips through both the base layer (create/update/clear) and the
+// override layer (create/update/clear).
+func (s *UsageBasedIntentOverrideAdapterSuite) TestUnitConfigRoundTrip() {
+	ctx := s.T().Context()
+	namespace := "usagebased-unitconfig-adapter"
+	charge := s.createCharge(namespace)
+
+	// base create→read: createCharge persisted a base unit_config (divide 1000)
+	fetched, err := s.adapter.GetByID(ctx, usagebased.GetByIDInput{ChargeID: charge.GetChargeID()})
+	s.Require().NoError(err)
+	s.Require().NotNil(fetched.Intent.GetBaseIntent().UnitConfig)
+	s.True(fetched.Intent.GetBaseIntent().UnitConfig.Equal(newTestUnitConfig(1000, "K")))
+
+	// base update→read: the base unit_config is mutable (lives alongside price)
+	s.Require().NoError(fetched.Intent.Mutate(chargesmeta.ChangeTargetBase, func(f *usagebased.IntentMutableFields) {
+		f.UnitConfig = newTestUnitConfig(1000000, "M")
+	}))
+	updated, err := s.adapter.UpdateCharge(ctx, fetched.ChargeBase)
+	s.Require().NoError(err)
+	s.True(updated.Intent.GetBaseIntent().UnitConfig.Equal(newTestUnitConfig(1000000, "M")))
+
+	fetched, err = s.adapter.GetByID(ctx, usagebased.GetByIDInput{ChargeID: charge.GetChargeID()})
+	s.Require().NoError(err)
+	s.True(fetched.Intent.GetBaseIntent().UnitConfig.Equal(newTestUnitConfig(1000000, "M")))
+
+	// base clear→read
+	s.Require().NoError(fetched.Intent.Mutate(chargesmeta.ChangeTargetBase, func(f *usagebased.IntentMutableFields) {
+		f.UnitConfig = nil
+	}))
+	updated, err = s.adapter.UpdateCharge(ctx, fetched.ChargeBase)
+	s.Require().NoError(err)
+	s.Nil(updated.Intent.GetBaseIntent().UnitConfig)
+
+	fetched, err = s.adapter.GetByID(ctx, usagebased.GetByIDInput{ChargeID: charge.GetChargeID()})
+	s.Require().NoError(err)
+	s.Nil(fetched.Intent.GetBaseIntent().UnitConfig)
+
+	// override create→read: the override layer carries its own unit_config snapshot
+	baseIntent := fetched.Intent.GetBaseIntent()
+	override := usagebased.IntentMutableFields{
+		IntentMutableFields: chargesmeta.IntentMutableFields{
+			Name:              "override with unit config",
+			TaxConfig:         baseIntent.TaxConfig,
+			ServicePeriod:     baseIntent.ServicePeriod,
+			FullServicePeriod: baseIntent.FullServicePeriod,
+			BillingPeriod:     baseIntent.BillingPeriod,
+		},
+		InvoiceAt:  baseIntent.InvoiceAt,
+		FeatureKey: baseIntent.FeatureKey,
+		Price:      baseIntent.Price,
+		Discounts:  baseIntent.Discounts,
+		UnitConfig: newTestUnitConfig(1000, "K"),
+	}
+	withOverride, err := s.adapter.CreateChargeOverride(ctx, fetched.ChargeBase, override)
+	s.Require().NoError(err)
+	s.Require().NotNil(withOverride.Intent.GetOverrideLayerMutableFields())
+	s.True(withOverride.Intent.GetOverrideLayerMutableFields().UnitConfig.Equal(newTestUnitConfig(1000, "K")))
+
+	fetched, err = s.adapter.GetByID(ctx, usagebased.GetByIDInput{ChargeID: charge.GetChargeID()})
+	s.Require().NoError(err)
+	s.Require().NotNil(fetched.Intent.GetOverrideLayerMutableFields())
+	s.True(fetched.Intent.GetOverrideLayerMutableFields().UnitConfig.Equal(newTestUnitConfig(1000, "K")))
+
+	// override update→read
+	override = *fetched.Intent.GetOverrideLayerMutableFields()
+	override.UnitConfig = newTestUnitConfig(1000000, "M")
+	fetched.Intent = usagebased.NewOverridableIntent(fetched.Intent.GetBaseIntent(), &override)
+	updated, err = s.adapter.UpdateCharge(ctx, fetched.ChargeBase)
+	s.Require().NoError(err)
+	s.True(updated.Intent.GetOverrideLayerMutableFields().UnitConfig.Equal(newTestUnitConfig(1000000, "M")))
+
+	fetched, err = s.adapter.GetByID(ctx, usagebased.GetByIDInput{ChargeID: charge.GetChargeID()})
+	s.Require().NoError(err)
+	s.True(fetched.Intent.GetOverrideLayerMutableFields().UnitConfig.Equal(newTestUnitConfig(1000000, "M")))
+
+	// override clear→read
+	override = *fetched.Intent.GetOverrideLayerMutableFields()
+	override.UnitConfig = nil
+	fetched.Intent = usagebased.NewOverridableIntent(fetched.Intent.GetBaseIntent(), &override)
+	updated, err = s.adapter.UpdateCharge(ctx, fetched.ChargeBase)
+	s.Require().NoError(err)
+	s.Nil(updated.Intent.GetOverrideLayerMutableFields().UnitConfig)
+
+	fetched, err = s.adapter.GetByID(ctx, usagebased.GetByIDInput{ChargeID: charge.GetChargeID()})
+	s.Require().NoError(err)
+	s.Require().NotNil(fetched.Intent.GetOverrideLayerMutableFields())
+	s.Nil(fetched.Intent.GetOverrideLayerMutableFields().UnitConfig)
+}
+
 func (s *UsageBasedIntentOverrideAdapterSuite) requireOverrideMatches(
 	override *usagebased.IntentMutableFields,
 	servicePeriod timeutil.ClosedPeriod,
@@ -331,6 +433,7 @@ func (s *UsageBasedIntentOverrideAdapterSuite) createCharge(namespace string) us
 						Price: *productcatalog.NewPriceFrom(productcatalog.UnitPrice{
 							Amount: alpacadecimal.NewFromFloat(0.1),
 						}),
+						UnitConfig: newTestUnitConfig(1000, "K"),
 					},
 					SettlementMode: productcatalog.CreditThenInvoiceSettlementMode,
 				}.AsOverridableIntent(),

openmeter/billing/charges/usagebased/adapter/mapper.go

@@ -51,6 +51,7 @@ func MapChargeBaseFromDB(entity *entdb.ChargeUsageBased) usagebased.ChargeBase {
 			FeatureKey:          entity.FeatureKey,
 			Discounts:           lo.FromPtr(entity.Discounts),
 			Price:               lo.FromPtr(entity.Price),
+			UnitConfig:          entity.UnitConfig,
 		},
 		SettlementMode: entity.SettlementMode,
 	}

openmeter/billing/charges/usagebased/charge.go

@@ -526,6 +526,11 @@ type IntentMutableFields struct {
 	Price productcatalog.Price `json:"price"`
 
 	Discounts productcatalog.Discounts `json:"discounts"`
+
+	// UnitConfig is the optional unit conversion snapshotted from the effective
+	// rate card. Like Price it is a mutable rating input (set on create and
+	// update) so re-rates read the config in effect for the charge.
+	UnitConfig *productcatalog.UnitConfig `json:"unitConfig,omitempty"`
 }
 
 func (f IntentMutableFields) Normalized() IntentMutableFields {
@@ -541,6 +546,10 @@ func (f IntentMutableFields) Clone() IntentMutableFields {
 	out.Price = *f.Price.Clone()
 	out.Discounts = f.Discounts.Clone()
 
+	if f.UnitConfig != nil {
+		out.UnitConfig = lo.ToPtr(f.UnitConfig.Clone())
+	}
+
 	return out
 }
 
@@ -563,6 +572,10 @@ func (f IntentMutableFields) Validate() error {
 		errs = append(errs, fmt.Errorf("price: %w", err))
 	}
 
+	if err := f.UnitConfig.Validate(); err != nil {
+		errs = append(errs, fmt.Errorf("unit config: %w", err))
+	}
+
 	if f.FeatureKey == "" {
 		errs = append(errs, fmt.Errorf("feature key is required"))
 	}

openmeter/billing/worker/subscriptionsync/service/reconciler/patchchargeusagebased.go

@@ -121,6 +121,9 @@ func newUsageBasedChargeIntent(target targetstate.StateItem) (charges.ChargeInte
 			FeatureKey: lo.FromPtr(rateCardMeta.FeatureKey),
 			Price:      *price,
 			Discounts:  rateCardMeta.Discounts,
+			// TODO(unit-config): copy rateCardMeta.UnitConfig here (with a
+			// round-trip test) when the "snapshot unit_config onto subscriptions"
+			// ticket lands; the charge adapter already persists Intent.UnitConfig.
 		},
 		SettlementMode: target.Subscription.SettlementMode,
 	}), nil