feat(customcurrencies): support resolving costbases

Author: turip

app/common/charges.go

@@ -257,6 +257,7 @@ func NewChargesUsageBasedService(
 	billingService billing.Service,
 	featureService feature.FeatureConnector,
 	ratingService rating.Service,
+	currenciesService currencies.Service,
 	streamingConnector streaming.Connector,
 ) (usagebased.Service, error) {
 	usageBasedSvc, err := usagebasedservice.New(usagebasedservice.Config{
@@ -269,6 +270,7 @@ func NewChargesUsageBasedService(
 		CustomerOverrideService: billingService,
 		FeatureService:          featureService,
 		RatingService:           ratingService,
+		Currencies:              currenciesService,
 		StreamingConnector:      streamingConnector,
 	})
 	if err != nil {
@@ -505,6 +507,7 @@ func newChargesRegistry(
 		billingService,
 		featureService,
 		ratingService,
+		currenciesService,
 		streamingConnector,
 	)
 	if err != nil {

openmeter/billing/charges/flatfee/service/creditheninvoice.go

@@ -391,12 +391,16 @@ func (s *CreditThenInvoiceStateMachine) UnsupportedShrinkOperation(_ context.Con
 	)
 }
 
-// ResolveDynamicCostBasis persists the dynamic cost basis effective at the
-// charge's service-period start. A persisted resolution is authoritative and
-// is returned unchanged on subsequent lifecycle attempts.
+// ResolveDynamicCostBasis idempotently persists the dynamic cost basis
+// effective at the charge's service-period start. Once resolved, the persisted
+// value is authoritative and must never be overwritten by lifecycle retries.
 func (s *CreditThenInvoiceStateMachine) ResolveDynamicCostBasis(ctx context.Context) error {
 	intent := s.Charge.Intent.GetCostBasisIntent()
-	if intent == nil || intent.Kind() != costbasis.ModeDynamic || s.Charge.State.ResolvedCostBasis != nil {
+	if intent == nil || intent.Kind() != costbasis.ModeDynamic {
+		return nil
+	}
+
+	if s.Charge.State.ResolvedCostBasis != nil {
 		return nil
 	}
 

openmeter/billing/charges/service/base_test.go

@@ -157,6 +157,7 @@ func (s *BaseSuite) SetupSuite() {
 		CustomerOverrideService: s.BillingService,
 		FeatureService:          s.FeatureService,
 		RatingService:           billingratingservice.New(billingratingservice.Config{UnitConfigEnabled: s.UnitConfigEnabled}),
+		Currencies:              currencyService,
 		StreamingConnector:      s.MockStreamingConnector,
 	})
 	s.NoError(err)

openmeter/billing/charges/service/invoicable_test.go

@@ -3166,6 +3166,7 @@ func (s *InvoicableChargesTestSuite) TestUsageBasedCreditOnlyWithCustomCurrency(
 			CustomerOverrideService: s.BillingService,
 			FeatureService:          s.FeatureService,
 			RatingService:           billingratingservice.New(billingratingservice.Config{UnitConfigEnabled: s.UnitConfigEnabled}),
+			Currencies:              s.CurrencyService,
 			StreamingConnector:      s.MockStreamingConnector,
 		})
 		s.Require().NoError(err)