feat: Update current-account domain for dimension-agnostic Amount (#1242)

* feat: Update current-account domain for dimension-agnostic Amount

Replace Money with Amount throughout the current-account service to
support multi-asset accounts (KWH, CARBON_CREDIT, GPU_HOUR, etc.).

- Add Amount = sharedamount.Amount type alias to domain/quantity.go
- Add NewAmountFromInstrument constructor re-export
- Keep Money = Amount and ErrCurrencyMismatch as deprecated aliases
- Update NewCurrentAccountWithDimension to use NewAmountFromInstrument
- Replace Currency()/CurrencyCode() with InstrumentCode() throughout
- Replace ErrCurrencyMismatch with ErrInstrumentMismatch in account.go
- Update persistence layer to use NewAmountFromInstrument
- Update service layer: grpc_mappers, lien_service, deposit/withdrawal
- Update all tests: use InstrumentCode(), toMinorUnits() helper
- Add multi-asset tests: KWH, CARBON_CREDIT account creation/deposit

Closes asset-agnostic-accounts#16

* fix: Update balance_ownership_test.go for cadomain.Amount API

Replace sharedmoney.Money with cadomain.Amount in MockCurrentAccountService:
- Use cadomain.NewMoney() to convert legacy money.Money for Deposit/Withdraw
- Use caBalance.ToMinorUnits() + money.NewFromMinorUnits() for GetBalance
- Remove unused sharedmoney import
EOF

* fix: set SAGA_ASSET_DIR in E2E workflow for saga script loading

The unified binary loads saga scripts at startup via loadSagaAsset(),
which resolves paths relative to SAGA_ASSET_DIR env var or the
executable directory. In the E2E workflow, the binary is at dist/meridian
but saga files are in the repo checkout root, so assets were not found.

Set SAGA_ASSET_DIR=$(pwd) so the binary finds saga scripts and handlers
schema at services/reference-data/saga/ and shared/pkg/saga/schema/.

* fix: add precision argument to NewCurrentAccountWithDimension test calls

After rebasing with PR #1241 (instrument precision resolution), the
NewCurrentAccountWithDimension function gained a required precision int
parameter. Update test calls for non-CURRENCY dimensions (ENERGY, CARBON)
to pass precision=0, as precision is not validated for non-currency instruments.

* fix: restrict NewMoneyFromInstrument to CURRENCY dimension only

NewMoneyFromInstrument hardcoded precision=2 and would silently mis-scale
non-CURRENCY dimensions (ENERGY, CARBON) when called with incorrect dimension.
Add an explicit CURRENCY dimension guard that returns ErrInvalidCurrency for
non-CURRENCY inputs, preserving the money-only semantics of this deprecated
compatibility API.

---------

Co-authored-by: Ben Coombs <bjcoombs@users.noreply.github.com>

Author: bjcoombs

.github/workflows/e2e.yml

@@ -154,6 +154,7 @@ jobs:
         run: |
           DATABASE_URL="postgres://root@localhost:26257/defaultdb?sslmode=disable" \
           LOCAL_DEV_MODE=true \
+          SAGA_ASSET_DIR="$(pwd)" \
             ./dist/meridian >/tmp/meridian.log 2>&1 &
 
       - name: Seed dev tenant and apply manifest

services/current-account/adapters/persistence/lien_repository.go

@@ -332,7 +332,7 @@ func toLienEntity(lien *domain.Lien) *LienEntity {
 		ID:                    lien.ID,
 		AccountID:             lien.AccountID,
 		AmountCents:           lien.Amount.ToMinorUnitsUnchecked(),
-		Currency:              string(lien.Amount.Currency()),
+		Currency:              lien.Amount.InstrumentCode(),
 		BucketID:              lien.BucketID,
 		Status:                string(lien.Status),
 		PaymentOrderReference: lien.PaymentOrderReference,

services/current-account/adapters/persistence/lien_repository_test.go

@@ -87,7 +87,7 @@ func TestLienRepository_Create(t *testing.T) {
 	amountCents, err := retrieved.Amount.ToMinorUnits()
 	require.NoError(t, err)
 	assert.Equal(t, int64(10000), amountCents)
-	assert.Equal(t, domain.CurrencyGBP, retrieved.Amount.Currency())
+	assert.Equal(t, "GBP", retrieved.Amount.InstrumentCode())
 	assert.Equal(t, "bucket-abc", retrieved.BucketID)
 	assert.Equal(t, domain.LienStatusActive, retrieved.Status)
 	assert.Equal(t, "PO-001", retrieved.PaymentOrderReference)

services/current-account/adapters/persistence/repository.go

@@ -691,11 +691,11 @@ func toDomain(entity *CurrentAccountEntity) (domain.CurrentAccount, error) {
 	// Use entity's in-memory balance fields if populated (e.g., from recent save),
 	// otherwise initialize with zero values.
 	// The service layer should populate from Position Keeping for authoritative balance.
-	balance, err := domain.NewMoneyFromInstrument(entity.InstrumentCode, entity.Dimension, entity.Balance)
+	balance, err := domain.NewAmountFromInstrument(entity.InstrumentCode, entity.Dimension, 0, entity.Balance)
 	if err != nil {
 		return domain.CurrentAccount{}, fmt.Errorf("failed to create balance: %w", err)
 	}
-	availableBalance, err := domain.NewMoneyFromInstrument(entity.InstrumentCode, entity.Dimension, entity.AvailableBalance)
+	availableBalance, err := domain.NewAmountFromInstrument(entity.InstrumentCode, entity.Dimension, 0, entity.AvailableBalance)
 	if err != nil {
 		return domain.CurrentAccount{}, fmt.Errorf("failed to create available balance: %w", err)
 	}

services/current-account/adapters/persistence/withdrawal_repository.go

@@ -174,7 +174,7 @@ func toWithdrawalEntity(withdrawal *domain.Withdrawal) *WithdrawalEntity {
 		ID:          withdrawal.ID,
 		AccountID:   withdrawal.AccountID,
 		AmountCents: withdrawal.Amount.ToMinorUnitsUnchecked(),
-		Currency:    string(withdrawal.Amount.Currency()),
+		Currency:    withdrawal.Amount.InstrumentCode(),
 		Status:      string(withdrawal.Status),
 		Reference:   withdrawal.Reference,
 		CreatedAt:   withdrawal.CreatedAt,

services/current-account/adapters/persistence/withdrawal_repository_test.go

@@ -124,7 +124,7 @@ func TestWithdrawalRepository_Create_Success(t *testing.T) {
 	amountCents, err := retrieved.Amount.ToMinorUnits()
 	require.NoError(t, err)
 	assert.Equal(t, int64(10000), amountCents)
-	assert.Equal(t, domain.CurrencyGBP, retrieved.Amount.Currency())
+	assert.Equal(t, "GBP", retrieved.Amount.InstrumentCode())
 	assert.Equal(t, domain.WithdrawalStatusPending, retrieved.Status)
 	assert.Equal(t, "WD-001", retrieved.Reference)
 	assert.Equal(t, 1, retrieved.Version)

services/current-account/domain/account.go

@@ -132,16 +132,13 @@ func NewCurrentAccount(accountID, externalIdentifier, partyID, instrumentCode st
 //
 // For non-CURRENCY dimensions, precision is trusted as provided by the caller (validated at the
 // API boundary by the gRPC service layer using Reference Data).
-//
-// NOTE: Balance creation for non-CURRENCY dimensions is gated by the Money type which currently
-// only supports CURRENCY. Full non-currency balance support is handled in task 16.
 func NewCurrentAccountWithDimension(accountID, externalIdentifier, partyID, instrumentCode, dimension string, precision int, opts ...AccountOption) (CurrentAccount, error) {
 	now := time.Now()
 	normalizedDimension := strings.ToUpper(dimension)
 
 	// For CURRENCY, validate precision against canonical registry value.
 	// If the currency code is not in the local registry (e.g. a currency only defined in
-	// the Reference Data service), precision validation is deferred: NewMoneyFromInstrument
+	// the Reference Data service), precision validation is deferred: NewAmountFromInstrument
 	// will return ErrInvalidCurrency if the code is genuinely unknown.
 	if normalizedDimension == quantity.DimensionCurrency {
 		if inst, ok := currency.ByCode(strings.ToUpper(instrumentCode)); ok {
@@ -152,7 +149,7 @@ func NewCurrentAccountWithDimension(accountID, externalIdentifier, partyID, inst
 		}
 	}
 
-	zeroMoney, err := NewMoneyFromInstrument(instrumentCode, normalizedDimension, 0)
+	zeroAmount, err := NewAmountFromInstrument(instrumentCode, normalizedDimension, precision, 0)
 	if err != nil {
 		return CurrentAccount{}, err
 	}
@@ -164,8 +161,8 @@ func NewCurrentAccountWithDimension(accountID, externalIdentifier, partyID, inst
 		instrumentCode:     instrumentCode,
 		dimension:          normalizedDimension,
 		partyID:            partyID,
-		balance:            zeroMoney,
-		availableBalance:   zeroMoney,
+		balance:            zeroAmount,
+		availableBalance:   zeroAmount,
 		status:             AccountStatusActive,
 		balanceUpdatedAt:   now,
 		version:            1,
@@ -200,8 +197,8 @@ func (a CurrentAccount) Deposit(amount Money) (CurrentAccount, error) {
 		return CurrentAccount{}, ErrAccountClosed
 	}
 
-	if amount.Currency() != a.balance.Currency() {
-		return CurrentAccount{}, ErrCurrencyMismatch
+	if amount.InstrumentCode() != a.balance.InstrumentCode() {
+		return CurrentAccount{}, ErrInstrumentMismatch
 	}
 
 	// Use immutable Add method
@@ -294,12 +291,12 @@ func (a CurrentAccount) PrepareForDebit(amount Money) (CurrentAccount, error) {
 		return CurrentAccount{}, ErrAccountClosed
 	}
 
-	if amount.Currency() != a.balance.Currency() {
-		return CurrentAccount{}, ErrCurrencyMismatch
+	if amount.InstrumentCode() != a.balance.InstrumentCode() {
+		return CurrentAccount{}, ErrInstrumentMismatch
 	}
 
 	// Check if sufficient funds (via availableBalance).
-	// Currency match is already verified above, so Compare cannot return an error here.
+	// Instrument match is already verified above, so Compare cannot return an error here.
 	cmp, err := amount.Compare(a.availableBalance)
 	if err != nil {
 		return CurrentAccount{}, err
@@ -347,12 +344,12 @@ func (a CurrentAccount) Withdraw(amount Money) (CurrentAccount, error) {
 		return CurrentAccount{}, ErrAccountClosed
 	}
 
-	if amount.Currency() != a.balance.Currency() {
-		return CurrentAccount{}, ErrCurrencyMismatch
+	if amount.InstrumentCode() != a.balance.InstrumentCode() {
+		return CurrentAccount{}, ErrInstrumentMismatch
 	}
 
 	// Check if sufficient funds.
-	// Currency match is already verified above, so Compare cannot return an error here.
+	// Instrument match is already verified above, so Compare cannot return an error here.
 	cmp, err := amount.Compare(a.availableBalance)
 	if err != nil {
 		return CurrentAccount{}, err