Merge pull request 'increased payout timeout' (#213) from timeout-210 into main

Reviewed-on: #213

.gitignore

@@ -10,3 +10,4 @@ generate_protos.sh
 update_dep.sh
 .vscode/
 .gocache/
+.cache/

api/billing/fees/go.mod

@@ -11,7 +11,7 @@ require (
 	github.com/tech/sendico/pkg v0.1.0
 	go.mongodb.org/mongo-driver v1.17.6
 	go.uber.org/zap v1.27.1
-	google.golang.org/grpc v1.77.0
+	google.golang.org/grpc v1.78.0
 	gopkg.in/yaml.v3 v3.0.1
 )
 
@@ -31,7 +31,7 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/montanaflynn/stats v0.7.1 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
-	github.com/nats-io/nats.go v1.47.0 // indirect
+	github.com/nats-io/nats.go v1.48.0 // indirect
 	github.com/nats-io/nkeys v0.4.12 // indirect
 	github.com/nats-io/nuid v1.0.1 // indirect
 	github.com/prometheus/client_golang v1.23.2
@@ -49,6 +49,6 @@ require (
 	golang.org/x/sync v0.19.0 // indirect
 	golang.org/x/sys v0.39.0 // indirect
 	golang.org/x/text v0.32.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 // indirect
-	google.golang.org/protobuf v1.36.10
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b // indirect
+	google.golang.org/protobuf v1.36.11
 )

api/billing/fees/go.sum

@@ -95,8 +95,8 @@ github.com/morikuni/aec v1.0.0 h1:nP9CBfwrvYnBRgY6qfDQkygYDmYwOilePFkwzv4dU8A=
 github.com/morikuni/aec v1.0.0/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7PXmsc=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
-github.com/nats-io/nats.go v1.47.0 h1:YQdADw6J/UfGUd2Oy6tn4Hq6YHxCaJrVKayxxFqYrgM=
-github.com/nats-io/nats.go v1.47.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
+github.com/nats-io/nats.go v1.48.0 h1:pSFyXApG+yWU/TgbKCjmm5K4wrHu86231/w84qRVR+U=
+github.com/nats-io/nats.go v1.48.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
 github.com/nats-io/nkeys v0.4.12 h1:nssm7JKOG9/x4J8II47VWCL1Ds29avyiQDRn0ckMvDc=
 github.com/nats-io/nkeys v0.4.12/go.mod h1:MT59A1HYcjIcyQDJStTfaOY6vhy9XTUjOFo+SVsvpBg=
 github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
@@ -212,12 +212,12 @@ golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
 gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 h1:gRkg/vSppuSQoDjxyiGfN4Upv/h/DQmIR10ZU8dh4Ww=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217/go.mod h1:7i2o+ce6H/6BluujYR+kqX3GKH+dChPTQU19wjRPiGk=
-google.golang.org/grpc v1.77.0 h1:wVVY6/8cGA6vvffn+wWK5ToddbgdU3d8MNENr4evgXM=
-google.golang.org/grpc v1.77.0/go.mod h1:z0BY1iVj0q8E1uSQCjL9cppRj+gnZjzDnzV0dHhrNig=
-google.golang.org/protobuf v1.36.10 h1:AYd7cD/uASjIL6Q9LiTjz8JLcrh/88q5UObnmY3aOOE=
-google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b h1:Mv8VFug0MP9e5vUxfBcE3vUkV6CImK3cMNMIDFjmzxU=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b/go.mod h1:j9x/tPzZkyxcgEFkiKEEGxfvyumM01BEtsW8xzOahRQ=
+google.golang.org/grpc v1.78.0 h1:K1XZG/yGDJnzMdd/uZHAkVqJE+xIDOcmdSFZkBUicNc=
+google.golang.org/grpc v1.78.0/go.mod h1:I47qjTo4OKbMkjA/aOOwxDIiPSBofUtQUI5EfpWvW7U=
+google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
+google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

api/billing/fees/internal/service/fees/internal/calculator/impl.go

@@ -90,10 +90,6 @@ func (c *quoteCalculator) Compute(ctx context.Context, plan *model.FeePlan, inte
 		}
 
 		ledgerAccountRef := strings.TrimSpace(rule.LedgerAccountRef)
-		if ledgerAccountRef == "" {
-			c.logger.Warn("fee rule missing ledger account reference", zap.String("rule_id", rule.RuleID))
-			continue
-		}
 
 		amount, scale, calcErr := c.calculateRuleAmount(baseAmount, baseScale, rule)
 		if calcErr != nil {
@@ -113,7 +109,8 @@ func (c *quoteCalculator) Compute(ctx context.Context, plan *model.FeePlan, inte
 
 		entrySide := mapEntrySide(rule.EntrySide)
 		if entrySide == accountingv1.EntrySide_ENTRY_SIDE_UNSPECIFIED {
-			entrySide = accountingv1.EntrySide_ENTRY_SIDE_CREDIT
+			// Default fees to debit (i.e. charge the customer) when entry side is not specified.
+			entrySide = accountingv1.EntrySide_ENTRY_SIDE_DEBIT
 		}
 
 		meta := map[string]string{

api/billing/fees/internal/service/fees/internal/resolver/impl.go

@@ -38,23 +38,23 @@ func New(plans storage.PlansStore, logger *zap.Logger) *feeResolver {
 	}
 }
 
-func (r *feeResolver) ResolveFeeRule(ctx context.Context, orgID *primitive.ObjectID, trigger model.Trigger, at time.Time, attrs map[string]string) (*model.FeePlan, *model.FeeRule, error) {
+func (r *feeResolver) ResolveFeeRule(ctx context.Context, orgRef *primitive.ObjectID, trigger model.Trigger, at time.Time, attrs map[string]string) (*model.FeePlan, *model.FeeRule, error) {
 	if r.plans == nil {
 		return nil, nil, merrors.InvalidArgument("fees: plans store is required")
 	}
 
 	// Try org-specific first if provided.
-	if orgID != nil && !orgID.IsZero() {
-		if plan, err := r.getOrgPlan(ctx, *orgID, at); err == nil {
+	if orgRef != nil && !orgRef.IsZero() {
+		if plan, err := r.getOrgPlan(ctx, *orgRef, at); err == nil {
 			if rule, selErr := selectRule(plan, trigger, at, attrs); selErr == nil {
 				return plan, rule, nil
 			} else if !errors.Is(selErr, ErrNoFeeRuleFound) {
-				r.logger.Warn("failed selecting rule for org plan", zap.Error(selErr), zap.String("org_ref", orgID.Hex()))
+				r.logger.Warn("failed selecting rule for org plan", zap.Error(selErr), zap.String("org_ref", orgRef.Hex()))
 				return nil, nil, selErr
 			}
-			r.logger.Debug("no matching rule in org plan; falling back to global", zap.String("org_ref", orgID.Hex()))
+			r.logger.Debug("no matching rule in org plan; falling back to global", zap.String("org_ref", orgRef.Hex()))
 		} else if !errors.Is(err, storage.ErrFeePlanNotFound) {
-			r.logger.Warn("failed resolving org fee plan", zap.Error(err), zap.String("org_ref", orgID.Hex()))
+			r.logger.Warn("failed resolving org fee plan", zap.Error(err), zap.String("org_ref", orgRef.Hex()))
 			return nil, nil, err
 		}
 	}

api/billing/fees/internal/service/fees/internal/resolver/resolver_test.go

@@ -32,8 +32,8 @@ func TestResolver_GlobalFallbackWhenOrgMissing(t *testing.T) {
 	if err != nil {
 		t.Fatalf("expected fallback to global, got error: %v", err)
 	}
-	if !plan.GetOrganizationRef().IsZero() {
-		t.Fatalf("expected global plan, got orgRef %s", plan.GetOrganizationRef().Hex())
+	if plan.OrganizationRef != nil && !plan.OrganizationRef.IsZero() {
+		t.Fatalf("expected global plan, got orgRef %s", plan.OrganizationRef.Hex())
 	}
 	if rule.RuleID != "global_capture" {
 		t.Fatalf("unexpected rule selected: %s", rule.RuleID)
@@ -59,8 +59,7 @@ func TestResolver_OrgOverridesGlobal(t *testing.T) {
 			{RuleID: "org_capture", Trigger: model.TriggerCapture, Priority: 10, Percentage: "0.03", EffectiveFrom: now.Add(-time.Hour)},
 		},
 	}
-	orgPlan.SetOrganizationRef(org)
-
+	orgPlan.OrganizationRef = &org
 	store := &memoryPlansStore{plans: []*model.FeePlan{globalPlan, orgPlan}}
 	resolver := New(store, zap.NewNop())
 
@@ -95,7 +94,7 @@ func TestResolver_SelectsHighestPriority(t *testing.T) {
 			{RuleID: "high", Trigger: model.TriggerCapture, Priority: 200, Percentage: "0.03", EffectiveFrom: now.Add(-time.Hour)},
 		},
 	}
-	plan.SetOrganizationRef(org)
+	plan.OrganizationRef = &org
 
 	store := &memoryPlansStore{plans: []*model.FeePlan{plan}}
 	resolver := New(store, zap.NewNop())
@@ -136,7 +135,7 @@ func TestResolver_EffectiveDateFiltering(t *testing.T) {
 			{RuleID: "expired", Trigger: model.TriggerCapture, Priority: 100, Percentage: "0.05", EffectiveFrom: past, EffectiveTo: &past},
 		},
 	}
-	orgPlan.SetOrganizationRef(org)
+	orgPlan.OrganizationRef = &org
 
 	globalPlan := &model.FeePlan{
 		Active:        true,
@@ -221,7 +220,7 @@ func TestResolver_MultipleActivePlansConflict(t *testing.T) {
 			{RuleID: "r1", Trigger: model.TriggerCapture, Priority: 10, Percentage: "0.05", EffectiveFrom: now.Add(-time.Hour)},
 		},
 	}
-	p1.SetOrganizationRef(org)
+	p1.OrganizationRef = &org
 	p2 := &model.FeePlan{
 		Active:        true,
 		EffectiveFrom: now.Add(-30 * time.Minute),
@@ -229,7 +228,7 @@ func TestResolver_MultipleActivePlansConflict(t *testing.T) {
 			{RuleID: "r2", Trigger: model.TriggerCapture, Priority: 20, Percentage: "0.03", EffectiveFrom: now.Add(-time.Hour)},
 		},
 	}
-	p2.SetOrganizationRef(org)
+	p2.OrganizationRef = &org
 
 	store := &memoryPlansStore{plans: []*model.FeePlan{p1, p2}}
 	resolver := New(store, zap.NewNop())
@@ -263,7 +262,7 @@ func (m *memoryPlansStore) GetActivePlan(ctx context.Context, orgRef primitive.O
 func (m *memoryPlansStore) FindActiveOrgPlan(_ context.Context, orgRef primitive.ObjectID, at time.Time) (*model.FeePlan, error) {
 	var matches []*model.FeePlan
 	for _, plan := range m.plans {
-		if plan == nil || plan.GetOrganizationRef() != orgRef {
+		if plan == nil || plan.OrganizationRef == nil || plan.OrganizationRef.IsZero() || (*plan.OrganizationRef != orgRef) {
 			continue
 		}
 		if !plan.Active {
@@ -289,7 +288,7 @@ func (m *memoryPlansStore) FindActiveOrgPlan(_ context.Context, orgRef primitive
 func (m *memoryPlansStore) FindActiveGlobalPlan(_ context.Context, at time.Time) (*model.FeePlan, error) {
 	var matches []*model.FeePlan
 	for _, plan := range m.plans {
-		if plan == nil || !plan.GetOrganizationRef().IsZero() {
+		if plan == nil || ((plan.OrganizationRef != nil) && !plan.OrganizationRef.IsZero()) {
 			continue
 		}
 		if !plan.Active {

api/billing/fees/internal/service/fees/logging.go

@@ -0,0 +1,88 @@
+package fees
+
+import (
+	"strings"
+	"time"
+
+	feesv1 "github.com/tech/sendico/pkg/proto/billing/fees/v1"
+	tracev1 "github.com/tech/sendico/pkg/proto/common/trace/v1"
+	"go.uber.org/zap"
+)
+
+func requestLogFields(meta *feesv1.RequestMeta, intent *feesv1.Intent) []zap.Field {
+	fields := logFieldsFromRequestMeta(meta)
+	fields = append(fields, logFieldsFromIntent(intent)...)
+	return fields
+}
+
+func logFieldsFromRequestMeta(meta *feesv1.RequestMeta) []zap.Field {
+	if meta == nil {
+		return nil
+	}
+	fields := make([]zap.Field, 0, 4)
+	if org := strings.TrimSpace(meta.GetOrganizationRef()); org != "" {
+		fields = append(fields, zap.String("organization_ref", org))
+	}
+	fields = append(fields, logFieldsFromTrace(meta.GetTrace())...)
+	return fields
+}
+
+func logFieldsFromIntent(intent *feesv1.Intent) []zap.Field {
+	if intent == nil {
+		return nil
+	}
+	fields := make([]zap.Field, 0, 5)
+	if trigger := intent.GetTrigger(); trigger != feesv1.Trigger_TRIGGER_UNSPECIFIED {
+		fields = append(fields, zap.String("trigger", trigger.String()))
+	}
+	if base := intent.GetBaseAmount(); base != nil {
+		if amount := strings.TrimSpace(base.GetAmount()); amount != "" {
+			fields = append(fields, zap.String("base_amount", amount))
+		}
+		if currency := strings.TrimSpace(base.GetCurrency()); currency != "" {
+			fields = append(fields, zap.String("base_currency", currency))
+		}
+	}
+	if booked := intent.GetBookedAt(); booked != nil && booked.IsValid() {
+		fields = append(fields, zap.Time("booked_at", booked.AsTime()))
+	}
+	if attrs := intent.GetAttributes(); len(attrs) > 0 {
+		fields = append(fields, zap.Int("attributes_count", len(attrs)))
+	}
+	return fields
+}
+
+func logFieldsFromTrace(trace *tracev1.TraceContext) []zap.Field {
+	if trace == nil {
+		return nil
+	}
+	fields := make([]zap.Field, 0, 3)
+	if reqRef := strings.TrimSpace(trace.GetRequestRef()); reqRef != "" {
+		fields = append(fields, zap.String("request_ref", reqRef))
+	}
+	if idem := strings.TrimSpace(trace.GetIdempotencyKey()); idem != "" {
+		fields = append(fields, zap.String("idempotency_key", idem))
+	}
+	if traceRef := strings.TrimSpace(trace.GetTraceRef()); traceRef != "" {
+		fields = append(fields, zap.String("trace_ref", traceRef))
+	}
+	return fields
+}
+
+func logFieldsFromTokenPayload(payload *feeQuoteTokenPayload) []zap.Field {
+	if payload == nil {
+		return nil
+	}
+	fields := make([]zap.Field, 0, 6)
+	if org := strings.TrimSpace(payload.OrganizationRef); org != "" {
+		fields = append(fields, zap.String("organization_ref", org))
+	}
+	if payload.ExpiresAtUnixMs > 0 {
+		fields = append(fields,
+			zap.Int64("expires_at_unix_ms", payload.ExpiresAtUnixMs),
+			zap.Time("expires_at", time.UnixMilli(payload.ExpiresAtUnixMs)))
+	}
+	fields = append(fields, logFieldsFromIntent(payload.Intent)...)
+	fields = append(fields, logFieldsFromTrace(payload.Trace)...)
+	return fields
+}

api/billing/fees/internal/service/fees/service.go

@@ -72,26 +72,57 @@ func (s *Service) Register(router routers.GRPC) error {
 }
 
 func (s *Service) QuoteFees(ctx context.Context, req *feesv1.QuoteFeesRequest) (resp *feesv1.QuoteFeesResponse, err error) {
+	var (
+		meta   *feesv1.RequestMeta
+		intent *feesv1.Intent
+	)
+	if req != nil {
+		meta = req.GetMeta()
+		intent = req.GetIntent()
+	}
+	logger := s.logger.With(requestLogFields(meta, intent)...)
+
 	start := s.clock.Now()
 	trigger := feesv1.Trigger_TRIGGER_UNSPECIFIED
-	if req != nil && req.GetIntent() != nil {
-		trigger = req.GetIntent().GetTrigger()
+	if intent != nil {
+		trigger = intent.GetTrigger()
 	}
 	var fxUsed bool
 	defer func() {
 		statusLabel := statusFromError(err)
+		linesCount := 0
+		appliedCount := 0
 		if err == nil && resp != nil {
 			fxUsed = resp.GetFxUsed() != nil
+			linesCount = len(resp.GetLines())
+			appliedCount = len(resp.GetApplied())
 		}
 		observeMetrics("quote", trigger, statusLabel, fxUsed, time.Since(start))
+
+		logFields := []zap.Field{
+			zap.String("status", statusLabel),
+			zap.Duration("duration", time.Since(start)),
+			zap.Bool("fx_used", fxUsed),
+			zap.String("trigger", trigger.String()),
+			zap.Int("lines", linesCount),
+			zap.Int("applied_rules", appliedCount),
+		}
+		if err != nil {
+			logger.Warn("QuoteFees finished", append(logFields, zap.Error(err))...)
+			return
+		}
+		logger.Info("QuoteFees finished", logFields...)
 	}()
 
+	logger.Debug("QuoteFees request received")
+
 	if err = s.validateQuoteRequest(req); err != nil {
 		return nil, err
 	}
 
 	orgRef, parseErr := primitive.ObjectIDFromHex(req.GetMeta().GetOrganizationRef())
 	if parseErr != nil {
+		logger.Warn("QuoteFees invalid organization_ref", zap.Error(parseErr))
 		err = status.Error(codes.InvalidArgument, "invalid organization_ref")
 		return nil, err
 	}
@@ -112,20 +143,59 @@ func (s *Service) QuoteFees(ctx context.Context, req *feesv1.QuoteFeesRequest) (
 }
 
 func (s *Service) PrecomputeFees(ctx context.Context, req *feesv1.PrecomputeFeesRequest) (resp *feesv1.PrecomputeFeesResponse, err error) {
+	var (
+		meta   *feesv1.RequestMeta
+		intent *feesv1.Intent
+	)
+	if req != nil {
+		meta = req.GetMeta()
+		intent = req.GetIntent()
+	}
+	logger := s.logger.With(requestLogFields(meta, intent)...)
+
 	start := s.clock.Now()
 	trigger := feesv1.Trigger_TRIGGER_UNSPECIFIED
-	if req != nil && req.GetIntent() != nil {
-		trigger = req.GetIntent().GetTrigger()
+	if intent != nil {
+		trigger = intent.GetTrigger()
 	}
-	var fxUsed bool
+	var (
+		fxUsed    bool
+		expiresAt time.Time
+	)
 	defer func() {
 		statusLabel := statusFromError(err)
+		linesCount := 0
+		appliedCount := 0
 		if err == nil && resp != nil {
 			fxUsed = resp.GetFxUsed() != nil
+			linesCount = len(resp.GetLines())
+			appliedCount = len(resp.GetApplied())
+			if ts := resp.GetExpiresAt(); ts != nil {
+				expiresAt = ts.AsTime()
+			}
 		}
 		observeMetrics("precompute", trigger, statusLabel, fxUsed, time.Since(start))
+
+		logFields := []zap.Field{
+			zap.String("status", statusLabel),
+			zap.Duration("duration", time.Since(start)),
+			zap.Bool("fx_used", fxUsed),
+			zap.String("trigger", trigger.String()),
+			zap.Int("lines", linesCount),
+			zap.Int("applied_rules", appliedCount),
+		}
+		if !expiresAt.IsZero() {
+			logFields = append(logFields, zap.Time("expires_at", expiresAt))
+		}
+		if err != nil {
+			logger.Warn("PrecomputeFees finished", append(logFields, zap.Error(err))...)
+			return
+		}
+		logger.Info("PrecomputeFees finished", logFields...)
 	}()
 
+	logger.Debug("PrecomputeFees request received")
+
 	if err = s.validatePrecomputeRequest(req); err != nil {
 		return nil, err
 	}
@@ -134,6 +204,7 @@ func (s *Service) PrecomputeFees(ctx context.Context, req *feesv1.PrecomputeFees
 
 	orgRef, parseErr := primitive.ObjectIDFromHex(req.GetMeta().GetOrganizationRef())
 	if parseErr != nil {
+		logger.Warn("PrecomputeFees invalid organization_ref", zap.Error(parseErr))
 		err = status.Error(codes.InvalidArgument, "invalid organization_ref")
 		return nil, err
 	}
@@ -148,7 +219,7 @@ func (s *Service) PrecomputeFees(ctx context.Context, req *feesv1.PrecomputeFees
 	if ttl <= 0 {
 		ttl = 60000
 	}
-	expiresAt := now.Add(time.Duration(ttl) * time.Millisecond)
+	expiresAt = now.Add(time.Duration(ttl) * time.Millisecond)
 
 	payload := feeQuoteTokenPayload{
 		OrganizationRef: req.GetMeta().GetOrganizationRef(),
@@ -159,7 +230,7 @@ func (s *Service) PrecomputeFees(ctx context.Context, req *feesv1.PrecomputeFees
 
 	var token string
 	if token, err = encodeTokenPayload(payload); err != nil {
-		s.logger.Warn("failed to encode fee quote token", zap.Error(err))
+		logger.Warn("failed to encode fee quote token", zap.Error(err))
 		err = status.Error(codes.Internal, "failed to encode fee quote token")
 		return nil, err
 	}
@@ -176,9 +247,18 @@ func (s *Service) PrecomputeFees(ctx context.Context, req *feesv1.PrecomputeFees
 }
 
 func (s *Service) ValidateFeeToken(ctx context.Context, req *feesv1.ValidateFeeTokenRequest) (resp *feesv1.ValidateFeeTokenResponse, err error) {
+	tokenLen := 0
+	if req != nil {
+		tokenLen = len(strings.TrimSpace(req.GetFeeQuoteToken()))
+	}
+	logger := s.logger.With(zap.Int("token_length", tokenLen))
+
 	start := s.clock.Now()
 	trigger := feesv1.Trigger_TRIGGER_UNSPECIFIED
-	var fxUsed bool
+	var (
+		fxUsed       bool
+		resultReason string
+	)
 	defer func() {
 		statusLabel := statusFromError(err)
 		if err == nil && resp != nil {
@@ -191,9 +271,28 @@ func (s *Service) ValidateFeeToken(ctx context.Context, req *feesv1.ValidateFeeT
 			}
 		}
 		observeMetrics("validate", trigger, statusLabel, fxUsed, time.Since(start))
+
+		logFields := []zap.Field{
+			zap.String("status", statusLabel),
+			zap.Duration("duration", time.Since(start)),
+			zap.Bool("fx_used", fxUsed),
+			zap.String("trigger", trigger.String()),
+			zap.Bool("valid", resp != nil && resp.GetValid()),
+		}
+		if resultReason != "" {
+			logFields = append(logFields, zap.String("reason", resultReason))
+		}
+		if err != nil {
+			logger.Warn("ValidateFeeToken finished", append(logFields, zap.Error(err))...)
+			return
+		}
+		logger.Info("ValidateFeeToken finished", logFields...)
 	}()
 
+	logger.Debug("ValidateFeeToken request received")
+
 	if req == nil || strings.TrimSpace(req.GetFeeQuoteToken()) == "" {
+		resultReason = "missing_token"
 		err = status.Error(codes.InvalidArgument, "fee_quote_token is required")
 		return nil, err
 	}
@@ -202,21 +301,29 @@ func (s *Service) ValidateFeeToken(ctx context.Context, req *feesv1.ValidateFeeT
 
 	payload, decodeErr := decodeTokenPayload(req.GetFeeQuoteToken())
 	if decodeErr != nil {
-		s.logger.Warn("failed to decode fee quote token", zap.Error(decodeErr))
+		resultReason = "invalid_token"
+		logger.Warn("failed to decode fee quote token", zap.Error(decodeErr))
 		resp = &feesv1.ValidateFeeTokenResponse{Meta: &feesv1.ResponseMeta{}, Valid: false, Reason: "invalid_token"}
 		return resp, nil
 	}
 
-	trigger = payload.Intent.GetTrigger()
+	logger = logger.With(logFieldsFromTokenPayload(&payload)...)
+
+	if payload.Intent != nil {
+		trigger = payload.Intent.GetTrigger()
+	}
 
 	if now.UnixMilli() > payload.ExpiresAtUnixMs {
+		resultReason = "expired"
+		logger.Info("fee quote token expired")
 		resp = &feesv1.ValidateFeeTokenResponse{Meta: &feesv1.ResponseMeta{}, Valid: false, Reason: "expired"}
 		return resp, nil
 	}
 
 	orgRef, parseErr := primitive.ObjectIDFromHex(payload.OrganizationRef)
 	if parseErr != nil {
-		s.logger.Warn("token contained invalid organization reference", zap.Error(parseErr))
+		resultReason = "invalid_token"
+		logger.Warn("token contained invalid organization reference", zap.Error(parseErr))
 		resp = &feesv1.ValidateFeeTokenResponse{Meta: &feesv1.ResponseMeta{}, Valid: false, Reason: "invalid_token"}
 		return resp, nil
 	}
@@ -280,6 +387,16 @@ func (s *Service) computeQuoteWithTime(ctx context.Context, orgRef primitive.Obj
 		bookedAt = intent.GetBookedAt().AsTime()
 	}
 
+	logFields := []zap.Field{
+		zap.Time("booked_at_used", bookedAt),
+	}
+	if !orgRef.IsZero() {
+		logFields = append(logFields, zap.String("organization_ref", orgRef.Hex()))
+	}
+	logFields = append(logFields, logFieldsFromIntent(intent)...)
+	logFields = append(logFields, logFieldsFromTrace(trace)...)
+	logger := s.logger.With(logFields...)
+
 	var orgPtr *primitive.ObjectID
 	if !orgRef.IsZero() {
 		orgPtr = &orgRef
@@ -288,7 +405,7 @@ func (s *Service) computeQuoteWithTime(ctx context.Context, orgRef primitive.Obj
 	plan, rule, err := s.resolver.ResolveFeeRule(ctx, orgPtr, convertTrigger(intent.GetTrigger()), bookedAt, intent.GetAttributes())
 	if err != nil {
 		switch {
-	case errors.Is(err, merrors.ErrNoData):
+		case errors.Is(err, merrors.ErrNoData):
 			return nil, nil, nil, status.Error(codes.NotFound, "fee rule not found")
 		case errors.Is(err, merrors.ErrDataConflict):
 			return nil, nil, nil, status.Error(codes.FailedPrecondition, "conflicting fee rules")
@@ -297,7 +414,7 @@ func (s *Service) computeQuoteWithTime(ctx context.Context, orgRef primitive.Obj
 		case errors.Is(err, storage.ErrFeePlanNotFound):
 			return nil, nil, nil, status.Error(codes.NotFound, "fee plan not found")
 		default:
-			s.logger.Warn("failed to resolve fee rule", zap.Error(err))
+			logger.Warn("failed to resolve fee rule", zap.Error(err))
 			return nil, nil, nil, status.Error(codes.Internal, "failed to resolve fee rule")
 		}
 	}
@@ -313,7 +430,7 @@ func (s *Service) computeQuoteWithTime(ctx context.Context, orgRef primitive.Obj
 		if errors.Is(calcErr, merrors.ErrInvalidArg) {
 			return nil, nil, nil, status.Error(codes.InvalidArgument, calcErr.Error())
 		}
-		s.logger.Warn("failed to compute fee quote", zap.Error(calcErr))
+		logger.Warn("failed to compute fee quote", zap.Error(calcErr))
 		return nil, nil, nil, status.Error(codes.Internal, "failed to compute fee quote")
 	}
 

api/billing/fees/internal/service/fees/service_test.go

@@ -49,7 +49,7 @@ func TestQuoteFees_ComputesDerivedLines(t *testing.T) {
 		},
 	}
 	plan.SetID(primitive.NewObjectID())
-	plan.SetOrganizationRef(orgRef)
+	plan.OrganizationRef = &orgRef
 
 	service := NewService(
 		zap.NewNop(),
@@ -163,7 +163,7 @@ func TestQuoteFees_FiltersByAttributesAndDates(t *testing.T) {
 		},
 	}
 	plan.SetID(primitive.NewObjectID())
-	plan.SetOrganizationRef(orgRef)
+	plan.OrganizationRef = &orgRef
 
 	service := NewService(
 		zap.NewNop(),
@@ -224,7 +224,7 @@ func TestQuoteFees_RoundingDown(t *testing.T) {
 		},
 	}
 	plan.SetID(primitive.NewObjectID())
-	plan.SetOrganizationRef(orgRef)
+	plan.OrganizationRef = &orgRef
 
 	service := NewService(
 		zap.NewNop(),
@@ -277,7 +277,7 @@ func TestQuoteFees_UsesInjectedCalculator(t *testing.T) {
 		},
 	}
 	plan.SetID(primitive.NewObjectID())
-	plan.SetOrganizationRef(orgRef)
+	plan.OrganizationRef = &orgRef
 
 	result := &types.CalculationResult{
 		Lines: []*feesv1.DerivedPostingLine{
@@ -353,7 +353,7 @@ func TestQuoteFees_PopulatesFxUsed(t *testing.T) {
 		},
 	}
 	plan.SetID(primitive.NewObjectID())
-	plan.SetOrganizationRef(orgRef)
+	plan.OrganizationRef = &orgRef
 
 	fakeOracle := &oracleclient.Fake{
 		LatestRateFn: func(ctx context.Context, req oracleclient.LatestRateParams) (*oracleclient.RateSnapshot, error) {
@@ -452,7 +452,7 @@ func (s *stubPlansStore) FindActiveOrgPlan(_ context.Context, orgRef primitive.O
 	if s.plan == nil {
 		return nil, storage.ErrFeePlanNotFound
 	}
-	if s.plan.GetOrganizationRef() != orgRef {
+	if (s.plan.OrganizationRef != nil) && (*s.plan.OrganizationRef != orgRef) {
 		return nil, storage.ErrFeePlanNotFound
 	}
 	if !s.plan.Active {

api/billing/fees/storage/model/plan.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/tech/sendico/pkg/db/storable"
 	"github.com/tech/sendico/pkg/model"
+	"go.mongodb.org/mongo-driver/bson/primitive"
 )
 
 const (
@@ -25,14 +26,14 @@ const (
 
 // FeePlan describes a collection of fee rules for an organisation.
 type FeePlan struct {
-	storable.Base               `bson:",inline" json:",inline"`
-	model.OrganizationBoundBase `bson:",inline" json:",inline"`
-	model.Describable           `bson:",inline" json:",inline"`
-	Active                      bool              `bson:"active"             json:"active"`
-	EffectiveFrom               time.Time         `bson:"effectiveFrom"      json:"effectiveFrom"`
-	EffectiveTo                 *time.Time        `bson:"effectiveTo,omitempty" json:"effectiveTo,omitempty"`
-	Rules                       []FeeRule         `bson:"rules,omitempty"    json:"rules,omitempty"`
-	Metadata                    map[string]string `bson:"metadata,omitempty" json:"metadata,omitempty"`
+	storable.Base     `bson:",inline" json:",inline"`
+	model.Describable `bson:",inline" json:",inline"`
+	OrganizationRef   *primitive.ObjectID `bson:"organizationRef,omitempty" json:"organizationRef,omitempty"`
+	Active            bool                `bson:"active"             json:"active"`
+	EffectiveFrom     time.Time           `bson:"effectiveFrom"      json:"effectiveFrom"`
+	EffectiveTo       *time.Time          `bson:"effectiveTo,omitempty" json:"effectiveTo,omitempty"`
+	Rules             []FeeRule           `bson:"rules,omitempty"    json:"rules,omitempty"`
+	Metadata          map[string]string   `bson:"metadata,omitempty" json:"metadata,omitempty"`
 }
 
 // Collection implements storable.Storable.

api/fx/ingestor/config.yml

@@ -11,12 +11,18 @@ market:
     - driver: CBR
       settings:
         base_url: "https://www.cbr.ru"
+        user_agent: "Mozilla/5.0 (compatible; SendicoFX/1.0; +https://app.sendico.io)"
+        accept_header: "application/xml,text/xml;q=0.9,*/*;q=0.8"
   pairs:
     BINANCE:
       - base: "USDT"
         quote: "EUR"
         symbol: "EURUSDT"
         invert: true
+      - base: "USD"
+        quote: "USDT"
+        symbol: "USDTUSD"
+        invert: true
       - base: "UAH"
         quote: "USDT"
         symbol: "USDTUAH"

api/fx/ingestor/go.mod

@@ -32,7 +32,7 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/montanaflynn/stats v0.7.1 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
-	github.com/nats-io/nats.go v1.47.0 // indirect
+	github.com/nats-io/nats.go v1.48.0 // indirect
 	github.com/nats-io/nkeys v0.4.12 // indirect
 	github.com/nats-io/nuid v1.0.1 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
@@ -49,7 +49,7 @@ require (
 	golang.org/x/sync v0.19.0 // indirect
 	golang.org/x/sys v0.39.0 // indirect
 	golang.org/x/text v0.32.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 // indirect
-	google.golang.org/grpc v1.77.0 // indirect
-	google.golang.org/protobuf v1.36.10 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b // indirect
+	google.golang.org/grpc v1.78.0 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
 )

api/fx/ingestor/go.sum

@@ -95,8 +95,8 @@ github.com/morikuni/aec v1.0.0 h1:nP9CBfwrvYnBRgY6qfDQkygYDmYwOilePFkwzv4dU8A=
 github.com/morikuni/aec v1.0.0/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7PXmsc=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
-github.com/nats-io/nats.go v1.47.0 h1:YQdADw6J/UfGUd2Oy6tn4Hq6YHxCaJrVKayxxFqYrgM=
-github.com/nats-io/nats.go v1.47.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
+github.com/nats-io/nats.go v1.48.0 h1:pSFyXApG+yWU/TgbKCjmm5K4wrHu86231/w84qRVR+U=
+github.com/nats-io/nats.go v1.48.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
 github.com/nats-io/nkeys v0.4.12 h1:nssm7JKOG9/x4J8II47VWCL1Ds29avyiQDRn0ckMvDc=
 github.com/nats-io/nkeys v0.4.12/go.mod h1:MT59A1HYcjIcyQDJStTfaOY6vhy9XTUjOFo+SVsvpBg=
 github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
@@ -212,12 +212,12 @@ golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
 gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 h1:gRkg/vSppuSQoDjxyiGfN4Upv/h/DQmIR10ZU8dh4Ww=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217/go.mod h1:7i2o+ce6H/6BluujYR+kqX3GKH+dChPTQU19wjRPiGk=
-google.golang.org/grpc v1.77.0 h1:wVVY6/8cGA6vvffn+wWK5ToddbgdU3d8MNENr4evgXM=
-google.golang.org/grpc v1.77.0/go.mod h1:z0BY1iVj0q8E1uSQCjL9cppRj+gnZjzDnzV0dHhrNig=
-google.golang.org/protobuf v1.36.10 h1:AYd7cD/uASjIL6Q9LiTjz8JLcrh/88q5UObnmY3aOOE=
-google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b h1:Mv8VFug0MP9e5vUxfBcE3vUkV6CImK3cMNMIDFjmzxU=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b/go.mod h1:j9x/tPzZkyxcgEFkiKEEGxfvyumM01BEtsW8xzOahRQ=
+google.golang.org/grpc v1.78.0 h1:K1XZG/yGDJnzMdd/uZHAkVqJE+xIDOcmdSFZkBUicNc=
+google.golang.org/grpc v1.78.0/go.mod h1:I47qjTo4OKbMkjA/aOOwxDIiPSBofUtQUI5EfpWvW7U=
+google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
+google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

api/fx/ingestor/internal/ingestor/service.go

@@ -85,6 +85,7 @@ func (s *Service) executePoll(ctx context.Context) error {
 
 func (s *Service) pollOnce(ctx context.Context) error {
 	var firstErr error
+	failures := 0
 	for _, pair := range s.pairs {
 		start := time.Now()
 		err := s.upsertPair(ctx, pair)
@@ -96,14 +97,24 @@ func (s *Service) pollOnce(ctx context.Context) error {
 			if firstErr == nil {
 				firstErr = err
 			}
+			failures++
 			s.logger.Warn("Failed to ingest pair",
 				zap.String("symbol", pair.Symbol),
 				zap.String("source", pair.Source.String()),
+				zap.String("provider", pair.Provider),
+				zap.String("base", pair.Base),
+				zap.String("quote", pair.Quote),
+				zap.Bool("invert", pair.Invert),
 				zap.Duration("elapsed", elapsed),
 				zap.Error(err),
 			)
 		}
 	}
+	if failures > 0 {
+		s.logger.Warn("Ingestion poll completed with failures", zap.Int("failures", failures), zap.Int("total", len(s.pairs)))
+	} else {
+		s.logger.Info("Ingestion poll completed", zap.Int("total", len(s.pairs)))
+	}
 	return firstErr
 }
 
@@ -115,7 +126,7 @@ func (s *Service) upsertPair(ctx context.Context, pair config.Pair) error {
 
 	ticker, err := connector.FetchTicker(ctx, pair.Symbol)
 	if err != nil {
-		return merrors.InternalWrap(err, "fetch ticker")
+		return merrors.InternalWrap(err, "fetch ticker: "+pair.Symbol)
 	}
 
 	bid, err := parseDecimal(ticker.BidPrice)
@@ -172,9 +183,14 @@ func (s *Service) upsertPair(ctx context.Context, pair config.Pair) error {
 	s.logger.Debug("Snapshot ingested",
 		zap.String("pair", pair.Base+"/"+pair.Quote),
 		zap.String("provider", pair.Provider),
+		zap.String("source", pair.Source.String()),
+		zap.String("provider_ref", snapshot.ProviderRef),
 		zap.String("bid", snapshot.Bid),
 		zap.String("ask", snapshot.Ask),
 		zap.String("mid", snapshot.Mid),
+		zap.String("spread_bps", snapshot.SpreadBps),
+		zap.Int64("asof_unix_ms", snapshot.AsOfUnixMs),
+		zap.String("rate_ref", snapshot.RateRef),
 	)
 
 	return nil

api/fx/ingestor/internal/market/cbr/connector.go

@@ -23,7 +23,7 @@ import (
 type cbrConnector struct {
 	id            mmodel.Driver
 	provider      string
-	client        *http.Client
+	http          *httpClient
 	base          string
 	dailyPath     string
 	directoryPath string
@@ -60,6 +60,8 @@ func NewConnector(logger mlogger.Logger, settings model.SettingsT) (mmodel.Conne
 	directoryPath := defaultDirectoryPath
 	dailyPath := defaultDailyPath
 	dynamicPath := defaultDynamicPath
+	userAgent := defaultUserAgent
+	acceptHeader := defaultAccept
 
 	if settings != nil {
 		if value, ok := settings["base_url"].(string); ok && strings.TrimSpace(value) != "" {
@@ -77,6 +79,12 @@ func NewConnector(logger mlogger.Logger, settings model.SettingsT) (mmodel.Conne
 		if value, ok := settings["dynamic_path"].(string); ok && strings.TrimSpace(value) != "" {
 			dynamicPath = strings.TrimSpace(value)
 		}
+		if value, ok := settings["user_agent"].(string); ok && strings.TrimSpace(value) != "" {
+			userAgent = strings.TrimSpace(value)
+		}
+		if value, ok := settings["accept_header"].(string); ok && strings.TrimSpace(value) != "" {
+			acceptHeader = strings.TrimSpace(value)
+		}
 		dialTimeout = common.DurationSetting(settings, "dial_timeout_seconds", dialTimeout)
 		dialKeepAlive = common.DurationSetting(settings, "dial_keep_alive_seconds", dialKeepAlive)
 		tlsHandshakeTimeout = common.DurationSetting(settings, "tls_handshake_timeout_seconds", tlsHandshakeTimeout)
@@ -99,13 +107,24 @@ func NewConnector(logger mlogger.Logger, settings model.SettingsT) (mmodel.Conne
 		transport = customTransport
 	}
 
+	client := &http.Client{
+		Timeout:   requestTimeout,
+		Transport: transport,
+	}
+	referer := parsed.String()
+
 	connector := &cbrConnector{
 		id:       mmodel.DriverCBR,
 		provider: provider,
-		client: &http.Client{
-			Timeout:   requestTimeout,
-			Transport: transport,
-		},
+		http: newHTTPClient(
+			logger,
+			client,
+			httpClientOptions{
+				userAgent: userAgent,
+				accept:    acceptHeader,
+				referer:   referer,
+			},
+		),
 		base:          strings.TrimRight(parsed.String(), "/"),
 		dailyPath:     dailyPath,
 		directoryPath: directoryPath,
@@ -161,20 +180,32 @@ func (c *cbrConnector) refreshDirectory() error {
 		return err
 	}
 
-	req, err := http.NewRequest(http.MethodGet, endpoint, nil)
+	req, err := c.http.NewRequest(context.Background(), http.MethodGet, endpoint)
 	if err != nil {
 		return merrors.InternalWrap(err, "cbr: build directory request")
 	}
 
-	resp, err := c.client.Do(req)
+	resp, err := c.http.Do(req)
 	if err != nil {
-		c.logger.Warn("CBR directory request failed", zap.Error(err))
+		c.logger.Warn(
+			"CBR directory request failed",
+			zap.Error(err),
+			zap.String("endpoint", endpoint),
+			zap.String("referer", c.http.headerValue("Referer")),
+			zap.String("user_agent", c.http.headerValue("User-Agent")),
+		)
 		return merrors.InternalWrap(err, "cbr: directory request failed")
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		c.logger.Warn("CBR directory returned non-OK status", zap.Int("status", resp.StatusCode))
+		c.logger.Warn(
+			"CBR directory returned non-OK status",
+			zap.Int("status", resp.StatusCode),
+			zap.String("endpoint", endpoint),
+			zap.String("referer", c.http.headerValue("Referer")),
+			zap.String("user_agent", c.http.headerValue("User-Agent")),
+		)
 		return merrors.Internal("cbr: unexpected status " + strconv.Itoa(resp.StatusCode))
 	}
 
@@ -183,12 +214,13 @@ func (c *cbrConnector) refreshDirectory() error {
 
 	var directory valuteDirectory
 	if err := decoder.Decode(&directory); err != nil {
-		c.logger.Warn("CBR directory decode failed", zap.Error(err))
+		c.logger.Warn("CBR directory decode failed", zap.Error(err), zap.String("endpoint", endpoint))
 		return merrors.InternalWrap(err, "cbr: decode directory")
 	}
 
-	mapping, err := buildValuteMapping(directory.Items)
+	mapping, err := buildValuteMapping(c.logger.Named("mapper"), directory.Items)
 	if err != nil {
+		c.logger.Warn("Failed to build currencies mapping", zap.Error(err), zap.String("endpoint", endpoint))
 		return err
 	}
 
@@ -200,23 +232,32 @@ func (c *cbrConnector) refreshDirectory() error {
 func (c *cbrConnector) fetchDailyRate(ctx context.Context, valute valuteInfo) (string, error) {
 	endpoint, err := c.buildURL(c.dailyPath, nil)
 	if err != nil {
+		c.logger.Warn("Failed to build daily fetch URL", zap.Error(err), zap.String("path", c.dailyPath))
 		return "", err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
+	req, err := c.http.NewRequest(ctx, http.MethodGet, endpoint)
 	if err != nil {
+		c.logger.Warn("Failed to request daily rate", zap.Error(err), zap.String("endpoint", endpoint))
 		return "", merrors.InternalWrap(err, "cbr: build daily request")
 	}
 
-	resp, err := c.client.Do(req)
+	resp, err := c.http.Do(req)
 	if err != nil {
-		c.logger.Warn("CBR daily request failed", zap.String("currency", valute.ISOCharCode), zap.Error(err))
+		c.logger.Warn("CBR daily request failed",
+			zap.Error(err), zap.String("currency", valute.ISOCharCode),
+			zap.String("endpoint", endpoint), zap.String("referer", c.http.headerValue("Referer")),
+			zap.String("user_agent", c.http.headerValue("User-Agent")),
+		)
 		return "", merrors.InternalWrap(err, "cbr: daily request failed")
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		c.logger.Warn("CBR daily returned non-OK status", zap.Int("status", resp.StatusCode))
+		c.logger.Warn(
+			"CBR daily returned non-OK status", zap.Int("status", resp.StatusCode),
+			zap.String("currency", valute.ISOCharCode), zap.String("endpoint", endpoint),
+		)
 		return "", merrors.Internal("cbr: unexpected status " + strconv.Itoa(resp.StatusCode))
 	}
 
@@ -225,7 +266,9 @@ func (c *cbrConnector) fetchDailyRate(ctx context.Context, valute valuteInfo) (s
 
 	var payload dailyRates
 	if err := decoder.Decode(&payload); err != nil {
-		c.logger.Warn("CBR daily decode failed", zap.Error(err))
+		c.logger.Warn("CBR daily decode failed", zap.Error(err),
+			zap.String("currency", valute.ISOCharCode), zap.String("endpoint", endpoint),
+		)
 		return "", merrors.InternalWrap(err, "cbr: decode daily response")
 	}
 
@@ -247,25 +290,40 @@ func (c *cbrConnector) fetchHistoricalRate(ctx context.Context, valute valuteInf
 		"date_req2": date.Format("02/01/2006"),
 		"VAL_NM_RQ": valute.ID,
 	}
+	dateStr := date.Format("2006-01-02")
 	endpoint, err := c.buildURL(c.dynamicPath, query)
 	if err != nil {
 		return "", err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
+	req, err := c.http.NewRequest(ctx, http.MethodGet, endpoint)
 	if err != nil {
 		return "", merrors.InternalWrap(err, "cbr: build historical request")
 	}
 
-	resp, err := c.client.Do(req)
+	resp, err := c.http.Do(req)
 	if err != nil {
-		c.logger.Warn("CBR historical request failed", zap.String("currency", valute.ISOCharCode), zap.Error(err))
+		c.logger.Warn(
+			"CBR historical request failed",
+			zap.String("currency", valute.ISOCharCode),
+			zap.String("date", dateStr),
+			zap.String("endpoint", endpoint),
+			zap.String("referer", c.http.headerValue("Referer")),
+			zap.String("user_agent", c.http.headerValue("User-Agent")),
+			zap.Error(err),
+		)
 		return "", merrors.InternalWrap(err, "cbr: historical request failed")
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		c.logger.Warn("CBR historical returned non-OK status", zap.Int("status", resp.StatusCode))
+		c.logger.Warn(
+			"CBR historical returned non-OK status",
+			zap.Int("status", resp.StatusCode),
+			zap.String("currency", valute.ISOCharCode),
+			zap.String("date", dateStr),
+			zap.String("endpoint", endpoint),
+		)
 		return "", merrors.Internal("cbr: unexpected status " + strconv.Itoa(resp.StatusCode))
 	}
 
@@ -274,7 +332,13 @@ func (c *cbrConnector) fetchHistoricalRate(ctx context.Context, valute valuteInf
 
 	var payload dynamicRates
 	if err := decoder.Decode(&payload); err != nil {
-		c.logger.Warn("CBR historical decode failed", zap.Error(err))
+		c.logger.Warn(
+			"CBR historical decode failed",
+			zap.String("currency", valute.ISOCharCode),
+			zap.String("date", dateStr),
+			zap.String("endpoint", endpoint),
+			zap.Error(err),
+		)
 		return "", merrors.InternalWrap(err, "cbr: decode historical response")
 	}
 
@@ -337,7 +401,7 @@ type valuteMapping struct {
 	byID  map[string]valuteInfo
 }
 
-func buildValuteMapping(items []valuteItem) (*valuteMapping, error) {
+func buildValuteMapping(logger *zap.Logger, items []valuteItem) (*valuteMapping, error) {
 	byISO := make(map[string]valuteInfo, len(items))
 	byID := make(map[string]valuteInfo, len(items))
 	byNum := make(map[string]string, len(items))
@@ -348,12 +412,19 @@ func buildValuteMapping(items []valuteItem) (*valuteMapping, error) {
 		isoNum := strings.TrimSpace(item.ISONum)
 		name := strings.TrimSpace(item.Name)
 		engName := strings.TrimSpace(item.EngName)
+
 		nominal, err := parseNominal(item.NominalStr)
 		if err != nil {
 			return nil, merrors.InvalidDataType("cbr: parse directory nominal: " + err.Error())
 		}
+
 		if id == "" || isoChar == "" {
-			return nil, merrors.InvalidDataType("cbr: directory contains entry with empty id or iso code")
+			logger.Info("Skipping invalid currency entry",
+				zap.String("id", id),
+				zap.String("iso_char", isoChar),
+				zap.String("name", name),
+			)
+			continue
 		}
 
 		info := valuteInfo{
@@ -365,12 +436,76 @@ func buildValuteMapping(items []valuteItem) (*valuteMapping, error) {
 			Nominal:     nominal,
 		}
 
-		if existing, ok := byISO[isoChar]; ok && existing.ID != id {
-			return nil, merrors.InvalidDataType("cbr: duplicate ISO code " + isoChar)
+		// Handle duplicate ISO char codes (e.g. DEM with different IDs / nominals).
+		if existing, ok := byISO[isoChar]; ok {
+			// Same ISO + same ID: duplicate entry, just ignore.
+			if existing.ID == id {
+				logger.Debug("Duplicate directory entry for same ISO and ID, ignoring",
+					zap.String("iso_code", isoChar),
+					zap.String("id", id),
+				)
+				continue
+			}
+
+			// Different IDs but same ISO char.
+			// Choose canonical entry:
+			//  1) Prefer nominal == 1
+			//  2) Otherwise prefer smaller nominal
+			keepExisting := true
+
+			if existing.Nominal != 1 && info.Nominal == 1 {
+				keepExisting = false
+			} else if existing.Nominal == 1 && info.Nominal != 1 {
+				keepExisting = true
+			} else if info.Nominal < existing.Nominal {
+				keepExisting = false
+			}
+
+			if keepExisting {
+				logger.Warn("Ignoring duplicate ISO currency entry with less preferred nominal",
+					zap.String("iso_code", isoChar),
+					zap.String("existing_id", existing.ID),
+					zap.Int64("existing_nominal", existing.Nominal),
+					zap.String("new_id", info.ID),
+					zap.Int64("new_nominal", info.Nominal),
+				)
+				// We keep the old one, just skip the new.
+				continue
+			}
+
+			// Replace existing mapping with the new, more canonical one.
+			logger.Warn("Replacing currency mapping due to more canonical nominal",
+				zap.String("iso_code", isoChar),
+				zap.String("old_id", existing.ID),
+				zap.Int64("old_nominal", existing.Nominal),
+				zap.String("new_id", info.ID),
+				zap.Int64("new_nominal", info.Nominal),
+			)
+
+			// Update byID: drop old ID, add new one
+			delete(byID, existing.ID)
+			byID[id] = info
+
+			// Update ISO mapping
+			byISO[isoChar] = info
+
+			// Update numeric-code index if present
+			if isoNum != "" {
+				if existingID, ok := byNum[isoNum]; ok && existingID != id {
+					return nil, merrors.InvalidDataType("cbr: duplicate ISO numeric code " + isoNum)
+				}
+				byNum[isoNum] = id
+			}
+
+			continue
 		}
+
+		// No existing ISO entry, do normal uniqueness checks.
+
 		if existing, ok := byID[id]; ok && existing.ISOCharCode != isoChar {
 			return nil, merrors.InvalidDataType("cbr: duplicate valute id " + id)
 		}
+
 		if isoNum != "" {
 			if existingID, ok := byNum[isoNum]; ok && existingID != id {
 				return nil, merrors.InvalidDataType("cbr: duplicate ISO numeric code " + isoNum)
@@ -378,6 +513,8 @@ func buildValuteMapping(items []valuteItem) (*valuteMapping, error) {
 			byNum[isoNum] = id
 		}
 
+		logger.Info("Installing currency code", zap.String("iso_code", isoChar), zap.String("id", id), zap.Int64("nominal", nominal))
+
 		byISO[isoChar] = info
 		byID[id] = info
 	}

api/fx/ingestor/internal/market/cbr/http_client.go

@@ -0,0 +1,85 @@
+package cbr
+
+import (
+	"context"
+	"net/http"
+	"strings"
+
+	"go.uber.org/zap"
+)
+
+const (
+	defaultUserAgent = "Mozilla/5.0 (compatible; SendicoFX/1.0; +https://app.sendico.io)"
+	defaultAccept    = "application/xml,text/xml;q=0.9,*/*;q=0.8"
+)
+
+// httpClient wraps http.Client to ensure CBR requests always carry required headers.
+type httpClient struct {
+	client  *http.Client
+	headers http.Header
+	logger  *zap.Logger
+}
+
+type httpClientOptions struct {
+	userAgent string
+	accept    string
+	referer   string
+}
+
+func newHTTPClient(logger *zap.Logger, client *http.Client, opts httpClientOptions) *httpClient {
+	userAgent := opts.userAgent
+	if strings.TrimSpace(userAgent) == "" {
+		userAgent = defaultUserAgent
+	}
+
+	accept := opts.accept
+	if strings.TrimSpace(accept) == "" {
+		accept = defaultAccept
+	}
+
+	referer := opts.referer
+	if strings.TrimSpace(referer) == "" {
+		referer = defaultCBRBaseURL
+	}
+	l := logger.Named("http_client")
+
+	headers := make(http.Header, 3)
+	headers.Set("User-Agent", userAgent)
+	headers.Set("Accept", accept)
+	headers.Set("Referer", referer)
+
+	l.Info("HTTP client initialized", zap.String("user_agent", userAgent),
+		zap.String("accept", accept), zap.String("referrer", referer))
+
+	return &httpClient{
+		client:  client,
+		headers: headers,
+		logger:  l,
+	}
+}
+
+func (h *httpClient) NewRequest(ctx context.Context, method, endpoint string) (*http.Request, error) {
+	return http.NewRequestWithContext(ctx, method, endpoint, nil)
+}
+
+func (h *httpClient) Do(req *http.Request) (*http.Response, error) {
+	enriched := req.Clone(req.Context())
+	for key, values := range h.headers {
+		if enriched.Header.Get(key) != "" {
+			continue
+		}
+		for _, value := range values {
+			enriched.Header.Add(key, value)
+		}
+	}
+	r, err := h.client.Do(enriched)
+	if err != nil {
+		h.logger.Warn("HTTP request failed", zap.Error(err), zap.String("method", req.Method),
+			zap.String("url", req.URL.String()))
+	}
+	return r, err
+}
+
+func (h *httpClient) headerValue(name string) string {
+	return h.headers.Get(name)
+}

api/fx/ingestor/main.go

@@ -40,15 +40,15 @@ func main() {
 
 	application, err := app.New(logger, *configFile)
 	if err != nil {
-		logger.Fatal("Failed to initialise application", zap.Error(err))
-	}
-
-	if err := application.Run(ctx); err != nil {
-		if errors.Is(err, context.Canceled) {
-			logger.Info("FX ingestor stopped")
-			return
+		logger.Error("Failed to initialise application", zap.Error(err))
+	} else {
+		if err := application.Run(ctx); err != nil {
+			if errors.Is(err, context.Canceled) {
+				logger.Info("FX ingestor stopped")
+				return
+			}
+			logger.Error("Ingestor terminated with error", zap.Error(err))
 		}
-		logger.Fatal("Ingestor terminated with error", zap.Error(err))
 	}
 
 	logger.Info("FX ingestor stopped")

api/fx/oracle/go.mod

@@ -13,8 +13,8 @@ require (
 	github.com/tech/sendico/pkg v0.1.0
 	go.mongodb.org/mongo-driver v1.17.6
 	go.uber.org/zap v1.27.1
-	google.golang.org/grpc v1.77.0
-	google.golang.org/protobuf v1.36.10
+	google.golang.org/grpc v1.78.0
+	google.golang.org/protobuf v1.36.11
 	gopkg.in/yaml.v3 v3.0.1
 )
 
@@ -33,7 +33,7 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/montanaflynn/stats v0.7.1 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
-	github.com/nats-io/nats.go v1.47.0 // indirect
+	github.com/nats-io/nats.go v1.48.0 // indirect
 	github.com/nats-io/nkeys v0.4.12 // indirect
 	github.com/nats-io/nuid v1.0.1 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
@@ -50,5 +50,5 @@ require (
 	golang.org/x/sync v0.19.0 // indirect
 	golang.org/x/sys v0.39.0 // indirect
 	golang.org/x/text v0.32.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b // indirect
 )

api/fx/oracle/go.sum

@@ -95,8 +95,8 @@ github.com/morikuni/aec v1.0.0 h1:nP9CBfwrvYnBRgY6qfDQkygYDmYwOilePFkwzv4dU8A=
 github.com/morikuni/aec v1.0.0/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7PXmsc=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
-github.com/nats-io/nats.go v1.47.0 h1:YQdADw6J/UfGUd2Oy6tn4Hq6YHxCaJrVKayxxFqYrgM=
-github.com/nats-io/nats.go v1.47.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
+github.com/nats-io/nats.go v1.48.0 h1:pSFyXApG+yWU/TgbKCjmm5K4wrHu86231/w84qRVR+U=
+github.com/nats-io/nats.go v1.48.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
 github.com/nats-io/nkeys v0.4.12 h1:nssm7JKOG9/x4J8II47VWCL1Ds29avyiQDRn0ckMvDc=
 github.com/nats-io/nkeys v0.4.12/go.mod h1:MT59A1HYcjIcyQDJStTfaOY6vhy9XTUjOFo+SVsvpBg=
 github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
@@ -212,12 +212,12 @@ golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
 gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 h1:gRkg/vSppuSQoDjxyiGfN4Upv/h/DQmIR10ZU8dh4Ww=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217/go.mod h1:7i2o+ce6H/6BluujYR+kqX3GKH+dChPTQU19wjRPiGk=
-google.golang.org/grpc v1.77.0 h1:wVVY6/8cGA6vvffn+wWK5ToddbgdU3d8MNENr4evgXM=
-google.golang.org/grpc v1.77.0/go.mod h1:z0BY1iVj0q8E1uSQCjL9cppRj+gnZjzDnzV0dHhrNig=
-google.golang.org/protobuf v1.36.10 h1:AYd7cD/uASjIL6Q9LiTjz8JLcrh/88q5UObnmY3aOOE=
-google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b h1:Mv8VFug0MP9e5vUxfBcE3vUkV6CImK3cMNMIDFjmzxU=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b/go.mod h1:j9x/tPzZkyxcgEFkiKEEGxfvyumM01BEtsW8xzOahRQ=
+google.golang.org/grpc v1.78.0 h1:K1XZG/yGDJnzMdd/uZHAkVqJE+xIDOcmdSFZkBUicNc=
+google.golang.org/grpc v1.78.0/go.mod h1:I47qjTo4OKbMkjA/aOOwxDIiPSBofUtQUI5EfpWvW7U=
+google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
+google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

api/fx/oracle/internal/service/oracle/logging.go

@@ -0,0 +1,90 @@
+package oracle
+
+import (
+	"strings"
+
+	fxv1 "github.com/tech/sendico/pkg/proto/common/fx/v1"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+	tracev1 "github.com/tech/sendico/pkg/proto/common/trace/v1"
+	oraclev1 "github.com/tech/sendico/pkg/proto/oracle/v1"
+	"go.uber.org/zap"
+)
+
+func quoteRequestFields(req *oraclev1.GetQuoteRequest) []zap.Field {
+	if req == nil {
+		return nil
+	}
+	fields := requestMetaFields(req.GetMeta())
+	if pair := req.GetPair(); pair != nil {
+		if base := strings.TrimSpace(pair.GetBase()); base != "" {
+			fields = append(fields, zap.String("pair_base", base))
+		}
+		if quote := strings.TrimSpace(pair.GetQuote()); quote != "" {
+			fields = append(fields, zap.String("pair_quote", quote))
+		}
+	}
+	if side := req.GetSide(); side != fxv1.Side_SIDE_UNSPECIFIED {
+		fields = append(fields, zap.String("side", side.String()))
+	}
+	if req.GetFirm() {
+		fields = append(fields, zap.Bool("firm", req.GetFirm()))
+	}
+	if ttl := req.GetTtlMs(); ttl > 0 {
+		fields = append(fields, zap.Int64("ttl_ms", ttl))
+	}
+	if maxAge := req.GetMaxAgeMs(); maxAge > 0 {
+		fields = append(fields, zap.Int32("max_age_ms", maxAge))
+	}
+	if provider := strings.TrimSpace(req.GetPreferredProvider()); provider != "" {
+		fields = append(fields, zap.String("preferred_provider", provider))
+	}
+	fields = append(fields, moneyFields("base_amount", req.GetBaseAmount())...)
+	fields = append(fields, moneyFields("quote_amount", req.GetQuoteAmount())...)
+	return fields
+}
+
+func requestMetaFields(meta *oraclev1.RequestMeta) []zap.Field {
+	if meta == nil {
+		return nil
+	}
+	fields := make([]zap.Field, 0, 4)
+	if org := strings.TrimSpace(meta.GetOrganizationRef()); org != "" {
+		fields = append(fields, zap.String("organization_ref", org))
+	}
+	if tenant := strings.TrimSpace(meta.GetTenantRef()); tenant != "" {
+		fields = append(fields, zap.String("tenant_ref", tenant))
+	}
+	fields = append(fields, traceFields(meta.GetTrace())...)
+	return fields
+}
+
+func moneyFields(prefix string, money *moneyv1.Money) []zap.Field {
+	if money == nil {
+		return nil
+	}
+	fields := make([]zap.Field, 0, 2)
+	if amt := strings.TrimSpace(money.GetAmount()); amt != "" {
+		fields = append(fields, zap.String(prefix, amt))
+	}
+	if ccy := strings.TrimSpace(money.GetCurrency()); ccy != "" {
+		fields = append(fields, zap.String(prefix+"_currency", ccy))
+	}
+	return fields
+}
+
+func traceFields(trace *tracev1.TraceContext) []zap.Field {
+	if trace == nil {
+		return nil
+	}
+	fields := make([]zap.Field, 0, 3)
+	if ref := strings.TrimSpace(trace.GetTraceRef()); ref != "" {
+		fields = append(fields, zap.String("trace_ref", ref))
+	}
+	if idem := strings.TrimSpace(trace.GetIdempotencyKey()); idem != "" {
+		fields = append(fields, zap.String("idempotency_key", idem))
+	}
+	if req := strings.TrimSpace(trace.GetRequestRef()); req != "" {
+		fields = append(fields, zap.String("request_ref", req))
+	}
+	return fields
+}

api/fx/oracle/internal/service/oracle/service.go

@@ -101,22 +101,27 @@ func (s *Service) getQuoteResponder(ctx context.Context, req *oraclev1.GetQuoteR
 	if req == nil {
 		req = &oraclev1.GetQuoteRequest{}
 	}
-	s.logger.Debug("Handling GetQuote", zap.String("pair", req.GetPair().GetBase()+"/"+req.GetPair().GetQuote()), zap.Bool("firm", req.GetFirm()))
+	logger := s.logger.With(quoteRequestFields(req)...)
+	logger.Debug("Handling GetQuote")
 	if req.GetSide() == fxv1.Side_SIDE_UNSPECIFIED {
+		logger.Warn("GetQuote invalid: side missing")
 		return gsresponse.InvalidArgument[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, errSideRequired)
 	}
 	if req.GetBaseAmount() != nil && req.GetQuoteAmount() != nil {
+		logger.Warn("GetQuote invalid: both base_amount and quote_amount provided")
 		return gsresponse.InvalidArgument[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, errAmountsMutuallyExclusive)
 	}
 	if req.GetBaseAmount() == nil && req.GetQuoteAmount() == nil {
+		logger.Warn("GetQuote invalid: amount missing")
 		return gsresponse.InvalidArgument[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, errAmountRequired)
 	}
 	if err := s.pingStorage(ctx); err != nil {
-		s.logger.Warn("Storage unavailable during GetQuote", zap.Error(err))
+		logger.Warn("Storage unavailable during GetQuote", zap.Error(err))
 		return gsresponse.Unavailable[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, err)
 	}
 	pairMsg := req.GetPair()
 	if pairMsg == nil || strings.TrimSpace(pairMsg.GetBase()) == "" || strings.TrimSpace(pairMsg.GetQuote()) == "" {
+		logger.Warn("GetQuote invalid: pair missing")
 		return gsresponse.InvalidArgument[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, errEmptyRequest)
 	}
 	pairKey := model.CurrencyPair{Base: strings.ToUpper(pairMsg.GetBase()), Quote: strings.ToUpper(pairMsg.GetQuote())}
@@ -125,8 +130,10 @@ func (s *Service) getQuoteResponder(ctx context.Context, req *oraclev1.GetQuoteR
 	if err != nil {
 		switch {
 		case errors.Is(err, merrors.ErrNoData):
+			logger.Warn("Pair not supported", zap.String("pair", pairKey.Base+"/"+pairKey.Quote))
 			return gsresponse.InvalidArgument[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, merrors.InvalidArgument("pair_not_supported"))
 		default:
+			logger.Warn("GetQuote failed to load pair", zap.Error(err))
 			return gsresponse.Internal[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, err)
 		}
 	}
@@ -143,8 +150,10 @@ func (s *Service) getQuoteResponder(ctx context.Context, req *oraclev1.GetQuoteR
 	if err != nil {
 		switch {
 		case errors.Is(err, merrors.ErrNoData):
+			logger.Warn("Rate not found", zap.String("pair", pairKey.Base+"/"+pairKey.Quote), zap.String("provider", provider))
 			return gsresponse.FailedPrecondition[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, "rate_not_found", err)
 		default:
+			logger.Warn("GetQuote failed to load rate", zap.Error(err), zap.String("pair", pairKey.Base+"/"+pairKey.Quote), zap.String("provider", provider))
 			return gsresponse.Internal[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, err)
 		}
 	}
@@ -153,27 +162,31 @@ func (s *Service) getQuoteResponder(ctx context.Context, req *oraclev1.GetQuoteR
 	if maxAge := req.GetMaxAgeMs(); maxAge > 0 {
 		age := now.UnixMilli() - rate.AsOfUnixMs
 		if age > int64(maxAge) {
-			s.logger.Warn("Rate snapshot stale", zap.Int64("age_ms", age), zap.Int32("max_age_ms", req.GetMaxAgeMs()), zap.String("pair", pairKey.Base+"/"+pairKey.Quote), zap.String("provider", provider))
+			logger.Warn("Rate snapshot stale", zap.Int64("age_ms", age), zap.Int32("max_age_ms", req.GetMaxAgeMs()), zap.String("pair", pairKey.Base+"/"+pairKey.Quote), zap.String("provider", provider))
 			return gsresponse.FailedPrecondition[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, "stale_rate", merrors.InvalidArgument("rate older than allowed window"))
 		}
 	}
 
 	comp, err := newQuoteComputation(pair, rate, req.GetSide(), provider)
 	if err != nil {
+		logger.Warn("GetQuote invalid input", zap.Error(err))
 		return gsresponse.InvalidArgument[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, err)
 	}
 
 	if req.GetBaseAmount() != nil {
 		if err := comp.withBaseInput(req.GetBaseAmount()); err != nil {
+			logger.Warn("GetQuote invalid base input", zap.Error(err))
 			return gsresponse.InvalidArgument[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, err)
 		}
 	} else if req.GetQuoteAmount() != nil {
 		if err := comp.withQuoteInput(req.GetQuoteAmount()); err != nil {
+			logger.Warn("GetQuote invalid quote input", zap.Error(err))
 			return gsresponse.InvalidArgument[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, err)
 		}
 	}
 
 	if err := comp.compute(); err != nil {
+		logger.Warn("GetQuote computation failed", zap.Error(err))
 		return gsresponse.Internal[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, err)
 	}
 
@@ -195,12 +208,14 @@ func (s *Service) getQuoteResponder(ctx context.Context, req *oraclev1.GetQuoteR
 		if err := s.storage.Quotes().Issue(ctx, quoteModel); err != nil {
 			switch {
 			case errors.Is(err, merrors.ErrDataConflict):
+				logger.Warn("GetQuote conflict issuing firm quote", zap.Error(err), zap.String("quote_ref", quoteModel.QuoteRef))
 				return gsresponse.Conflict[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, err)
 			default:
+				logger.Warn("GetQuote failed to issue firm quote", zap.Error(err), zap.String("quote_ref", quoteModel.QuoteRef))
 				return gsresponse.Internal[oraclev1.GetQuoteResponse](s.logger, mservice.FXOracle, err)
 			}
 		}
-		s.logger.Info("Firm quote stored", zap.String("quote_ref", quoteModel.QuoteRef), zap.String("pair", pairKey.Base+"/"+pairKey.Quote), zap.String("provider", quoteModel.Provider), zap.Int64("expires_at_ms", quoteModel.ExpiresAtUnixMs))
+		logger.Info("Firm quote stored", zap.String("quote_ref", quoteModel.QuoteRef), zap.String("pair", pairKey.Base+"/"+pairKey.Quote), zap.String("provider", quoteModel.Provider), zap.Int64("expires_at_ms", quoteModel.ExpiresAtUnixMs))
 	}
 
 	resp := &oraclev1.GetQuoteResponse{
@@ -214,18 +229,24 @@ func (s *Service) validateQuoteResponder(ctx context.Context, req *oraclev1.Vali
 	if req == nil {
 		req = &oraclev1.ValidateQuoteRequest{}
 	}
-	s.logger.Debug("Handling ValidateQuote", zap.String("quote_ref", req.GetQuoteRef()))
+	logger := s.logger.With(requestMetaFields(req.GetMeta())...)
+	if ref := strings.TrimSpace(req.GetQuoteRef()); ref != "" {
+		logger = logger.With(zap.String("quote_ref", ref))
+	}
+	logger.Debug("Handling ValidateQuote")
 	if req.GetQuoteRef() == "" {
+		logger.Warn("ValidateQuote invalid: quote_ref missing")
 		return gsresponse.InvalidArgument[oraclev1.ValidateQuoteResponse](s.logger, mservice.FXOracle, errQuoteRefRequired)
 	}
 	if err := s.pingStorage(ctx); err != nil {
-		s.logger.Warn("Storage unavailable during ValidateQuote", zap.Error(err))
+		logger.Warn("Storage unavailable during ValidateQuote", zap.Error(err))
 		return gsresponse.Unavailable[oraclev1.ValidateQuoteResponse](s.logger, mservice.FXOracle, err)
 	}
 	quote, err := s.storage.Quotes().GetByRef(ctx, req.GetQuoteRef())
 	if err != nil {
 		switch {
 		case errors.Is(err, merrors.ErrNoData):
+			logger.Warn("ValidateQuote: quote not found", zap.String("quote_ref", req.GetQuoteRef()))
 			resp := &oraclev1.ValidateQuoteResponse{
 				Meta:   buildResponseMeta(req.GetMeta()),
 				Quote:  nil,
@@ -234,6 +255,7 @@ func (s *Service) validateQuoteResponder(ctx context.Context, req *oraclev1.Vali
 			}
 			return gsresponse.Success(resp)
 		default:
+			logger.Warn("ValidateQuote failed", zap.Error(err))
 			return gsresponse.Internal[oraclev1.ValidateQuoteResponse](s.logger, mservice.FXOracle, err)
 		}
 	}
@@ -255,6 +277,11 @@ func (s *Service) validateQuoteResponder(ctx context.Context, req *oraclev1.Vali
 		Valid:  valid,
 		Reason: reason,
 	}
+	if !valid {
+		logger.Info("ValidateQuote invalid", zap.String("reason", reason), zap.Bool("firm", quote.Firm))
+	} else {
+		logger.Debug("ValidateQuote valid", zap.Bool("firm", quote.Firm))
+	}
 	return gsresponse.Success(resp)
 }
 
@@ -262,29 +289,43 @@ func (s *Service) consumeQuoteResponder(ctx context.Context, req *oraclev1.Consu
 	if req == nil {
 		req = &oraclev1.ConsumeQuoteRequest{}
 	}
-	s.logger.Debug("Handling ConsumeQuote", zap.String("quote_ref", req.GetQuoteRef()), zap.String("ledger_txn_ref", req.GetLedgerTxnRef()))
+	logger := s.logger.With(requestMetaFields(req.GetMeta())...)
+	if ref := strings.TrimSpace(req.GetQuoteRef()); ref != "" {
+		logger = logger.With(zap.String("quote_ref", ref))
+	}
+	if ledger := strings.TrimSpace(req.GetLedgerTxnRef()); ledger != "" {
+		logger = logger.With(zap.String("ledger_txn_ref", ledger))
+	}
+	logger.Debug("Handling ConsumeQuote")
 	if req.GetQuoteRef() == "" {
+		logger.Warn("ConsumeQuote invalid: quote_ref missing")
 		return gsresponse.InvalidArgument[oraclev1.ConsumeQuoteResponse](s.logger, mservice.FXOracle, errQuoteRefRequired)
 	}
 	if req.GetLedgerTxnRef() == "" {
+		logger.Warn("ConsumeQuote invalid: ledger_txn_ref missing")
 		return gsresponse.InvalidArgument[oraclev1.ConsumeQuoteResponse](s.logger, mservice.FXOracle, errLedgerTxnRefRequired)
 	}
 	if err := s.pingStorage(ctx); err != nil {
-		s.logger.Warn("Storage unavailable during ConsumeQuote", zap.Error(err))
+		logger.Warn("Storage unavailable during ConsumeQuote", zap.Error(err))
 		return gsresponse.Unavailable[oraclev1.ConsumeQuoteResponse](s.logger, mservice.FXOracle, err)
 	}
 	_, err := s.storage.Quotes().Consume(ctx, req.GetQuoteRef(), req.GetLedgerTxnRef(), time.Now())
 	if err != nil {
 		switch {
 		case errors.Is(err, storage.ErrQuoteExpired):
+			logger.Warn("ConsumeQuote failed: expired")
 			return gsresponse.FailedPrecondition[oraclev1.ConsumeQuoteResponse](s.logger, mservice.FXOracle, "expired", err)
 		case errors.Is(err, storage.ErrQuoteConsumed):
+			logger.Warn("ConsumeQuote failed: already consumed")
 			return gsresponse.FailedPrecondition[oraclev1.ConsumeQuoteResponse](s.logger, mservice.FXOracle, "consumed", err)
 		case errors.Is(err, storage.ErrQuoteNotFirm):
+			logger.Warn("ConsumeQuote failed: quote not firm")
 			return gsresponse.FailedPrecondition[oraclev1.ConsumeQuoteResponse](s.logger, mservice.FXOracle, "not_firm", err)
 		case errors.Is(err, merrors.ErrNoData):
+			logger.Warn("ConsumeQuote failed: quote not found")
 			return gsresponse.NotFound[oraclev1.ConsumeQuoteResponse](s.logger, mservice.FXOracle, err)
 		default:
+			logger.Warn("ConsumeQuote failed", zap.Error(err))
 			return gsresponse.Internal[oraclev1.ConsumeQuoteResponse](s.logger, mservice.FXOracle, err)
 		}
 	}
@@ -294,7 +335,7 @@ func (s *Service) consumeQuoteResponder(ctx context.Context, req *oraclev1.Consu
 		Consumed: true,
 		Reason:   "consumed",
 	}
-	s.logger.Debug("Quote consumed", zap.String("quote_ref", req.GetQuoteRef()), zap.String("ledger_txn_ref", req.GetLedgerTxnRef()))
+	logger.Info("Quote consumed")
 	return gsresponse.Success(resp)
 }
 
@@ -302,13 +343,21 @@ func (s *Service) latestRateResponder(ctx context.Context, req *oraclev1.LatestR
 	if req == nil {
 		req = &oraclev1.LatestRateRequest{}
 	}
-	s.logger.Debug("Handling LatestRate", zap.String("pair", req.GetPair().GetBase()+"/"+req.GetPair().GetQuote()))
+	logger := s.logger.With(requestMetaFields(req.GetMeta())...)
+	if pair := req.GetPair(); pair != nil {
+		logger = logger.With(zap.String("pair_base", strings.TrimSpace(pair.GetBase())), zap.String("pair_quote", strings.TrimSpace(pair.GetQuote())))
+	}
+	if provider := strings.TrimSpace(req.GetProvider()); provider != "" {
+		logger = logger.With(zap.String("provider", provider))
+	}
+	logger.Debug("Handling LatestRate")
 	if err := s.pingStorage(ctx); err != nil {
-		s.logger.Warn("Storage unavailable during LatestRate", zap.Error(err))
+		logger.Warn("Storage unavailable during LatestRate", zap.Error(err))
 		return gsresponse.Unavailable[oraclev1.LatestRateResponse](s.logger, mservice.FXOracle, err)
 	}
 	pairMsg := req.GetPair()
 	if pairMsg == nil || strings.TrimSpace(pairMsg.GetBase()) == "" || strings.TrimSpace(pairMsg.GetQuote()) == "" {
+		logger.Warn("LatestRate invalid: pair missing")
 		return gsresponse.InvalidArgument[oraclev1.LatestRateResponse](s.logger, mservice.FXOracle, errEmptyRequest)
 	}
 	pair := model.CurrencyPair{Base: strings.ToUpper(pairMsg.GetBase()), Quote: strings.ToUpper(pairMsg.GetQuote())}
@@ -317,8 +366,10 @@ func (s *Service) latestRateResponder(ctx context.Context, req *oraclev1.LatestR
 	if err != nil {
 		switch {
 		case errors.Is(err, merrors.ErrNoData):
+			logger.Warn("LatestRate pair not found")
 			return gsresponse.NotFound[oraclev1.LatestRateResponse](s.logger, mservice.FXOracle, err)
 		default:
+			logger.Warn("LatestRate failed to load pair", zap.Error(err))
 			return gsresponse.Internal[oraclev1.LatestRateResponse](s.logger, mservice.FXOracle, err)
 		}
 	}
@@ -335,8 +386,10 @@ func (s *Service) latestRateResponder(ctx context.Context, req *oraclev1.LatestR
 	if err != nil {
 		switch {
 		case errors.Is(err, merrors.ErrNoData):
+			logger.Warn("LatestRate not found", zap.String("provider", provider))
 			return gsresponse.NotFound[oraclev1.LatestRateResponse](s.logger, mservice.FXOracle, err)
 		default:
+			logger.Warn("LatestRate failed", zap.Error(err))
 			return gsresponse.Internal[oraclev1.LatestRateResponse](s.logger, mservice.FXOracle, err)
 		}
 	}
@@ -345,6 +398,7 @@ func (s *Service) latestRateResponder(ctx context.Context, req *oraclev1.LatestR
 		Meta: buildResponseMeta(req.GetMeta()),
 		Rate: rateModelToProto(rate),
 	}
+	logger.Debug("LatestRate succeeded", zap.String("provider", provider), zap.Int64("asof_unix_ms", rate.AsOfUnixMs))
 	return gsresponse.Success(resp)
 }
 
@@ -352,13 +406,15 @@ func (s *Service) listPairsResponder(ctx context.Context, req *oraclev1.ListPair
 	if req == nil {
 		req = &oraclev1.ListPairsRequest{}
 	}
-	s.logger.Debug("Handling ListPairs")
+	logger := s.logger.With(requestMetaFields(req.GetMeta())...)
+	logger.Debug("Handling ListPairs")
 	if err := s.pingStorage(ctx); err != nil {
-		s.logger.Warn("Storage unavailable during ListPairs", zap.Error(err))
+		logger.Warn("Storage unavailable during ListPairs", zap.Error(err))
 		return gsresponse.Unavailable[oraclev1.ListPairsResponse](s.logger, mservice.FXOracle, err)
 	}
 	pairs, err := s.storage.Pairs().ListEnabled(ctx)
 	if err != nil {
+		logger.Warn("ListPairs failed", zap.Error(err))
 		return gsresponse.Internal[oraclev1.ListPairsResponse](s.logger, mservice.FXOracle, err)
 	}
 	result := make([]*oraclev1.PairMeta, 0, len(pairs))
@@ -369,7 +425,7 @@ func (s *Service) listPairsResponder(ctx context.Context, req *oraclev1.ListPair
 		Meta:  buildResponseMeta(req.GetMeta()),
 		Pairs: result,
 	}
-	s.logger.Debug("ListPairs returning metadata", zap.Int("pairs", len(resp.GetPairs())))
+	logger.Debug("ListPairs returning metadata", zap.Int("pairs", len(resp.GetPairs())))
 	return gsresponse.Success(resp)
 }
 

api/fx/storage/go.mod

@@ -28,5 +28,5 @@ require (
 	golang.org/x/crypto v0.46.0 // indirect
 	golang.org/x/sync v0.19.0 // indirect
 	golang.org/x/text v0.32.0 // indirect
-	google.golang.org/protobuf v1.36.10 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
 )

api/fx/storage/go.sum

@@ -169,7 +169,7 @@ golang.org/x/tools v0.0.0-20190425150028-36563e24a262/go.mod h1:RgjU9mgBXZiqYHBn
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-google.golang.org/protobuf v1.36.10 h1:AYd7cD/uASjIL6Q9LiTjz8JLcrh/88q5UObnmY3aOOE=
-google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
+google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
+google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

api/fx/storage/mongo/repository.go

@@ -50,28 +50,28 @@ func New(logger mlogger.Logger, conn *db.MongoConnection) (*Store, error) {
 	defer cancel()
 
 	if err := s.Ping(ctx); err != nil {
-		s.logger.Error("mongo ping failed during store init", zap.Error(err))
+		s.logger.Error("Mongo ping failed during store init", zap.Error(err))
 		return nil, err
 	}
 
 	ratesStore, err := store.NewRates(s.logger, db)
 	if err != nil {
-		s.logger.Error("failed to initialize rates store", zap.Error(err))
+		s.logger.Error("Failed to initialize rates store", zap.Error(err))
 		return nil, err
 	}
 	quotesStore, err := store.NewQuotes(s.logger, db, txFactory)
 	if err != nil {
-		s.logger.Error("failed to initialize quotes store", zap.Error(err))
+		s.logger.Error("Failed to initialize quotes store", zap.Error(err))
 		return nil, err
 	}
 	pairsStore, err := store.NewPair(s.logger, db)
 	if err != nil {
-		s.logger.Error("failed to initialize pair store", zap.Error(err))
+		s.logger.Error("Failed to initialize pair store", zap.Error(err))
 		return nil, err
 	}
 	currencyStore, err := store.NewCurrency(s.logger, db)
 	if err != nil {
-		s.logger.Error("failed to initialize currency store", zap.Error(err))
+		s.logger.Error("Failed to initialize currency store", zap.Error(err))
 		return nil, err
 	}
 
@@ -80,7 +80,7 @@ func New(logger mlogger.Logger, conn *db.MongoConnection) (*Store, error) {
 	s.pairs = pairsStore
 	s.currencies = currencyStore
 
-	s.logger.Info("mongo storage ready")
+	s.logger.Info("Mongo storage ready")
 	return s, nil
 }
 

api/fx/storage/mongo/store/currency.go

@@ -29,11 +29,11 @@ func NewCurrency(logger mlogger.Logger, db *mongo.Database) (storage.CurrencySto
 		Unique: true,
 	}
 	if err := repo.CreateIndex(index); err != nil {
-		logger.Error("failed to ensure currencies index", zap.Error(err))
+		logger.Error("Failed to ensure currencies index", zap.Error(err))
 		return nil, err
 	}
 	childLogger := logger.Named(model.CurrenciesCollection)
-	childLogger.Debug("currency store initialised", zap.String("collection", model.CurrenciesCollection))
+	childLogger.Debug("Currency store initialised", zap.String("collection", model.CurrenciesCollection))
 
 	return &currencyStore{
 		logger: childLogger,
@@ -43,17 +43,17 @@ func NewCurrency(logger mlogger.Logger, db *mongo.Database) (storage.CurrencySto
 
 func (c *currencyStore) Get(ctx context.Context, code string) (*model.Currency, error) {
 	if code == "" {
-		c.logger.Warn("attempt to fetch currency with empty code")
+		c.logger.Warn("Attempt to fetch currency with empty code")
 		return nil, merrors.InvalidArgument("currencyStore: empty code")
 	}
 	result := &model.Currency{}
 	if err := c.repo.FindOneByFilter(ctx, repository.Filter("code", code), result); err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			c.logger.Debug("currency not found", zap.String("code", code))
+			c.logger.Debug("Currency not found", zap.String("code", code))
 		}
 		return nil, err
 	}
-	c.logger.Debug("currency loaded", zap.String("code", code))
+	c.logger.Debug("Currency loaded", zap.String("code", code))
 	return result, nil
 }
 
@@ -77,20 +77,20 @@ func (c *currencyStore) List(ctx context.Context, codes ...string) ([]*model.Cur
 		return nil
 	})
 	if err != nil {
-		c.logger.Error("failed to list currencies", zap.Error(err))
+		c.logger.Warn("Failed to list currencies", zap.Error(err))
 		return nil, err
 	}
-	c.logger.Debug("listed currencies", zap.Int("count", len(currencies)))
+	c.logger.Debug("Listed currencies", zap.Int("count", len(currencies)))
 	return currencies, nil
 }
 
 func (c *currencyStore) Upsert(ctx context.Context, currency *model.Currency) error {
 	if currency == nil {
-		c.logger.Warn("attempt to upsert nil currency")
+		c.logger.Warn("Attempt to upsert nil currency")
 		return merrors.InvalidArgument("currencyStore: nil currency")
 	}
 	if currency.Code == "" {
-		c.logger.Warn("attempt to upsert currency with empty code")
+		c.logger.Warn("Attempt to upsert currency with empty code")
 		return merrors.InvalidArgument("currencyStore: empty code")
 	}
 
@@ -98,16 +98,16 @@ func (c *currencyStore) Upsert(ctx context.Context, currency *model.Currency) er
 	filter := repository.Filter("code", currency.Code)
 	if err := c.repo.FindOneByFilter(ctx, filter, existing); err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			c.logger.Debug("inserting new currency", zap.String("code", currency.Code))
+			c.logger.Debug("Inserting new currency", zap.String("code", currency.Code))
 			return c.repo.Insert(ctx, currency, filter)
 		}
-		c.logger.Error("failed to fetch currency", zap.Error(err), zap.String("code", currency.Code))
+		c.logger.Warn("Failed to fetch currency", zap.Error(err), zap.String("code", currency.Code))
 		return err
 	}
 
 	if existing.GetID() != nil {
 		currency.SetID(*existing.GetID())
 	}
-	c.logger.Debug("updating currency", zap.String("code", currency.Code))
+	c.logger.Debug("Updating currency", zap.String("code", currency.Code))
 	return c.repo.Update(ctx, currency)
 }

api/fx/storage/mongo/store/pair.go

@@ -29,10 +29,10 @@ func NewPair(logger mlogger.Logger, db *mongo.Database) (storage.PairStore, erro
 		Unique: true,
 	}
 	if err := repo.CreateIndex(index); err != nil {
-		logger.Error("failed to ensure pairs index", zap.Error(err))
+		logger.Error("Failed to ensure pairs index", zap.Error(err))
 		return nil, err
 	}
-	logger.Debug("pair store initialised", zap.String("collection", model.PairsCollection))
+	logger.Debug("Pair store initialised", zap.String("collection", model.PairsCollection))
 
 	return &pairStore{
 		logger: logger.Named(model.PairsCollection),
@@ -53,16 +53,16 @@ func (p *pairStore) ListEnabled(ctx context.Context) ([]*model.Pair, error) {
 		return nil
 	})
 	if err != nil {
-		p.logger.Error("failed to list enabled pairs", zap.Error(err))
+		p.logger.Warn("Failed to list enabled pairs", zap.Error(err))
 		return nil, err
 	}
-	p.logger.Debug("listed enabled pairs", zap.Int("count", len(pairs)))
+	p.logger.Debug("Listed enabled pairs", zap.Int("count", len(pairs)))
 	return pairs, nil
 }
 
 func (p *pairStore) Get(ctx context.Context, pair model.CurrencyPair) (*model.Pair, error) {
 	if pair.Base == "" || pair.Quote == "" {
-		p.logger.Warn("attempt to fetch pair with empty currency", zap.String("base", pair.Base), zap.String("quote", pair.Quote))
+		p.logger.Warn("Attempt to fetch pair with empty currency", zap.String("base", pair.Base), zap.String("quote", pair.Quote))
 		return nil, merrors.InvalidArgument("pairStore: incomplete pair")
 	}
 	result := &model.Pair{}
@@ -71,21 +71,21 @@ func (p *pairStore) Get(ctx context.Context, pair model.CurrencyPair) (*model.Pa
 		Filter(repository.Field("pair").Dot("quote"), pair.Quote)
 	if err := p.repo.FindOneByFilter(ctx, query, result); err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			p.logger.Debug("pair not found", zap.String("base", pair.Base), zap.String("quote", pair.Quote))
+			p.logger.Debug("Pair not found", zap.String("base", pair.Base), zap.String("quote", pair.Quote))
 		}
 		return nil, err
 	}
-	p.logger.Debug("pair loaded", zap.String("base", pair.Base), zap.String("quote", pair.Quote))
+	p.logger.Debug("Pair loaded", zap.String("base", pair.Base), zap.String("quote", pair.Quote))
 	return result, nil
 }
 
 func (p *pairStore) Upsert(ctx context.Context, pair *model.Pair) error {
 	if pair == nil {
-		p.logger.Warn("attempt to upsert nil pair")
+		p.logger.Warn("Attempt to upsert nil pair")
 		return merrors.InvalidArgument("pairStore: nil pair")
 	}
 	if pair.Pair.Base == "" || pair.Pair.Quote == "" {
-		p.logger.Warn("attempt to upsert pair with empty currency", zap.String("base", pair.Pair.Base), zap.String("quote", pair.Pair.Quote))
+		p.logger.Warn("Attempt to upsert pair with empty currency", zap.String("base", pair.Pair.Base), zap.String("quote", pair.Pair.Quote))
 		return merrors.InvalidArgument("pairStore: incomplete pair")
 	}
 
@@ -96,16 +96,16 @@ func (p *pairStore) Upsert(ctx context.Context, pair *model.Pair) error {
 	err := p.repo.FindOneByFilter(ctx, query, existing)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			p.logger.Debug("inserting new pair", zap.String("base", pair.Pair.Base), zap.String("quote", pair.Pair.Quote))
+			p.logger.Debug("Inserting new pair", zap.String("base", pair.Pair.Base), zap.String("quote", pair.Pair.Quote))
 			return p.repo.Insert(ctx, pair, query)
 		}
-		p.logger.Error("failed to fetch pair", zap.Error(err), zap.String("base", pair.Pair.Base), zap.String("quote", pair.Pair.Quote))
+		p.logger.Warn("Failed to fetch pair", zap.Error(err), zap.String("base", pair.Pair.Base), zap.String("quote", pair.Pair.Quote))
 		return err
 	}
 
 	if existing.GetID() != nil {
 		pair.SetID(*existing.GetID())
 	}
-	p.logger.Debug("updating pair", zap.String("base", pair.Pair.Base), zap.String("quote", pair.Pair.Quote))
+	p.logger.Debug("Updating pair", zap.String("base", pair.Pair.Base), zap.String("quote", pair.Pair.Quote))
 	return p.repo.Update(ctx, pair)
 }

api/fx/storage/mongo/store/quotes.go

@@ -56,12 +56,12 @@ func NewQuotes(logger mlogger.Logger, db *mongo.Database, txFactory transaction.
 
 	for _, def := range indexes {
 		if err := repo.CreateIndex(def); err != nil {
-			logger.Error("failed to ensure quotes index", zap.Error(err))
+			logger.Error("Failed to ensure quotes index", zap.Error(err))
 			return nil, err
 		}
 	}
 	childLogger := logger.Named(model.QuotesCollection)
-	childLogger.Debug("quotes store initialised", zap.String("collection", model.QuotesCollection))
+	childLogger.Debug("Quotes store initialised", zap.String("collection", model.QuotesCollection))
 
 	return &quotesStore{
 		logger:    childLogger,
@@ -72,11 +72,11 @@ func NewQuotes(logger mlogger.Logger, db *mongo.Database, txFactory transaction.
 
 func (q *quotesStore) Issue(ctx context.Context, quote *model.Quote) error {
 	if quote == nil {
-		q.logger.Warn("attempt to issue nil quote")
+		q.logger.Warn("Attempt to issue nil quote")
 		return merrors.InvalidArgument("quotesStore: nil quote")
 	}
 	if quote.QuoteRef == "" {
-		q.logger.Warn("attempt to issue quote with empty ref")
+		q.logger.Warn("Attempt to issue quote with empty ref")
 		return merrors.InvalidArgument("quotesStore: empty quoteRef")
 	}
 
@@ -89,32 +89,32 @@ func (q *quotesStore) Issue(ctx context.Context, quote *model.Quote) error {
 	quote.ConsumedByLedgerTxnRef = ""
 	quote.ConsumedAtUnixMs = nil
 	if err := q.repo.Insert(ctx, quote, repository.Filter("quoteRef", quote.QuoteRef)); err != nil {
-		q.logger.Error("failed to insert quote", zap.Error(err), zap.String("quote_ref", quote.QuoteRef))
+		q.logger.Warn("Failed to insert quote", zap.Error(err), zap.String("quote_ref", quote.QuoteRef))
 		return err
 	}
-	q.logger.Debug("quote issued", zap.String("quote_ref", quote.QuoteRef), zap.Bool("firm", quote.Firm))
+	q.logger.Debug("Quote issued", zap.String("quote_ref", quote.QuoteRef), zap.Bool("firm", quote.Firm))
 	return nil
 }
 
 func (q *quotesStore) GetByRef(ctx context.Context, quoteRef string) (*model.Quote, error) {
 	if quoteRef == "" {
-		q.logger.Warn("attempt to fetch quote with empty ref")
+		q.logger.Warn("Attempt to fetch quote with empty ref")
 		return nil, merrors.InvalidArgument("quotesStore: empty quoteRef")
 	}
 	quote := &model.Quote{}
 	if err := q.repo.FindOneByFilter(ctx, repository.Filter("quoteRef", quoteRef), quote); err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			q.logger.Debug("quote not found", zap.String("quote_ref", quoteRef))
+			q.logger.Debug("Quote not found", zap.String("quote_ref", quoteRef))
 		}
 		return nil, err
 	}
-	q.logger.Debug("quote loaded", zap.String("quote_ref", quoteRef), zap.String("status", string(quote.Status)))
+	q.logger.Debug("Quote loaded", zap.String("quote_ref", quoteRef), zap.String("status", string(quote.Status)))
 	return quote, nil
 }
 
 func (q *quotesStore) Consume(ctx context.Context, quoteRef, ledgerTxnRef string, when time.Time) (*model.Quote, error) {
 	if quoteRef == "" || ledgerTxnRef == "" {
-		q.logger.Warn("attempt to consume quote with missing identifiers", zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
+		q.logger.Warn("Attempt to consume quote with missing identifiers", zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
 		return nil, merrors.InvalidArgument("quotesStore: missing identifiers")
 	}
 
@@ -122,7 +122,7 @@ func (q *quotesStore) Consume(ctx context.Context, quoteRef, ledgerTxnRef string
 		when = time.Now()
 	}
 
-	q.logger.Debug("consuming quote", zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
+	q.logger.Debug("Consuming quote", zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
 	txn := q.txFactory.CreateTransaction()
 	result, err := txn.Execute(ctx, func(txCtx context.Context) (any, error) {
 		quote := &model.Quote{}
@@ -131,7 +131,7 @@ func (q *quotesStore) Consume(ctx context.Context, quoteRef, ledgerTxnRef string
 		}
 
 		if !quote.Firm {
-			q.logger.Warn("quote not firm", zap.String("quote_ref", quoteRef))
+			q.logger.Warn("Quote not firm", zap.String("quote_ref", quoteRef))
 			return nil, storage.ErrQuoteNotFirm
 		}
 
@@ -140,16 +140,16 @@ func (q *quotesStore) Consume(ctx context.Context, quoteRef, ledgerTxnRef string
 			if err := q.repo.Update(txCtx, quote); err != nil {
 				return nil, err
 			}
-			q.logger.Info("quote expired during consume", zap.String("quote_ref", quoteRef))
+			q.logger.Info("Quote expired during consume", zap.String("quote_ref", quoteRef))
 			return nil, storage.ErrQuoteExpired
 		}
 
 		if quote.Status == model.QuoteStatusConsumed {
 			if quote.ConsumedByLedgerTxnRef == ledgerTxnRef {
-				q.logger.Debug("quote already consumed by ledger", zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
+				q.logger.Debug("Quote already consumed by ledger", zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
 				return quote, nil
 			}
-			q.logger.Warn("quote consumed by different ledger", zap.String("quote_ref", quoteRef), zap.String("existing_ledger_ref", quote.ConsumedByLedgerTxnRef))
+			q.logger.Warn("Quote consumed by different ledger", zap.String("quote_ref", quoteRef), zap.String("existing_ledger_ref", quote.ConsumedByLedgerTxnRef))
 			return nil, storage.ErrQuoteConsumed
 		}
 
@@ -157,11 +157,11 @@ func (q *quotesStore) Consume(ctx context.Context, quoteRef, ledgerTxnRef string
 		if err := q.repo.Update(txCtx, quote); err != nil {
 			return nil, err
 		}
-		q.logger.Info("quote consumed", zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
+		q.logger.Info("Quote consumed", zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
 		return quote, nil
 	})
 	if err != nil {
-		q.logger.Error("quote consumption failed", zap.Error(err), zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
+		q.logger.Warn("Quote consumption failed", zap.Error(err), zap.String("quote_ref", quoteRef), zap.String("ledger_ref", ledgerTxnRef))
 		return nil, err
 	}
 	quote, _ := result.(*model.Quote)
@@ -173,7 +173,7 @@ func (q *quotesStore) Consume(ctx context.Context, quoteRef, ledgerTxnRef string
 
 func (q *quotesStore) ExpireIssuedBefore(ctx context.Context, cutoff time.Time) (int, error) {
 	if cutoff.IsZero() {
-		q.logger.Warn("attempt to expire quotes with zero cutoff")
+		q.logger.Warn("Attempt to expire quotes with zero cutoff")
 		return 0, merrors.InvalidArgument("quotesStore: cutoff time is zero")
 	}
 
@@ -188,11 +188,11 @@ func (q *quotesStore) ExpireIssuedBefore(ctx context.Context, cutoff time.Time)
 
 	updated, err := q.repo.PatchMany(ctx, filter, patch)
 	if err != nil {
-		q.logger.Error("failed to expire quotes", zap.Error(err))
+		q.logger.Warn("Failed to expire quotes", zap.Error(err))
 		return 0, err
 	}
 	if updated > 0 {
-		q.logger.Info("quotes expired", zap.Int("count", updated))
+		q.logger.Info("Quotes expired", zap.Int("count", updated))
 	}
 	return updated, nil
 }

api/fx/storage/mongo/store/rates.go

@@ -51,11 +51,11 @@ func NewRates(logger mlogger.Logger, db *mongo.Database) (storage.RatesStore, er
 
 	for _, def := range indexes {
 		if err := repo.CreateIndex(def); err != nil {
-			logger.Error("failed to ensure rates index", zap.Error(err))
+			logger.Error("Failed to ensure rates index", zap.Error(err))
 			return nil, err
 		}
 	}
-	logger.Debug("rates store initialised", zap.String("collection", model.RatesCollection))
+	logger.Debug("Rates store initialised", zap.String("collection", model.RatesCollection))
 	return &ratesStore{
 		logger: logger.Named(model.RatesCollection),
 		repo:   repo,
@@ -64,11 +64,11 @@ func NewRates(logger mlogger.Logger, db *mongo.Database) (storage.RatesStore, er
 
 func (r *ratesStore) UpsertSnapshot(ctx context.Context, snapshot *model.RateSnapshot) error {
 	if snapshot == nil {
-		r.logger.Warn("attempt to upsert nil snapshot")
+		r.logger.Warn("Attempt to upsert nil snapshot")
 		return merrors.InvalidArgument("ratesStore: nil snapshot")
 	}
 	if snapshot.RateRef == "" {
-		r.logger.Warn("attempt to upsert snapshot with empty rate_ref")
+		r.logger.Warn("Attempt to upsert snapshot with empty rate_ref")
 		return merrors.InvalidArgument("ratesStore: empty rateRef")
 	}
 
@@ -82,17 +82,17 @@ func (r *ratesStore) UpsertSnapshot(ctx context.Context, snapshot *model.RateSna
 	err := r.repo.FindOneByFilter(ctx, filter, existing)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			r.logger.Debug("inserting new rate snapshot", zap.String("rate_ref", snapshot.RateRef))
+			r.logger.Debug("Inserting new rate snapshot", zap.String("rate_ref", snapshot.RateRef))
 			return r.repo.Insert(ctx, snapshot, filter)
 		}
-		r.logger.Error("failed to query rate snapshot", zap.Error(err), zap.String("rate_ref", snapshot.RateRef))
+		r.logger.Warn("Failed to query rate snapshot", zap.Error(err), zap.String("rate_ref", snapshot.RateRef))
 		return err
 	}
 
 	if existing.GetID() != nil {
 		snapshot.SetID(*existing.GetID())
 	}
-	r.logger.Debug("updating rate snapshot", zap.String("rate_ref", snapshot.RateRef))
+	r.logger.Debug("Updating rate snapshot", zap.String("rate_ref", snapshot.RateRef))
 	return r.repo.Update(ctx, snapshot)
 }
 

api/gateway/chain/client/client.go

@@ -24,6 +24,8 @@ type Client interface {
 	GetTransfer(ctx context.Context, req *chainv1.GetTransferRequest) (*chainv1.GetTransferResponse, error)
 	ListTransfers(ctx context.Context, req *chainv1.ListTransfersRequest) (*chainv1.ListTransfersResponse, error)
 	EstimateTransferFee(ctx context.Context, req *chainv1.EstimateTransferFeeRequest) (*chainv1.EstimateTransferFeeResponse, error)
+	ComputeGasTopUp(ctx context.Context, req *chainv1.ComputeGasTopUpRequest) (*chainv1.ComputeGasTopUpResponse, error)
+	EnsureGasTopUp(ctx context.Context, req *chainv1.EnsureGasTopUpRequest) (*chainv1.EnsureGasTopUpResponse, error)
 	Close() error
 }
 
@@ -36,6 +38,8 @@ type grpcGatewayClient interface {
 	GetTransfer(ctx context.Context, in *chainv1.GetTransferRequest, opts ...grpc.CallOption) (*chainv1.GetTransferResponse, error)
 	ListTransfers(ctx context.Context, in *chainv1.ListTransfersRequest, opts ...grpc.CallOption) (*chainv1.ListTransfersResponse, error)
 	EstimateTransferFee(ctx context.Context, in *chainv1.EstimateTransferFeeRequest, opts ...grpc.CallOption) (*chainv1.EstimateTransferFeeResponse, error)
+	ComputeGasTopUp(ctx context.Context, in *chainv1.ComputeGasTopUpRequest, opts ...grpc.CallOption) (*chainv1.ComputeGasTopUpResponse, error)
+	EnsureGasTopUp(ctx context.Context, in *chainv1.EnsureGasTopUpRequest, opts ...grpc.CallOption) (*chainv1.EnsureGasTopUpResponse, error)
 }
 
 type chainGatewayClient struct {
@@ -139,6 +143,18 @@ func (c *chainGatewayClient) EstimateTransferFee(ctx context.Context, req *chain
 	return c.client.EstimateTransferFee(ctx, req)
 }
 
+func (c *chainGatewayClient) ComputeGasTopUp(ctx context.Context, req *chainv1.ComputeGasTopUpRequest) (*chainv1.ComputeGasTopUpResponse, error) {
+	ctx, cancel := c.callContext(ctx)
+	defer cancel()
+	return c.client.ComputeGasTopUp(ctx, req)
+}
+
+func (c *chainGatewayClient) EnsureGasTopUp(ctx context.Context, req *chainv1.EnsureGasTopUpRequest) (*chainv1.EnsureGasTopUpResponse, error) {
+	ctx, cancel := c.callContext(ctx)
+	defer cancel()
+	return c.client.EnsureGasTopUp(ctx, req)
+}
+
 func (c *chainGatewayClient) callContext(ctx context.Context) (context.Context, context.CancelFunc) {
 	timeout := c.cfg.CallTimeout
 	if timeout <= 0 {

api/gateway/chain/client/fake.go

@@ -16,6 +16,8 @@ type Fake struct {
 	GetTransferFn         func(ctx context.Context, req *chainv1.GetTransferRequest) (*chainv1.GetTransferResponse, error)
 	ListTransfersFn       func(ctx context.Context, req *chainv1.ListTransfersRequest) (*chainv1.ListTransfersResponse, error)
 	EstimateTransferFeeFn func(ctx context.Context, req *chainv1.EstimateTransferFeeRequest) (*chainv1.EstimateTransferFeeResponse, error)
+	ComputeGasTopUpFn     func(ctx context.Context, req *chainv1.ComputeGasTopUpRequest) (*chainv1.ComputeGasTopUpResponse, error)
+	EnsureGasTopUpFn      func(ctx context.Context, req *chainv1.EnsureGasTopUpRequest) (*chainv1.EnsureGasTopUpResponse, error)
 	CloseFn               func() error
 }
 
@@ -75,6 +77,20 @@ func (f *Fake) EstimateTransferFee(ctx context.Context, req *chainv1.EstimateTra
 	return &chainv1.EstimateTransferFeeResponse{}, nil
 }
 
+func (f *Fake) ComputeGasTopUp(ctx context.Context, req *chainv1.ComputeGasTopUpRequest) (*chainv1.ComputeGasTopUpResponse, error) {
+	if f.ComputeGasTopUpFn != nil {
+		return f.ComputeGasTopUpFn(ctx, req)
+	}
+	return &chainv1.ComputeGasTopUpResponse{}, nil
+}
+
+func (f *Fake) EnsureGasTopUp(ctx context.Context, req *chainv1.EnsureGasTopUpRequest) (*chainv1.EnsureGasTopUpResponse, error) {
+	if f.EnsureGasTopUpFn != nil {
+		return f.EnsureGasTopUpFn(ctx, req)
+	}
+	return &chainv1.EnsureGasTopUpResponse{}, nil
+}
+
 func (f *Fake) Close() error {
 	if f.CloseFn != nil {
 		return f.CloseFn()

api/gateway/chain/config.yml

@@ -34,16 +34,23 @@ messaging:
     reconnect_wait: 5
 
 chains:
-  - name: arbitrum_one
-    rpc_url_env: CHAIN_GATEWAY_ARBITRUM_RPC_URL
+  - name: tron_mainnet
+    chain_id: 728126428 # 0x2b6653dc
+    native_token: TRX
+    rpc_url_env: CHAIN_GATEWAY_RPC_URL
+    gas_topup_policy:
+      buffer_percent: 0.10
+      min_native_balance_trx: 10
+      rounding_unit_trx: 1
+      max_topup_trx: 100
     tokens:
-      - symbol: USDC
-        contract: "0xaf88d065e77c8cc2239327c5edb3a432268e5831"
       - symbol: USDT
-        contract: "0xfd086bc7cd5c481dcc9c85ebe478a1c0b69fcbb9"
+        contract: "0xa614f803b6fd780986a42c78ec9c7f77e6ded13c"
+      - symbol: USDC
+        contract: "0x3487b63d30b5b2c87fb7ffa8bcfade38eaac1abe"
 
 service_wallet:
-  chain: arbitrum_one
+  chain: tron_mainnet
   address_env: CHAIN_GATEWAY_SERVICE_WALLET_ADDRESS
   private_key_env: CHAIN_GATEWAY_SERVICE_WALLET_KEY
 
@@ -58,3 +65,4 @@ key_management:
 
 cache:
   wallet_balance_ttl_seconds: 120
+  rpc_request_timeout_seconds: 15

api/gateway/chain/go.mod

@@ -15,14 +15,14 @@ require (
 	github.com/tech/sendico/pkg v0.1.0
 	go.mongodb.org/mongo-driver v1.17.6
 	go.uber.org/zap v1.27.1
-	google.golang.org/grpc v1.77.0
-	google.golang.org/protobuf v1.36.10
+	google.golang.org/grpc v1.78.0
+	google.golang.org/protobuf v1.36.11
 	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
 	github.com/Microsoft/go-winio v0.6.2 // indirect
-	github.com/ProjectZKM/Ziren/crates/go-runtime/zkvm_runtime v0.0.0-20251208031133-be43a854e4be // indirect
+	github.com/ProjectZKM/Ziren/crates/go-runtime/zkvm_runtime v0.0.0-20251229120209-a0d175451f7b // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/bits-and-blooms/bitset v1.24.4 // indirect
 	github.com/bmatcuk/doublestar/v4 v4.9.1 // indirect
@@ -60,7 +60,7 @@ require (
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/montanaflynn/stats v0.7.1 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
-	github.com/nats-io/nats.go v1.47.0 // indirect
+	github.com/nats-io/nats.go v1.48.0 // indirect
 	github.com/nats-io/nkeys v0.4.12 // indirect
 	github.com/nats-io/nuid v1.0.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
@@ -86,5 +86,5 @@ require (
 	golang.org/x/sys v0.39.0 // indirect
 	golang.org/x/text v0.32.0 // indirect
 	golang.org/x/time v0.14.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b // indirect
 )

api/gateway/chain/go.sum

@@ -6,8 +6,8 @@ github.com/DataDog/zstd v1.4.5 h1:EndNeuB0l9syBZhut0wns3gV1hL8zX8LIu6ZiVHWLIQ=
 github.com/DataDog/zstd v1.4.5/go.mod h1:1jcaCB/ufaK+sKp1NBhlGmpz41jOoPQ35bpF36t7BBo=
 github.com/Microsoft/go-winio v0.6.2 h1:F2VQgta7ecxGYO8k3ZZz3RS8fVIXVxONVUPlNERoyfY=
 github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA8Ipt1oGCvU=
-github.com/ProjectZKM/Ziren/crates/go-runtime/zkvm_runtime v0.0.0-20251208031133-be43a854e4be h1:1LtMLkGIqE5IQZ7Vdh4zv8A6LECInKF86/fTVxKxYLE=
-github.com/ProjectZKM/Ziren/crates/go-runtime/zkvm_runtime v0.0.0-20251208031133-be43a854e4be/go.mod h1:ioLG6R+5bUSO1oeGSDxOV3FADARuMoytZCSX6MEMQkI=
+github.com/ProjectZKM/Ziren/crates/go-runtime/zkvm_runtime v0.0.0-20251229120209-a0d175451f7b h1:g/wCbvJGhOAqfGBjWnqtD6CVsXdr3G4GCbjLR6z9kNw=
+github.com/ProjectZKM/Ziren/crates/go-runtime/zkvm_runtime v0.0.0-20251229120209-a0d175451f7b/go.mod h1:ioLG6R+5bUSO1oeGSDxOV3FADARuMoytZCSX6MEMQkI=
 github.com/VictoriaMetrics/fastcache v1.13.0 h1:AW4mheMR5Vd9FkAPUv+NH6Nhw+fmbTMGMsNAoA/+4G0=
 github.com/VictoriaMetrics/fastcache v1.13.0/go.mod h1:hHXhl4DA2fTL2HTZDJFXWgW0LNjo6B+4aj2Wmng3TjU=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
@@ -207,8 +207,8 @@ github.com/morikuni/aec v1.0.0 h1:nP9CBfwrvYnBRgY6qfDQkygYDmYwOilePFkwzv4dU8A=
 github.com/morikuni/aec v1.0.0/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7PXmsc=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
-github.com/nats-io/nats.go v1.47.0 h1:YQdADw6J/UfGUd2Oy6tn4Hq6YHxCaJrVKayxxFqYrgM=
-github.com/nats-io/nats.go v1.47.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
+github.com/nats-io/nats.go v1.48.0 h1:pSFyXApG+yWU/TgbKCjmm5K4wrHu86231/w84qRVR+U=
+github.com/nats-io/nats.go v1.48.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
 github.com/nats-io/nkeys v0.4.12 h1:nssm7JKOG9/x4J8II47VWCL1Ds29avyiQDRn0ckMvDc=
 github.com/nats-io/nkeys v0.4.12/go.mod h1:MT59A1HYcjIcyQDJStTfaOY6vhy9XTUjOFo+SVsvpBg=
 github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
@@ -362,12 +362,12 @@ golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
 gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 h1:gRkg/vSppuSQoDjxyiGfN4Upv/h/DQmIR10ZU8dh4Ww=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217/go.mod h1:7i2o+ce6H/6BluujYR+kqX3GKH+dChPTQU19wjRPiGk=
-google.golang.org/grpc v1.77.0 h1:wVVY6/8cGA6vvffn+wWK5ToddbgdU3d8MNENr4evgXM=
-google.golang.org/grpc v1.77.0/go.mod h1:z0BY1iVj0q8E1uSQCjL9cppRj+gnZjzDnzV0dHhrNig=
-google.golang.org/protobuf v1.36.10 h1:AYd7cD/uASjIL6Q9LiTjz8JLcrh/88q5UObnmY3aOOE=
-google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b h1:Mv8VFug0MP9e5vUxfBcE3vUkV6CImK3cMNMIDFjmzxU=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b/go.mod h1:j9x/tPzZkyxcgEFkiKEEGxfvyumM01BEtsW8xzOahRQ=
+google.golang.org/grpc v1.78.0 h1:K1XZG/yGDJnzMdd/uZHAkVqJE+xIDOcmdSFZkBUicNc=
+google.golang.org/grpc v1.78.0/go.mod h1:I47qjTo4OKbMkjA/aOOwxDIiPSBofUtQUI5EfpWvW7U=
+google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
+google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

api/gateway/chain/internal/keymanager/vault/manager.go

@@ -45,22 +45,22 @@ func New(logger mlogger.Logger, cfg Config) (*Manager, error) {
 	}
 	address := strings.TrimSpace(cfg.Address)
 	if address == "" {
-		logger.Error("vault address missing")
+		logger.Error("Vault address missing")
 		return nil, merrors.InvalidArgument("vault key manager: address is required")
 	}
 	tokenEnv := strings.TrimSpace(cfg.TokenEnv)
 	if tokenEnv == "" {
-		logger.Error("vault token env missing")
+		logger.Error("Vault token env missing")
 		return nil, merrors.InvalidArgument("vault key manager: token_env is required")
 	}
 	token := strings.TrimSpace(os.Getenv(tokenEnv))
 	if token == "" {
-		logger.Error("vault token missing; expected Vault Agent to export token", zap.String("env", tokenEnv))
+		logger.Error("Vault token missing; expected Vault Agent to export token", zap.String("env", tokenEnv))
 		return nil, merrors.InvalidArgument("vault key manager: token env " + tokenEnv + " is not set (expected Vault Agent sink to populate it)")
 	}
 	mountPath := strings.Trim(strings.TrimSpace(cfg.MountPath), "/")
 	if mountPath == "" {
-		logger.Error("vault mount path missing")
+		logger.Error("Vault mount path missing")
 		return nil, merrors.InvalidArgument("vault key manager: mount_path is required")
 	}
 	keyPrefix := strings.Trim(strings.TrimSpace(cfg.KeyPrefix), "/")
@@ -73,7 +73,7 @@ func New(logger mlogger.Logger, cfg Config) (*Manager, error) {
 
 	client, err := api.NewClient(clientCfg)
 	if err != nil {
-		logger.Error("failed to create vault client", zap.Error(err))
+		logger.Error("Failed to create vault client", zap.Error(err))
 		return nil, merrors.Internal("vault key manager: failed to create client: " + err.Error())
 	}
 	client.SetToken(token)
@@ -94,17 +94,17 @@ func New(logger mlogger.Logger, cfg Config) (*Manager, error) {
 // CreateManagedWalletKey creates a new managed wallet key and stores it in Vault.
 func (m *Manager) CreateManagedWalletKey(ctx context.Context, walletRef string, network string) (*keymanager.ManagedWalletKey, error) {
 	if strings.TrimSpace(walletRef) == "" {
-		m.logger.Warn("walletRef missing for managed key creation", zap.String("network", network))
+		m.logger.Warn("WalletRef missing for managed key creation", zap.String("network", network))
 		return nil, merrors.InvalidArgument("vault key manager: walletRef is required")
 	}
 	if strings.TrimSpace(network) == "" {
-		m.logger.Warn("network missing for managed key creation", zap.String("wallet_ref", walletRef))
+		m.logger.Warn("Network missing for managed key creation", zap.String("wallet_ref", walletRef))
 		return nil, merrors.InvalidArgument("vault key manager: network is required")
 	}
 
 	privateKey, err := ecdsa.GenerateKey(secp256k1.S256(), rand.Reader)
 	if err != nil {
-		m.logger.Warn("failed to generate managed wallet key", zap.String("wallet_ref", walletRef), zap.String("network", network), zap.Error(err))
+		m.logger.Warn("Failed to generate managed wallet key", zap.String("wallet_ref", walletRef), zap.String("network", network), zap.Error(err))
 		return nil, merrors.Internal("vault key manager: failed to generate key: " + err.Error())
 	}
 	privateKeyBytes := crypto.FromECDSA(privateKey)
@@ -115,7 +115,7 @@ func (m *Manager) CreateManagedWalletKey(ctx context.Context, walletRef string,
 
 	err = m.persistKey(ctx, walletRef, network, privateKeyBytes, publicKeyBytes, address)
 	if err != nil {
-		m.logger.Warn("failed to persist managed wallet key", zap.String("wallet_ref", walletRef), zap.String("network", network), zap.Error(err))
+		m.logger.Warn("Failed to persist managed wallet key", zap.String("wallet_ref", walletRef), zap.String("network", network), zap.Error(err))
 		zeroBytes(privateKeyBytes)
 		zeroBytes(publicKeyBytes)
 		return nil, err
@@ -123,7 +123,7 @@ func (m *Manager) CreateManagedWalletKey(ctx context.Context, walletRef string,
 	zeroBytes(privateKeyBytes)
 	zeroBytes(publicKeyBytes)
 
-	m.logger.Info("managed wallet key created",
+	m.logger.Info("Managed wallet key created",
 		zap.String("wallet_ref", walletRef),
 		zap.String("network", network),
 		zap.String("address", strings.ToLower(address)),
@@ -158,43 +158,43 @@ func (m *Manager) buildKeyID(network, walletRef string) string {
 // SignTransaction loads the key material from Vault and signs the transaction.
 func (m *Manager) SignTransaction(ctx context.Context, keyID string, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error) {
 	if strings.TrimSpace(keyID) == "" {
-		m.logger.Warn("signing failed: empty key id")
+		m.logger.Warn("Signing failed: empty key id")
 		return nil, merrors.InvalidArgument("vault key manager: keyID is required")
 	}
 	if tx == nil {
-		m.logger.Warn("signing failed: nil transaction", zap.String("key_id", keyID))
+		m.logger.Warn("Signing failed: nil transaction", zap.String("key_id", keyID))
 		return nil, merrors.InvalidArgument("vault key manager: transaction is nil")
 	}
 	if chainID == nil {
-		m.logger.Warn("signing failed: nil chain id", zap.String("key_id", keyID))
+		m.logger.Warn("Signing failed: nil chain id", zap.String("key_id", keyID))
 		return nil, merrors.InvalidArgument("vault key manager: chainID is nil")
 	}
 
 	material, err := m.loadKey(ctx, keyID)
 	if err != nil {
-		m.logger.Warn("failed to load key material", zap.String("key_id", keyID), zap.Error(err))
+		m.logger.Warn("Failed to load key material", zap.String("key_id", keyID), zap.Error(err))
 		return nil, err
 	}
 
 	keyBytes, err := hex.DecodeString(material.PrivateKey)
 	if err != nil {
-		m.logger.Warn("invalid key material", zap.String("key_id", keyID), zap.Error(err))
+		m.logger.Warn("Invalid key material", zap.String("key_id", keyID), zap.Error(err))
 		return nil, merrors.Internal("vault key manager: invalid key material: " + err.Error())
 	}
 	defer zeroBytes(keyBytes)
 
 	privateKey, err := crypto.ToECDSA(keyBytes)
 	if err != nil {
-		m.logger.Warn("failed to construct private key", zap.String("key_id", keyID), zap.Error(err))
+		m.logger.Warn("Failed to construct private key", zap.String("key_id", keyID), zap.Error(err))
 		return nil, merrors.Internal("vault key manager: failed to construct private key: " + err.Error())
 	}
 
 	signed, err := types.SignTx(tx, types.LatestSignerForChainID(chainID), privateKey)
 	if err != nil {
-		m.logger.Warn("failed to sign transaction", zap.String("key_id", keyID), zap.Error(err))
+		m.logger.Warn("Failed to sign transaction", zap.String("key_id", keyID), zap.Error(err))
 		return nil, merrors.Internal("vault key manager: failed to sign transaction: " + err.Error())
 	}
-	m.logger.Info("transaction signed with managed key",
+	m.logger.Info("Transaction signed with managed key",
 		zap.String("key_id", keyID),
 		zap.String("network", material.Network),
 		zap.String("tx_hash", signed.Hash().Hex()),
@@ -213,23 +213,23 @@ func (m *Manager) loadKey(ctx context.Context, keyID string) (*keyMaterial, erro
 	secretPath := strings.Trim(strings.TrimPrefix(keyID, "/"), "/")
 	secret, err := m.store.Get(ctx, secretPath)
 	if err != nil {
-		m.logger.Warn("failed to read secret", zap.String("path", secretPath), zap.Error(err))
+		m.logger.Warn("Failed to read secret", zap.String("path", secretPath), zap.Error(err))
 		return nil, merrors.Internal("vault key manager: failed to read secret at " + secretPath + ": " + err.Error())
 	}
 	if secret == nil || secret.Data == nil {
-		m.logger.Warn("secret not found", zap.String("path", secretPath))
+		m.logger.Warn("Secret not found", zap.String("path", secretPath))
 		return nil, merrors.NoData("vault key manager: secret " + secretPath + " not found")
 	}
 
 	getString := func(key string) (string, error) {
 		val, ok := secret.Data[key]
 		if !ok {
-			m.logger.Warn("secret missing field", zap.String("path", secretPath), zap.String("field", key))
+			m.logger.Warn("Secret missing field", zap.String("path", secretPath), zap.String("field", key))
 			return "", merrors.Internal("vault key manager: secret " + secretPath + " missing " + key)
 		}
 		str, ok := val.(string)
 		if !ok || strings.TrimSpace(str) == "" {
-			m.logger.Warn("secret field invalid", zap.String("path", secretPath), zap.String("field", key))
+			m.logger.Warn("Secret field invalid", zap.String("path", secretPath), zap.String("field", key))
 			return "", merrors.Internal("vault key manager: secret " + secretPath + " invalid " + key)
 		}
 		return str, nil

api/gateway/chain/internal/server/internal/serverimp.go

@@ -2,14 +2,18 @@ package serverimp
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"strings"
 	"time"
 
 	"github.com/mitchellh/mapstructure"
+	"github.com/shopspring/decimal"
 	"github.com/tech/sendico/gateway/chain/internal/keymanager"
 	vaultmanager "github.com/tech/sendico/gateway/chain/internal/keymanager/vault"
 	gatewayservice "github.com/tech/sendico/gateway/chain/internal/service/gateway"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/drivers"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/rpcclient"
 	gatewayshared "github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
 	"github.com/tech/sendico/gateway/chain/storage"
 	gatewaymongo "github.com/tech/sendico/gateway/chain/storage/mongo"
@@ -30,6 +34,8 @@ type Imp struct {
 
 	config *config
 	app    *grpcapp.App[storage.Repository]
+
+	rpcClients *rpcclient.Clients
 }
 
 type config struct {
@@ -41,11 +47,12 @@ type config struct {
 }
 
 type chainConfig struct {
-	Name        string        `yaml:"name"`
-	RPCURLEnv   string        `yaml:"rpc_url_env"`
-	ChainID     uint64        `yaml:"chain_id"`
-	NativeToken string        `yaml:"native_token"`
-	Tokens      []tokenConfig `yaml:"tokens"`
+	Name           string                `yaml:"name"`
+	RPCURLEnv      string                `yaml:"rpc_url_env"`
+	ChainID        uint64                `yaml:"chain_id"`
+	NativeToken    string                `yaml:"native_token"`
+	Tokens         []tokenConfig         `yaml:"tokens"`
+	GasTopUpPolicy *gasTopUpPolicyConfig `yaml:"gas_topup_policy"`
 }
 
 type serviceWalletConfig struct {
@@ -61,6 +68,19 @@ type tokenConfig struct {
 	ContractEnv string `yaml:"contract_env"`
 }
 
+type gasTopUpPolicyConfig struct {
+	gasTopUpRuleConfig `yaml:",inline"`
+	Native             *gasTopUpRuleConfig `yaml:"native"`
+	Contract           *gasTopUpRuleConfig `yaml:"contract"`
+}
+
+type gasTopUpRuleConfig struct {
+	BufferPercent       float64 `yaml:"buffer_percent"`
+	MinNativeBalanceTRX float64 `yaml:"min_native_balance_trx"`
+	RoundingUnitTRX     float64 `yaml:"rounding_unit_trx"`
+	MaxTopUpTRX         float64 `yaml:"max_topup_trx"`
+}
+
 // Create initialises the chain gateway server implementation.
 func Create(logger mlogger.Logger, file string, debug bool) (*Imp, error) {
 	return &Imp{
@@ -84,6 +104,9 @@ func (i *Imp) Shutdown() {
 	defer cancel()
 
 	i.app.Shutdown(ctx)
+	if i.rpcClients != nil {
+		i.rpcClients.Close()
+	}
 }
 
 func (i *Imp) Start() error {
@@ -98,20 +121,34 @@ func (i *Imp) Start() error {
 	}
 
 	cl := i.logger.Named("config")
-	networkConfigs := resolveNetworkConfigs(cl.Named("network"), cfg.Chains)
+	networkConfigs, err := resolveNetworkConfigs(cl.Named("network"), cfg.Chains)
+	if err != nil {
+		i.logger.Error("Invalid chain network configuration", zap.Error(err))
+		return err
+	}
+	rpcClients, err := rpcclient.Prepare(context.Background(), i.logger.Named("rpc"), networkConfigs)
+	if err != nil {
+		i.logger.Error("Failed to prepare rpc clients", zap.Error(err))
+		return err
+	}
+	i.rpcClients = rpcClients
 	walletConfig := resolveServiceWallet(cl.Named("wallet"), cfg.ServiceWallet)
 	keyManager, err := resolveKeyManager(i.logger.Named("key_manager"), cfg.KeyManagement)
 	if err != nil {
 		return err
 	}
+	driverRegistry, err := drivers.NewRegistry(i.logger.Named("drivers"), networkConfigs)
+	if err != nil {
+		return err
+	}
 
 	serviceFactory := func(logger mlogger.Logger, repo storage.Repository, producer msg.Producer) (grpcapp.Service, error) {
-		executor := gatewayservice.NewOnChainExecutor(logger, keyManager)
 		opts := []gatewayservice.Option{
 			gatewayservice.WithNetworks(networkConfigs),
 			gatewayservice.WithServiceWallet(walletConfig),
 			gatewayservice.WithKeyManager(keyManager),
-			gatewayservice.WithTransferExecutor(executor),
+			gatewayservice.WithRPCClients(rpcClients),
+			gatewayservice.WithDriverRegistry(driverRegistry),
 			gatewayservice.WithSettings(cfg.Settings),
 		}
 		return gatewayservice.NewService(logger, repo, producer, opts...), nil
@@ -129,7 +166,7 @@ func (i *Imp) Start() error {
 func (i *Imp) loadConfig() (*config, error) {
 	data, err := os.ReadFile(i.file)
 	if err != nil {
-		i.logger.Error("could not read configuration file", zap.String("config_file", i.file), zap.Error(err))
+		i.logger.Error("Could not read configuration file", zap.String("config_file", i.file), zap.Error(err))
 		return nil, err
 	}
 
@@ -137,7 +174,7 @@ func (i *Imp) loadConfig() (*config, error) {
 		Config: &grpcapp.Config{},
 	}
 	if err := yaml.Unmarshal(data, cfg); err != nil {
-		i.logger.Error("failed to parse configuration", zap.Error(err))
+		i.logger.Error("Failed to parse configuration", zap.Error(err))
 		return nil, err
 	}
 
@@ -157,22 +194,23 @@ func (i *Imp) loadConfig() (*config, error) {
 	return cfg, nil
 }
 
-func resolveNetworkConfigs(logger mlogger.Logger, chains []chainConfig) []gatewayshared.Network {
+func resolveNetworkConfigs(logger mlogger.Logger, chains []chainConfig) ([]gatewayshared.Network, error) {
 	result := make([]gatewayshared.Network, 0, len(chains))
 	for _, chain := range chains {
 		if strings.TrimSpace(chain.Name) == "" {
-			logger.Warn("skipping unnamed chain configuration")
+			logger.Warn("Skipping unnamed chain configuration")
 			continue
 		}
 		rpcURL := strings.TrimSpace(os.Getenv(chain.RPCURLEnv))
 		if rpcURL == "" {
-			logger.Warn("chain RPC endpoint not configured", zap.String("chain", chain.Name), zap.String("env", chain.RPCURLEnv))
+			logger.Error("RPC url not configured", zap.String("chain", chain.Name), zap.String("env", chain.RPCURLEnv))
+			return nil, merrors.InvalidArgument(fmt.Sprintf("chain RPC endpoint not configured (chain=%s env=%s)", chain.Name, chain.RPCURLEnv))
 		}
 		contracts := make([]gatewayshared.TokenContract, 0, len(chain.Tokens))
 		for _, token := range chain.Tokens {
 			symbol := strings.TrimSpace(token.Symbol)
 			if symbol == "" {
-				logger.Warn("skipping token with empty symbol", zap.String("chain", chain.Name))
+				logger.Warn("Skipping token with empty symbol", zap.String("chain", chain.Name))
 				continue
 			}
 			addr := strings.TrimSpace(token.Contract)
@@ -182,9 +220,9 @@ func resolveNetworkConfigs(logger mlogger.Logger, chains []chainConfig) []gatewa
 			}
 			if addr == "" {
 				if env != "" {
-					logger.Warn("token contract not configured", zap.String("token", symbol), zap.String("env", env), zap.String("chain", chain.Name))
+					logger.Warn("Token contract not configured", zap.String("token", symbol), zap.String("env", env), zap.String("chain", chain.Name))
 				} else {
-					logger.Warn("token contract not configured", zap.String("token", symbol), zap.String("chain", chain.Name))
+					logger.Warn("Token contract not configured", zap.String("token", symbol), zap.String("chain", chain.Name))
 				}
 				continue
 			}
@@ -194,15 +232,84 @@ func resolveNetworkConfigs(logger mlogger.Logger, chains []chainConfig) []gatewa
 			})
 		}
 
+		gasPolicy, err := buildGasTopUpPolicy(chain.Name, chain.GasTopUpPolicy)
+		if err != nil {
+			logger.Error("Invalid gas top-up policy", zap.String("chain", chain.Name), zap.Error(err))
+			return nil, err
+		}
+
 		result = append(result, gatewayshared.Network{
-			Name:         chain.Name,
-			RPCURL:       rpcURL,
-			ChainID:      chain.ChainID,
-			NativeToken:  chain.NativeToken,
-			TokenConfigs: contracts,
+			Name:           chain.Name,
+			RPCURL:         rpcURL,
+			ChainID:        chain.ChainID,
+			NativeToken:    chain.NativeToken,
+			TokenConfigs:   contracts,
+			GasTopUpPolicy: gasPolicy,
 		})
 	}
-	return result
+	return result, nil
+}
+
+func buildGasTopUpPolicy(chainName string, cfg *gasTopUpPolicyConfig) (*gatewayshared.GasTopUpPolicy, error) {
+	if cfg == nil {
+		return nil, nil
+	}
+	defaultRule, defaultSet, err := parseGasTopUpRule(chainName, "default", cfg.gasTopUpRuleConfig)
+	if err != nil {
+		return nil, err
+	}
+	if !defaultSet {
+		return nil, merrors.InvalidArgument(fmt.Sprintf("chain %s gas_topup_policy is required", chainName))
+	}
+
+	policy := &gatewayshared.GasTopUpPolicy{
+		Default: defaultRule,
+	}
+
+	if cfg.Native != nil {
+		rule, set, err := parseGasTopUpRule(chainName, "native", *cfg.Native)
+		if err != nil {
+			return nil, err
+		}
+		if set {
+			policy.Native = &rule
+		}
+	}
+	if cfg.Contract != nil {
+		rule, set, err := parseGasTopUpRule(chainName, "contract", *cfg.Contract)
+		if err != nil {
+			return nil, err
+		}
+		if set {
+			policy.Contract = &rule
+		}
+	}
+
+	return policy, nil
+}
+
+func parseGasTopUpRule(chainName, label string, cfg gasTopUpRuleConfig) (gatewayshared.GasTopUpRule, bool, error) {
+	if cfg.BufferPercent == 0 && cfg.MinNativeBalanceTRX == 0 && cfg.RoundingUnitTRX == 0 && cfg.MaxTopUpTRX == 0 {
+		return gatewayshared.GasTopUpRule{}, false, nil
+	}
+	if cfg.BufferPercent < 0 {
+		return gatewayshared.GasTopUpRule{}, true, merrors.InvalidArgument(fmt.Sprintf("chain %s gas_topup_policy %s buffer_percent must be >= 0", chainName, label))
+	}
+	if cfg.MinNativeBalanceTRX < 0 {
+		return gatewayshared.GasTopUpRule{}, true, merrors.InvalidArgument(fmt.Sprintf("chain %s gas_topup_policy %s min_native_balance_trx must be >= 0", chainName, label))
+	}
+	if cfg.RoundingUnitTRX <= 0 {
+		return gatewayshared.GasTopUpRule{}, true, merrors.InvalidArgument(fmt.Sprintf("chain %s gas_topup_policy %s rounding_unit_trx must be > 0", chainName, label))
+	}
+	if cfg.MaxTopUpTRX <= 0 {
+		return gatewayshared.GasTopUpRule{}, true, merrors.InvalidArgument(fmt.Sprintf("chain %s gas_topup_policy %s max_topup_trx must be > 0", chainName, label))
+	}
+	return gatewayshared.GasTopUpRule{
+		BufferPercent:    decimal.NewFromFloat(cfg.BufferPercent),
+		MinNativeBalance: decimal.NewFromFloat(cfg.MinNativeBalanceTRX),
+		RoundingUnit:     decimal.NewFromFloat(cfg.RoundingUnitTRX),
+		MaxTopUp:         decimal.NewFromFloat(cfg.MaxTopUpTRX),
+	}, true, nil
 }
 
 func resolveServiceWallet(logger mlogger.Logger, cfg serviceWalletConfig) gatewayshared.ServiceWallet {
@@ -215,13 +322,13 @@ func resolveServiceWallet(logger mlogger.Logger, cfg serviceWalletConfig) gatewa
 
 	if address == "" {
 		if cfg.AddressEnv != "" {
-			logger.Warn("service wallet address not configured", zap.String("env", cfg.AddressEnv))
+			logger.Warn("Service wallet address not configured", zap.String("env", cfg.AddressEnv))
 		} else {
-			logger.Warn("service wallet address not configured", zap.String("chain", cfg.Chain))
+			logger.Warn("Service wallet address not configured", zap.String("chain", cfg.Chain))
 		}
 	}
 	if privateKey == "" {
-		logger.Warn("service wallet private key not configured", zap.String("env", cfg.PrivateKeyEnv))
+		logger.Warn("Service wallet private key not configured", zap.String("env", cfg.PrivateKeyEnv))
 	}
 
 	return gatewayshared.ServiceWallet{
@@ -235,7 +342,7 @@ func resolveKeyManager(logger mlogger.Logger, cfg keymanager.Config) (keymanager
 	driver := strings.ToLower(strings.TrimSpace(string(cfg.Driver)))
 	if driver == "" {
 		err := merrors.InvalidArgument("key management driver is not configured")
-		logger.Error("key management driver missing")
+		logger.Error("Key management driver missing")
 		return nil, err
 	}
 
@@ -244,19 +351,19 @@ func resolveKeyManager(logger mlogger.Logger, cfg keymanager.Config) (keymanager
 		settings := vaultmanager.Config{}
 		if len(cfg.Settings) > 0 {
 			if err := mapstructure.Decode(cfg.Settings, &settings); err != nil {
-				logger.Error("failed to decode vault key manager settings", zap.Error(err), zap.Any("settings", cfg.Settings))
+				logger.Error("Failed to decode vault key manager settings", zap.Error(err), zap.Any("settings", cfg.Settings))
 				return nil, merrors.InvalidArgument("invalid vault key manager settings: " + err.Error())
 			}
 		}
 		manager, err := vaultmanager.New(logger, settings)
 		if err != nil {
-			logger.Error("failed to initialise vault key manager", zap.Error(err))
+			logger.Error("Failed to initialise vault key manager", zap.Error(err))
 			return nil, err
 		}
 		return manager, nil
 	default:
 		err := merrors.InvalidArgument("unsupported key management driver: " + driver)
-		logger.Error("unsupported key management driver", zap.String("driver", driver))
+		logger.Error("Unsupported key management driver", zap.String("driver", driver))
 		return nil, err
 	}
 }

api/gateway/chain/internal/service/gateway/commands/registry.go

@@ -23,6 +23,8 @@ type Registry struct {
 	GetTransfer      Unary[chainv1.GetTransferRequest, chainv1.GetTransferResponse]
 	ListTransfers    Unary[chainv1.ListTransfersRequest, chainv1.ListTransfersResponse]
 	EstimateTransfer Unary[chainv1.EstimateTransferFeeRequest, chainv1.EstimateTransferFeeResponse]
+	ComputeGasTopUp  Unary[chainv1.ComputeGasTopUpRequest, chainv1.ComputeGasTopUpResponse]
+	EnsureGasTopUp   Unary[chainv1.EnsureGasTopUpRequest, chainv1.EnsureGasTopUpResponse]
 }
 
 type RegistryDeps struct {
@@ -40,5 +42,7 @@ func NewRegistry(deps RegistryDeps) Registry {
 		GetTransfer:         transfer.NewGetTransfer(deps.Transfer.WithLogger("transfer.get")),
 		ListTransfers:       transfer.NewListTransfers(deps.Transfer.WithLogger("transfer.list")),
 		EstimateTransfer:    transfer.NewEstimateTransfer(deps.Transfer.WithLogger("transfer.estimate_fee")),
+		ComputeGasTopUp:     transfer.NewComputeGasTopUp(deps.Transfer.WithLogger("gas_topup.compute")),
+		EnsureGasTopUp:      transfer.NewEnsureGasTopUp(deps.Transfer.WithLogger("gas_topup.ensure")),
 	}
 }

api/gateway/chain/internal/service/gateway/commands/transfer/deps.go

@@ -2,7 +2,10 @@ package transfer
 
 import (
 	"context"
+	"time"
 
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/drivers"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/rpcclient"
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
 	"github.com/tech/sendico/gateway/chain/storage"
 	clockpkg "github.com/tech/sendico/pkg/clock"
@@ -11,9 +14,11 @@ import (
 
 type Deps struct {
 	Logger           mlogger.Logger
-	Networks         map[string]shared.Network
+	Drivers          *drivers.Registry
+	Networks         *rpcclient.Registry
 	Storage          storage.Repository
 	Clock            clockpkg.Clock
+	RPCTimeout       time.Duration
 	EnsureRepository func(context.Context) error
 	LaunchExecution  func(transferRef, sourceWalletRef string, network shared.Network)
 }

api/gateway/chain/internal/service/gateway/commands/transfer/destination.go

@@ -17,21 +17,21 @@ func resolveDestination(ctx context.Context, deps Deps, dest *chainv1.TransferDe
 	managedRef := strings.TrimSpace(dest.GetManagedWalletRef())
 	external := strings.TrimSpace(dest.GetExternalAddress())
 	if managedRef != "" && external != "" {
-		deps.Logger.Warn("both managed and external destination provided")
+		deps.Logger.Warn("Both managed and external destination provided")
 		return model.TransferDestination{}, merrors.InvalidArgument("destination must be managed_wallet_ref or external_address")
 	}
 	if managedRef != "" {
 		wallet, err := deps.Storage.Wallets().Get(ctx, managedRef)
 		if err != nil {
-			deps.Logger.Warn("destination wallet lookup failed", zap.Error(err), zap.String("managed_wallet_ref", managedRef))
+			deps.Logger.Warn("Destination wallet lookup failed", zap.Error(err), zap.String("managed_wallet_ref", managedRef))
 			return model.TransferDestination{}, err
 		}
 		if !strings.EqualFold(wallet.Network, source.Network) {
-			deps.Logger.Warn("destination wallet network mismatch", zap.String("source_network", source.Network), zap.String("dest_network", wallet.Network))
+			deps.Logger.Warn("Destination wallet network mismatch", zap.String("source_network", source.Network), zap.String("dest_network", wallet.Network))
 			return model.TransferDestination{}, merrors.InvalidArgument("destination wallet network mismatch")
 		}
 		if strings.TrimSpace(wallet.DepositAddress) == "" {
-			deps.Logger.Warn("destination wallet missing deposit address", zap.String("managed_wallet_ref", managedRef))
+			deps.Logger.Warn("Destination wallet missing deposit address", zap.String("managed_wallet_ref", managedRef))
 			return model.TransferDestination{}, merrors.InvalidArgument("destination wallet missing deposit address")
 		}
 		return model.TransferDestination{
@@ -40,11 +40,26 @@ func resolveDestination(ctx context.Context, deps Deps, dest *chainv1.TransferDe
 		}, nil
 	}
 	if external == "" {
-		deps.Logger.Warn("destination external address missing")
+		deps.Logger.Warn("Destination external address missing")
 		return model.TransferDestination{}, merrors.InvalidArgument("destination is required")
 	}
+	if deps.Drivers == nil {
+		deps.Logger.Warn("Chain drivers missing", zap.String("network", source.Network))
+		return model.TransferDestination{}, merrors.Internal("chain drivers not configured")
+	}
+	chainDriver, err := deps.Drivers.Driver(source.Network)
+	if err != nil {
+		deps.Logger.Warn("Unsupported chain driver", zap.String("network", source.Network), zap.Error(err))
+		return model.TransferDestination{}, merrors.InvalidArgument("unsupported chain for wallet")
+	}
+	normalized, err := chainDriver.NormalizeAddress(external)
+	if err != nil {
+		deps.Logger.Warn("Invalid external address", zap.Error(err))
+		return model.TransferDestination{}, err
+	}
 	return model.TransferDestination{
-		ExternalAddress: strings.ToLower(external),
-		Memo:            strings.TrimSpace(dest.GetMemo()),
+		ExternalAddress:         normalized,
+		ExternalAddressOriginal: external,
+		Memo:                    strings.TrimSpace(dest.GetMemo()),
 	}, nil
 }

api/gateway/chain/internal/service/gateway/commands/transfer/destination_address.go

@@ -4,11 +4,12 @@ import (
 	"context"
 	"strings"
 
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
 	"github.com/tech/sendico/gateway/chain/storage/model"
 	"github.com/tech/sendico/pkg/merrors"
 )
 
-func destinationAddress(ctx context.Context, deps Deps, dest model.TransferDestination) (string, error) {
+func destinationAddress(ctx context.Context, deps Deps, chainDriver driver.Driver, dest model.TransferDestination) (string, error) {
 	if ref := strings.TrimSpace(dest.ManagedWalletRef); ref != "" {
 		wallet, err := deps.Storage.Wallets().Get(ctx, ref)
 		if err != nil {
@@ -17,10 +18,10 @@ func destinationAddress(ctx context.Context, deps Deps, dest model.TransferDesti
 		if strings.TrimSpace(wallet.DepositAddress) == "" {
 			return "", merrors.Internal("destination wallet missing deposit address")
 		}
-		return wallet.DepositAddress, nil
+		return chainDriver.NormalizeAddress(wallet.DepositAddress)
 	}
 	if addr := strings.TrimSpace(dest.ExternalAddress); addr != "" {
-		return strings.ToLower(addr), nil
+		return chainDriver.NormalizeAddress(addr)
 	}
 	return "", merrors.InvalidArgument("transfer destination address not resolved")
 }

api/gateway/chain/internal/service/gateway/commands/transfer/fee.go

@@ -3,22 +3,13 @@ package transfer
 import (
 	"context"
 	"errors"
-	"math/big"
 	"strings"
-	"time"
 
-	"github.com/ethereum/go-ethereum"
-	"github.com/ethereum/go-ethereum/accounts/abi"
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/ethclient"
-	"github.com/shopspring/decimal"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
-	"github.com/tech/sendico/gateway/chain/storage/model"
 	"github.com/tech/sendico/pkg/api/routers/gsresponse"
 	"github.com/tech/sendico/pkg/merrors"
-	"github.com/tech/sendico/pkg/mlogger"
 	"github.com/tech/sendico/pkg/mservice"
-	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
 	chainv1 "github.com/tech/sendico/pkg/proto/gateway/chain/v1"
 	"go.uber.org/zap"
 )
@@ -33,216 +24,94 @@ func NewEstimateTransfer(deps Deps) *estimateTransferFeeCommand {
 
 func (c *estimateTransferFeeCommand) Execute(ctx context.Context, req *chainv1.EstimateTransferFeeRequest) gsresponse.Responder[chainv1.EstimateTransferFeeResponse] {
 	if err := c.deps.EnsureRepository(ctx); err != nil {
-		c.deps.Logger.Warn("repository unavailable", zap.Error(err))
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
 		return gsresponse.Unavailable[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	if req == nil {
-		c.deps.Logger.Warn("nil request")
+		c.deps.Logger.Warn("Empty request received")
 		return gsresponse.InvalidArgument[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("request is required"))
 	}
 
 	sourceWalletRef := strings.TrimSpace(req.GetSourceWalletRef())
 	if sourceWalletRef == "" {
-		c.deps.Logger.Warn("source wallet ref missing")
+		c.deps.Logger.Warn("Source wallet ref missing")
 		return gsresponse.InvalidArgument[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("source_wallet_ref is required"))
 	}
 	amount := req.GetAmount()
 	if amount == nil || strings.TrimSpace(amount.GetAmount()) == "" || strings.TrimSpace(amount.GetCurrency()) == "" {
-		c.deps.Logger.Warn("amount missing or incomplete")
+		c.deps.Logger.Warn("Amount missing or incomplete")
 		return gsresponse.InvalidArgument[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("amount is required"))
 	}
 
 	sourceWallet, err := c.deps.Storage.Wallets().Get(ctx, sourceWalletRef)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			c.deps.Logger.Warn("source wallet not found", zap.String("source_wallet_ref", sourceWalletRef))
+			c.deps.Logger.Warn("Source wallet not found", zap.String("source_wallet_ref", sourceWalletRef))
 			return gsresponse.NotFound[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, err)
 		}
-		c.deps.Logger.Warn("storage get wallet failed", zap.Error(err), zap.String("source_wallet_ref", sourceWalletRef))
+		c.deps.Logger.Warn("Storage get wallet failed", zap.Error(err), zap.String("source_wallet_ref", sourceWalletRef))
 		return gsresponse.Auto[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 
 	networkKey := strings.ToLower(strings.TrimSpace(sourceWallet.Network))
-	networkCfg, ok := c.deps.Networks[networkKey]
+	networkCfg, ok := c.deps.Networks.Network(networkKey)
 	if !ok {
-		c.deps.Logger.Warn("unsupported chain", zap.String("network", networkKey))
+		c.deps.Logger.Warn("Unsupported chain", zap.String("network", networkKey))
+		return gsresponse.InvalidArgument[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("unsupported chain for wallet"))
+	}
+	if c.deps.Drivers == nil {
+		c.deps.Logger.Warn("Chain drivers missing", zap.String("network", networkKey))
+		return gsresponse.Internal[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, merrors.Internal("chain drivers not configured"))
+	}
+	chainDriver, err := c.deps.Drivers.Driver(networkKey)
+	if err != nil {
+		c.deps.Logger.Warn("Unsupported chain driver", zap.String("network", networkKey), zap.Error(err))
 		return gsresponse.InvalidArgument[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("unsupported chain for wallet"))
 	}
 
 	dest, err := resolveDestination(ctx, c.deps, req.GetDestination(), sourceWallet)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			c.deps.Logger.Warn("destination not found", zap.String("destination_wallet_ref", req.GetDestination().GetManagedWalletRef()))
+			c.deps.Logger.Warn("Destination not found", zap.String("destination_wallet_ref", req.GetDestination().GetManagedWalletRef()))
 			return gsresponse.NotFound[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, err)
 		}
-		c.deps.Logger.Warn("invalid destination", zap.Error(err))
+		c.deps.Logger.Warn("Invalid destination", zap.Error(err))
 		return gsresponse.InvalidArgument[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 
-	destinationAddress, err := destinationAddress(ctx, c.deps, dest)
+	destinationAddress, err := destinationAddress(ctx, c.deps, chainDriver, dest)
 	if err != nil {
-		c.deps.Logger.Warn("failed to resolve destination address", zap.Error(err))
+		c.deps.Logger.Warn("Failed to resolve destination address", zap.Error(err))
 		return gsresponse.InvalidArgument[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 
-	feeMoney, err := estimateNetworkFee(ctx, c.deps.Logger, networkCfg, sourceWallet, destinationAddress, amount)
+	walletForFee := sourceWallet
+	nativeCurrency := shared.NativeCurrency(networkCfg)
+	if nativeCurrency != "" && strings.EqualFold(nativeCurrency, amount.GetCurrency()) {
+		copyWallet := *sourceWallet
+		copyWallet.ContractAddress = ""
+		copyWallet.TokenSymbol = nativeCurrency
+		walletForFee = &copyWallet
+	}
+
+	driverDeps := driver.Deps{
+		Logger:     c.deps.Logger,
+		Registry:   c.deps.Networks,
+		RPCTimeout: c.deps.RPCTimeout,
+	}
+	feeMoney, err := chainDriver.EstimateFee(ctx, driverDeps, networkCfg, walletForFee, destinationAddress, amount)
 	if err != nil {
-		c.deps.Logger.Warn("fee estimation failed", zap.Error(err))
+		c.deps.Logger.Warn("Fee estimation failed", zap.Error(err))
 		return gsresponse.Auto[chainv1.EstimateTransferFeeResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 
+	contextLabel := "erc20_transfer"
+	if strings.TrimSpace(walletForFee.ContractAddress) == "" {
+		contextLabel = "native_transfer"
+	}
 	resp := &chainv1.EstimateTransferFeeResponse{
 		NetworkFee:        feeMoney,
-		EstimationContext: "erc20_transfer",
+		EstimationContext: contextLabel,
 	}
 	return gsresponse.Success(resp)
 }
-
-func estimateNetworkFee(ctx context.Context, logger mlogger.Logger, network shared.Network, wallet *model.ManagedWallet, destination string, amount *moneyv1.Money) (*moneyv1.Money, error) {
-	rpcURL := strings.TrimSpace(network.RPCURL)
-	if rpcURL == "" {
-		return nil, merrors.InvalidArgument("network rpc url not configured")
-	}
-	if strings.TrimSpace(wallet.ContractAddress) == "" {
-		return nil, merrors.NotImplemented("native token transfers not supported")
-	}
-	if !common.IsHexAddress(wallet.ContractAddress) {
-		return nil, merrors.InvalidArgument("invalid token contract address")
-	}
-	if !common.IsHexAddress(wallet.DepositAddress) {
-		return nil, merrors.InvalidArgument("invalid source wallet address")
-	}
-	if !common.IsHexAddress(destination) {
-		return nil, merrors.InvalidArgument("invalid destination address")
-	}
-
-	client, err := ethclient.DialContext(ctx, rpcURL)
-	if err != nil {
-		return nil, merrors.Internal("failed to connect to rpc: " + err.Error())
-	}
-	defer client.Close()
-
-	timeoutCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
-	defer cancel()
-
-	tokenABI, err := abi.JSON(strings.NewReader(erc20TransferABI))
-	if err != nil {
-		return nil, merrors.Internal("failed to parse erc20 abi: " + err.Error())
-	}
-	tokenAddr := common.HexToAddress(wallet.ContractAddress)
-	toAddr := common.HexToAddress(destination)
-	fromAddr := common.HexToAddress(wallet.DepositAddress)
-
-	decimals, err := erc20Decimals(timeoutCtx, client, tokenABI, tokenAddr)
-	if err != nil {
-		logger.Warn("failed to read token decimals", zap.Error(err))
-		return nil, err
-	}
-
-	amountBase, err := toBaseUnits(strings.TrimSpace(amount.GetAmount()), decimals)
-	if err != nil {
-		return nil, err
-	}
-
-	input, err := tokenABI.Pack("transfer", toAddr, amountBase)
-	if err != nil {
-		return nil, merrors.Internal("failed to encode transfer call: " + err.Error())
-	}
-
-	gasPrice, err := client.SuggestGasPrice(timeoutCtx)
-	if err != nil {
-		return nil, merrors.Internal("failed to suggest gas price: " + err.Error())
-	}
-
-	callMsg := ethereum.CallMsg{
-		From:     fromAddr,
-		To:       &tokenAddr,
-		GasPrice: gasPrice,
-		Data:     input,
-	}
-	gasLimit, err := client.EstimateGas(timeoutCtx, callMsg)
-	if err != nil {
-		return nil, merrors.Internal("failed to estimate gas: " + err.Error())
-	}
-
-	fee := new(big.Int).Mul(gasPrice, new(big.Int).SetUint64(gasLimit))
-	feeDec := decimal.NewFromBigInt(fee, 0)
-
-	currency := strings.ToUpper(strings.TrimSpace(network.NativeToken))
-	if currency == "" {
-		currency = strings.ToUpper(network.Name)
-	}
-
-	return &moneyv1.Money{
-		Currency: currency,
-		Amount:   feeDec.String(),
-	}, nil
-}
-
-func erc20Decimals(ctx context.Context, client *ethclient.Client, tokenABI abi.ABI, token common.Address) (uint8, error) {
-	callData, err := tokenABI.Pack("decimals")
-	if err != nil {
-		return 0, merrors.Internal("failed to encode decimals call: " + err.Error())
-	}
-	msg := ethereum.CallMsg{
-		To:   &token,
-		Data: callData,
-	}
-	output, err := client.CallContract(ctx, msg, nil)
-	if err != nil {
-		return 0, merrors.Internal("decimals call failed: " + err.Error())
-	}
-	values, err := tokenABI.Unpack("decimals", output)
-	if err != nil {
-		return 0, merrors.Internal("failed to unpack decimals: " + err.Error())
-	}
-	if len(values) == 0 {
-		return 0, merrors.Internal("decimals call returned no data")
-	}
-	decimals, ok := values[0].(uint8)
-	if !ok {
-		return 0, merrors.Internal("decimals call returned unexpected type")
-	}
-	return decimals, nil
-}
-
-func toBaseUnits(amount string, decimals uint8) (*big.Int, error) {
-	value, err := decimal.NewFromString(strings.TrimSpace(amount))
-	if err != nil {
-		return nil, merrors.InvalidArgument("invalid amount " + amount + ": " + err.Error())
-	}
-	if value.IsNegative() {
-		return nil, merrors.InvalidArgument("amount must be positive")
-	}
-	multiplier := decimal.NewFromInt(1).Shift(int32(decimals))
-	scaled := value.Mul(multiplier)
-	if !scaled.Equal(scaled.Truncate(0)) {
-		return nil, merrors.InvalidArgument("amount " + amount + " exceeds token precision")
-	}
-	return scaled.BigInt(), nil
-}
-
-const erc20TransferABI = `
-[
-	{
-		"constant": true,
-		"inputs": [],
-		"name": "decimals",
-		"outputs": [{ "name": "", "type": "uint8" }],
-		"payable": false,
-		"stateMutability": "view",
-        "type": "function"
-	},
-	{
-		"constant": false,
-		"inputs": [
-			{ "name": "_to", "type": "address" },
-			{ "name": "_value", "type": "uint256" }
-		],
-		"name": "transfer",
-		"outputs": [{ "name": "", "type": "bool" }],
-		"payable": false,
-		"stateMutability": "nonpayable",
-		"type": "function"
-	}
-]`

api/gateway/chain/internal/service/gateway/commands/transfer/gas_topup.go

@@ -0,0 +1,290 @@
+package transfer
+
+import (
+	"context"
+	"strings"
+
+	"github.com/shopspring/decimal"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/commands/wallet"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver/evm"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver/tron"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	"github.com/tech/sendico/pkg/api/routers/gsresponse"
+	"github.com/tech/sendico/pkg/merrors"
+	"github.com/tech/sendico/pkg/mlogger"
+	"github.com/tech/sendico/pkg/mservice"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+	chainv1 "github.com/tech/sendico/pkg/proto/gateway/chain/v1"
+	"go.uber.org/zap"
+)
+
+type computeGasTopUpCommand struct {
+	deps Deps
+}
+
+func NewComputeGasTopUp(deps Deps) *computeGasTopUpCommand {
+	return &computeGasTopUpCommand{deps: deps}
+}
+
+func (c *computeGasTopUpCommand) Execute(ctx context.Context, req *chainv1.ComputeGasTopUpRequest) gsresponse.Responder[chainv1.ComputeGasTopUpResponse] {
+	if err := c.deps.EnsureRepository(ctx); err != nil {
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
+		return gsresponse.Unavailable[chainv1.ComputeGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, err)
+	}
+	if req == nil {
+		c.deps.Logger.Warn("Nil request")
+		return gsresponse.InvalidArgument[chainv1.ComputeGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("request is required"))
+	}
+
+	walletRef := strings.TrimSpace(req.GetWalletRef())
+	if walletRef == "" {
+		c.deps.Logger.Warn("Wallet ref missing")
+		return gsresponse.InvalidArgument[chainv1.ComputeGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("wallet_ref is required"))
+	}
+	estimatedFee := req.GetEstimatedTotalFee()
+	if estimatedFee == nil || strings.TrimSpace(estimatedFee.GetAmount()) == "" || strings.TrimSpace(estimatedFee.GetCurrency()) == "" {
+		c.deps.Logger.Warn("Estimated fee missing")
+		return gsresponse.InvalidArgument[chainv1.ComputeGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("estimated_total_fee is required"))
+	}
+
+	topUp, capHit, decision, nativeBalance, walletModel, err := computeGasTopUp(ctx, c.deps, walletRef, estimatedFee)
+	if err != nil {
+		return gsresponse.Auto[chainv1.ComputeGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, err)
+	}
+
+	logDecision(c.deps.Logger, walletRef, estimatedFee, nativeBalance, topUp, capHit, decision, walletModel)
+
+	return gsresponse.Success(&chainv1.ComputeGasTopUpResponse{
+		TopupAmount: topUp,
+		CapHit:      capHit,
+	})
+}
+
+type ensureGasTopUpCommand struct {
+	deps Deps
+}
+
+func NewEnsureGasTopUp(deps Deps) *ensureGasTopUpCommand {
+	return &ensureGasTopUpCommand{deps: deps}
+}
+
+func (c *ensureGasTopUpCommand) Execute(ctx context.Context, req *chainv1.EnsureGasTopUpRequest) gsresponse.Responder[chainv1.EnsureGasTopUpResponse] {
+	if err := c.deps.EnsureRepository(ctx); err != nil {
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
+		return gsresponse.Unavailable[chainv1.EnsureGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, err)
+	}
+	if req == nil {
+		c.deps.Logger.Warn("Nil request")
+		return gsresponse.InvalidArgument[chainv1.EnsureGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("request is required"))
+	}
+
+	idempotencyKey := strings.TrimSpace(req.GetIdempotencyKey())
+	if idempotencyKey == "" {
+		c.deps.Logger.Warn("Idempotency key missing")
+		return gsresponse.InvalidArgument[chainv1.EnsureGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("idempotency_key is required"))
+	}
+	organizationRef := strings.TrimSpace(req.GetOrganizationRef())
+	if organizationRef == "" {
+		c.deps.Logger.Warn("Organization ref missing")
+		return gsresponse.InvalidArgument[chainv1.EnsureGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("organization_ref is required"))
+	}
+	sourceWalletRef := strings.TrimSpace(req.GetSourceWalletRef())
+	if sourceWalletRef == "" {
+		c.deps.Logger.Warn("Source wallet ref missing")
+		return gsresponse.InvalidArgument[chainv1.EnsureGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("source_wallet_ref is required"))
+	}
+	targetWalletRef := strings.TrimSpace(req.GetTargetWalletRef())
+	if targetWalletRef == "" {
+		c.deps.Logger.Warn("Target wallet ref missing")
+		return gsresponse.InvalidArgument[chainv1.EnsureGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("target_wallet_ref is required"))
+	}
+	estimatedFee := req.GetEstimatedTotalFee()
+	if estimatedFee == nil || strings.TrimSpace(estimatedFee.GetAmount()) == "" || strings.TrimSpace(estimatedFee.GetCurrency()) == "" {
+		c.deps.Logger.Warn("Estimated fee missing")
+		return gsresponse.InvalidArgument[chainv1.EnsureGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("estimated_total_fee is required"))
+	}
+
+	topUp, capHit, decision, nativeBalance, walletModel, err := computeGasTopUp(ctx, c.deps, targetWalletRef, estimatedFee)
+	if err != nil {
+		return gsresponse.Auto[chainv1.EnsureGasTopUpResponse](c.deps.Logger, mservice.ChainGateway, err)
+	}
+
+	logDecision(c.deps.Logger, targetWalletRef, estimatedFee, nativeBalance, topUp, capHit, decision, walletModel)
+
+	if topUp == nil || strings.TrimSpace(topUp.GetAmount()) == "" {
+		return gsresponse.Success(&chainv1.EnsureGasTopUpResponse{
+			TopupAmount: nil,
+			CapHit:      capHit,
+		})
+	}
+
+	submitReq := &chainv1.SubmitTransferRequest{
+		IdempotencyKey:  idempotencyKey,
+		OrganizationRef: organizationRef,
+		SourceWalletRef: sourceWalletRef,
+		Destination: &chainv1.TransferDestination{
+			Destination: &chainv1.TransferDestination_ManagedWalletRef{ManagedWalletRef: targetWalletRef},
+		},
+		Amount:          topUp,
+		Metadata:        shared.CloneMetadata(req.GetMetadata()),
+		ClientReference: strings.TrimSpace(req.GetClientReference()),
+	}
+
+	submitResponder := NewSubmitTransfer(c.deps.WithLogger("transfer.submit")).Execute(ctx, submitReq)
+	return func(ctx context.Context) (*chainv1.EnsureGasTopUpResponse, error) {
+		submitResp, err := submitResponder(ctx)
+		if err != nil {
+			return nil, err
+		}
+		return &chainv1.EnsureGasTopUpResponse{
+			TopupAmount: topUp,
+			CapHit:      capHit,
+			Transfer:    submitResp.GetTransfer(),
+		}, nil
+	}
+}
+
+func computeGasTopUp(ctx context.Context, deps Deps, walletRef string, estimatedFee *moneyv1.Money) (*moneyv1.Money, bool, *tron.GasTopUpDecision, *moneyv1.Money, *model.ManagedWallet, error) {
+	walletRef = strings.TrimSpace(walletRef)
+	estimatedFee = shared.CloneMoney(estimatedFee)
+	walletModel, err := deps.Storage.Wallets().Get(ctx, walletRef)
+	if err != nil {
+		return nil, false, nil, nil, nil, err
+	}
+
+	networkKey := strings.ToLower(strings.TrimSpace(walletModel.Network))
+	networkCfg, ok := deps.Networks.Network(networkKey)
+	if !ok {
+		return nil, false, nil, nil, nil, merrors.InvalidArgument("unsupported chain for wallet")
+	}
+
+	nativeBalance, err := nativeBalanceForWallet(ctx, deps, walletModel)
+	if err != nil {
+		return nil, false, nil, nil, nil, err
+	}
+
+	if strings.HasPrefix(networkKey, "tron") {
+		topUp, decision, err := tron.ComputeGasTopUp(networkCfg, walletModel, estimatedFee, nativeBalance)
+		if err != nil {
+			return nil, false, nil, nil, nil, err
+		}
+		return topUp, decision.CapHit, &decision, nativeBalance, walletModel, nil
+	}
+
+	if networkCfg.GasTopUpPolicy != nil {
+		topUp, capHit, err := evm.ComputeGasTopUp(networkCfg, walletModel, estimatedFee, nativeBalance)
+		if err != nil {
+			return nil, false, nil, nil, nil, err
+		}
+		return topUp, capHit, nil, nativeBalance, walletModel, nil
+	}
+
+	topUp, err := defaultGasTopUp(estimatedFee, nativeBalance)
+	if err != nil {
+		return nil, false, nil, nil, nil, err
+	}
+	return topUp, false, nil, nativeBalance, walletModel, nil
+}
+
+func nativeBalanceForWallet(ctx context.Context, deps Deps, walletModel *model.ManagedWallet) (*moneyv1.Money, error) {
+	if walletModel == nil {
+		return nil, merrors.InvalidArgument("wallet is required")
+	}
+	walletDeps := wallet.Deps{
+		Logger:           deps.Logger.Named("wallet"),
+		Drivers:          deps.Drivers,
+		Networks:         deps.Networks,
+		KeyManager:       nil,
+		Storage:          deps.Storage,
+		Clock:            deps.Clock,
+		BalanceCacheTTL:  0,
+		RPCTimeout:       deps.RPCTimeout,
+		EnsureRepository: deps.EnsureRepository,
+	}
+	_, nativeBalance, err := wallet.OnChainWalletBalances(ctx, walletDeps, walletModel)
+	if err != nil {
+		return nil, err
+	}
+	if nativeBalance == nil || strings.TrimSpace(nativeBalance.GetAmount()) == "" || strings.TrimSpace(nativeBalance.GetCurrency()) == "" {
+		return nil, merrors.InvalidArgument("native balance is unavailable")
+	}
+	return nativeBalance, nil
+}
+
+func defaultGasTopUp(estimatedFee *moneyv1.Money, currentBalance *moneyv1.Money) (*moneyv1.Money, error) {
+	if estimatedFee == nil || strings.TrimSpace(estimatedFee.GetAmount()) == "" || strings.TrimSpace(estimatedFee.GetCurrency()) == "" {
+		return nil, merrors.InvalidArgument("estimated fee is required")
+	}
+	if currentBalance == nil || strings.TrimSpace(currentBalance.GetAmount()) == "" || strings.TrimSpace(currentBalance.GetCurrency()) == "" {
+		return nil, merrors.InvalidArgument("native balance is required")
+	}
+	if !strings.EqualFold(estimatedFee.GetCurrency(), currentBalance.GetCurrency()) {
+		return nil, merrors.InvalidArgument("native balance currency mismatch")
+	}
+
+	estimated, err := decimal.NewFromString(strings.TrimSpace(estimatedFee.GetAmount()))
+	if err != nil {
+		return nil, err
+	}
+	current, err := decimal.NewFromString(strings.TrimSpace(currentBalance.GetAmount()))
+	if err != nil {
+		return nil, err
+	}
+	required := estimated.Sub(current)
+	if !required.IsPositive() {
+		return nil, nil
+	}
+	return &moneyv1.Money{
+		Currency: strings.ToUpper(strings.TrimSpace(estimatedFee.GetCurrency())),
+		Amount:   required.String(),
+	}, nil
+}
+
+func logDecision(logger mlogger.Logger, walletRef string, estimatedFee *moneyv1.Money, nativeBalance *moneyv1.Money, topUp *moneyv1.Money, capHit bool, decision *tron.GasTopUpDecision, walletModel *model.ManagedWallet) {
+	if logger == nil {
+		return
+	}
+	fields := []zap.Field{
+		zap.String("wallet_ref", walletRef),
+		zap.String("estimated_total_fee", amountString(estimatedFee)),
+		zap.String("current_native_balance", amountString(nativeBalance)),
+		zap.String("topup_amount", amountString(topUp)),
+		zap.Bool("cap_hit", capHit),
+	}
+	if walletModel != nil {
+		fields = append(fields, zap.String("network", strings.TrimSpace(walletModel.Network)))
+	}
+	if decision != nil {
+		fields = append(fields,
+			zap.String("estimated_total_fee_trx", decision.EstimatedFeeTRX.String()),
+			zap.String("current_native_balance_trx", decision.CurrentBalanceTRX.String()),
+			zap.String("required_trx", decision.RequiredTRX.String()),
+			zap.String("buffered_required_trx", decision.BufferedRequiredTRX.String()),
+			zap.String("min_balance_topup_trx", decision.MinBalanceTopUpTRX.String()),
+			zap.String("raw_topup_trx", decision.RawTopUpTRX.String()),
+			zap.String("rounded_topup_trx", decision.RoundedTopUpTRX.String()),
+			zap.String("topup_trx", decision.TopUpTRX.String()),
+			zap.String("operation_type", decision.OperationType),
+		)
+	}
+	logger.Info("Gas top-up decision", fields...)
+}
+
+func amountString(m *moneyv1.Money) string {
+	if m == nil {
+		return ""
+	}
+	amount := strings.TrimSpace(m.GetAmount())
+	currency := strings.TrimSpace(m.GetCurrency())
+	if amount == "" && currency == "" {
+		return ""
+	}
+	if currency == "" {
+		return amount
+	}
+	if amount == "" {
+		return currency
+	}
+	return amount + " " + currency
+}

api/gateway/chain/internal/service/gateway/commands/transfer/get.go

@@ -22,25 +22,25 @@ func NewGetTransfer(deps Deps) *getTransferCommand {
 
 func (c *getTransferCommand) Execute(ctx context.Context, req *chainv1.GetTransferRequest) gsresponse.Responder[chainv1.GetTransferResponse] {
 	if err := c.deps.EnsureRepository(ctx); err != nil {
-		c.deps.Logger.Warn("repository unavailable", zap.Error(err))
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
 		return gsresponse.Unavailable[chainv1.GetTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	if req == nil {
-		c.deps.Logger.Warn("nil request")
+		c.deps.Logger.Warn("Nil request")
 		return gsresponse.InvalidArgument[chainv1.GetTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("nil request"))
 	}
 	transferRef := strings.TrimSpace(req.GetTransferRef())
 	if transferRef == "" {
-		c.deps.Logger.Warn("transfer_ref missing")
+		c.deps.Logger.Warn("Transfer_ref missing")
 		return gsresponse.InvalidArgument[chainv1.GetTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("transfer_ref is required"))
 	}
 	transfer, err := c.deps.Storage.Transfers().Get(ctx, transferRef)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			c.deps.Logger.Warn("not found", zap.String("transfer_ref", transferRef))
+			c.deps.Logger.Warn("Not found", zap.String("transfer_ref", transferRef))
 			return gsresponse.NotFound[chainv1.GetTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 		}
-		c.deps.Logger.Warn("storage get failed", zap.Error(err), zap.String("transfer_ref", transferRef))
+		c.deps.Logger.Warn("Storage get failed", zap.Error(err), zap.String("transfer_ref", transferRef))
 		return gsresponse.Auto[chainv1.GetTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	return gsresponse.Success(&chainv1.GetTransferResponse{Transfer: toProtoTransfer(transfer)})

api/gateway/chain/internal/service/gateway/commands/transfer/list.go

@@ -23,7 +23,7 @@ func NewListTransfers(deps Deps) *listTransfersCommand {
 
 func (c *listTransfersCommand) Execute(ctx context.Context, req *chainv1.ListTransfersRequest) gsresponse.Responder[chainv1.ListTransfersResponse] {
 	if err := c.deps.EnsureRepository(ctx); err != nil {
-		c.deps.Logger.Warn("repository unavailable", zap.Error(err))
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
 		return gsresponse.Unavailable[chainv1.ListTransfersResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	filter := model.TransferFilter{}
@@ -41,7 +41,7 @@ func (c *listTransfersCommand) Execute(ctx context.Context, req *chainv1.ListTra
 
 	result, err := c.deps.Storage.Transfers().List(ctx, filter)
 	if err != nil {
-		c.deps.Logger.Warn("storage list failed", zap.Error(err))
+		c.deps.Logger.Warn("Storage list failed", zap.Error(err))
 		return gsresponse.Auto[chainv1.ListTransfersResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 

api/gateway/chain/internal/service/gateway/commands/transfer/submit.go

@@ -25,94 +25,102 @@ func NewSubmitTransfer(deps Deps) *submitTransferCommand {
 
 func (c *submitTransferCommand) Execute(ctx context.Context, req *chainv1.SubmitTransferRequest) gsresponse.Responder[chainv1.SubmitTransferResponse] {
 	if err := c.deps.EnsureRepository(ctx); err != nil {
-		c.deps.Logger.Warn("repository unavailable", zap.Error(err))
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
 		return gsresponse.Unavailable[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	if req == nil {
-		c.deps.Logger.Warn("nil request")
+		c.deps.Logger.Warn("Nil request")
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("nil request"))
 	}
 
 	idempotencyKey := strings.TrimSpace(req.GetIdempotencyKey())
 	if idempotencyKey == "" {
-		c.deps.Logger.Warn("missing idempotency key")
+		c.deps.Logger.Warn("Missing idempotency key")
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("idempotency_key is required"))
 	}
 	organizationRef := strings.TrimSpace(req.GetOrganizationRef())
 	if organizationRef == "" {
-		c.deps.Logger.Warn("missing organization ref")
+		c.deps.Logger.Warn("Missing organization ref")
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("organization_ref is required"))
 	}
 	sourceWalletRef := strings.TrimSpace(req.GetSourceWalletRef())
 	if sourceWalletRef == "" {
-		c.deps.Logger.Warn("missing source wallet ref")
+		c.deps.Logger.Warn("Missing source wallet ref")
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("source_wallet_ref is required"))
 	}
 	amount := req.GetAmount()
 	if amount == nil {
-		c.deps.Logger.Warn("missing amount")
+		c.deps.Logger.Warn("Missing amount")
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("amount is required"))
 	}
 	amountCurrency := strings.ToUpper(strings.TrimSpace(amount.GetCurrency()))
 	if amountCurrency == "" {
-		c.deps.Logger.Warn("missing amount currency")
+		c.deps.Logger.Warn("Missing amount currency")
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("amount.currency is required"))
 	}
 	amountValue := strings.TrimSpace(amount.GetAmount())
 	if amountValue == "" {
-		c.deps.Logger.Warn("missing amount value")
+		c.deps.Logger.Warn("Missing amount value")
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("amount.amount is required"))
 	}
 
 	sourceWallet, err := c.deps.Storage.Wallets().Get(ctx, sourceWalletRef)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			c.deps.Logger.Warn("source wallet not found", zap.String("source_wallet_ref", sourceWalletRef))
+			c.deps.Logger.Warn("Source wallet not found", zap.String("source_wallet_ref", sourceWalletRef))
 			return gsresponse.NotFound[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 		}
-		c.deps.Logger.Warn("storage get wallet failed", zap.Error(err), zap.String("source_wallet_ref", sourceWalletRef))
+		c.deps.Logger.Warn("Storage get wallet failed", zap.Error(err), zap.String("source_wallet_ref", sourceWalletRef))
 		return gsresponse.Auto[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	if !strings.EqualFold(sourceWallet.OrganizationRef, organizationRef) {
-		c.deps.Logger.Warn("organization mismatch", zap.String("wallet_org", sourceWallet.OrganizationRef), zap.String("req_org", organizationRef))
+		c.deps.Logger.Warn("Organization mismatch", zap.String("wallet_org", sourceWallet.OrganizationRef), zap.String("req_org", organizationRef))
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("organization_ref mismatch with wallet"))
 	}
 	networkKey := strings.ToLower(strings.TrimSpace(sourceWallet.Network))
-	networkCfg, ok := c.deps.Networks[networkKey]
+	networkCfg, ok := c.deps.Networks.Network(networkKey)
 	if !ok {
-		c.deps.Logger.Warn("unsupported chain", zap.String("network", networkKey))
+		c.deps.Logger.Warn("Unsupported chain", zap.String("network", networkKey))
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("unsupported chain for wallet"))
 	}
 
 	destination, err := resolveDestination(ctx, c.deps, req.GetDestination(), sourceWallet)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			c.deps.Logger.Warn("destination not found", zap.String("destination_wallet_ref", req.GetDestination().GetManagedWalletRef()))
+			c.deps.Logger.Warn("Destination not found", zap.String("destination_wallet_ref", req.GetDestination().GetManagedWalletRef()))
 			return gsresponse.NotFound[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 		}
-		c.deps.Logger.Warn("invalid destination", zap.Error(err))
+		c.deps.Logger.Warn("Invalid destination", zap.Error(err))
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 
 	fees, feeSum, err := convertFees(req.GetFees(), amountCurrency)
 	if err != nil {
-		c.deps.Logger.Warn("fee conversion failed", zap.Error(err))
+		c.deps.Logger.Warn("Fee conversion failed", zap.Error(err))
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	amountDec, err := decimal.NewFromString(amountValue)
 	if err != nil {
-		c.deps.Logger.Warn("invalid amount", zap.Error(err))
+		c.deps.Logger.Warn("Invalid amount", zap.Error(err))
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("invalid amount"))
 	}
 	netDec := amountDec.Sub(feeSum)
 	if netDec.IsNegative() {
-		c.deps.Logger.Warn("fees exceed amount", zap.String("amount", amountValue), zap.String("fee_sum", feeSum.String()))
+		c.deps.Logger.Warn("Fees exceed amount", zap.String("amount", amountValue), zap.String("fee_sum", feeSum.String()))
 		return gsresponse.InvalidArgument[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("fees exceed amount"))
 	}
 
 	netAmount := shared.CloneMoney(amount)
 	netAmount.Amount = netDec.String()
 
+	effectiveTokenSymbol := sourceWallet.TokenSymbol
+	effectiveContractAddress := sourceWallet.ContractAddress
+	nativeCurrency := shared.NativeCurrency(networkCfg)
+	if nativeCurrency != "" && strings.EqualFold(nativeCurrency, amountCurrency) {
+		effectiveTokenSymbol = nativeCurrency
+		effectiveContractAddress = ""
+	}
+
 	transfer := &model.Transfer{
 		IdempotencyKey:  idempotencyKey,
 		TransferRef:     shared.GenerateTransferRef(),
@@ -120,8 +128,8 @@ func (c *submitTransferCommand) Execute(ctx context.Context, req *chainv1.Submit
 		SourceWalletRef: sourceWalletRef,
 		Destination:     destination,
 		Network:         sourceWallet.Network,
-		TokenSymbol:     sourceWallet.TokenSymbol,
-		ContractAddress: sourceWallet.ContractAddress,
+		TokenSymbol:     effectiveTokenSymbol,
+		ContractAddress: effectiveContractAddress,
 		RequestedAmount: shared.CloneMoney(amount),
 		NetAmount:       netAmount,
 		Fees:            fees,
@@ -133,10 +141,10 @@ func (c *submitTransferCommand) Execute(ctx context.Context, req *chainv1.Submit
 	saved, err := c.deps.Storage.Transfers().Create(ctx, transfer)
 	if err != nil {
 		if errors.Is(err, merrors.ErrDataConflict) {
-			c.deps.Logger.Debug("transfer already exists", zap.String("transfer_ref", transfer.TransferRef), zap.String("idempotency_key", idempotencyKey))
+			c.deps.Logger.Debug("Transfer already exists", zap.String("transfer_ref", transfer.TransferRef), zap.String("idempotency_key", idempotencyKey))
 			return gsresponse.Success(&chainv1.SubmitTransferResponse{Transfer: toProtoTransfer(saved)})
 		}
-		c.deps.Logger.Warn("storage create failed", zap.Error(err), zap.String("transfer_ref", transfer.TransferRef))
+		c.deps.Logger.Warn("Storage create failed", zap.Error(err), zap.String("transfer_ref", transfer.TransferRef))
 		return gsresponse.Auto[chainv1.SubmitTransferResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 

api/gateway/chain/internal/service/gateway/commands/wallet/balance.go

@@ -29,41 +29,41 @@ func NewGetWalletBalance(deps Deps) *getWalletBalanceCommand {
 
 func (c *getWalletBalanceCommand) Execute(ctx context.Context, req *chainv1.GetWalletBalanceRequest) gsresponse.Responder[chainv1.GetWalletBalanceResponse] {
 	if err := c.deps.EnsureRepository(ctx); err != nil {
-		c.deps.Logger.Warn("repository unavailable", zap.Error(err))
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
 		return gsresponse.Unavailable[chainv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	if req == nil {
-		c.deps.Logger.Warn("nil request")
+		c.deps.Logger.Warn("Nil request")
 		return gsresponse.InvalidArgument[chainv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("nil request"))
 	}
 	walletRef := strings.TrimSpace(req.GetWalletRef())
 	if walletRef == "" {
-		c.deps.Logger.Warn("wallet_ref missing")
+		c.deps.Logger.Warn("Wallet_ref missing")
 		return gsresponse.InvalidArgument[chainv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("wallet_ref is required"))
 	}
 	wallet, err := c.deps.Storage.Wallets().Get(ctx, walletRef)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			c.deps.Logger.Warn("not found", zap.String("wallet_ref", walletRef))
+			c.deps.Logger.Warn("Not found", zap.String("wallet_ref", walletRef))
 			return gsresponse.NotFound[chainv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, err)
 		}
-		c.deps.Logger.Warn("storage get failed", zap.Error(err), zap.String("wallet_ref", walletRef))
+		c.deps.Logger.Warn("Storage get failed", zap.Error(err), zap.String("wallet_ref", walletRef))
 		return gsresponse.Auto[chainv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 
-	balance, chainErr := onChainWalletBalance(ctx, c.deps, wallet)
+	tokenBalance, nativeBalance, chainErr := OnChainWalletBalances(ctx, c.deps, wallet)
 	if chainErr != nil {
-		c.deps.Logger.Warn("on-chain balance fetch failed, attempting cached balance", zap.Error(chainErr), zap.String("wallet_ref", walletRef))
+		c.deps.Logger.Warn("On-chain balance fetch failed, attempting cached balance", zap.Error(chainErr), zap.String("wallet_ref", walletRef))
 		stored, err := c.deps.Storage.Wallets().GetBalance(ctx, walletRef)
 		if err != nil {
 			if errors.Is(err, merrors.ErrNoData) {
-				c.deps.Logger.Warn("cached balance not found", zap.String("wallet_ref", walletRef))
+				c.deps.Logger.Warn("Cached balance not found", zap.String("wallet_ref", walletRef))
 				return gsresponse.Auto[chainv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, chainErr)
 			}
 			return gsresponse.Auto[chainv1.GetWalletBalanceResponse](c.deps.Logger, mservice.ChainGateway, err)
 		}
 		if c.isCachedBalanceStale(stored) {
-			c.deps.Logger.Warn("cached balance is stale",
+			c.deps.Logger.Info("Cached balance is stale",
 				zap.String("wallet_ref", walletRef),
 				zap.Time("calculated_at", stored.CalculatedAt),
 				zap.Duration("ttl", c.cacheTTL()),
@@ -74,39 +74,49 @@ func (c *getWalletBalanceCommand) Execute(ctx context.Context, req *chainv1.GetW
 	}
 
 	calculatedAt := c.now()
-	c.persistCachedBalance(ctx, walletRef, balance, calculatedAt)
+	c.persistCachedBalance(ctx, walletRef, tokenBalance, nativeBalance, calculatedAt)
 
 	return gsresponse.Success(&chainv1.GetWalletBalanceResponse{
-		Balance: onChainBalanceToProto(balance, calculatedAt),
+		Balance: onChainBalanceToProto(tokenBalance, nativeBalance, calculatedAt),
 	})
 }
 
-func onChainBalanceToProto(balance *moneyv1.Money, calculatedAt time.Time) *chainv1.WalletBalance {
-	if balance == nil {
+func onChainBalanceToProto(balance *moneyv1.Money, native *moneyv1.Money, calculatedAt time.Time) *chainv1.WalletBalance {
+	if balance == nil && native == nil {
 		return nil
 	}
-	zero := zeroMoney(balance.Currency)
+	currency := ""
+	if balance != nil {
+		currency = balance.Currency
+	}
+	zero := zeroMoney(currency)
 	return &chainv1.WalletBalance{
 		Available:       balance,
+		NativeAvailable: native,
 		PendingInbound:  zero,
 		PendingOutbound: zero,
 		CalculatedAt:    timestamppb.New(calculatedAt.UTC()),
 	}
 }
 
-func (c *getWalletBalanceCommand) persistCachedBalance(ctx context.Context, walletRef string, available *moneyv1.Money, calculatedAt time.Time) {
-	if available == nil {
+func (c *getWalletBalanceCommand) persistCachedBalance(ctx context.Context, walletRef string, available *moneyv1.Money, nativeAvailable *moneyv1.Money, calculatedAt time.Time) {
+	if available == nil && nativeAvailable == nil {
 		return
 	}
 	record := &model.WalletBalance{
 		WalletRef:       walletRef,
 		Available:       shared.CloneMoney(available),
-		PendingInbound:  zeroMoney(available.Currency),
-		PendingOutbound: zeroMoney(available.Currency),
+		NativeAvailable: shared.CloneMoney(nativeAvailable),
 		CalculatedAt:    calculatedAt,
 	}
+	currency := ""
+	if available != nil {
+		currency = available.Currency
+	}
+	record.PendingInbound = zeroMoney(currency)
+	record.PendingOutbound = zeroMoney(currency)
 	if err := c.deps.Storage.Wallets().SaveBalance(ctx, record); err != nil {
-		c.deps.Logger.Warn("failed to cache wallet balance", zap.String("wallet_ref", walletRef), zap.Error(err))
+		c.deps.Logger.Warn("Failed to cache wallet balance", zap.String("wallet_ref", walletRef), zap.Error(err))
 	}
 }
 

api/gateway/chain/internal/service/gateway/commands/wallet/create.go

@@ -9,6 +9,7 @@ import (
 	"github.com/tech/sendico/gateway/chain/storage/model"
 	"github.com/tech/sendico/pkg/api/routers/gsresponse"
 	"github.com/tech/sendico/pkg/merrors"
+	pkgmodel "github.com/tech/sendico/pkg/model"
 	"github.com/tech/sendico/pkg/mservice"
 	chainv1 "github.com/tech/sendico/pkg/proto/gateway/chain/v1"
 	"go.uber.org/zap"
@@ -24,78 +25,118 @@ func NewCreateManagedWallet(deps Deps) *createManagedWalletCommand {
 
 func (c *createManagedWalletCommand) Execute(ctx context.Context, req *chainv1.CreateManagedWalletRequest) gsresponse.Responder[chainv1.CreateManagedWalletResponse] {
 	if err := c.deps.EnsureRepository(ctx); err != nil {
-		c.deps.Logger.Warn("repository unavailable", zap.Error(err))
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
 		return gsresponse.Unavailable[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	if req == nil {
-		c.deps.Logger.Warn("nil request")
+		c.deps.Logger.Warn("Nil request")
 		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("nil request"))
 	}
 
 	idempotencyKey := strings.TrimSpace(req.GetIdempotencyKey())
 	if idempotencyKey == "" {
-		c.deps.Logger.Warn("missing idempotency key")
+		c.deps.Logger.Warn("Missing idempotency key")
 		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("idempotency_key is required"))
 	}
 	organizationRef := strings.TrimSpace(req.GetOrganizationRef())
 	if organizationRef == "" {
-		c.deps.Logger.Warn("missing organization ref")
+		c.deps.Logger.Warn("Missing organization ref")
 		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("organization_ref is required"))
 	}
 	ownerRef := strings.TrimSpace(req.GetOwnerRef())
 	if ownerRef == "" {
-		c.deps.Logger.Warn("missing owner ref")
+		c.deps.Logger.Warn("Missing owner ref")
 		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("owner_ref is required"))
 	}
 
 	asset := req.GetAsset()
 	if asset == nil {
-		c.deps.Logger.Warn("missing asset")
+		c.deps.Logger.Warn("Missing asset")
 		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("asset is required"))
 	}
 
 	chainKey, _ := shared.ChainKeyFromEnum(asset.GetChain())
 	if chainKey == "" {
-		c.deps.Logger.Warn("unsupported chain", zap.Any("chain", asset.GetChain()))
+		c.deps.Logger.Warn("Unsupported chain", zap.Any("chain", asset.GetChain()))
 		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("unsupported chain"))
 	}
-	networkCfg, ok := c.deps.Networks[chainKey]
+	networkCfg, ok := c.deps.Networks.Network(chainKey)
 	if !ok {
-		c.deps.Logger.Warn("unsupported chain in config", zap.String("chain", chainKey))
+		c.deps.Logger.Warn("Unsupported chain in config", zap.String("chain", chainKey))
+		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("unsupported chain"))
+	}
+	if c.deps.Drivers == nil {
+		c.deps.Logger.Warn("Chain drivers missing", zap.String("chain", chainKey))
+		return gsresponse.Internal[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.Internal("chain drivers not configured"))
+	}
+	chainDriver, err := c.deps.Drivers.Driver(chainKey)
+	if err != nil {
+		c.deps.Logger.Warn("Unsupported chain driver", zap.String("chain", chainKey), zap.Error(err))
 		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("unsupported chain"))
 	}
 
 	tokenSymbol := strings.ToUpper(strings.TrimSpace(asset.GetTokenSymbol()))
 	if tokenSymbol == "" {
-		c.deps.Logger.Warn("missing token symbol")
+		c.deps.Logger.Warn("Missing token symbol")
 		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("asset.token_symbol is required"))
 	}
 	contractAddress := strings.ToLower(strings.TrimSpace(asset.GetContractAddress()))
 	if contractAddress == "" {
-		contractAddress = shared.ResolveContractAddress(networkCfg.TokenConfigs, tokenSymbol)
-		if contractAddress == "" {
-			c.deps.Logger.Warn("unsupported token", zap.String("token", tokenSymbol), zap.String("chain", chainKey))
-			return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("unsupported token for chain"))
+		if !strings.EqualFold(tokenSymbol, networkCfg.NativeToken) {
+			contractAddress = shared.ResolveContractAddress(networkCfg.TokenConfigs, tokenSymbol)
+			if contractAddress == "" {
+				c.deps.Logger.Warn("Unsupported token", zap.String("token", tokenSymbol), zap.String("chain", chainKey))
+				return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("unsupported token for chain"))
+			}
 		}
 	}
 
 	walletRef := shared.GenerateWalletRef()
 	if c.deps.KeyManager == nil {
-		c.deps.Logger.Warn("key manager missing")
+		c.deps.Logger.Warn("Key manager missing")
 		return gsresponse.Internal[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.Internal("key manager not configured"))
 	}
 
 	keyInfo, err := c.deps.KeyManager.CreateManagedWalletKey(ctx, walletRef, chainKey)
 	if err != nil {
-		c.deps.Logger.Warn("key manager error", zap.Error(err))
+		c.deps.Logger.Warn("Key manager error", zap.Error(err))
 		return gsresponse.Auto[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	if keyInfo == nil || strings.TrimSpace(keyInfo.Address) == "" {
-		c.deps.Logger.Warn("key manager returned empty address")
+		c.deps.Logger.Warn("Key manager returned empty address")
 		return gsresponse.Internal[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.Internal("key manager returned empty address"))
 	}
+	depositAddress, err := chainDriver.FormatAddress(keyInfo.Address)
+	if err != nil {
+		c.deps.Logger.Warn("Invalid derived deposit address", zap.String("wallet_ref", walletRef), zap.Error(err))
+		return gsresponse.InvalidArgument[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, err)
+	}
+
+	metadata := shared.CloneMetadata(req.GetMetadata())
+	desc := req.GetDescribable()
+	name := strings.TrimSpace(desc.GetName())
+	if name == "" {
+		name = strings.TrimSpace(metadata["name"])
+	}
+	var description *string
+	if desc != nil && desc.Description != nil {
+		if trimmed := strings.TrimSpace(desc.GetDescription()); trimmed != "" {
+			description = &trimmed
+		}
+	}
+	if description == nil {
+		if trimmed := strings.TrimSpace(metadata["description"]); trimmed != "" {
+			description = &trimmed
+		}
+	}
+	if name == "" {
+		name = walletRef
+	}
 
 	wallet := &model.ManagedWallet{
+		Describable: pkgmodel.Describable{
+			Name: name,
+		},
 		IdempotencyKey:  idempotencyKey,
 		WalletRef:       walletRef,
 		OrganizationRef: organizationRef,
@@ -103,19 +144,22 @@ func (c *createManagedWalletCommand) Execute(ctx context.Context, req *chainv1.C
 		Network:         chainKey,
 		TokenSymbol:     tokenSymbol,
 		ContractAddress: contractAddress,
-		DepositAddress:  strings.ToLower(keyInfo.Address),
+		DepositAddress:  depositAddress,
 		KeyReference:    keyInfo.KeyID,
 		Status:          model.ManagedWalletStatusActive,
-		Metadata:        shared.CloneMetadata(req.GetMetadata()),
+		Metadata:        metadata,
+	}
+	if description != nil {
+		wallet.Describable.Description = description
 	}
 
 	created, err := c.deps.Storage.Wallets().Create(ctx, wallet)
 	if err != nil {
 		if errors.Is(err, merrors.ErrDataConflict) {
-			c.deps.Logger.Debug("wallet already exists", zap.String("wallet_ref", walletRef), zap.String("idempotency_key", idempotencyKey))
+			c.deps.Logger.Debug("Wallet already exists", zap.String("wallet_ref", walletRef), zap.String("idempotency_key", idempotencyKey))
 			return gsresponse.Success(&chainv1.CreateManagedWalletResponse{Wallet: toProtoManagedWallet(created)})
 		}
-		c.deps.Logger.Warn("storage create failed", zap.Error(err), zap.String("wallet_ref", walletRef))
+		c.deps.Logger.Warn("Storage create failed", zap.Error(err), zap.String("wallet_ref", walletRef))
 		return gsresponse.Auto[chainv1.CreateManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 

api/gateway/chain/internal/service/gateway/commands/wallet/deps.go

@@ -5,7 +5,8 @@ import (
 	"time"
 
 	"github.com/tech/sendico/gateway/chain/internal/keymanager"
-	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/drivers"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/rpcclient"
 	"github.com/tech/sendico/gateway/chain/storage"
 	clockpkg "github.com/tech/sendico/pkg/clock"
 	"github.com/tech/sendico/pkg/mlogger"
@@ -13,17 +14,20 @@ import (
 
 type Deps struct {
 	Logger           mlogger.Logger
-	Networks         map[string]shared.Network
+	Drivers          *drivers.Registry
+	Networks         *rpcclient.Registry
 	KeyManager       keymanager.Manager
 	Storage          storage.Repository
 	Clock            clockpkg.Clock
 	BalanceCacheTTL  time.Duration
+	RPCTimeout       time.Duration
 	EnsureRepository func(context.Context) error
 }
 
 func (d Deps) WithLogger(name string) Deps {
-	if d.Logger != nil {
-		d.Logger = d.Logger.Named(name)
+	if d.Logger == nil {
+		panic("wallet deps: logger is required")
 	}
+	d.Logger = d.Logger.Named(name)
 	return d
 }

api/gateway/chain/internal/service/gateway/commands/wallet/get.go

@@ -22,25 +22,25 @@ func NewGetManagedWallet(deps Deps) *getManagedWalletCommand {
 
 func (c *getManagedWalletCommand) Execute(ctx context.Context, req *chainv1.GetManagedWalletRequest) gsresponse.Responder[chainv1.GetManagedWalletResponse] {
 	if err := c.deps.EnsureRepository(ctx); err != nil {
-		c.deps.Logger.Warn("repository unavailable", zap.Error(err))
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
 		return gsresponse.Unavailable[chainv1.GetManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	if req == nil {
-		c.deps.Logger.Warn("nil request")
+		c.deps.Logger.Warn("Nil request")
 		return gsresponse.InvalidArgument[chainv1.GetManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("nil request"))
 	}
 	walletRef := strings.TrimSpace(req.GetWalletRef())
 	if walletRef == "" {
-		c.deps.Logger.Warn("wallet_ref missing")
+		c.deps.Logger.Warn("Wallet_ref missing")
 		return gsresponse.InvalidArgument[chainv1.GetManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, merrors.InvalidArgument("wallet_ref is required"))
 	}
 	wallet, err := c.deps.Storage.Wallets().Get(ctx, walletRef)
 	if err != nil {
 		if errors.Is(err, merrors.ErrNoData) {
-			c.deps.Logger.Warn("not found", zap.String("wallet_ref", walletRef))
+			c.deps.Logger.Warn("Not found", zap.String("wallet_ref", walletRef))
 			return gsresponse.NotFound[chainv1.GetManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, err)
 		}
-		c.deps.Logger.Warn("storage get failed", zap.Error(err), zap.String("wallet_ref", walletRef))
+		c.deps.Logger.Warn("Storage get failed", zap.Error(err), zap.String("wallet_ref", walletRef))
 		return gsresponse.Auto[chainv1.GetManagedWalletResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	return gsresponse.Success(&chainv1.GetManagedWalletResponse{Wallet: toProtoManagedWallet(wallet)})

api/gateway/chain/internal/service/gateway/commands/wallet/list.go

@@ -23,7 +23,7 @@ func NewListManagedWallets(deps Deps) *listManagedWalletsCommand {
 
 func (c *listManagedWalletsCommand) Execute(ctx context.Context, req *chainv1.ListManagedWalletsRequest) gsresponse.Responder[chainv1.ListManagedWalletsResponse] {
 	if err := c.deps.EnsureRepository(ctx); err != nil {
-		c.deps.Logger.Warn("repository unavailable", zap.Error(err))
+		c.deps.Logger.Warn("Repository unavailable", zap.Error(err))
 		return gsresponse.Unavailable[chainv1.ListManagedWalletsResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 	filter := model.ManagedWalletFilter{}
@@ -42,7 +42,7 @@ func (c *listManagedWalletsCommand) Execute(ctx context.Context, req *chainv1.Li
 
 	result, err := c.deps.Storage.Wallets().List(ctx, filter)
 	if err != nil {
-		c.deps.Logger.Warn("storage list failed", zap.Error(err))
+		c.deps.Logger.Warn("Storage list failed", zap.Error(err))
 		return gsresponse.Auto[chainv1.ListManagedWalletsResponse](c.deps.Logger, mservice.ChainGateway, err)
 	}
 

api/gateway/chain/internal/service/gateway/commands/wallet/onchain_balance.go

@@ -2,123 +2,61 @@ package wallet
 
 import (
 	"context"
-	"math/big"
+	"fmt"
 	"strings"
-	"time"
 
-	"github.com/ethereum/go-ethereum"
-	"github.com/ethereum/go-ethereum/accounts/abi"
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/ethclient"
-	"github.com/shopspring/decimal"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
 	"github.com/tech/sendico/gateway/chain/storage/model"
 	"github.com/tech/sendico/pkg/merrors"
 	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+	"go.uber.org/zap"
 )
 
-func onChainWalletBalance(ctx context.Context, deps Deps, wallet *model.ManagedWallet) (*moneyv1.Money, error) {
-	network := deps.Networks[strings.ToLower(strings.TrimSpace(wallet.Network))]
-	rpcURL := strings.TrimSpace(network.RPCURL)
-	if rpcURL == "" {
-		return nil, merrors.Internal("network rpc url is not configured")
+func OnChainWalletBalances(ctx context.Context, deps Deps, wallet *model.ManagedWallet) (*moneyv1.Money, *moneyv1.Money, error) {
+	logger := deps.Logger
+	if wallet == nil {
+		return nil, nil, merrors.InvalidArgument("wallet is required")
 	}
-	contract := strings.TrimSpace(wallet.ContractAddress)
-	if contract == "" || !common.IsHexAddress(contract) {
-		return nil, merrors.InvalidArgument("invalid contract address")
+	if deps.Networks == nil {
+		return nil, nil, merrors.Internal("rpc clients not initialised")
 	}
-	if wallet.DepositAddress == "" || !common.IsHexAddress(wallet.DepositAddress) {
-		return nil, merrors.InvalidArgument("invalid wallet address")
+	if deps.Drivers == nil {
+		return nil, nil, merrors.Internal("chain drivers not configured")
 	}
 
-	client, err := ethclient.DialContext(ctx, rpcURL)
-	if err != nil {
-		return nil, merrors.Internal("failed to connect rpc: " + err.Error())
-	}
-	defer client.Close()
-
-	timeoutCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
-	defer cancel()
-
-	tokenABI, err := abi.JSON(strings.NewReader(erc20ABIJSON))
-	if err != nil {
-		return nil, merrors.Internal("failed to parse erc20 abi: " + err.Error())
-	}
-	tokenAddr := common.HexToAddress(contract)
-	walletAddr := common.HexToAddress(wallet.DepositAddress)
-
-	decimals, err := readDecimals(timeoutCtx, client, tokenABI, tokenAddr)
-	if err != nil {
-		return nil, err
-	}
-
-	bal, err := readBalanceOf(timeoutCtx, client, tokenABI, tokenAddr, walletAddr)
-	if err != nil {
-		return nil, err
-	}
-
-	dec := decimal.NewFromBigInt(bal, 0).Shift(-int32(decimals))
-	return &moneyv1.Money{Currency: wallet.TokenSymbol, Amount: dec.String()}, nil
-}
-
-func readDecimals(ctx context.Context, client *ethclient.Client, tokenABI abi.ABI, token common.Address) (uint8, error) {
-	data, err := tokenABI.Pack("decimals")
-	if err != nil {
-		return 0, merrors.Internal("failed to encode decimals call: " + err.Error())
-	}
-	msg := ethereum.CallMsg{To: &token, Data: data}
-	out, err := client.CallContract(ctx, msg, nil)
-	if err != nil {
-		return 0, merrors.Internal("decimals call failed: " + err.Error())
-	}
-	values, err := tokenABI.Unpack("decimals", out)
-	if err != nil || len(values) == 0 {
-		return 0, merrors.Internal("failed to unpack decimals")
-	}
-	if val, ok := values[0].(uint8); ok {
-		return val, nil
-	}
-	return 0, merrors.Internal("decimals returned unexpected type")
-}
-
-func readBalanceOf(ctx context.Context, client *ethclient.Client, tokenABI abi.ABI, token common.Address, wallet common.Address) (*big.Int, error) {
-	data, err := tokenABI.Pack("balanceOf", wallet)
-	if err != nil {
-		return nil, merrors.Internal("failed to encode balanceOf: " + err.Error())
-	}
-	msg := ethereum.CallMsg{To: &token, Data: data}
-	out, err := client.CallContract(ctx, msg, nil)
-	if err != nil {
-		return nil, merrors.Internal("balanceOf call failed: " + err.Error())
-	}
-	values, err := tokenABI.Unpack("balanceOf", out)
-	if err != nil || len(values) == 0 {
-		return nil, merrors.Internal("failed to unpack balanceOf")
-	}
-	raw, ok := values[0].(*big.Int)
+	networkKey := strings.ToLower(strings.TrimSpace(wallet.Network))
+	network, ok := deps.Networks.Network(networkKey)
 	if !ok {
-		return nil, merrors.Internal("balanceOf returned unexpected type")
+		logger.Warn("Requested network is not configured",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", networkKey),
+		)
+		return nil, nil, merrors.Internal(fmt.Sprintf("Requested network '%s' is not configured", networkKey))
 	}
-	return decimal.NewFromBigInt(raw, 0).BigInt(), nil
-}
 
-const erc20ABIJSON = `
-[
-	{
-		"constant": true,
-		"inputs": [],
-		"name": "decimals",
-		"outputs": [{ "name": "", "type": "uint8" }],
-		"payable": false,
-		"stateMutability": "view",
-        "type": "function"
-	},
-	{
-		"constant": true,
-		"inputs": [{ "name": "_owner", "type": "address" }],
-		"name": "balanceOf",
-		"outputs": [{ "name": "balance", "type": "uint256" }],
-		"payable": false,
-		"stateMutability": "view",
-		"type": "function"
+	chainDriver, err := deps.Drivers.Driver(networkKey)
+	if err != nil {
+		logger.Warn("Chain driver not configured",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", networkKey),
+			zap.Error(err),
+		)
+		return nil, nil, merrors.InvalidArgument("unsupported chain")
 	}
-]`
+
+	driverDeps := driver.Deps{
+		Logger:     deps.Logger,
+		Registry:   deps.Networks,
+		KeyManager: deps.KeyManager,
+		RPCTimeout: deps.RPCTimeout,
+	}
+	tokenBalance, err := chainDriver.Balance(ctx, driverDeps, network, wallet)
+	if err != nil {
+		return nil, nil, err
+	}
+	nativeBalance, err := chainDriver.NativeBalance(ctx, driverDeps, network, wallet)
+	if err != nil {
+		return nil, nil, err
+	}
+	return tokenBalance, nativeBalance, nil
+}

api/gateway/chain/internal/service/gateway/commands/wallet/proto.go

@@ -1,8 +1,11 @@
 package wallet
 
 import (
+	"strings"
+
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
 	"github.com/tech/sendico/gateway/chain/storage/model"
+	describablev1 "github.com/tech/sendico/pkg/proto/common/describable/v1"
 	chainv1 "github.com/tech/sendico/pkg/proto/gateway/chain/v1"
 	"google.golang.org/protobuf/types/known/timestamppb"
 )
@@ -16,6 +19,25 @@ func toProtoManagedWallet(wallet *model.ManagedWallet) *chainv1.ManagedWallet {
 		TokenSymbol:     wallet.TokenSymbol,
 		ContractAddress: wallet.ContractAddress,
 	}
+	name := strings.TrimSpace(wallet.Name)
+	if name == "" {
+		name = strings.TrimSpace(wallet.Metadata["name"])
+	}
+	if name == "" {
+		name = wallet.WalletRef
+	}
+	description := ""
+	switch {
+	case wallet.Description != nil:
+		description = strings.TrimSpace(*wallet.Description)
+	default:
+		description = strings.TrimSpace(wallet.Metadata["description"])
+	}
+	desc := &describablev1.Describable{Name: name}
+	if description != "" {
+		desc.Description = &description
+	}
+
 	return &chainv1.ManagedWallet{
 		WalletRef:       wallet.WalletRef,
 		OrganizationRef: wallet.OrganizationRef,
@@ -26,6 +48,7 @@ func toProtoManagedWallet(wallet *model.ManagedWallet) *chainv1.ManagedWallet {
 		Metadata:        shared.CloneMetadata(wallet.Metadata),
 		CreatedAt:       timestamppb.New(wallet.CreatedAt.UTC()),
 		UpdatedAt:       timestamppb.New(wallet.UpdatedAt.UTC()),
+		Describable:     desc,
 	}
 }
 
@@ -35,6 +58,7 @@ func toProtoWalletBalance(balance *model.WalletBalance) *chainv1.WalletBalance {
 	}
 	return &chainv1.WalletBalance{
 		Available:       shared.CloneMoney(balance.Available),
+		NativeAvailable: shared.CloneMoney(balance.NativeAvailable),
 		PendingInbound:  shared.CloneMoney(balance.PendingInbound),
 		PendingOutbound: shared.CloneMoney(balance.PendingOutbound),
 		CalculatedAt:    timestamppb.New(balance.CalculatedAt.UTC()),

api/gateway/chain/internal/service/gateway/driver/arbitrum/driver.go

@@ -0,0 +1,173 @@
+package arbitrum
+
+import (
+	"context"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver/evm"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	"github.com/tech/sendico/pkg/mlogger"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+	"go.uber.org/zap"
+)
+
+// Driver implements Arbitrum-specific behavior using the shared EVM logic.
+type Driver struct {
+	logger mlogger.Logger
+}
+
+func New(logger mlogger.Logger) *Driver {
+	return &Driver{logger: logger.Named("arbitrum")}
+}
+
+func (d *Driver) Name() string {
+	return "arbitrum"
+}
+
+func (d *Driver) FormatAddress(address string) (string, error) {
+	d.logger.Debug("Format address", zap.String("address", address))
+	normalized, err := evm.NormalizeAddress(address)
+	if err != nil {
+		d.logger.Warn("Format address failed", zap.String("address", address), zap.Error(err))
+	}
+	return normalized, err
+}
+
+func (d *Driver) NormalizeAddress(address string) (string, error) {
+	d.logger.Debug("Normalize address", zap.String("address", address))
+	normalized, err := evm.NormalizeAddress(address)
+	if err != nil {
+		d.logger.Warn("Normalize address failed", zap.String("address", address), zap.Error(err))
+	}
+	return normalized, err
+}
+
+func (d *Driver) Balance(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet) (*moneyv1.Money, error) {
+	d.logger.Debug("Balance request",
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("network", network.Name),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	result, err := evm.Balance(ctx, driverDeps, network, wallet, wallet.DepositAddress)
+	if err != nil {
+		d.logger.Warn("Balance failed",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else if result != nil {
+		d.logger.Debug("Balance result",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("amount", result.Amount),
+			zap.String("currency", result.Currency),
+		)
+	}
+	return result, err
+}
+
+func (d *Driver) NativeBalance(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet) (*moneyv1.Money, error) {
+	d.logger.Debug("Native balance request",
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("network", network.Name),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	result, err := evm.NativeBalance(ctx, driverDeps, network, wallet, wallet.DepositAddress)
+	if err != nil {
+		d.logger.Warn("Native balance failed",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else if result != nil {
+		d.logger.Debug("Native balance result",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("amount", result.Amount),
+			zap.String("currency", result.Currency),
+		)
+	}
+	return result, err
+}
+
+func (d *Driver) EstimateFee(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet, destination string, amount *moneyv1.Money) (*moneyv1.Money, error) {
+	d.logger.Debug("Estimate fee request",
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("network", network.Name),
+		zap.String("destination", destination),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	result, err := evm.EstimateFee(ctx, driverDeps, network, wallet, wallet.DepositAddress, destination, amount)
+	if err != nil {
+		d.logger.Warn("Estimate fee failed",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else if result != nil {
+		d.logger.Debug("Estimate fee result",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("amount", result.Amount),
+			zap.String("currency", result.Currency),
+		)
+	}
+	return result, err
+}
+
+func (d *Driver) SubmitTransfer(ctx context.Context, deps driver.Deps, network shared.Network, transfer *model.Transfer, source *model.ManagedWallet, destination string) (string, error) {
+	d.logger.Debug("Submit transfer request",
+		zap.String("transfer_ref", transfer.TransferRef),
+		zap.String("network", network.Name),
+		zap.String("destination", destination),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	txHash, err := evm.SubmitTransfer(ctx, driverDeps, network, transfer, source, source.DepositAddress, destination)
+	if err != nil {
+		d.logger.Warn("Submit transfer failed",
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else {
+		d.logger.Debug("Submit transfer result",
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("network", network.Name),
+			zap.String("tx_hash", txHash),
+		)
+	}
+	return txHash, err
+}
+
+func (d *Driver) AwaitConfirmation(ctx context.Context, deps driver.Deps, network shared.Network, txHash string) (*types.Receipt, error) {
+	d.logger.Debug("Await confirmation",
+		zap.String("tx_hash", txHash),
+		zap.String("network", network.Name),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	receipt, err := evm.AwaitConfirmation(ctx, driverDeps, network, txHash)
+	if err != nil {
+		d.logger.Warn("Await confirmation failed",
+			zap.String("tx_hash", txHash),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else if receipt != nil {
+		d.logger.Debug("Await confirmation result",
+			zap.String("tx_hash", txHash),
+			zap.String("network", network.Name),
+			zap.Uint64("block_number", receipt.BlockNumber.Uint64()),
+			zap.Uint64("status", receipt.Status),
+		)
+	}
+	return receipt, err
+}
+
+var _ driver.Driver = (*Driver)(nil)

api/gateway/chain/internal/service/gateway/driver/driver.go

@@ -0,0 +1,34 @@
+package driver
+
+import (
+	"context"
+	"time"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/tech/sendico/gateway/chain/internal/keymanager"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/rpcclient"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	"github.com/tech/sendico/pkg/mlogger"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+)
+
+// Deps bundles dependencies shared across chain drivers.
+type Deps struct {
+	Logger     mlogger.Logger
+	Registry   *rpcclient.Registry
+	KeyManager keymanager.Manager
+	RPCTimeout time.Duration
+}
+
+// Driver defines chain-specific behavior for wallet and transfer operations.
+type Driver interface {
+	Name() string
+	FormatAddress(address string) (string, error)
+	NormalizeAddress(address string) (string, error)
+	Balance(ctx context.Context, deps Deps, network shared.Network, wallet *model.ManagedWallet) (*moneyv1.Money, error)
+	NativeBalance(ctx context.Context, deps Deps, network shared.Network, wallet *model.ManagedWallet) (*moneyv1.Money, error)
+	EstimateFee(ctx context.Context, deps Deps, network shared.Network, wallet *model.ManagedWallet, destination string, amount *moneyv1.Money) (*moneyv1.Money, error)
+	SubmitTransfer(ctx context.Context, deps Deps, network shared.Network, transfer *model.Transfer, source *model.ManagedWallet, destination string) (string, error)
+	AwaitConfirmation(ctx context.Context, deps Deps, network shared.Network, txHash string) (*types.Receipt, error)
+}

api/gateway/chain/internal/service/gateway/driver/ethereum/driver.go

@@ -0,0 +1,173 @@
+package ethereum
+
+import (
+	"context"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver/evm"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	"github.com/tech/sendico/pkg/mlogger"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+	"go.uber.org/zap"
+)
+
+// Driver implements Ethereum-specific behavior using the shared EVM logic.
+type Driver struct {
+	logger mlogger.Logger
+}
+
+func New(logger mlogger.Logger) *Driver {
+	return &Driver{logger: logger.Named("ethereum")}
+}
+
+func (d *Driver) Name() string {
+	return "ethereum"
+}
+
+func (d *Driver) FormatAddress(address string) (string, error) {
+	d.logger.Debug("Format address", zap.String("address", address))
+	normalized, err := evm.NormalizeAddress(address)
+	if err != nil {
+		d.logger.Warn("Format address failed", zap.String("address", address), zap.Error(err))
+	}
+	return normalized, err
+}
+
+func (d *Driver) NormalizeAddress(address string) (string, error) {
+	d.logger.Debug("Normalize address", zap.String("address", address))
+	normalized, err := evm.NormalizeAddress(address)
+	if err != nil {
+		d.logger.Warn("Normalize address failed", zap.String("address", address), zap.Error(err))
+	}
+	return normalized, err
+}
+
+func (d *Driver) Balance(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet) (*moneyv1.Money, error) {
+	d.logger.Debug("Balance request",
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("network", network.Name),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	result, err := evm.Balance(ctx, driverDeps, network, wallet, wallet.DepositAddress)
+	if err != nil {
+		d.logger.Warn("Balance failed",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else if result != nil {
+		d.logger.Debug("Balance result",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("amount", result.Amount),
+			zap.String("currency", result.Currency),
+		)
+	}
+	return result, err
+}
+
+func (d *Driver) NativeBalance(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet) (*moneyv1.Money, error) {
+	d.logger.Debug("Native balance request",
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("network", network.Name),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	result, err := evm.NativeBalance(ctx, driverDeps, network, wallet, wallet.DepositAddress)
+	if err != nil {
+		d.logger.Warn("Native balance failed",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else if result != nil {
+		d.logger.Debug("Native balance result",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("amount", result.Amount),
+			zap.String("currency", result.Currency),
+		)
+	}
+	return result, err
+}
+
+func (d *Driver) EstimateFee(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet, destination string, amount *moneyv1.Money) (*moneyv1.Money, error) {
+	d.logger.Debug("Estimate fee request",
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("network", network.Name),
+		zap.String("destination", destination),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	result, err := evm.EstimateFee(ctx, driverDeps, network, wallet, wallet.DepositAddress, destination, amount)
+	if err != nil {
+		d.logger.Warn("Estimate fee failed",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else if result != nil {
+		d.logger.Debug("Estimate fee result",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("amount", result.Amount),
+			zap.String("currency", result.Currency),
+		)
+	}
+	return result, err
+}
+
+func (d *Driver) SubmitTransfer(ctx context.Context, deps driver.Deps, network shared.Network, transfer *model.Transfer, source *model.ManagedWallet, destination string) (string, error) {
+	d.logger.Debug("Submit transfer request",
+		zap.String("transfer_ref", transfer.TransferRef),
+		zap.String("network", network.Name),
+		zap.String("destination", destination),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	txHash, err := evm.SubmitTransfer(ctx, driverDeps, network, transfer, source, source.DepositAddress, destination)
+	if err != nil {
+		d.logger.Warn("Submit transfer failed",
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else {
+		d.logger.Debug("Submit transfer result",
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("network", network.Name),
+			zap.String("tx_hash", txHash),
+		)
+	}
+	return txHash, err
+}
+
+func (d *Driver) AwaitConfirmation(ctx context.Context, deps driver.Deps, network shared.Network, txHash string) (*types.Receipt, error) {
+	d.logger.Debug("Await confirmation",
+		zap.String("tx_hash", txHash),
+		zap.String("network", network.Name),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	receipt, err := evm.AwaitConfirmation(ctx, driverDeps, network, txHash)
+	if err != nil {
+		d.logger.Warn("Await confirmation failed",
+			zap.String("tx_hash", txHash),
+			zap.String("network", network.Name),
+			zap.Error(err),
+		)
+	} else if receipt != nil {
+		d.logger.Debug("Await confirmation result",
+			zap.String("tx_hash", txHash),
+			zap.String("network", network.Name),
+			zap.Uint64("block_number", receipt.BlockNumber.Uint64()),
+			zap.Uint64("status", receipt.Status),
+		)
+	}
+	return receipt, err
+}
+
+var _ driver.Driver = (*Driver)(nil)

api/gateway/chain/internal/service/gateway/driver/evm/estimate_gas_test.go

@@ -0,0 +1,31 @@
+package evm
+
+import (
+	"math/big"
+	"strings"
+	"testing"
+
+	"github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/stretchr/testify/require"
+)
+
+func TestTronEstimateCallUsesData(t *testing.T) {
+	from := common.HexToAddress("0xfa89b4d534bdeb2713d4ffd893e79d6535fb58f8")
+	to := common.HexToAddress("0xa614f803b6fd780986a42c78ec9c7f77e6ded13c")
+	callMsg := ethereum.CallMsg{
+		From:     from,
+		To:       &to,
+		GasPrice: big.NewInt(100),
+		Data:     []byte{0xa9, 0x05, 0x9c, 0xbb},
+	}
+
+	call := tronEstimateCall(callMsg)
+
+	require.Equal(t, strings.ToLower(from.Hex()), call["from"])
+	require.Equal(t, strings.ToLower(to.Hex()), call["to"])
+	require.Equal(t, "0x64", call["gasPrice"])
+	require.Equal(t, "0xa9059cbb", call["data"])
+	_, hasInput := call["input"]
+	require.False(t, hasInput)
+}

api/gateway/chain/internal/service/gateway/driver/evm/evm.go

@@ -0,0 +1,747 @@
+package evm
+
+import (
+	"context"
+	"errors"
+	"math/big"
+	"strings"
+	"time"
+
+	"github.com/ethereum/go-ethereum"
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/rpc"
+	"github.com/shopspring/decimal"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	"github.com/tech/sendico/pkg/merrors"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+	"go.uber.org/zap"
+)
+
+var (
+	erc20ABI abi.ABI
+)
+
+func init() {
+	var err error
+	erc20ABI, err = abi.JSON(strings.NewReader(erc20ABIJSON))
+	if err != nil {
+		panic("evm driver: failed to parse erc20 abi: " + err.Error())
+	}
+}
+
+const erc20ABIJSON = `
+[
+	{
+		"constant": false,
+		"inputs": [
+			{ "name": "_to", "type": "address" },
+			{ "name": "_value", "type": "uint256" }
+		],
+		"name": "transfer",
+		"outputs": [{ "name": "", "type": "bool" }],
+		"payable": false,
+		"stateMutability": "nonpayable",
+		"type": "function"
+	},
+	{
+		"constant": true,
+		"inputs": [],
+		"name": "decimals",
+		"outputs": [{ "name": "", "type": "uint8" }],
+		"payable": false,
+		"stateMutability": "view",
+        "type": "function"
+	}
+]`
+
+// NormalizeAddress validates and normalizes EVM hex addresses.
+func NormalizeAddress(address string) (string, error) {
+	trimmed := strings.TrimSpace(address)
+	if trimmed == "" {
+		return "", merrors.InvalidArgument("address is required")
+	}
+	if !common.IsHexAddress(trimmed) {
+		return "", merrors.InvalidArgument("invalid hex address")
+	}
+	return strings.ToLower(common.HexToAddress(trimmed).Hex()), nil
+}
+
+func nativeCurrency(network shared.Network) string {
+	currency := strings.ToUpper(strings.TrimSpace(network.NativeToken))
+	if currency == "" {
+		currency = strings.ToUpper(network.Name)
+	}
+	return currency
+}
+
+func parseBaseUnitAmount(amount string) (*big.Int, error) {
+	trimmed := strings.TrimSpace(amount)
+	if trimmed == "" {
+		return nil, merrors.InvalidArgument("amount is required")
+	}
+	value, ok := new(big.Int).SetString(trimmed, 10)
+	if !ok {
+		return nil, merrors.InvalidArgument("invalid amount")
+	}
+	if value.Sign() < 0 {
+		return nil, merrors.InvalidArgument("amount must be non-negative")
+	}
+	return value, nil
+}
+
+// Balance fetches ERC20 token balance for the provided address.
+func Balance(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet, address string) (*moneyv1.Money, error) {
+	logger := deps.Logger.Named("evm")
+	registry := deps.Registry
+
+	if registry == nil {
+		return nil, merrors.Internal("rpc clients not initialised")
+	}
+	if wallet == nil {
+		return nil, merrors.InvalidArgument("wallet is required")
+	}
+
+	normalizedAddress, err := NormalizeAddress(address)
+	if err != nil {
+		return nil, err
+	}
+
+	rpcURL := strings.TrimSpace(network.RPCURL)
+	logFields := []zap.Field{
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("network", strings.ToLower(strings.TrimSpace(network.Name))),
+		zap.String("token_symbol", strings.ToUpper(strings.TrimSpace(wallet.TokenSymbol))),
+		zap.String("contract", strings.ToLower(strings.TrimSpace(wallet.ContractAddress))),
+		zap.String("wallet_address", normalizedAddress),
+	}
+	if rpcURL == "" {
+		logger.Warn("Network rpc url is not configured", logFields...)
+		return nil, merrors.Internal("network rpc url is not configured")
+	}
+
+	contract := strings.TrimSpace(wallet.ContractAddress)
+	if contract == "" {
+		logger.Debug("Native balance requested", logFields...)
+		return NativeBalance(ctx, deps, network, wallet, normalizedAddress)
+	}
+	if !common.IsHexAddress(contract) {
+		logger.Warn("Invalid contract address for balance fetch", logFields...)
+		return nil, merrors.InvalidArgument("invalid contract address")
+	}
+
+	logger.Info("Fetching on-chain wallet balance", logFields...)
+
+	rpcClient, err := registry.RPCClient(network.Name)
+	if err != nil {
+		logger.Warn("Failed to fetch rpc client", append(logFields, zap.Error(err))...)
+		return nil, err
+	}
+
+	timeout := deps.RPCTimeout
+	if timeout <= 0 {
+		timeout = 10 * time.Second
+	}
+	timeoutCtx, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
+	logger.Debug("Calling token decimals", logFields...)
+	decimals, err := readDecimals(timeoutCtx, rpcClient, contract)
+	if err != nil {
+		logger.Warn("Token decimals call failed", append(logFields, zap.Error(err))...)
+		return nil, err
+	}
+
+	logger.Debug("Calling token balanceOf", append(logFields, zap.Uint8("decimals", decimals))...)
+	bal, err := readBalanceOf(timeoutCtx, rpcClient, contract, normalizedAddress)
+	if err != nil {
+		logger.Warn("Token balanceOf call failed", append(logFields, zap.Uint8("decimals", decimals), zap.Error(err))...)
+		return nil, err
+	}
+
+	dec := decimal.NewFromBigInt(bal, 0).Shift(-int32(decimals))
+	logger.Info("On-chain wallet balance fetched",
+		append(logFields,
+			zap.Uint8("decimals", decimals),
+			zap.String("balance_raw", bal.String()),
+			zap.String("balance", dec.String()),
+		)...,
+	)
+	return &moneyv1.Money{Currency: wallet.TokenSymbol, Amount: dec.String()}, nil
+}
+
+// NativeBalance fetches native token balance for the provided address.
+func NativeBalance(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet, address string) (*moneyv1.Money, error) {
+	logger := deps.Logger.Named("evm")
+	registry := deps.Registry
+
+	if registry == nil {
+		return nil, merrors.Internal("rpc clients not initialised")
+	}
+	if wallet == nil {
+		return nil, merrors.InvalidArgument("wallet is required")
+	}
+
+	normalizedAddress, err := NormalizeAddress(address)
+	if err != nil {
+		return nil, err
+	}
+
+	rpcURL := strings.TrimSpace(network.RPCURL)
+	logFields := []zap.Field{
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("network", strings.ToLower(strings.TrimSpace(network.Name))),
+		zap.String("wallet_address", normalizedAddress),
+	}
+	if rpcURL == "" {
+		logger.Warn("Network rpc url is not configured", logFields...)
+		return nil, merrors.Internal("network rpc url is not configured")
+	}
+
+	client, err := registry.Client(network.Name)
+	if err != nil {
+		logger.Warn("Failed to fetch rpc client", append(logFields, zap.Error(err))...)
+		return nil, err
+	}
+
+	timeout := deps.RPCTimeout
+	if timeout <= 0 {
+		timeout = 10 * time.Second
+	}
+	timeoutCtx, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
+	bal, err := client.BalanceAt(timeoutCtx, common.HexToAddress(normalizedAddress), nil)
+	if err != nil {
+		logger.Warn("Native balance call failed", append(logFields, zap.Error(err))...)
+		return nil, err
+	}
+
+	logger.Info("On-chain native balance fetched",
+		append(logFields,
+			zap.String("balance_raw", bal.String()),
+		)...,
+	)
+	return &moneyv1.Money{
+		Currency: nativeCurrency(network),
+		Amount:   bal.String(),
+	}, nil
+}
+
+// EstimateFee estimates ERC20 transfer fees for the given parameters.
+func EstimateFee(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet, fromAddress, destination string, amount *moneyv1.Money) (*moneyv1.Money, error) {
+	logger := deps.Logger.Named("evm")
+	registry := deps.Registry
+
+	if registry == nil {
+		return nil, merrors.Internal("rpc clients not initialised")
+	}
+	if wallet == nil {
+		return nil, merrors.InvalidArgument("wallet is required")
+	}
+	if amount == nil {
+		return nil, merrors.InvalidArgument("amount is required")
+	}
+
+	rpcURL := strings.TrimSpace(network.RPCURL)
+	if rpcURL == "" {
+		return nil, merrors.InvalidArgument("network rpc url not configured")
+	}
+	if _, err := NormalizeAddress(fromAddress); err != nil {
+		return nil, merrors.InvalidArgument("invalid source wallet address")
+	}
+	if _, err := NormalizeAddress(destination); err != nil {
+		return nil, merrors.InvalidArgument("invalid destination address")
+	}
+
+	client, err := registry.Client(network.Name)
+	if err != nil {
+		logger.Warn("Failed to resolve client", zap.Error(err), zap.String("network_name", network.Name))
+		return nil, err
+	}
+	rpcClient, err := registry.RPCClient(network.Name)
+	if err != nil {
+		logger.Warn("Failed to resolve RPC client", zap.Error(err), zap.String("network_name", network.Name))
+		return nil, err
+	}
+
+	timeout := deps.RPCTimeout
+	if timeout <= 0 {
+		timeout = 15 * time.Second
+	}
+	timeoutCtx, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
+	contract := strings.TrimSpace(wallet.ContractAddress)
+	toAddr := common.HexToAddress(destination)
+	fromAddr := common.HexToAddress(fromAddress)
+
+	if contract == "" {
+		amountBase, err := parseBaseUnitAmount(amount.GetAmount())
+		if err != nil {
+			logger.Warn("Failed to parse base unit amount", zap.Error(err), zap.String("amount", amount.GetAmount()))
+			return nil, err
+		}
+		gasPrice, err := client.SuggestGasPrice(timeoutCtx)
+		if err != nil {
+			logger.Warn("Failed to suggest gas price", zap.Error(err))
+			return nil, merrors.Internal("failed to suggest gas price: " + err.Error())
+		}
+		callMsg := ethereum.CallMsg{
+			From:     fromAddr,
+			To:       &toAddr,
+			GasPrice: gasPrice,
+			Value:    amountBase,
+		}
+		gasLimit, err := estimateGas(timeoutCtx, network, client, rpcClient, callMsg)
+		if err != nil {
+			logger.Warn("Failed to estimate gas", zap.Error(err), zap.Any("call_mesasge", callMsg))
+			return nil, merrors.Internal("failed to estimate gas: " + err.Error())
+		}
+		fee := new(big.Int).Mul(gasPrice, new(big.Int).SetUint64(gasLimit))
+		feeDec := decimal.NewFromBigInt(fee, 0)
+		return &moneyv1.Money{
+			Currency: nativeCurrency(network),
+			Amount:   feeDec.String(),
+		}, nil
+	}
+	if !common.IsHexAddress(contract) {
+		logger.Warn("Failed to validate contract", zap.String("contract", contract))
+		return nil, merrors.InvalidArgument("invalid token contract address")
+	}
+
+	tokenAddr := common.HexToAddress(contract)
+
+	decimals, err := erc20Decimals(timeoutCtx, rpcClient, tokenAddr)
+	if err != nil {
+		logger.Warn("Failed to read token decimals", zap.Error(err))
+		return nil, err
+	}
+
+	amountBase, err := toBaseUnits(strings.TrimSpace(amount.GetAmount()), decimals)
+	if err != nil {
+		return nil, err
+	}
+
+	input, err := erc20ABI.Pack("transfer", toAddr, amountBase)
+	if err != nil {
+		logger.Warn("Failed to encode transfer call", zap.Error(err))
+		return nil, merrors.Internal("failed to encode transfer call: " + err.Error())
+	}
+
+	gasPrice, err := client.SuggestGasPrice(timeoutCtx)
+	if err != nil {
+		logger.Warn("Failed to suggest gas price", zap.Error(err))
+		return nil, merrors.Internal("failed to suggest gas price: " + err.Error())
+	}
+
+	callMsg := ethereum.CallMsg{
+		From:     fromAddr,
+		To:       &tokenAddr,
+		GasPrice: gasPrice,
+		Data:     input,
+	}
+	gasLimit, err := estimateGas(timeoutCtx, network, client, rpcClient, callMsg)
+	if err != nil {
+		logger.Warn("Failed to estimate gas", zap.Error(err), zap.Any("call_message", callMsg))
+		return nil, merrors.Internal("failed to estimate gas: " + err.Error())
+	}
+
+	fee := new(big.Int).Mul(gasPrice, new(big.Int).SetUint64(gasLimit))
+	feeDec := decimal.NewFromBigInt(fee, 0)
+
+	return &moneyv1.Money{
+		Currency: nativeCurrency(network),
+		Amount:   feeDec.String(),
+	}, nil
+}
+
+// SubmitTransfer submits an ERC20 transfer on an EVM-compatible chain.
+func SubmitTransfer(ctx context.Context, deps driver.Deps, network shared.Network, transfer *model.Transfer, source *model.ManagedWallet, fromAddress, destination string) (string, error) {
+	logger := deps.Logger.Named("evm")
+	registry := deps.Registry
+
+	if deps.KeyManager == nil {
+		logger.Warn("Key manager not configured")
+		return "", executorInternal("key manager is not configured", nil)
+	}
+	if registry == nil {
+		return "", executorInternal("rpc clients not initialised", nil)
+	}
+	rpcURL := strings.TrimSpace(network.RPCURL)
+	if rpcURL == "" {
+		logger.Warn("Network rpc url missing", zap.String("network", network.Name))
+		return "", executorInvalid("network rpc url is not configured")
+	}
+	if source == nil || transfer == nil {
+		logger.Warn("Transfer context missing")
+		return "", executorInvalid("transfer context missing")
+	}
+	if strings.TrimSpace(source.KeyReference) == "" {
+		logger.Warn("Source wallet missing key reference", zap.String("wallet_ref", source.WalletRef))
+		return "", executorInvalid("source wallet missing key reference")
+	}
+	if _, err := NormalizeAddress(fromAddress); err != nil {
+		logger.Warn("Invalid source wallet address", zap.String("wallet_ref", source.WalletRef))
+		return "", executorInvalid("invalid source wallet address")
+	}
+	if _, err := NormalizeAddress(destination); err != nil {
+		logger.Warn("Invalid destination address", zap.String("transfer_ref", transfer.TransferRef), zap.String("address", destination))
+		return "", executorInvalid("invalid destination address " + destination)
+	}
+
+	logger.Info("Submitting transfer",
+		zap.String("transfer_ref", transfer.TransferRef),
+		zap.String("source_wallet_ref", source.WalletRef),
+		zap.String("network", network.Name),
+		zap.String("destination", strings.ToLower(destination)),
+	)
+
+	client, err := registry.Client(network.Name)
+	if err != nil {
+		logger.Warn("Failed to initialise RPC client", zap.Error(err), zap.String("network", network.Name))
+		return "", err
+	}
+	rpcClient, err := registry.RPCClient(network.Name)
+	if err != nil {
+		logger.Warn("Failed to initialise RPC client", zap.String("network", network.Name))
+		return "", err
+	}
+
+	sourceAddress := common.HexToAddress(fromAddress)
+	destinationAddr := common.HexToAddress(destination)
+
+	ctx, cancel := context.WithTimeout(ctx, 60*time.Second)
+	defer cancel()
+
+	nonce, err := client.PendingNonceAt(ctx, sourceAddress)
+	if err != nil {
+		logger.Warn("Failed to fetch nonce", zap.Error(err),
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("wallet_ref", source.WalletRef),
+		)
+		return "", executorInternal("failed to fetch nonce", err)
+	}
+
+	gasPrice, err := client.SuggestGasPrice(ctx)
+	if err != nil {
+		logger.Warn("Failed to suggest gas price", zap.Error(err),
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("network", network.Name),
+		)
+		return "", executorInternal("failed to suggest gas price", err)
+	}
+
+	chainID := new(big.Int).SetUint64(network.ChainID)
+
+	contract := strings.TrimSpace(transfer.ContractAddress)
+	amount := transfer.NetAmount
+	if amount == nil || strings.TrimSpace(amount.Amount) == "" {
+		logger.Warn("Transfer missing net amount", zap.String("transfer_ref", transfer.TransferRef))
+		return "", executorInvalid("transfer missing net amount")
+	}
+
+	var tx *types.Transaction
+	if contract == "" {
+		amountInt, err := parseBaseUnitAmount(amount.Amount)
+		if err != nil {
+			logger.Warn("Invalid native amount", zap.Error(err), zap.String("transfer_ref", transfer.TransferRef))
+			return "", err
+		}
+		callMsg := ethereum.CallMsg{
+			From:     sourceAddress,
+			To:       &destinationAddr,
+			GasPrice: gasPrice,
+			Value:    amountInt,
+		}
+		gasLimit, err := estimateGas(ctx, network, client, rpcClient, callMsg)
+		if err != nil {
+			logger.Warn("Failed to estimate gas", zap.Error(err),
+				zap.String("transfer_ref", transfer.TransferRef),
+			)
+			return "", executorInternal("failed to estimate gas", err)
+		}
+		tx = types.NewTransaction(nonce, destinationAddr, amountInt, gasLimit, gasPrice, nil)
+	} else {
+		if !common.IsHexAddress(contract) {
+			logger.Warn("Invalid token contract address",
+				zap.String("transfer_ref", transfer.TransferRef),
+				zap.String("contract", contract),
+			)
+			return "", executorInvalid("invalid token contract address " + contract)
+		}
+		tokenAddress := common.HexToAddress(contract)
+
+		decimals, err := erc20Decimals(ctx, rpcClient, tokenAddress)
+		if err != nil {
+			logger.Warn("Failed to read token decimals", zap.Error(err),
+				zap.String("transfer_ref", transfer.TransferRef),
+				zap.String("contract", contract),
+			)
+			return "", err
+		}
+
+		amountInt, err := toBaseUnits(amount.Amount, decimals)
+		if err != nil {
+			logger.Warn("Failed to convert amount to base units", zap.Error(err),
+				zap.String("transfer_ref", transfer.TransferRef),
+				zap.String("amount", amount.Amount),
+			)
+			return "", err
+		}
+
+		input, err := erc20ABI.Pack("transfer", destinationAddr, amountInt)
+		if err != nil {
+			logger.Warn("Failed to encode transfer call", zap.Error(err),
+				zap.String("transfer_ref", transfer.TransferRef),
+			)
+			return "", executorInternal("failed to encode transfer call", err)
+		}
+
+		callMsg := ethereum.CallMsg{
+			From:     sourceAddress,
+			To:       &tokenAddress,
+			GasPrice: gasPrice,
+			Data:     input,
+		}
+		gasLimit, err := estimateGas(ctx, network, client, rpcClient, callMsg)
+		if err != nil {
+			logger.Warn("Failed to estimate gas", zap.Error(err),
+				zap.String("transfer_ref", transfer.TransferRef),
+			)
+			return "", executorInternal("failed to estimate gas", err)
+		}
+
+		tx = types.NewTransaction(nonce, tokenAddress, big.NewInt(0), gasLimit, gasPrice, input)
+	}
+
+	signedTx, err := deps.KeyManager.SignTransaction(ctx, source.KeyReference, tx, chainID)
+	if err != nil {
+		logger.Warn("Failed to sign transaction", zap.Error(err),
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("wallet_ref", source.WalletRef),
+		)
+		return "", err
+	}
+
+	if err := client.SendTransaction(ctx, signedTx); err != nil {
+		logger.Warn("Failed to send transaction", zap.Error(err),
+			zap.String("transfer_ref", transfer.TransferRef),
+		)
+		return "", executorInternal("failed to send transaction", err)
+	}
+
+	txHash := signedTx.Hash().Hex()
+	logger.Info("Transaction submitted",
+		zap.String("transfer_ref", transfer.TransferRef),
+		zap.String("tx_hash", txHash),
+		zap.String("network", network.Name),
+	)
+
+	return txHash, nil
+}
+
+// AwaitConfirmation waits for the transaction receipt.
+func AwaitConfirmation(ctx context.Context, deps driver.Deps, network shared.Network, txHash string) (*types.Receipt, error) {
+	logger := deps.Logger.Named("evm")
+	registry := deps.Registry
+
+	if strings.TrimSpace(txHash) == "" {
+		logger.Warn("Missing transaction hash for confirmation", zap.String("network", network.Name))
+		return nil, executorInvalid("tx hash is required")
+	}
+	rpcURL := strings.TrimSpace(network.RPCURL)
+	if rpcURL == "" {
+		logger.Warn("Network rpc url missing while awaiting confirmation", zap.String("tx_hash", txHash))
+		return nil, executorInvalid("network rpc url is not configured")
+	}
+	if registry == nil {
+		return nil, executorInternal("rpc clients not initialised", nil)
+	}
+
+	client, err := registry.Client(network.Name)
+	if err != nil {
+		return nil, err
+	}
+
+	hash := common.HexToHash(txHash)
+	ticker := time.NewTicker(3 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		receipt, err := client.TransactionReceipt(ctx, hash)
+		if err != nil {
+			if errors.Is(err, ethereum.NotFound) {
+				select {
+				case <-ticker.C:
+					logger.Debug("Transaction not yet mined",
+						zap.String("tx_hash", txHash),
+						zap.String("network", network.Name),
+					)
+					continue
+				case <-ctx.Done():
+					logger.Warn("Context cancelled while awaiting confirmation",
+						zap.String("tx_hash", txHash),
+						zap.String("network", network.Name),
+					)
+					return nil, ctx.Err()
+				}
+			}
+			logger.Warn("Failed to fetch transaction receipt",
+				zap.String("tx_hash", txHash),
+				zap.String("network", network.Name),
+				zap.Error(err),
+			)
+			return nil, executorInternal("failed to fetch transaction receipt", err)
+		}
+		logger.Info("Transaction confirmed",
+			zap.String("tx_hash", txHash),
+			zap.String("network", network.Name),
+			zap.Uint64("block_number", receipt.BlockNumber.Uint64()),
+			zap.Uint64("status", receipt.Status),
+		)
+		return receipt, nil
+	}
+}
+
+func readDecimals(ctx context.Context, client *rpc.Client, token string) (uint8, error) {
+	call := map[string]string{
+		"to":   strings.ToLower(common.HexToAddress(token).Hex()),
+		"data": "0x313ce567",
+	}
+	var hexResp string
+	if err := client.CallContext(ctx, &hexResp, "eth_call", call, "latest"); err != nil {
+		return 0, merrors.Internal("decimals call failed: " + err.Error())
+	}
+	val, err := shared.DecodeHexUint8(hexResp)
+	if err != nil {
+		return 0, merrors.Internal("decimals decode failed: " + err.Error())
+	}
+	return val, nil
+}
+
+func readBalanceOf(ctx context.Context, client *rpc.Client, token string, wallet string) (*big.Int, error) {
+	tokenAddr := common.HexToAddress(token)
+	walletAddr := common.HexToAddress(wallet)
+	addr := strings.TrimPrefix(walletAddr.Hex(), "0x")
+	if len(addr) < 64 {
+		addr = strings.Repeat("0", 64-len(addr)) + addr
+	}
+	call := map[string]string{
+		"to":   strings.ToLower(tokenAddr.Hex()),
+		"data": "0x70a08231" + addr,
+	}
+	var hexResp string
+	if err := client.CallContext(ctx, &hexResp, "eth_call", call, "latest"); err != nil {
+		return nil, merrors.Internal("balanceOf call failed: " + err.Error())
+	}
+	bigVal, err := shared.DecodeHexBig(hexResp)
+	if err != nil {
+		return nil, merrors.Internal("balanceOf decode failed: " + err.Error())
+	}
+	return bigVal, nil
+}
+
+func erc20Decimals(ctx context.Context, client *rpc.Client, token common.Address) (uint8, error) {
+	call := map[string]string{
+		"to":   strings.ToLower(token.Hex()),
+		"data": "0x313ce567",
+	}
+	var hexResp string
+	if err := client.CallContext(ctx, &hexResp, "eth_call", call, "latest"); err != nil {
+		return 0, executorInternal("decimals call failed", err)
+	}
+	val, err := shared.DecodeHexUint8(hexResp)
+	if err != nil {
+		return 0, executorInternal("decimals decode failed", err)
+	}
+	return val, nil
+}
+
+type gasEstimator interface {
+	EstimateGas(ctx context.Context, msg ethereum.CallMsg) (uint64, error)
+}
+
+func estimateGas(ctx context.Context, network shared.Network, client gasEstimator, rpcClient *rpc.Client, callMsg ethereum.CallMsg) (uint64, error) {
+	if isTronNetwork(network) {
+		if rpcClient == nil {
+			return 0, merrors.Internal("rpc client not initialised")
+		}
+		return estimateGasTron(ctx, rpcClient, callMsg)
+	}
+	return client.EstimateGas(ctx, callMsg)
+}
+
+func estimateGasTron(ctx context.Context, rpcClient *rpc.Client, callMsg ethereum.CallMsg) (uint64, error) {
+	call := tronEstimateCall(callMsg)
+	var hexResp string
+	if err := rpcClient.CallContext(ctx, &hexResp, "eth_estimateGas", call); err != nil {
+		return 0, err
+	}
+	val, err := shared.DecodeHexBig(hexResp)
+	if err != nil {
+		return 0, err
+	}
+	if val == nil {
+		return 0, merrors.Internal("failed to decode gas estimate")
+	}
+	return val.Uint64(), nil
+}
+
+func tronEstimateCall(callMsg ethereum.CallMsg) map[string]string {
+	call := make(map[string]string)
+	if callMsg.From != (common.Address{}) {
+		call["from"] = strings.ToLower(callMsg.From.Hex())
+	}
+	if callMsg.To != nil {
+		call["to"] = strings.ToLower(callMsg.To.Hex())
+	}
+	if callMsg.Gas > 0 {
+		call["gas"] = hexutil.EncodeUint64(callMsg.Gas)
+	}
+	if callMsg.GasPrice != nil {
+		call["gasPrice"] = hexutil.EncodeBig(callMsg.GasPrice)
+	}
+	if callMsg.Value != nil {
+		call["value"] = hexutil.EncodeBig(callMsg.Value)
+	}
+	if len(callMsg.Data) > 0 {
+		call["data"] = hexutil.Encode(callMsg.Data)
+	}
+	return call
+}
+
+func isTronNetwork(network shared.Network) bool {
+	return strings.HasPrefix(strings.ToLower(strings.TrimSpace(network.Name)), "tron")
+}
+
+func toBaseUnits(amount string, decimals uint8) (*big.Int, error) {
+	value, err := decimal.NewFromString(strings.TrimSpace(amount))
+	if err != nil {
+		return nil, merrors.InvalidArgument("invalid amount " + amount + ": " + err.Error())
+	}
+	if value.IsNegative() {
+		return nil, merrors.InvalidArgument("amount must be positive")
+	}
+	multiplier := decimal.NewFromInt(1).Shift(int32(decimals))
+	scaled := value.Mul(multiplier)
+	if !scaled.Equal(scaled.Truncate(0)) {
+		return nil, merrors.InvalidArgument("amount " + amount + " exceeds token precision")
+	}
+	return scaled.BigInt(), nil
+}
+
+func executorInvalid(msg string) error {
+	return merrors.InvalidArgument("executor: " + msg)
+}
+
+func executorInternal(msg string, err error) error {
+	if err != nil {
+		msg = msg + ": " + err.Error()
+	}
+	return merrors.Internal("executor: " + msg)
+}

api/gateway/chain/internal/service/gateway/driver/evm/gas_topup.go

@@ -0,0 +1,108 @@
+package evm
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/shopspring/decimal"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	"github.com/tech/sendico/pkg/merrors"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+)
+
+var evmBaseUnitFactor = decimal.NewFromInt(1_000_000_000_000_000_000)
+
+// ComputeGasTopUp applies the network policy to decide an EVM native-token top-up amount.
+func ComputeGasTopUp(network shared.Network, wallet *model.ManagedWallet, estimatedFee *moneyv1.Money, currentBalance *moneyv1.Money) (*moneyv1.Money, bool, error) {
+	if wallet == nil {
+		return nil, false, merrors.InvalidArgument("wallet is required")
+	}
+	if estimatedFee == nil || strings.TrimSpace(estimatedFee.GetAmount()) == "" || strings.TrimSpace(estimatedFee.GetCurrency()) == "" {
+		return nil, false, merrors.InvalidArgument("estimated fee is required")
+	}
+	if currentBalance == nil || strings.TrimSpace(currentBalance.GetAmount()) == "" || strings.TrimSpace(currentBalance.GetCurrency()) == "" {
+		return nil, false, merrors.InvalidArgument("current native balance is required")
+	}
+	if network.GasTopUpPolicy == nil {
+		return nil, false, merrors.InvalidArgument("gas top-up policy is not configured")
+	}
+
+	nativeCurrency := strings.TrimSpace(network.NativeToken)
+	if nativeCurrency == "" {
+		nativeCurrency = strings.ToUpper(strings.TrimSpace(network.Name))
+	}
+	if !strings.EqualFold(nativeCurrency, estimatedFee.GetCurrency()) {
+		return nil, false, merrors.InvalidArgument(fmt.Sprintf("estimated fee currency mismatch (expected %s)", nativeCurrency))
+	}
+	if !strings.EqualFold(nativeCurrency, currentBalance.GetCurrency()) {
+		return nil, false, merrors.InvalidArgument(fmt.Sprintf("native balance currency mismatch (expected %s)", nativeCurrency))
+	}
+
+	estimatedNative, err := evmToNative(estimatedFee)
+	if err != nil {
+		return nil, false, err
+	}
+	currentNative, err := evmToNative(currentBalance)
+	if err != nil {
+		return nil, false, err
+	}
+
+	isContract := strings.TrimSpace(wallet.ContractAddress) != ""
+	rule, ok := network.GasTopUpPolicy.Rule(isContract)
+	if !ok {
+		return nil, false, merrors.InvalidArgument("gas top-up policy is not configured")
+	}
+	if rule.RoundingUnit.LessThanOrEqual(decimal.Zero) {
+		return nil, false, merrors.InvalidArgument("gas top-up rounding unit must be > 0")
+	}
+	if rule.MaxTopUp.LessThanOrEqual(decimal.Zero) {
+		return nil, false, merrors.InvalidArgument("gas top-up max top-up must be > 0")
+	}
+
+	required := estimatedNative.Sub(currentNative)
+	if required.IsNegative() {
+		required = decimal.Zero
+	}
+	bufferedRequired := required.Mul(decimal.NewFromInt(1).Add(rule.BufferPercent))
+
+	minBalanceTopUp := rule.MinNativeBalance.Sub(currentNative)
+	if minBalanceTopUp.IsNegative() {
+		minBalanceTopUp = decimal.Zero
+	}
+
+	rawTopUp := bufferedRequired
+	if minBalanceTopUp.GreaterThan(rawTopUp) {
+		rawTopUp = minBalanceTopUp
+	}
+
+	roundedTopUp := decimal.Zero
+	if rawTopUp.IsPositive() {
+		roundedTopUp = rawTopUp.Div(rule.RoundingUnit).Ceil().Mul(rule.RoundingUnit)
+	}
+
+	topUp := roundedTopUp
+	capHit := false
+	if topUp.GreaterThan(rule.MaxTopUp) {
+		topUp = rule.MaxTopUp
+		capHit = true
+	}
+
+	if !topUp.IsPositive() {
+		return nil, capHit, nil
+	}
+
+	baseUnits := topUp.Mul(evmBaseUnitFactor).Ceil().Truncate(0)
+	return &moneyv1.Money{
+		Currency: strings.ToUpper(nativeCurrency),
+		Amount:   baseUnits.StringFixed(0),
+	}, capHit, nil
+}
+
+func evmToNative(amount *moneyv1.Money) (decimal.Decimal, error) {
+	value, err := decimal.NewFromString(strings.TrimSpace(amount.GetAmount()))
+	if err != nil {
+		return decimal.Zero, err
+	}
+	return value.Div(evmBaseUnitFactor), nil
+}

api/gateway/chain/internal/service/gateway/driver/evm/gas_topup_test.go

@@ -0,0 +1,146 @@
+package evm
+
+import (
+	"testing"
+
+	"github.com/shopspring/decimal"
+	"github.com/stretchr/testify/require"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+)
+
+func TestComputeGasTopUp_BalanceSufficient(t *testing.T) {
+	network := ethNetwork(defaultPolicy())
+	wallet := &model.ManagedWallet{}
+
+	topUp, capHit, err := ComputeGasTopUp(network, wallet, ethMoney("5"), ethMoney("30"))
+	require.NoError(t, err)
+	require.Nil(t, topUp)
+	require.False(t, capHit)
+}
+
+func TestComputeGasTopUp_BufferedRequired(t *testing.T) {
+	network := ethNetwork(defaultPolicy())
+	wallet := &model.ManagedWallet{}
+
+	topUp, capHit, err := ComputeGasTopUp(network, wallet, ethMoney("50"), ethMoney("10"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.False(t, capHit)
+	require.Equal(t, "46000000000000000000", topUp.GetAmount())
+	require.Equal(t, "ETH", topUp.GetCurrency())
+}
+
+func TestComputeGasTopUp_MinBalanceBinding(t *testing.T) {
+	network := ethNetwork(defaultPolicy())
+	wallet := &model.ManagedWallet{}
+
+	topUp, capHit, err := ComputeGasTopUp(network, wallet, ethMoney("5"), ethMoney("1"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.False(t, capHit)
+	require.Equal(t, "19000000000000000000", topUp.GetAmount())
+}
+
+func TestComputeGasTopUp_RoundsUp(t *testing.T) {
+	policy := shared.GasTopUpPolicy{
+		Default: shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0),
+			MinNativeBalance: decimal.NewFromFloat(0),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(100),
+		},
+	}
+	network := ethNetwork(&policy)
+	wallet := &model.ManagedWallet{}
+
+	topUp, capHit, err := ComputeGasTopUp(network, wallet, ethMoney("1.1"), ethMoney("0"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.False(t, capHit)
+	require.Equal(t, "2000000000000000000", topUp.GetAmount())
+}
+
+func TestComputeGasTopUp_CapHit(t *testing.T) {
+	policy := shared.GasTopUpPolicy{
+		Default: shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0),
+			MinNativeBalance: decimal.NewFromFloat(0),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(10),
+		},
+	}
+	network := ethNetwork(&policy)
+	wallet := &model.ManagedWallet{}
+
+	topUp, capHit, err := ComputeGasTopUp(network, wallet, ethMoney("100"), ethMoney("0"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.True(t, capHit)
+	require.Equal(t, "10000000000000000000", topUp.GetAmount())
+}
+
+func TestComputeGasTopUp_MinBalanceWhenRequiredZero(t *testing.T) {
+	network := ethNetwork(defaultPolicy())
+	wallet := &model.ManagedWallet{}
+
+	topUp, capHit, err := ComputeGasTopUp(network, wallet, ethMoney("0"), ethMoney("5"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.False(t, capHit)
+	require.Equal(t, "15000000000000000000", topUp.GetAmount())
+}
+
+func TestComputeGasTopUp_ContractPolicyOverride(t *testing.T) {
+	policy := shared.GasTopUpPolicy{
+		Default: shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0.1),
+			MinNativeBalance: decimal.NewFromFloat(10),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(100),
+		},
+		Contract: &shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0.5),
+			MinNativeBalance: decimal.NewFromFloat(5),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(100),
+		},
+	}
+	network := ethNetwork(&policy)
+	wallet := &model.ManagedWallet{ContractAddress: "0xcontract"}
+
+	topUp, capHit, err := ComputeGasTopUp(network, wallet, ethMoney("10"), ethMoney("0"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.False(t, capHit)
+	require.Equal(t, "15000000000000000000", topUp.GetAmount())
+}
+
+func defaultPolicy() *shared.GasTopUpPolicy {
+	return &shared.GasTopUpPolicy{
+		Default: shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0.15),
+			MinNativeBalance: decimal.NewFromFloat(20),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(500),
+		},
+	}
+}
+
+func ethNetwork(policy *shared.GasTopUpPolicy) shared.Network {
+	return shared.Network{
+		Name:           "ethereum_mainnet",
+		NativeToken:    "ETH",
+		GasTopUpPolicy: policy,
+	}
+}
+
+func ethMoney(eth string) *moneyv1.Money {
+	value, _ := decimal.NewFromString(eth)
+	baseUnits := value.Mul(evmBaseUnitFactor).Truncate(0)
+	return &moneyv1.Money{
+		Currency: "ETH",
+		Amount:   baseUnits.StringFixed(0),
+	}
+}

api/gateway/chain/internal/service/gateway/driver/tron/address.go

@@ -0,0 +1,193 @@
+package tron
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"math/big"
+	"strings"
+
+	"github.com/tech/sendico/pkg/merrors"
+)
+
+const tronHexPrefix = "0x"
+
+var base58Alphabet = []byte("123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz")
+
+func normalizeAddress(address string) (string, error) {
+	trimmed := strings.TrimSpace(address)
+	if trimmed == "" {
+		return "", merrors.InvalidArgument("address is required")
+	}
+	if strings.HasPrefix(trimmed, tronHexPrefix) || isHexString(trimmed) {
+		return hexToBase58(trimmed)
+	}
+	decoded, err := base58Decode(trimmed)
+	if err != nil {
+		return "", err
+	}
+	if err := validateChecksum(decoded); err != nil {
+		return "", err
+	}
+	return base58Encode(decoded), nil
+}
+
+func rpcAddress(address string) (string, error) {
+	trimmed := strings.TrimSpace(address)
+	if trimmed == "" {
+		return "", merrors.InvalidArgument("address is required")
+	}
+	if strings.HasPrefix(trimmed, tronHexPrefix) || isHexString(trimmed) {
+		return normalizeHexRPC(trimmed)
+	}
+	return base58ToHex(trimmed)
+}
+
+func hexToBase58(address string) (string, error) {
+	bytesAddr, err := parseHexAddress(address)
+	if err != nil {
+		return "", err
+	}
+	payload := append(bytesAddr, checksum(bytesAddr)...)
+	return base58Encode(payload), nil
+}
+
+func base58ToHex(address string) (string, error) {
+	decoded, err := base58Decode(address)
+	if err != nil {
+		return "", err
+	}
+	if err := validateChecksum(decoded); err != nil {
+		return "", err
+	}
+	return tronHexPrefix + hex.EncodeToString(decoded[1:21]), nil
+}
+
+func parseHexAddress(address string) ([]byte, error) {
+	trimmed := strings.TrimPrefix(strings.TrimSpace(address), tronHexPrefix)
+	if trimmed == "" {
+		return nil, merrors.InvalidArgument("address is required")
+	}
+	if len(trimmed)%2 == 1 {
+		trimmed = "0" + trimmed
+	}
+	decoded, err := hex.DecodeString(trimmed)
+	if err != nil {
+		return nil, merrors.InvalidArgument("invalid hex address")
+	}
+	switch len(decoded) {
+	case 20:
+		prefixed := make([]byte, 21)
+		prefixed[0] = 0x41
+		copy(prefixed[1:], decoded)
+		return prefixed, nil
+	case 21:
+		if decoded[0] != 0x41 {
+			return nil, merrors.InvalidArgument("invalid tron address prefix")
+		}
+		return decoded, nil
+	default:
+		return nil, merrors.InvalidArgument(fmt.Sprintf("invalid tron address length %d", len(decoded)))
+	}
+}
+
+func normalizeHexRPC(address string) (string, error) {
+	decoded, err := parseHexAddress(address)
+	if err != nil {
+		return "", err
+	}
+	return tronHexPrefix + hex.EncodeToString(decoded[1:21]), nil
+}
+
+func validateChecksum(decoded []byte) error {
+	if len(decoded) != 25 {
+		return merrors.InvalidArgument("invalid tron address length")
+	}
+	payload := decoded[:21]
+	expected := checksum(payload)
+	if !bytes.Equal(expected, decoded[21:]) {
+		return merrors.InvalidArgument("invalid tron address checksum")
+	}
+	if payload[0] != 0x41 {
+		return merrors.InvalidArgument("invalid tron address prefix")
+	}
+	return nil
+}
+
+func checksum(payload []byte) []byte {
+	first := sha256.Sum256(payload)
+	second := sha256.Sum256(first[:])
+	return second[:4]
+}
+
+func base58Encode(input []byte) string {
+	if len(input) == 0 {
+		return ""
+	}
+	x := new(big.Int).SetBytes(input)
+	base := big.NewInt(58)
+	zero := big.NewInt(0)
+	mod := new(big.Int)
+
+	encoded := make([]byte, 0, len(input))
+	for x.Cmp(zero) > 0 {
+		x.DivMod(x, base, mod)
+		encoded = append(encoded, base58Alphabet[mod.Int64()])
+	}
+	for _, b := range input {
+		if b != 0 {
+			break
+		}
+		encoded = append(encoded, base58Alphabet[0])
+	}
+	reverse(encoded)
+	return string(encoded)
+}
+
+func base58Decode(input string) ([]byte, error) {
+	result := big.NewInt(0)
+	base := big.NewInt(58)
+
+	for i := 0; i < len(input); i++ {
+		idx := bytes.IndexByte(base58Alphabet, input[i])
+		if idx < 0 {
+			return nil, merrors.InvalidArgument("invalid base58 address")
+		}
+		result.Mul(result, base)
+		result.Add(result, big.NewInt(int64(idx)))
+	}
+
+	decoded := result.Bytes()
+	zeroCount := 0
+	for zeroCount < len(input) && input[zeroCount] == base58Alphabet[0] {
+		zeroCount++
+	}
+	if zeroCount > 0 {
+		decoded = append(make([]byte, zeroCount), decoded...)
+	}
+	return decoded, nil
+}
+
+func reverse(data []byte) {
+	for i, j := 0, len(data)-1; i < j; i, j = i+1, j-1 {
+		data[i], data[j] = data[j], data[i]
+	}
+}
+
+func isHexString(value string) bool {
+	trimmed := strings.TrimPrefix(strings.TrimSpace(value), tronHexPrefix)
+	if trimmed == "" {
+		return false
+	}
+	for _, r := range trimmed {
+		switch {
+		case r >= '0' && r <= '9':
+		case r >= 'a' && r <= 'f':
+		case r >= 'A' && r <= 'F':
+		default:
+			return false
+		}
+	}
+	return true
+}

api/gateway/chain/internal/service/gateway/driver/tron/driver.go

@@ -0,0 +1,245 @@
+package tron
+
+import (
+	"context"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver/evm"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	"github.com/tech/sendico/pkg/merrors"
+	"github.com/tech/sendico/pkg/mlogger"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+	"go.uber.org/zap"
+)
+
+// Driver implements Tron-specific behavior, including address conversion.
+type Driver struct {
+	logger mlogger.Logger
+}
+
+func New(logger mlogger.Logger) *Driver {
+	return &Driver{logger: logger.Named("tron")}
+}
+
+func (d *Driver) Name() string {
+	return "tron"
+}
+
+func (d *Driver) FormatAddress(address string) (string, error) {
+	d.logger.Debug("Format address", zap.String("address", address))
+	normalized, err := normalizeAddress(address)
+	if err != nil {
+		d.logger.Warn("Format address failed", zap.String("address", address), zap.Error(err))
+	}
+	return normalized, err
+}
+
+func (d *Driver) NormalizeAddress(address string) (string, error) {
+	d.logger.Debug("Normalize address", zap.String("address", address))
+	normalized, err := normalizeAddress(address)
+	if err != nil {
+		d.logger.Warn("Normalize address failed", zap.String("address", address), zap.Error(err))
+	}
+	return normalized, err
+}
+
+func (d *Driver) Balance(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet) (*moneyv1.Money, error) {
+	if wallet == nil {
+		return nil, merrors.InvalidArgument("wallet is required")
+	}
+	d.logger.Debug("Balance request", zap.String("wallet_ref", wallet.WalletRef), zap.String("network", network.Name))
+	rpcAddr, err := rpcAddress(wallet.DepositAddress)
+	if err != nil {
+		d.logger.Warn("Balance address conversion failed", zap.Error(err),
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("address", wallet.DepositAddress),
+		)
+		return nil, err
+	}
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	result, err := evm.Balance(ctx, driverDeps, network, wallet, rpcAddr)
+	if err != nil {
+		d.logger.Warn("Balance failed", zap.Error(err),
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+		)
+	} else if result != nil {
+		d.logger.Debug("Balance result",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("amount", result.Amount),
+			zap.String("currency", result.Currency),
+		)
+	}
+	return result, err
+}
+
+func (d *Driver) NativeBalance(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet) (*moneyv1.Money, error) {
+	if wallet == nil {
+		return nil, merrors.InvalidArgument("wallet is required")
+	}
+	d.logger.Debug("Native balance request", zap.String("wallet_ref", wallet.WalletRef), zap.String("network", network.Name))
+	rpcAddr, err := rpcAddress(wallet.DepositAddress)
+	if err != nil {
+		d.logger.Warn("Native balance address conversion failed", zap.Error(err),
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("address", wallet.DepositAddress),
+		)
+		return nil, err
+	}
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	result, err := evm.NativeBalance(ctx, driverDeps, network, wallet, rpcAddr)
+	if err != nil {
+		d.logger.Warn("Native balance failed", zap.Error(err),
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+		)
+	} else if result != nil {
+		d.logger.Debug("Native balance result",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("amount", result.Amount),
+			zap.String("currency", result.Currency),
+		)
+	}
+	return result, err
+}
+
+func (d *Driver) EstimateFee(ctx context.Context, deps driver.Deps, network shared.Network, wallet *model.ManagedWallet, destination string, amount *moneyv1.Money) (*moneyv1.Money, error) {
+	if wallet == nil {
+		return nil, merrors.InvalidArgument("wallet is required")
+	}
+	if amount == nil {
+		return nil, merrors.InvalidArgument("amount is required")
+	}
+	d.logger.Debug("Estimate fee request",
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("network", network.Name),
+		zap.String("destination", destination),
+	)
+	rpcFrom, err := rpcAddress(wallet.DepositAddress)
+	if err != nil {
+		d.logger.Warn("Estimate fee address conversion failed", zap.Error(err),
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("address", wallet.DepositAddress),
+		)
+		return nil, err
+	}
+	rpcTo, err := rpcAddress(destination)
+	if err != nil {
+		d.logger.Warn("Estimate fee destination conversion failed", zap.Error(err),
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("destination", destination),
+		)
+		return nil, err
+	}
+	if rpcFrom == rpcTo {
+		return &moneyv1.Money{
+			Currency: nativeCurrency(network),
+			Amount:   "0",
+		}, nil
+	}
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	result, err := evm.EstimateFee(ctx, driverDeps, network, wallet, rpcFrom, rpcTo, amount)
+	if err != nil {
+		d.logger.Warn("Estimate fee failed", zap.Error(err),
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("from_address", wallet.DepositAddress),
+			zap.String("from_rpc", rpcFrom),
+			zap.String("to_address", destination),
+			zap.String("to_rpc", rpcTo),
+		)
+	} else if result != nil {
+		d.logger.Debug("Estimate fee result",
+			zap.String("wallet_ref", wallet.WalletRef),
+			zap.String("network", network.Name),
+			zap.String("amount", result.Amount),
+			zap.String("currency", result.Currency),
+		)
+	}
+	return result, err
+}
+
+func (d *Driver) SubmitTransfer(ctx context.Context, deps driver.Deps, network shared.Network, transfer *model.Transfer, source *model.ManagedWallet, destination string) (string, error) {
+	if source == nil {
+		return "", merrors.InvalidArgument("source wallet is required")
+	}
+	d.logger.Debug("Submit transfer request",
+		zap.String("transfer_ref", transfer.TransferRef),
+		zap.String("network", network.Name),
+		zap.String("destination", destination),
+	)
+	rpcFrom, err := rpcAddress(source.DepositAddress)
+	if err != nil {
+		d.logger.Warn("Submit transfer address conversion failed", zap.Error(err),
+			zap.String("wallet_ref", source.WalletRef),
+			zap.String("address", source.DepositAddress),
+		)
+		return "", err
+	}
+	rpcTo, err := rpcAddress(destination)
+	if err != nil {
+		d.logger.Warn("Submit transfer destination conversion failed", zap.Error(err),
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("destination", destination),
+		)
+		return "", err
+	}
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	txHash, err := evm.SubmitTransfer(ctx, driverDeps, network, transfer, source, rpcFrom, rpcTo)
+	if err != nil {
+		d.logger.Warn("Submit transfer failed", zap.Error(err),
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("network", network.Name),
+		)
+	} else {
+		d.logger.Debug("Submit transfer result",
+			zap.String("transfer_ref", transfer.TransferRef),
+			zap.String("network", network.Name),
+			zap.String("tx_hash", txHash),
+		)
+	}
+	return txHash, err
+}
+
+func (d *Driver) AwaitConfirmation(ctx context.Context, deps driver.Deps, network shared.Network, txHash string) (*types.Receipt, error) {
+	d.logger.Debug("Awaiting confirmation",
+		zap.String("tx_hash", txHash),
+		zap.String("network", network.Name),
+	)
+	driverDeps := deps
+	driverDeps.Logger = d.logger
+	receipt, err := evm.AwaitConfirmation(ctx, driverDeps, network, txHash)
+	if err != nil {
+		d.logger.Warn("Awaiting of confirmation failed", zap.Error(err),
+			zap.String("tx_hash", txHash),
+			zap.String("network", network.Name),
+		)
+	} else if receipt != nil {
+		d.logger.Debug("Await confirmation result",
+			zap.String("tx_hash", txHash),
+			zap.String("network", network.Name),
+			zap.Uint64("block_number", receipt.BlockNumber.Uint64()),
+			zap.Uint64("status", receipt.Status),
+		)
+	}
+	return receipt, err
+}
+
+func nativeCurrency(network shared.Network) string {
+	currency := strings.ToUpper(strings.TrimSpace(network.NativeToken))
+	if currency == "" {
+		currency = strings.ToUpper(strings.TrimSpace(network.Name))
+	}
+	return currency
+}
+
+var _ driver.Driver = (*Driver)(nil)

api/gateway/chain/internal/service/gateway/driver/tron/driver_test.go

@@ -0,0 +1,33 @@
+package tron
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+	"go.uber.org/zap"
+)
+
+func TestEstimateFeeSelfTransferReturnsZero(t *testing.T) {
+	logger := zap.NewNop()
+	d := New(logger)
+	wallet := &model.ManagedWallet{
+		WalletRef:      "wallet_ref",
+		DepositAddress: "TGBDXEg9rxSqGFJDcb889zqTjDwx1bmLRF",
+	}
+	network := shared.Network{
+		Name:        "tron_mainnet",
+		NativeToken: "TRX",
+	}
+	amount := &moneyv1.Money{Currency: "TRX", Amount: "1000000"}
+
+	fee, err := d.EstimateFee(context.Background(), driver.Deps{}, network, wallet, wallet.DepositAddress, amount)
+	require.NoError(t, err)
+	require.NotNil(t, fee)
+	require.Equal(t, "TRX", fee.GetCurrency())
+	require.Equal(t, "0", fee.GetAmount())
+}

api/gateway/chain/internal/service/gateway/driver/tron/gas_topup.go

@@ -0,0 +1,143 @@
+package tron
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/shopspring/decimal"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	"github.com/tech/sendico/pkg/merrors"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+)
+
+var tronBaseUnitFactor = decimal.NewFromInt(1_000_000)
+
+// GasTopUpDecision captures the applied policy inputs and outputs (in TRX units).
+type GasTopUpDecision struct {
+	CurrentBalanceTRX   decimal.Decimal
+	EstimatedFeeTRX     decimal.Decimal
+	RequiredTRX         decimal.Decimal
+	BufferedRequiredTRX decimal.Decimal
+	MinBalanceTopUpTRX  decimal.Decimal
+	RawTopUpTRX         decimal.Decimal
+	RoundedTopUpTRX     decimal.Decimal
+	TopUpTRX            decimal.Decimal
+	CapHit              bool
+	OperationType       string
+}
+
+// ComputeGasTopUp applies the network policy to decide a TRX top-up amount.
+func ComputeGasTopUp(network shared.Network, wallet *model.ManagedWallet, estimatedFee *moneyv1.Money, currentBalance *moneyv1.Money) (*moneyv1.Money, GasTopUpDecision, error) {
+	decision := GasTopUpDecision{}
+	if wallet == nil {
+		return nil, decision, merrors.InvalidArgument("wallet is required")
+	}
+	if estimatedFee == nil || strings.TrimSpace(estimatedFee.GetAmount()) == "" || strings.TrimSpace(estimatedFee.GetCurrency()) == "" {
+		return nil, decision, merrors.InvalidArgument("estimated fee is required")
+	}
+	if currentBalance == nil || strings.TrimSpace(currentBalance.GetAmount()) == "" || strings.TrimSpace(currentBalance.GetCurrency()) == "" {
+		return nil, decision, merrors.InvalidArgument("current native balance is required")
+	}
+	if network.GasTopUpPolicy == nil {
+		return nil, decision, merrors.InvalidArgument("gas top-up policy is not configured")
+	}
+
+	nativeCurrency := strings.TrimSpace(network.NativeToken)
+	if nativeCurrency == "" {
+		nativeCurrency = strings.ToUpper(strings.TrimSpace(network.Name))
+	}
+	if !strings.EqualFold(nativeCurrency, estimatedFee.GetCurrency()) {
+		return nil, decision, merrors.InvalidArgument(fmt.Sprintf("estimated fee currency mismatch (expected %s)", nativeCurrency))
+	}
+	if !strings.EqualFold(nativeCurrency, currentBalance.GetCurrency()) {
+		return nil, decision, merrors.InvalidArgument(fmt.Sprintf("native balance currency mismatch (expected %s)", nativeCurrency))
+	}
+
+	estimatedTRX, err := tronToTRX(estimatedFee)
+	if err != nil {
+		return nil, decision, err
+	}
+	currentTRX, err := tronToTRX(currentBalance)
+	if err != nil {
+		return nil, decision, err
+	}
+
+	isContract := strings.TrimSpace(wallet.ContractAddress) != ""
+	rule, ok := network.GasTopUpPolicy.Rule(isContract)
+	if !ok {
+		return nil, decision, merrors.InvalidArgument("gas top-up policy is not configured")
+	}
+	if rule.RoundingUnit.LessThanOrEqual(decimal.Zero) {
+		return nil, decision, merrors.InvalidArgument("gas top-up rounding unit must be > 0")
+	}
+	if rule.MaxTopUp.LessThanOrEqual(decimal.Zero) {
+		return nil, decision, merrors.InvalidArgument("gas top-up max top-up must be > 0")
+	}
+
+	required := estimatedTRX.Sub(currentTRX)
+	if required.IsNegative() {
+		required = decimal.Zero
+	}
+	bufferedRequired := required.Mul(decimal.NewFromInt(1).Add(rule.BufferPercent))
+
+	minBalanceTopUp := rule.MinNativeBalance.Sub(currentTRX)
+	if minBalanceTopUp.IsNegative() {
+		minBalanceTopUp = decimal.Zero
+	}
+
+	rawTopUp := bufferedRequired
+	if minBalanceTopUp.GreaterThan(rawTopUp) {
+		rawTopUp = minBalanceTopUp
+	}
+
+	roundedTopUp := decimal.Zero
+	if rawTopUp.IsPositive() {
+		roundedTopUp = rawTopUp.Div(rule.RoundingUnit).Ceil().Mul(rule.RoundingUnit)
+	}
+
+	topUp := roundedTopUp
+	capHit := false
+	if topUp.GreaterThan(rule.MaxTopUp) {
+		topUp = rule.MaxTopUp
+		capHit = true
+	}
+
+	decision = GasTopUpDecision{
+		CurrentBalanceTRX:   currentTRX,
+		EstimatedFeeTRX:     estimatedTRX,
+		RequiredTRX:         required,
+		BufferedRequiredTRX: bufferedRequired,
+		MinBalanceTopUpTRX:  minBalanceTopUp,
+		RawTopUpTRX:         rawTopUp,
+		RoundedTopUpTRX:     roundedTopUp,
+		TopUpTRX:            topUp,
+		CapHit:              capHit,
+		OperationType:       operationType(isContract),
+	}
+
+	if !topUp.IsPositive() {
+		return nil, decision, nil
+	}
+
+	baseUnits := topUp.Mul(tronBaseUnitFactor).Ceil().Truncate(0)
+	return &moneyv1.Money{
+		Currency: strings.ToUpper(nativeCurrency),
+		Amount:   baseUnits.StringFixed(0),
+	}, decision, nil
+}
+
+func tronToTRX(amount *moneyv1.Money) (decimal.Decimal, error) {
+	value, err := decimal.NewFromString(strings.TrimSpace(amount.GetAmount()))
+	if err != nil {
+		return decimal.Zero, err
+	}
+	return value.Div(tronBaseUnitFactor), nil
+}
+
+func operationType(contract bool) string {
+	if contract {
+		return "trc20"
+	}
+	return "native"
+}

api/gateway/chain/internal/service/gateway/driver/tron/gas_topup_test.go

@@ -0,0 +1,147 @@
+package tron
+
+import (
+	"testing"
+
+	"github.com/shopspring/decimal"
+	"github.com/stretchr/testify/require"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/gateway/chain/storage/model"
+	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
+)
+
+func TestComputeGasTopUp_BalanceSufficient(t *testing.T) {
+	network := tronNetwork(defaultPolicy())
+	wallet := &model.ManagedWallet{}
+
+	topUp, decision, err := ComputeGasTopUp(network, wallet, tronMoney("5"), tronMoney("30"))
+	require.NoError(t, err)
+	require.Nil(t, topUp)
+	require.True(t, decision.TopUpTRX.IsZero())
+}
+
+func TestComputeGasTopUp_BufferedRequired(t *testing.T) {
+	network := tronNetwork(defaultPolicy())
+	wallet := &model.ManagedWallet{}
+
+	topUp, decision, err := ComputeGasTopUp(network, wallet, tronMoney("50"), tronMoney("10"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.Equal(t, "46000000", topUp.GetAmount())
+	require.Equal(t, "TRX", topUp.GetCurrency())
+	require.Equal(t, "46", decision.TopUpTRX.String())
+}
+
+func TestComputeGasTopUp_MinBalanceBinding(t *testing.T) {
+	network := tronNetwork(defaultPolicy())
+	wallet := &model.ManagedWallet{}
+
+	topUp, decision, err := ComputeGasTopUp(network, wallet, tronMoney("5"), tronMoney("1"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.Equal(t, "19000000", topUp.GetAmount())
+	require.Equal(t, "19", decision.TopUpTRX.String())
+}
+
+func TestComputeGasTopUp_RoundsUp(t *testing.T) {
+	policy := shared.GasTopUpPolicy{
+		Default: shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0),
+			MinNativeBalance: decimal.NewFromFloat(0),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(100),
+		},
+	}
+	network := tronNetwork(&policy)
+	wallet := &model.ManagedWallet{}
+
+	topUp, decision, err := ComputeGasTopUp(network, wallet, tronMoney("1.1"), tronMoney("0"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.Equal(t, "2000000", topUp.GetAmount())
+	require.Equal(t, "2", decision.TopUpTRX.String())
+}
+
+func TestComputeGasTopUp_CapHit(t *testing.T) {
+	policy := shared.GasTopUpPolicy{
+		Default: shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0),
+			MinNativeBalance: decimal.NewFromFloat(0),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(10),
+		},
+	}
+	network := tronNetwork(&policy)
+	wallet := &model.ManagedWallet{}
+
+	topUp, decision, err := ComputeGasTopUp(network, wallet, tronMoney("100"), tronMoney("0"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.Equal(t, "10000000", topUp.GetAmount())
+	require.True(t, decision.CapHit)
+}
+
+func TestComputeGasTopUp_MinBalanceWhenRequiredZero(t *testing.T) {
+	network := tronNetwork(defaultPolicy())
+	wallet := &model.ManagedWallet{}
+
+	topUp, decision, err := ComputeGasTopUp(network, wallet, tronMoney("0"), tronMoney("5"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.Equal(t, "15000000", topUp.GetAmount())
+	require.Equal(t, "15", decision.TopUpTRX.String())
+}
+
+func TestComputeGasTopUp_ContractPolicyOverride(t *testing.T) {
+	policy := shared.GasTopUpPolicy{
+		Default: shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0.1),
+			MinNativeBalance: decimal.NewFromFloat(10),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(100),
+		},
+		Contract: &shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0.5),
+			MinNativeBalance: decimal.NewFromFloat(5),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(100),
+		},
+	}
+	network := tronNetwork(&policy)
+	wallet := &model.ManagedWallet{ContractAddress: "0xcontract"}
+
+	topUp, decision, err := ComputeGasTopUp(network, wallet, tronMoney("10"), tronMoney("0"))
+	require.NoError(t, err)
+	require.NotNil(t, topUp)
+	require.Equal(t, "15000000", topUp.GetAmount())
+	require.Equal(t, "15", decision.TopUpTRX.String())
+	require.Equal(t, "trc20", decision.OperationType)
+}
+
+func defaultPolicy() *shared.GasTopUpPolicy {
+	return &shared.GasTopUpPolicy{
+		Default: shared.GasTopUpRule{
+			BufferPercent:    decimal.NewFromFloat(0.15),
+			MinNativeBalance: decimal.NewFromFloat(20),
+			RoundingUnit:     decimal.NewFromFloat(1),
+			MaxTopUp:         decimal.NewFromFloat(500),
+		},
+	}
+}
+
+func tronNetwork(policy *shared.GasTopUpPolicy) shared.Network {
+	return shared.Network{
+		Name:           "tron_mainnet",
+		NativeToken:    "TRX",
+		GasTopUpPolicy: policy,
+	}
+}
+
+func tronMoney(trx string) *moneyv1.Money {
+	value, _ := decimal.NewFromString(trx)
+	baseUnits := value.Mul(tronBaseUnitFactor).Truncate(0)
+	return &moneyv1.Money{
+		Currency: "TRX",
+		Amount:   baseUnits.StringFixed(0),
+	}
+}

api/gateway/chain/internal/service/gateway/drivers/registry.go

@@ -0,0 +1,74 @@
+package drivers
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver/arbitrum"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver/ethereum"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver/tron"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/pkg/merrors"
+	"github.com/tech/sendico/pkg/mlogger"
+	"go.uber.org/zap"
+)
+
+// Registry maps configured network keys to chain drivers.
+type Registry struct {
+	byNetwork map[string]driver.Driver
+}
+
+// NewRegistry selects drivers for the configured networks.
+func NewRegistry(logger mlogger.Logger, networks []shared.Network) (*Registry, error) {
+	if logger == nil {
+		return nil, merrors.InvalidArgument("driver registry: logger is required")
+	}
+	result := &Registry{byNetwork: map[string]driver.Driver{}}
+	for _, network := range networks {
+		name := strings.ToLower(strings.TrimSpace(network.Name))
+		if name == "" {
+			continue
+		}
+		chainDriver, err := resolveDriver(logger, name)
+		if err != nil {
+			logger.Error("Unsupported chain driver", zap.String("network", name), zap.Error(err))
+			return nil, err
+		}
+		result.byNetwork[name] = chainDriver
+	}
+	if len(result.byNetwork) == 0 {
+		return nil, merrors.InvalidArgument("driver registry: no supported networks configured")
+	}
+	logger.Info("Chain drivers configured", zap.Int("count", len(result.byNetwork)))
+	return result, nil
+}
+
+// Driver resolves a driver for the provided network key.
+func (r *Registry) Driver(network string) (driver.Driver, error) {
+	if r == nil || len(r.byNetwork) == 0 {
+		return nil, merrors.Internal("driver registry is not configured")
+	}
+	key := strings.ToLower(strings.TrimSpace(network))
+	if key == "" {
+		return nil, merrors.InvalidArgument("network is required")
+	}
+	chainDriver, ok := r.byNetwork[key]
+	if !ok {
+		return nil, merrors.InvalidArgument(fmt.Sprintf("unsupported chain network %s", key))
+	}
+	return chainDriver, nil
+}
+
+func resolveDriver(logger mlogger.Logger, network string) (driver.Driver, error) {
+	switch {
+	case strings.HasPrefix(network, "tron"):
+		return tron.New(logger), nil
+	case strings.HasPrefix(network, "arbitrum"):
+		return arbitrum.New(logger), nil
+	case strings.HasPrefix(network, "ethereum"):
+		return ethereum.New(logger), nil
+	default:
+		return nil, merrors.InvalidArgument("unsupported chain network " + network)
+	}
+}

api/gateway/chain/internal/service/gateway/executor.go

@@ -5,15 +5,15 @@ import (
 	"errors"
 	"math/big"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/accounts/abi"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
-	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/shopspring/decimal"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/rpcclient"
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
 	"go.uber.org/zap"
 
@@ -30,11 +30,11 @@ type TransferExecutor interface {
 }
 
 // NewOnChainExecutor constructs a TransferExecutor that talks to an EVM-compatible chain.
-func NewOnChainExecutor(logger mlogger.Logger, keyManager keymanager.Manager) TransferExecutor {
+func NewOnChainExecutor(logger mlogger.Logger, keyManager keymanager.Manager, clients *rpcclient.Clients) TransferExecutor {
 	return &onChainExecutor{
 		logger:     logger.Named("executor"),
 		keyManager: keyManager,
-		clients:    map[string]*ethclient.Client{},
+		clients:    clients,
 	}
 }
 
@@ -42,49 +42,52 @@ type onChainExecutor struct {
 	logger     mlogger.Logger
 	keyManager keymanager.Manager
 
-	mu      sync.Mutex
-	clients map[string]*ethclient.Client
+	clients *rpcclient.Clients
 }
 
 func (o *onChainExecutor) SubmitTransfer(ctx context.Context, transfer *model.Transfer, source *model.ManagedWallet, destinationAddress string, network shared.Network) (string, error) {
 	if o.keyManager == nil {
-		o.logger.Error("key manager not configured")
+		o.logger.Warn("Key manager not configured")
 		return "", executorInternal("key manager is not configured", nil)
 	}
 	rpcURL := strings.TrimSpace(network.RPCURL)
 	if rpcURL == "" {
-		o.logger.Error("network rpc url missing", zap.String("network", network.Name))
+		o.logger.Warn("Network rpc url missing", zap.String("network", network.Name))
 		return "", executorInvalid("network rpc url is not configured")
 	}
 	if source == nil || transfer == nil {
-		o.logger.Error("transfer context missing")
+		o.logger.Warn("Transfer context missing")
 		return "", executorInvalid("transfer context missing")
 	}
 	if strings.TrimSpace(source.KeyReference) == "" {
-		o.logger.Error("source wallet missing key reference", zap.String("wallet_ref", source.WalletRef))
+		o.logger.Warn("Source wallet missing key reference", zap.String("wallet_ref", source.WalletRef))
 		return "", executorInvalid("source wallet missing key reference")
 	}
 	if strings.TrimSpace(source.DepositAddress) == "" {
-		o.logger.Error("source wallet missing deposit address", zap.String("wallet_ref", source.WalletRef))
+		o.logger.Warn("Source wallet missing deposit address", zap.String("wallet_ref", source.WalletRef))
 		return "", executorInvalid("source wallet missing deposit address")
 	}
 	if !common.IsHexAddress(destinationAddress) {
-		o.logger.Error("invalid destination address", zap.String("transfer_ref", transfer.TransferRef), zap.String("address", destinationAddress))
+		o.logger.Warn("Invalid destination address", zap.String("transfer_ref", transfer.TransferRef), zap.String("address", destinationAddress))
 		return "", executorInvalid("invalid destination address " + destinationAddress)
 	}
 
-	o.logger.Info("submitting transfer",
+	o.logger.Info("Submitting transfer",
 		zap.String("transfer_ref", transfer.TransferRef),
 		zap.String("source_wallet_ref", source.WalletRef),
 		zap.String("network", network.Name),
 		zap.String("destination", strings.ToLower(destinationAddress)),
 	)
 
-	client, err := o.getClient(ctx, rpcURL)
+	client, err := o.clients.Client(network.Name)
 	if err != nil {
-		o.logger.Warn("failed to initialise rpc client",
+		o.logger.Warn("Failed to initialise RPC client", zap.Error(err), zap.String("network", network.Name))
+		return "", err
+	}
+	rpcClient, err := o.clients.RPCClient(network.Name)
+	if err != nil {
+		o.logger.Warn("Failed to initialise RPC client",
 			zap.String("network", network.Name),
-			zap.String("rpc_url", rpcURL),
 			zap.Error(err),
 		)
 		return "", err
@@ -98,17 +101,16 @@ func (o *onChainExecutor) SubmitTransfer(ctx context.Context, transfer *model.Tr
 
 	nonce, err := client.PendingNonceAt(ctx, sourceAddress)
 	if err != nil {
-		o.logger.Warn("failed to fetch nonce",
+		o.logger.Warn("Failed to fetch nonce", zap.Error(err),
 			zap.String("transfer_ref", transfer.TransferRef),
 			zap.String("wallet_ref", source.WalletRef),
-			zap.Error(err),
 		)
 		return "", executorInternal("failed to fetch nonce", err)
 	}
 
 	gasPrice, err := client.SuggestGasPrice(ctx)
 	if err != nil {
-		o.logger.Warn("failed to suggest gas price",
+		o.logger.Warn("Failed to suggest gas price",
 			zap.String("transfer_ref", transfer.TransferRef),
 			zap.String("network", network.Name),
 			zap.Error(err),
@@ -122,12 +124,12 @@ func (o *onChainExecutor) SubmitTransfer(ctx context.Context, transfer *model.Tr
 	chainID := new(big.Int).SetUint64(network.ChainID)
 
 	if strings.TrimSpace(transfer.ContractAddress) == "" {
-		o.logger.Warn("native token transfer requested but not supported", zap.String("transfer_ref", transfer.TransferRef))
+		o.logger.Warn("Native token transfer requested but not supported", zap.String("transfer_ref", transfer.TransferRef))
 		return "", merrors.NotImplemented("executor: native token transfers not yet supported")
 	}
 
 	if !common.IsHexAddress(transfer.ContractAddress) {
-		o.logger.Warn("invalid token contract address",
+		o.logger.Warn("Invalid token contract address",
 			zap.String("transfer_ref", transfer.TransferRef),
 			zap.String("contract", transfer.ContractAddress),
 		)
@@ -135,34 +137,32 @@ func (o *onChainExecutor) SubmitTransfer(ctx context.Context, transfer *model.Tr
 	}
 	tokenAddress := common.HexToAddress(transfer.ContractAddress)
 
-	decimals, err := erc20Decimals(ctx, client, tokenAddress)
+	decimals, err := erc20Decimals(ctx, rpcClient, tokenAddress)
 	if err != nil {
-		o.logger.Warn("failed to read token decimals",
+		o.logger.Warn("Failed to read token decimals", zap.Error(err),
 			zap.String("transfer_ref", transfer.TransferRef),
 			zap.String("contract", transfer.ContractAddress),
-			zap.Error(err),
 		)
 		return "", err
 	}
 
 	amount := transfer.NetAmount
 	if amount == nil || strings.TrimSpace(amount.Amount) == "" {
-		o.logger.Warn("transfer missing net amount", zap.String("transfer_ref", transfer.TransferRef))
+		o.logger.Warn("Transfer missing net amount", zap.String("transfer_ref", transfer.TransferRef))
 		return "", executorInvalid("transfer missing net amount")
 	}
 	amountInt, err := toBaseUnits(amount.Amount, decimals)
 	if err != nil {
-		o.logger.Warn("failed to convert amount to base units",
+		o.logger.Warn("Failed to convert amount to base units", zap.Error(err),
 			zap.String("transfer_ref", transfer.TransferRef),
 			zap.String("amount", amount.Amount),
-			zap.Error(err),
 		)
 		return "", err
 	}
 
 	input, err := erc20ABI.Pack("transfer", destination, amountInt)
 	if err != nil {
-		o.logger.Warn("failed to encode transfer call",
+		o.logger.Warn("Failed to encode transfer call",
 			zap.String("transfer_ref", transfer.TransferRef),
 			zap.Error(err),
 		)
@@ -177,7 +177,7 @@ func (o *onChainExecutor) SubmitTransfer(ctx context.Context, transfer *model.Tr
 	}
 	gasLimit, err := client.EstimateGas(ctx, callMsg)
 	if err != nil {
-		o.logger.Warn("failed to estimate gas",
+		o.logger.Warn("Failed to estimate gas",
 			zap.String("transfer_ref", transfer.TransferRef),
 			zap.Error(err),
 		)
@@ -188,24 +188,22 @@ func (o *onChainExecutor) SubmitTransfer(ctx context.Context, transfer *model.Tr
 
 	signedTx, err := o.keyManager.SignTransaction(ctx, source.KeyReference, tx, chainID)
 	if err != nil {
-		o.logger.Warn("failed to sign transaction",
+		o.logger.Warn("Failed to sign transaction", zap.Error(err),
 			zap.String("transfer_ref", transfer.TransferRef),
 			zap.String("wallet_ref", source.WalletRef),
-			zap.Error(err),
 		)
 		return "", err
 	}
 
 	if err := client.SendTransaction(ctx, signedTx); err != nil {
-		o.logger.Warn("failed to send transaction",
+		o.logger.Warn("Failed to send transaction", zap.Error(err),
 			zap.String("transfer_ref", transfer.TransferRef),
-			zap.Error(err),
 		)
 		return "", executorInternal("failed to send transaction", err)
 	}
 
 	txHash = signedTx.Hash().Hex()
-	o.logger.Info("transaction submitted",
+	o.logger.Info("Transaction submitted",
 		zap.String("transfer_ref", transfer.TransferRef),
 		zap.String("tx_hash", txHash),
 		zap.String("network", network.Name),
@@ -214,42 +212,18 @@ func (o *onChainExecutor) SubmitTransfer(ctx context.Context, transfer *model.Tr
 	return txHash, nil
 }
 
-func (o *onChainExecutor) getClient(ctx context.Context, rpcURL string) (*ethclient.Client, error) {
-	o.mu.Lock()
-	client, ok := o.clients[rpcURL]
-	o.mu.Unlock()
-	if ok {
-		return client, nil
-	}
-
-	c, err := ethclient.DialContext(ctx, rpcURL)
-	if err != nil {
-		return nil, executorInternal("failed to connect to rpc "+rpcURL, err)
-	}
-
-	o.mu.Lock()
-	defer o.mu.Unlock()
-	if existing, ok := o.clients[rpcURL]; ok {
-		// Another routine initialised it in the meantime; prefer the existing client and close the new one.
-		c.Close()
-		return existing, nil
-	}
-	o.clients[rpcURL] = c
-	return c, nil
-}
-
 func (o *onChainExecutor) AwaitConfirmation(ctx context.Context, network shared.Network, txHash string) (*types.Receipt, error) {
 	if strings.TrimSpace(txHash) == "" {
-		o.logger.Warn("missing transaction hash for confirmation", zap.String("network", network.Name))
+		o.logger.Warn("Missing transaction hash for confirmation", zap.String("network", network.Name))
 		return nil, executorInvalid("tx hash is required")
 	}
 	rpcURL := strings.TrimSpace(network.RPCURL)
 	if rpcURL == "" {
-		o.logger.Warn("network rpc url missing while awaiting confirmation", zap.String("tx_hash", txHash))
+		o.logger.Warn("Network RPC url missing while awaiting confirmation", zap.String("tx_hash", txHash))
 		return nil, executorInvalid("network rpc url is not configured")
 	}
 
-	client, err := o.getClient(ctx, rpcURL)
+	client, err := o.clients.Client(network.Name)
 	if err != nil {
 		return nil, err
 	}
@@ -264,27 +238,27 @@ func (o *onChainExecutor) AwaitConfirmation(ctx context.Context, network shared.
 			if errors.Is(err, ethereum.NotFound) {
 				select {
 				case <-ticker.C:
-					o.logger.Debug("transaction not yet mined",
+					o.logger.Debug("Transaction not yet mined",
 						zap.String("tx_hash", txHash),
 						zap.String("network", network.Name),
 					)
 					continue
 				case <-ctx.Done():
-					o.logger.Warn("context cancelled while awaiting confirmation",
+					o.logger.Warn("Context cancelled while awaiting confirmation",
 						zap.String("tx_hash", txHash),
 						zap.String("network", network.Name),
 					)
 					return nil, ctx.Err()
 				}
 			}
-			o.logger.Warn("failed to fetch transaction receipt",
+			o.logger.Warn("Failed to fetch transaction receipt",
 				zap.String("tx_hash", txHash),
 				zap.String("network", network.Name),
 				zap.Error(err),
 			)
 			return nil, executorInternal("failed to fetch transaction receipt", err)
 		}
-		o.logger.Info("transaction confirmed",
+		o.logger.Info("Transaction confirmed",
 			zap.String("tx_hash", txHash),
 			zap.String("network", network.Name),
 			zap.Uint64("block_number", receipt.BlockNumber.Uint64()),
@@ -331,31 +305,20 @@ const erc20ABIJSON = `
 	}
 ]`
 
-func erc20Decimals(ctx context.Context, client *ethclient.Client, token common.Address) (uint8, error) {
-	callData, err := erc20ABI.Pack("decimals")
-	if err != nil {
-		return 0, executorInternal("failed to encode decimals call", err)
+func erc20Decimals(ctx context.Context, client *rpc.Client, token common.Address) (uint8, error) {
+	call := map[string]string{
+		"to":   strings.ToLower(token.Hex()),
+		"data": "0x313ce567",
 	}
-	msg := ethereum.CallMsg{
-		To:   &token,
-		Data: callData,
-	}
-	output, err := client.CallContract(ctx, msg, nil)
-	if err != nil {
+	var hexResp string
+	if err := client.CallContext(ctx, &hexResp, "eth_call", call, "latest"); err != nil {
 		return 0, executorInternal("decimals call failed", err)
 	}
-	values, err := erc20ABI.Unpack("decimals", output)
+	val, err := shared.DecodeHexUint8(hexResp)
 	if err != nil {
-		return 0, executorInternal("failed to unpack decimals", err)
+		return 0, executorInternal("decimals decode failed", err)
 	}
-	if len(values) == 0 {
-		return 0, executorInternal("decimals call returned no data", nil)
-	}
-	decimals, ok := values[0].(uint8)
-	if !ok {
-		return 0, executorInternal("decimals call returned unexpected type", nil)
-	}
-	return decimals, nil
+	return val, nil
 }
 
 func toBaseUnits(amount string, decimals uint8) (*big.Int, error) {

api/gateway/chain/internal/service/gateway/options.go

@@ -4,6 +4,8 @@ import (
 	"strings"
 
 	"github.com/tech/sendico/gateway/chain/internal/keymanager"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/drivers"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/rpcclient"
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
 	clockpkg "github.com/tech/sendico/pkg/clock"
 )
@@ -18,10 +20,10 @@ func WithKeyManager(manager keymanager.Manager) Option {
 	}
 }
 
-// WithTransferExecutor configures the executor responsible for on-chain submissions.
-func WithTransferExecutor(executor TransferExecutor) Option {
+// WithRPCClients configures pre-initialised RPC clients.
+func WithRPCClients(clients *rpcclient.Clients) Option {
 	return func(s *Service) {
-		s.executor = executor
+		s.rpcClients = clients
 	}
 }
 
@@ -59,6 +61,13 @@ func WithServiceWallet(wallet shared.ServiceWallet) Option {
 	}
 }
 
+// WithDriverRegistry configures the chain driver registry.
+func WithDriverRegistry(registry *drivers.Registry) Option {
+	return func(s *Service) {
+		s.drivers = registry
+	}
+}
+
 // WithClock overrides the service clock.
 func WithClock(clk clockpkg.Clock) Option {
 	return func(s *Service) {

api/gateway/chain/internal/service/gateway/rpcclient/clients.go

@@ -0,0 +1,204 @@
+package rpcclient
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/ethereum/go-ethereum/rpc"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/pkg/merrors"
+	"github.com/tech/sendico/pkg/mlogger"
+	"go.uber.org/zap"
+)
+
+// Clients holds pre-initialised RPC clients keyed by network name.
+type Clients struct {
+	logger  mlogger.Logger
+	clients map[string]clientEntry
+}
+
+type clientEntry struct {
+	eth *ethclient.Client
+	rpc *rpc.Client
+}
+
+// Prepare dials all configured networks up front and returns a ready-to-use client set.
+func Prepare(ctx context.Context, logger mlogger.Logger, networks []shared.Network) (*Clients, error) {
+	if logger == nil {
+		return nil, merrors.Internal("rpc clients: logger is required")
+	}
+	clientLogger := logger.Named("rpc_client")
+	result := &Clients{
+		logger:  clientLogger,
+		clients: make(map[string]clientEntry),
+	}
+
+	for _, network := range networks {
+		name := strings.ToLower(strings.TrimSpace(network.Name))
+		rpcURL := strings.TrimSpace(network.RPCURL)
+		if name == "" {
+			clientLogger.Warn("Skipping network with empty name during rpc client preparation")
+			continue
+		}
+		if rpcURL == "" {
+			result.Close()
+			err := merrors.InvalidArgument(fmt.Sprintf("rpc url not configured for network %s", name))
+			clientLogger.Warn("Rpc url missing", zap.String("network", name))
+			return nil, err
+		}
+
+		fields := []zap.Field{
+			zap.String("network", name),
+		}
+		clientLogger.Info("Initialising rpc client", fields...)
+
+		dialCtx, cancel := context.WithTimeout(ctx, 15*time.Second)
+		httpClient := &http.Client{
+			Transport: &loggingRoundTripper{
+				logger:   clientLogger,
+				network:  name,
+				endpoint: rpcURL,
+				base:     http.DefaultTransport,
+			},
+		}
+		rpcCli, err := rpc.DialOptions(dialCtx, rpcURL, rpc.WithHTTPClient(httpClient))
+		cancel()
+		if err != nil {
+			result.Close()
+			clientLogger.Warn("Failed to dial rpc endpoint", append(fields, zap.Error(err))...)
+			return nil, merrors.Internal(fmt.Sprintf("rpc dial failed for %s: %s", name, err.Error()))
+		}
+		client := ethclient.NewClient(rpcCli)
+		result.clients[name] = clientEntry{
+			eth: client,
+			rpc: rpcCli,
+		}
+		clientLogger.Info("RPC client ready", fields...)
+	}
+
+	if len(result.clients) == 0 {
+		clientLogger.Warn("No rpc clients were initialised")
+		return nil, merrors.InvalidArgument("no rpc clients initialised")
+	} else {
+		clientLogger.Info("RPC clients initialised", zap.Int("count", len(result.clients)))
+	}
+
+	return result, nil
+}
+
+// Client returns a prepared client for the given network name.
+func (c *Clients) Client(network string) (*ethclient.Client, error) {
+	if c == nil {
+		return nil, merrors.Internal("RPC clients not initialised")
+	}
+	name := strings.ToLower(strings.TrimSpace(network))
+	entry, ok := c.clients[name]
+	if !ok || entry.eth == nil {
+		return nil, merrors.InvalidArgument(fmt.Sprintf("RPC client not configured for network %s", name))
+	}
+	return entry.eth, nil
+}
+
+// RPCClient returns the raw RPC client for low-level calls.
+func (c *Clients) RPCClient(network string) (*rpc.Client, error) {
+	if c == nil {
+		return nil, merrors.Internal("rpc clients not initialised")
+	}
+	name := strings.ToLower(strings.TrimSpace(network))
+	entry, ok := c.clients[name]
+	if !ok || entry.rpc == nil {
+		return nil, merrors.InvalidArgument(fmt.Sprintf("rpc client not configured for network %s", name))
+	}
+	return entry.rpc, nil
+}
+
+// Close tears down all RPC clients, logging each close.
+func (c *Clients) Close() {
+	if c == nil {
+		return
+	}
+	for name, entry := range c.clients {
+		if entry.rpc != nil {
+			entry.rpc.Close()
+		} else if entry.eth != nil {
+			entry.eth.Close()
+		}
+		if c.logger != nil {
+			c.logger.Info("RPC client closed", zap.String("network", name))
+		}
+	}
+}
+
+type loggingRoundTripper struct {
+	logger   mlogger.Logger
+	network  string
+	endpoint string
+	base     http.RoundTripper
+}
+
+func (l *loggingRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	if l.base == nil {
+		l.base = http.DefaultTransport
+	}
+
+	var reqBody []byte
+	if req.Body != nil {
+		raw, _ := io.ReadAll(req.Body)
+		reqBody = raw
+		req.Body = io.NopCloser(strings.NewReader(string(raw)))
+	}
+
+	fields := []zap.Field{
+		zap.String("network", l.network),
+	}
+	if len(reqBody) > 0 {
+		fields = append(fields, zap.String("rpc_request", truncate(string(reqBody), 2048)))
+	}
+	l.logger.Debug("RPC request", fields...)
+
+	resp, err := l.base.RoundTrip(req)
+	if err != nil {
+		l.logger.Warn("RPC http request failed", append(fields, zap.Error(err))...)
+		return nil, err
+	}
+
+	bodyBytes, _ := io.ReadAll(resp.Body)
+	resp.Body.Close()
+	resp.Body = io.NopCloser(strings.NewReader(string(bodyBytes)))
+
+	respFields := append(fields,
+		zap.Int("status_code", resp.StatusCode),
+	)
+	if contentType := strings.TrimSpace(resp.Header.Get("Content-Type")); contentType != "" {
+		respFields = append(respFields, zap.String("content_type", contentType))
+	}
+	if len(bodyBytes) > 0 {
+		respFields = append(respFields, zap.String("rpc_response", truncate(string(bodyBytes), 2048)))
+	}
+	l.logger.Debug("RPC response", respFields...)
+	if resp.StatusCode >= 400 {
+		l.logger.Warn("RPC response error", respFields...)
+	} else if len(bodyBytes) == 0 {
+		l.logger.Warn("RPC response empty body", respFields...)
+	} else if len(bodyBytes) > 0 && !json.Valid(bodyBytes) {
+		l.logger.Warn("RPC response invalid JSON", respFields...)
+	}
+
+	return resp, nil
+}
+
+func truncate(s string, max int) string {
+	if len(s) <= max {
+		return s
+	}
+	if max <= 3 {
+		return s[:max]
+	}
+	return s[:max-3] + "..."
+}

api/gateway/chain/internal/service/gateway/rpcclient/registry.go

@@ -0,0 +1,54 @@
+package rpcclient
+
+import (
+	"strings"
+
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/ethereum/go-ethereum/rpc"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
+	"github.com/tech/sendico/pkg/merrors"
+)
+
+// Registry binds static network metadata with prepared RPC clients.
+type Registry struct {
+	networks map[string]shared.Network
+	clients  *Clients
+}
+
+// NewRegistry constructs a registry keyed by lower-cased network name.
+func NewRegistry(networks map[string]shared.Network, clients *Clients) *Registry {
+	return &Registry{
+		networks: networks,
+		clients:  clients,
+	}
+}
+
+// Network fetches network metadata by key (case-insensitive).
+func (r *Registry) Network(key string) (shared.Network, bool) {
+	if r == nil || len(r.networks) == 0 {
+		return shared.Network{}, false
+	}
+	n, ok := r.networks[strings.ToLower(strings.TrimSpace(key))]
+	return n, ok
+}
+
+// Client returns the prepared RPC client for the given network name.
+func (r *Registry) Client(key string) (*ethclient.Client, error) {
+	if r == nil || r.clients == nil {
+		return nil, merrors.Internal("rpc clients not initialised")
+	}
+	return r.clients.Client(strings.ToLower(strings.TrimSpace(key)))
+}
+
+// RPCClient returns the raw RPC client for low-level calls.
+func (r *Registry) RPCClient(key string) (*rpc.Client, error) {
+	if r == nil || r.clients == nil {
+		return nil, merrors.Internal("rpc clients not initialised")
+	}
+	return r.clients.RPCClient(strings.ToLower(strings.TrimSpace(key)))
+}
+
+// Networks exposes the registry map for iteration when needed.
+func (r *Registry) Networks() map[string]shared.Network {
+	return r.networks
+}

api/gateway/chain/internal/service/gateway/service.go

@@ -7,6 +7,8 @@ import (
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/commands"
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/commands/transfer"
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/commands/wallet"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/drivers"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/rpcclient"
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
 	"github.com/tech/sendico/gateway/chain/storage"
 	"github.com/tech/sendico/pkg/api/routers"
@@ -38,11 +40,13 @@ type Service struct {
 
 	settings CacheSettings
 
-	networks      map[string]shared.Network
-	serviceWallet shared.ServiceWallet
-	keyManager    keymanager.Manager
-	executor      TransferExecutor
-	commands      commands.Registry
+	networks        map[string]shared.Network
+	serviceWallet   shared.ServiceWallet
+	keyManager      keymanager.Manager
+	rpcClients      *rpcclient.Clients
+	networkRegistry *rpcclient.Registry
+	drivers         *drivers.Registry
+	commands        commands.Registry
 
 	chainv1.UnimplementedChainGatewayServiceServer
 }
@@ -73,6 +77,7 @@ func NewService(logger mlogger.Logger, repo storage.Repository, producer msg.Pro
 		svc.networks = map[string]shared.Network{}
 	}
 	svc.settings = svc.settings.withDefaults()
+	svc.networkRegistry = rpcclient.NewRegistry(svc.networks, svc.rpcClients)
 
 	svc.commands = commands.NewRegistry(commands.RegistryDeps{
 		Wallet:   commandsWalletDeps(svc),
@@ -121,6 +126,14 @@ func (s *Service) EstimateTransferFee(ctx context.Context, req *chainv1.Estimate
 	return executeUnary(ctx, s, "EstimateTransferFee", s.commands.EstimateTransfer.Execute, req)
 }
 
+func (s *Service) ComputeGasTopUp(ctx context.Context, req *chainv1.ComputeGasTopUpRequest) (*chainv1.ComputeGasTopUpResponse, error) {
+	return executeUnary(ctx, s, "ComputeGasTopUp", s.commands.ComputeGasTopUp.Execute, req)
+}
+
+func (s *Service) EnsureGasTopUp(ctx context.Context, req *chainv1.EnsureGasTopUpRequest) (*chainv1.EnsureGasTopUpResponse, error) {
+	return executeUnary(ctx, s, "EnsureGasTopUp", s.commands.EnsureGasTopUp.Execute, req)
+}
+
 func (s *Service) ensureRepository(ctx context.Context) error {
 	if s.storage == nil {
 		return errStorageUnavailable
@@ -131,11 +144,13 @@ func (s *Service) ensureRepository(ctx context.Context) error {
 func commandsWalletDeps(s *Service) wallet.Deps {
 	return wallet.Deps{
 		Logger:           s.logger.Named("command"),
-		Networks:         s.networks,
+		Drivers:          s.drivers,
+		Networks:         s.networkRegistry,
 		KeyManager:       s.keyManager,
 		Storage:          s.storage,
 		Clock:            s.clock,
 		BalanceCacheTTL:  s.settings.walletBalanceCacheTTL(),
+		RPCTimeout:       s.settings.rpcTimeout(),
 		EnsureRepository: s.ensureRepository,
 	}
 }
@@ -143,9 +158,11 @@ func commandsWalletDeps(s *Service) wallet.Deps {
 func commandsTransferDeps(s *Service) transfer.Deps {
 	return transfer.Deps{
 		Logger:           s.logger.Named("transfer_cmd"),
-		Networks:         s.networks,
+		Drivers:          s.drivers,
+		Networks:         s.networkRegistry,
 		Storage:          s.storage,
 		Clock:            s.clock,
+		RPCTimeout:       s.settings.rpcTimeout(),
 		EnsureRepository: s.ensureRepository,
 		LaunchExecution:  s.launchTransferExecution,
 	}

api/gateway/chain/internal/service/gateway/service_test.go

@@ -18,6 +18,7 @@ import (
 	"google.golang.org/grpc/status"
 
 	"github.com/tech/sendico/gateway/chain/internal/keymanager"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/drivers"
 	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
 	"github.com/tech/sendico/gateway/chain/storage"
 	"github.com/tech/sendico/gateway/chain/storage/model"
@@ -65,6 +66,25 @@ func TestCreateManagedWallet_Idempotent(t *testing.T) {
 	require.Equal(t, 1, repo.wallets.count())
 }
 
+func TestCreateManagedWallet_NativeTokenWithoutContract(t *testing.T) {
+	svc, _ := newTestService(t)
+	ctx := context.Background()
+
+	resp, err := svc.CreateManagedWallet(ctx, &ichainv1.CreateManagedWalletRequest{
+		IdempotencyKey:  "idem-native",
+		OrganizationRef: "org-1",
+		OwnerRef:        "owner-1",
+		Asset: &ichainv1.Asset{
+			Chain:       ichainv1.ChainNetwork_CHAIN_NETWORK_ETHEREUM_MAINNET,
+			TokenSymbol: "ETH",
+		},
+	})
+	require.NoError(t, err)
+	require.NotNil(t, resp.GetWallet())
+	require.Equal(t, "ETH", resp.GetWallet().GetAsset().GetTokenSymbol())
+	require.Empty(t, resp.GetWallet().GetAsset().GetContractAddress())
+}
+
 func TestSubmitTransfer_ManagedDestination(t *testing.T) {
 	svc, repo := newTestService(t)
 	ctx := context.Background()
@@ -143,6 +163,37 @@ func TestGetWalletBalance_NotFound(t *testing.T) {
 	require.Equal(t, codes.NotFound, st.Code())
 }
 
+func TestGetWalletBalance_ReturnsCachedNativeAvailable(t *testing.T) {
+	svc, repo := newTestService(t)
+	ctx := context.Background()
+
+	createResp, err := svc.CreateManagedWallet(ctx, &ichainv1.CreateManagedWalletRequest{
+		IdempotencyKey:  "idem-balance",
+		OrganizationRef: "org-1",
+		OwnerRef:        "owner-1",
+		Asset: &ichainv1.Asset{
+			Chain:       ichainv1.ChainNetwork_CHAIN_NETWORK_ETHEREUM_MAINNET,
+			TokenSymbol: "USDC",
+		},
+	})
+	require.NoError(t, err)
+	walletRef := createResp.GetWallet().GetWalletRef()
+
+	err = repo.wallets.SaveBalance(ctx, &model.WalletBalance{
+		WalletRef:       walletRef,
+		Available:       &moneyv1.Money{Currency: "USDC", Amount: "25"},
+		NativeAvailable: &moneyv1.Money{Currency: "ETH", Amount: "0.5"},
+		CalculatedAt:    time.Now().UTC(),
+	})
+	require.NoError(t, err)
+
+	resp, err := svc.GetWalletBalance(ctx, &ichainv1.GetWalletBalanceRequest{WalletRef: walletRef})
+	require.NoError(t, err)
+	require.NotNil(t, resp.GetBalance())
+	require.Equal(t, "0.5", resp.GetBalance().GetNativeAvailable().GetAmount())
+	require.Equal(t, "ETH", resp.GetBalance().GetNativeAvailable().GetCurrency())
+}
+
 // ---- in-memory storage implementation ----
 
 type inMemoryRepository struct {
@@ -526,18 +577,23 @@ func sanitizeLimit(requested int32, def, max int64) int64 {
 	return int64(requested)
 }
 
-func newTestService(_ *testing.T) (*Service, *inMemoryRepository) {
+func newTestService(t *testing.T) (*Service, *inMemoryRepository) {
 	repo := newInMemoryRepository()
 	logger := zap.NewNop()
+	networks := []shared.Network{{
+		Name:        "ethereum_mainnet",
+		NativeToken: "ETH",
+		TokenConfigs: []shared.TokenContract{
+			{Symbol: "USDC", ContractAddress: "0xusdc"},
+		},
+	}}
+	driverRegistry, err := drivers.NewRegistry(logger.Named("drivers"), networks)
+	require.NoError(t, err)
 	svc := NewService(logger, repo, nil,
 		WithKeyManager(&fakeKeyManager{}),
-		WithNetworks([]shared.Network{{
-			Name: "ethereum_mainnet",
-			TokenConfigs: []shared.TokenContract{
-				{Symbol: "USDC", ContractAddress: "0xusdc"},
-			},
-		}}),
+		WithNetworks(networks),
 		WithServiceWallet(shared.ServiceWallet{Network: "ethereum_mainnet", Address: "0xservice"}),
+		WithDriverRegistry(driverRegistry),
 	)
 	return svc, repo
 }

api/gateway/chain/internal/service/gateway/settings.go

@@ -3,15 +3,18 @@ package gateway
 import "time"
 
 const defaultWalletBalanceCacheTTL = 120 * time.Second
+const defaultRPCRequestTimeout = 15 * time.Second
 
 // CacheSettings holds tunable gateway behaviour.
 type CacheSettings struct {
 	WalletBalanceCacheTTLSeconds int `yaml:"wallet_balance_ttl_seconds"`
+	RPCRequestTimeoutSeconds     int `yaml:"rpc_request_timeout_seconds"`
 }
 
 func defaultSettings() CacheSettings {
 	return CacheSettings{
 		WalletBalanceCacheTTLSeconds: int(defaultWalletBalanceCacheTTL.Seconds()),
+		RPCRequestTimeoutSeconds:     int(defaultRPCRequestTimeout.Seconds()),
 	}
 }
 
@@ -19,6 +22,9 @@ func (s CacheSettings) withDefaults() CacheSettings {
 	if s.WalletBalanceCacheTTLSeconds <= 0 {
 		s.WalletBalanceCacheTTLSeconds = int(defaultWalletBalanceCacheTTL.Seconds())
 	}
+	if s.RPCRequestTimeoutSeconds <= 0 {
+		s.RPCRequestTimeoutSeconds = int(defaultRPCRequestTimeout.Seconds())
+	}
 	return s
 }
 
@@ -28,3 +34,10 @@ func (s CacheSettings) walletBalanceCacheTTL() time.Duration {
 	}
 	return time.Duration(s.WalletBalanceCacheTTLSeconds) * time.Second
 }
+
+func (s CacheSettings) rpcTimeout() time.Duration {
+	if s.RPCRequestTimeoutSeconds <= 0 {
+		return defaultRPCRequestTimeout
+	}
+	return time.Duration(s.RPCRequestTimeoutSeconds) * time.Second
+}

api/gateway/chain/internal/service/gateway/shared/gas_topup.go

@@ -0,0 +1,32 @@
+package shared
+
+import "github.com/shopspring/decimal"
+
+// GasTopUpRule defines buffer, minimum, rounding, and cap behavior for native gas top-ups.
+type GasTopUpRule struct {
+	BufferPercent    decimal.Decimal
+	MinNativeBalance decimal.Decimal
+	RoundingUnit     decimal.Decimal
+	MaxTopUp         decimal.Decimal
+}
+
+// GasTopUpPolicy captures default and optional overrides for native vs contract transfers.
+type GasTopUpPolicy struct {
+	Default  GasTopUpRule
+	Native   *GasTopUpRule
+	Contract *GasTopUpRule
+}
+
+// Rule selects the policy rule for the transfer type.
+func (p *GasTopUpPolicy) Rule(contractTransfer bool) (GasTopUpRule, bool) {
+	if p == nil {
+		return GasTopUpRule{}, false
+	}
+	if contractTransfer && p.Contract != nil {
+		return *p.Contract, true
+	}
+	if !contractTransfer && p.Native != nil {
+		return *p.Native, true
+	}
+	return p.Default, true
+}

api/gateway/chain/internal/service/gateway/shared/helpers.go

@@ -119,13 +119,23 @@ func TransferStatusToProto(status model.TransferStatus) chainv1.TransferStatus {
 	}
 }
 
+// NativeCurrency returns the canonical native token symbol for a network.
+func NativeCurrency(network Network) string {
+	currency := strings.ToUpper(strings.TrimSpace(network.NativeToken))
+	if currency == "" {
+		currency = strings.ToUpper(strings.TrimSpace(network.Name))
+	}
+	return currency
+}
+
 // Network describes a supported blockchain network and known token contracts.
 type Network struct {
-	Name         string
-	RPCURL       string
-	ChainID      uint64
-	NativeToken  string
-	TokenConfigs []TokenContract
+	Name           string
+	RPCURL         string
+	ChainID        uint64
+	NativeToken    string
+	TokenConfigs   []TokenContract
+	GasTopUpPolicy *GasTopUpPolicy
 }
 
 // TokenContract captures the metadata needed to work with a specific on-chain token.

api/gateway/chain/internal/service/gateway/shared/hex.go

@@ -0,0 +1,49 @@
+package shared
+
+import (
+	"errors"
+	"math/big"
+	"strings"
+)
+
+var (
+	errHexEmpty      = errors.New("hex value is empty")
+	errHexInvalid    = errors.New("invalid hex number")
+	errHexOutOfRange = errors.New("hex number out of range")
+)
+
+// DecodeHexBig parses a hex string that may include leading zero digits.
+func DecodeHexBig(input string) (*big.Int, error) {
+	trimmed := strings.TrimSpace(input)
+	if trimmed == "" {
+		return nil, errHexEmpty
+	}
+	noPrefix := strings.TrimPrefix(trimmed, "0x")
+	if noPrefix == "" {
+		return nil, errHexEmpty
+	}
+	value := strings.TrimLeft(noPrefix, "0")
+	if value == "" {
+		return big.NewInt(0), nil
+	}
+	val := new(big.Int)
+	if _, ok := val.SetString(value, 16); !ok {
+		return nil, errHexInvalid
+	}
+	return val, nil
+}
+
+// DecodeHexUint8 parses a hex string into uint8, allowing leading zeros.
+func DecodeHexUint8(input string) (uint8, error) {
+	val, err := DecodeHexBig(input)
+	if err != nil {
+		return 0, err
+	}
+	if val == nil {
+		return 0, errHexInvalid
+	}
+	if val.BitLen() > 8 {
+		return 0, errHexOutOfRange
+	}
+	return uint8(val.Uint64()), nil
+}

api/gateway/chain/internal/service/gateway/shared/hex_test.go

@@ -0,0 +1,16 @@
+package shared
+
+import "testing"
+
+func TestDecodeHexUint8_LeadingZeros(t *testing.T) {
+	t.Parallel()
+
+	const resp = "0x0000000000000000000000000000000000000000000000000000000000000006"
+	val, err := DecodeHexUint8(resp)
+	if err != nil {
+		t.Fatalf("DecodeHexUint8 error: %v", err)
+	}
+	if val != 6 {
+		t.Fatalf("DecodeHexUint8 value = %d, want 6", val)
+	}
+}

api/gateway/chain/internal/service/gateway/transfer_execution.go

@@ -7,15 +7,15 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/driver"
+	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
 	"github.com/tech/sendico/gateway/chain/storage/model"
 	"github.com/tech/sendico/pkg/merrors"
 	"go.uber.org/zap"
-
-	"github.com/tech/sendico/gateway/chain/internal/service/gateway/shared"
 )
 
 func (s *Service) launchTransferExecution(transferRef, sourceWalletRef string, network shared.Network) {
-	if s.executor == nil {
+	if s.drivers == nil {
 		return
 	}
 
@@ -24,7 +24,7 @@ func (s *Service) launchTransferExecution(transferRef, sourceWalletRef string, n
 		defer cancel()
 
 		if err := s.executeTransfer(ctx, ref, walletRef, net); err != nil {
-			s.logger.Error("failed to execute transfer", zap.String("transfer_ref", ref), zap.Error(err))
+			s.logger.Warn("Failed to execute transfer", zap.String("transfer_ref", ref), zap.Error(err))
 		}
 	}(transferRef, sourceWalletRef, network)
 }
@@ -41,49 +41,73 @@ func (s *Service) executeTransfer(ctx context.Context, transferRef, sourceWallet
 	}
 
 	if _, err := s.storage.Transfers().UpdateStatus(ctx, transferRef, model.TransferStatusSigning, "", ""); err != nil {
-		s.logger.Warn("failed to update transfer status to signing", zap.String("transfer_ref", transferRef), zap.Error(err))
+		s.logger.Warn("Failed to update transfer status to signing", zap.String("transfer_ref", transferRef), zap.Error(err))
 	}
 
-	destinationAddress, err := s.destinationAddress(ctx, transfer.Destination)
+	driverDeps := s.driverDeps()
+	chainDriver, err := s.driverForNetwork(network.Name)
 	if err != nil {
 		_, _ = s.storage.Transfers().UpdateStatus(ctx, transferRef, model.TransferStatusFailed, err.Error(), "")
 		return err
 	}
 
-	txHash, err := s.executor.SubmitTransfer(ctx, transfer, sourceWallet, destinationAddress, network)
+	destinationAddress, err := s.destinationAddress(ctx, chainDriver, transfer.Destination)
+	if err != nil {
+		_, _ = s.storage.Transfers().UpdateStatus(ctx, transferRef, model.TransferStatusFailed, err.Error(), "")
+		return err
+	}
+
+	sourceAddress, err := chainDriver.NormalizeAddress(sourceWallet.DepositAddress)
+	if err != nil {
+		_, _ = s.storage.Transfers().UpdateStatus(ctx, transferRef, model.TransferStatusFailed, err.Error(), "")
+		return err
+	}
+	if chainDriver.Name() == "tron" && sourceAddress == destinationAddress {
+		s.logger.Info("Self transfer detected; skipping submission",
+			zap.String("transfer_ref", transferRef),
+			zap.String("wallet_ref", sourceWalletRef),
+			zap.String("network", network.Name),
+		)
+		if _, err := s.storage.Transfers().UpdateStatus(ctx, transferRef, model.TransferStatusConfirmed, "", ""); err != nil {
+			s.logger.Warn("Failed to update transfer status to confirmed", zap.String("transfer_ref", transferRef), zap.Error(err))
+		}
+		return nil
+	}
+
+	txHash, err := chainDriver.SubmitTransfer(ctx, driverDeps, network, transfer, sourceWallet, destinationAddress)
 	if err != nil {
 		_, _ = s.storage.Transfers().UpdateStatus(ctx, transferRef, model.TransferStatusFailed, err.Error(), "")
 		return err
 	}
 
 	if _, err := s.storage.Transfers().UpdateStatus(ctx, transferRef, model.TransferStatusSubmitted, "", txHash); err != nil {
-		s.logger.Warn("failed to update transfer status to submitted", zap.String("transfer_ref", transferRef), zap.Error(err))
+		s.logger.Warn("Failed to update transfer status to submitted", zap.String("transfer_ref", transferRef), zap.Error(err))
 	}
 
 	receiptCtx, cancel := context.WithTimeout(ctx, 10*time.Minute)
 	defer cancel()
-	receipt, err := s.executor.AwaitConfirmation(receiptCtx, network, txHash)
+	receipt, err := chainDriver.AwaitConfirmation(receiptCtx, driverDeps, network, txHash)
 	if err != nil {
 		if !errors.Is(err, context.DeadlineExceeded) && !errors.Is(err, context.Canceled) {
-			s.logger.Warn("failed to await transfer confirmation", zap.String("transfer_ref", transferRef), zap.Error(err))
+			s.logger.Warn("Failed to await transfer confirmation", zap.String("transfer_ref", transferRef), zap.Error(err))
 		}
 		return err
 	}
 
 	if receipt != nil && receipt.Status == types.ReceiptStatusSuccessful {
 		if _, err := s.storage.Transfers().UpdateStatus(ctx, transferRef, model.TransferStatusConfirmed, "", txHash); err != nil {
-			s.logger.Warn("failed to update transfer status to confirmed", zap.String("transfer_ref", transferRef), zap.Error(err))
+			s.logger.Warn("Failed to update transfer status to confirmed", zap.String("transfer_ref", transferRef), zap.Error(err))
 		}
 		return nil
 	}
 
 	if _, err := s.storage.Transfers().UpdateStatus(ctx, transferRef, model.TransferStatusFailed, "transaction reverted", txHash); err != nil {
-		s.logger.Warn("failed to update transfer status to failed", zap.String("transfer_ref", transferRef), zap.Error(err))
+		s.logger.Warn("Failed to update transfer status to failed", zap.String("transfer_ref", transferRef), zap.Error(err))
 	}
 	return nil
 }
 
-func (s *Service) destinationAddress(ctx context.Context, dest model.TransferDestination) (string, error) {
+func (s *Service) destinationAddress(ctx context.Context, chainDriver driver.Driver, dest model.TransferDestination) (string, error) {
 	if ref := strings.TrimSpace(dest.ManagedWalletRef); ref != "" {
 		wallet, err := s.storage.Wallets().Get(ctx, ref)
 		if err != nil {
@@ -92,10 +116,26 @@ func (s *Service) destinationAddress(ctx context.Context, dest model.TransferDes
 		if strings.TrimSpace(wallet.DepositAddress) == "" {
 			return "", merrors.Internal("destination wallet missing deposit address")
 		}
-		return wallet.DepositAddress, nil
+		return chainDriver.NormalizeAddress(wallet.DepositAddress)
 	}
 	if addr := strings.TrimSpace(dest.ExternalAddress); addr != "" {
-		return strings.ToLower(addr), nil
+		return chainDriver.NormalizeAddress(addr)
 	}
 	return "", merrors.InvalidArgument("transfer destination address not resolved")
 }
+
+func (s *Service) driverDeps() driver.Deps {
+	return driver.Deps{
+		Logger:     s.logger.Named("driver"),
+		Registry:   s.networkRegistry,
+		KeyManager: s.keyManager,
+		RPCTimeout: s.settings.rpcTimeout(),
+	}
+}
+
+func (s *Service) driverForNetwork(network string) (driver.Driver, error) {
+	if s.drivers == nil {
+		return nil, merrors.Internal("chain drivers not configured")
+	}
+	return s.drivers.Driver(network)
+}

api/gateway/chain/storage/model/transfer.go

@@ -28,9 +28,10 @@ type ServiceFee struct {
 }
 
 type TransferDestination struct {
-	ManagedWalletRef string `bson:"managedWalletRef,omitempty" json:"managedWalletRef,omitempty"`
-	ExternalAddress  string `bson:"externalAddress,omitempty" json:"externalAddress,omitempty"`
-	Memo             string `bson:"memo,omitempty" json:"memo,omitempty"`
+	ManagedWalletRef        string `bson:"managedWalletRef,omitempty" json:"managedWalletRef,omitempty"`
+	ExternalAddress         string `bson:"externalAddress,omitempty" json:"externalAddress,omitempty"`
+	ExternalAddressOriginal string `bson:"externalAddressOriginal,omitempty" json:"externalAddressOriginal,omitempty"`
+	Memo                    string `bson:"memo,omitempty" json:"memo,omitempty"`
 }
 
 // Transfer models an on-chain transfer orchestrated by the gateway.
@@ -85,7 +86,8 @@ func (t *Transfer) Normalize() {
 	t.TokenSymbol = strings.TrimSpace(strings.ToUpper(t.TokenSymbol))
 	t.ContractAddress = strings.TrimSpace(strings.ToLower(t.ContractAddress))
 	t.Destination.ManagedWalletRef = strings.TrimSpace(t.Destination.ManagedWalletRef)
-	t.Destination.ExternalAddress = strings.TrimSpace(strings.ToLower(t.Destination.ExternalAddress))
+	t.Destination.ExternalAddress = normalizeWalletAddress(t.Destination.ExternalAddress)
+	t.Destination.ExternalAddressOriginal = strings.TrimSpace(t.Destination.ExternalAddressOriginal)
 	t.Destination.Memo = strings.TrimSpace(t.Destination.Memo)
 	t.ClientReference = strings.TrimSpace(t.ClientReference)
 }

api/gateway/chain/storage/model/transfer_test.go

@@ -0,0 +1,50 @@
+package model
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestTransferNormalizePreservesBase58ExternalAddress(t *testing.T) {
+	address := "TGBDXEg9rxSqGFJDcb889zqTjDwx1bmLRF"
+	transfer := &Transfer{
+		IdempotencyKey:  "idemp",
+		TransferRef:     "ref",
+		OrganizationRef: "org",
+		SourceWalletRef: "wallet",
+		Network:         "tron_mainnet",
+		TokenSymbol:     "USDT",
+		Destination: TransferDestination{
+			ExternalAddress:         address,
+			ExternalAddressOriginal: address,
+		},
+	}
+
+	transfer.Normalize()
+
+	if transfer.Destination.ExternalAddress != address {
+		t.Fatalf("expected external address to preserve case, got %q", transfer.Destination.ExternalAddress)
+	}
+	if transfer.Destination.ExternalAddressOriginal != address {
+		t.Fatalf("expected external address original to preserve case, got %q", transfer.Destination.ExternalAddressOriginal)
+	}
+}
+
+func TestTransferNormalizeLowercasesHexExternalAddress(t *testing.T) {
+	address := "0xAABBCCDDEEFF00112233445566778899AABBCCDD"
+	transfer := &Transfer{
+		Destination: TransferDestination{
+			ExternalAddress:         address,
+			ExternalAddressOriginal: address,
+		},
+	}
+
+	transfer.Normalize()
+
+	if transfer.Destination.ExternalAddress != strings.ToLower(address) {
+		t.Fatalf("expected hex external address to be lowercased, got %q", transfer.Destination.ExternalAddress)
+	}
+	if transfer.Destination.ExternalAddressOriginal != address {
+		t.Fatalf("expected external address original to preserve case, got %q", transfer.Destination.ExternalAddressOriginal)
+	}
+}

api/gateway/chain/storage/model/wallet.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/tech/sendico/pkg/db/storable"
+	pkgmodel "github.com/tech/sendico/pkg/model"
 	"github.com/tech/sendico/pkg/mservice"
 	moneyv1 "github.com/tech/sendico/pkg/proto/common/money/v1"
 )
@@ -19,7 +20,8 @@ const (
 
 // ManagedWallet represents a user-controlled on-chain wallet managed by the service.
 type ManagedWallet struct {
-	storable.Base `bson:",inline" json:",inline"`
+	storable.Base        `bson:",inline" json:",inline"`
+	pkgmodel.Describable `bson:",inline" json:",inline"`
 
 	IdempotencyKey  string              `bson:"idempotencyKey" json:"idempotencyKey"`
 	WalletRef       string              `bson:"walletRef" json:"walletRef"`
@@ -45,6 +47,7 @@ type WalletBalance struct {
 
 	WalletRef       string         `bson:"walletRef" json:"walletRef"`
 	Available       *moneyv1.Money `bson:"available" json:"available"`
+	NativeAvailable *moneyv1.Money `bson:"nativeAvailable,omitempty" json:"nativeAvailable,omitempty"`
 	PendingInbound  *moneyv1.Money `bson:"pendingInbound,omitempty" json:"pendingInbound,omitempty"`
 	PendingOutbound *moneyv1.Money `bson:"pendingOutbound,omitempty" json:"pendingOutbound,omitempty"`
 	CalculatedAt    time.Time      `bson:"calculatedAt" json:"calculatedAt"`
@@ -77,10 +80,19 @@ func (m *ManagedWallet) Normalize() {
 	m.WalletRef = strings.TrimSpace(m.WalletRef)
 	m.OrganizationRef = strings.TrimSpace(m.OrganizationRef)
 	m.OwnerRef = strings.TrimSpace(m.OwnerRef)
+	m.Name = strings.TrimSpace(m.Name)
+	if m.Description != nil {
+		desc := strings.TrimSpace(*m.Description)
+		if desc == "" {
+			m.Description = nil
+		} else {
+			m.Description = &desc
+		}
+	}
 	m.Network = strings.TrimSpace(strings.ToLower(m.Network))
 	m.TokenSymbol = strings.TrimSpace(strings.ToUpper(m.TokenSymbol))
 	m.ContractAddress = strings.TrimSpace(strings.ToLower(m.ContractAddress))
-	m.DepositAddress = strings.TrimSpace(strings.ToLower(m.DepositAddress))
+	m.DepositAddress = normalizeWalletAddress(m.DepositAddress)
 	m.KeyReference = strings.TrimSpace(m.KeyReference)
 }
 
@@ -88,3 +100,31 @@ func (m *ManagedWallet) Normalize() {
 func (b *WalletBalance) Normalize() {
 	b.WalletRef = strings.TrimSpace(b.WalletRef)
 }
+
+func normalizeWalletAddress(address string) string {
+	trimmed := strings.TrimSpace(address)
+	if trimmed == "" {
+		return ""
+	}
+	if isHexAddress(trimmed) {
+		return strings.ToLower(trimmed)
+	}
+	return trimmed
+}
+
+func isHexAddress(value string) bool {
+	trimmed := strings.TrimPrefix(strings.TrimSpace(value), "0x")
+	if len(trimmed) != 40 && len(trimmed) != 42 {
+		return false
+	}
+	for _, r := range trimmed {
+		switch {
+		case r >= '0' && r <= '9':
+		case r >= 'a' && r <= 'f':
+		case r >= 'A' && r <= 'F':
+		default:
+			return false
+		}
+	}
+	return true
+}

api/gateway/chain/storage/mongo/repository.go

@@ -44,23 +44,23 @@ func New(logger mlogger.Logger, conn *db.MongoConnection) (*Store, error) {
 	defer cancel()
 
 	if err := result.Ping(ctx); err != nil {
-		result.logger.Error("mongo ping failed during repository initialisation", zap.Error(err))
+		result.logger.Error("Mongo ping failed during repository initialisation", zap.Error(err))
 		return nil, err
 	}
 
 	walletsStore, err := store.NewWallets(result.logger, result.db)
 	if err != nil {
-		result.logger.Error("failed to initialise wallets store", zap.Error(err))
+		result.logger.Error("Failed to initialise wallets store", zap.Error(err))
 		return nil, err
 	}
 	transfersStore, err := store.NewTransfers(result.logger, result.db)
 	if err != nil {
-		result.logger.Error("failed to initialise transfers store", zap.Error(err))
+		result.logger.Error("Failed to initialise transfers store", zap.Error(err))
 		return nil, err
 	}
 	depositsStore, err := store.NewDeposits(result.logger, result.db)
 	if err != nil {
-		result.logger.Error("failed to initialise deposits store", zap.Error(err))
+		result.logger.Error("Failed to initialise deposits store", zap.Error(err))
 		return nil, err
 	}
 

api/gateway/chain/storage/mongo/store/deposits.go

@@ -48,13 +48,13 @@ func NewDeposits(logger mlogger.Logger, db *mongo.Database) (*Deposits, error) {
 	}
 	for _, def := range indexes {
 		if err := repo.CreateIndex(def); err != nil {
-			logger.Error("failed to ensure deposit index", zap.Error(err), zap.String("collection", repo.Collection()))
+			logger.Error("Failed to ensure deposit index", zap.Error(err), zap.String("collection", repo.Collection()))
 			return nil, err
 		}
 	}
 
 	childLogger := logger.Named("deposits")
-	childLogger.Debug("deposits store initialised")
+	childLogger.Debug("Deposits store initialised")
 
 	return &Deposits{logger: childLogger, repo: repo}, nil
 }

api/gateway/chain/storage/mongo/store/transfers.go

@@ -53,13 +53,13 @@ func NewTransfers(logger mlogger.Logger, db *mongo.Database) (*Transfers, error)
 	}
 	for _, def := range indexes {
 		if err := repo.CreateIndex(def); err != nil {
-			logger.Error("failed to ensure transfer index", zap.Error(err), zap.String("collection", repo.Collection()))
+			logger.Error("Failed to ensure transfer index", zap.Error(err), zap.String("collection", repo.Collection()))
 			return nil, err
 		}
 	}
 
 	childLogger := logger.Named("transfers")
-	childLogger.Debug("transfers store initialised")
+	childLogger.Debug("Transfers store initialised")
 
 	return &Transfers{
 		logger: childLogger,
@@ -89,12 +89,12 @@ func (t *Transfers) Create(ctx context.Context, transfer *model.Transfer) (*mode
 	}
 	if err := t.repo.Insert(ctx, transfer, repository.Filter("idempotencyKey", transfer.IdempotencyKey)); err != nil {
 		if errors.Is(err, merrors.ErrDataConflict) {
-			t.logger.Debug("transfer already exists", zap.String("transfer_ref", transfer.TransferRef), zap.String("idempotency_key", transfer.IdempotencyKey))
+			t.logger.Debug("Transfer already exists", zap.String("transfer_ref", transfer.TransferRef), zap.String("idempotency_key", transfer.IdempotencyKey))
 			return transfer, nil
 		}
 		return nil, err
 	}
-	t.logger.Debug("transfer created", zap.String("transfer_ref", transfer.TransferRef))
+	t.logger.Debug("Transfer created", zap.String("transfer_ref", transfer.TransferRef))
 	return transfer, nil
 }
 
@@ -126,7 +126,7 @@ func (t *Transfers) List(ctx context.Context, filter model.TransferFilter) (*mod
 		if oid, err := primitive.ObjectIDFromHex(cursor); err == nil {
 			query = query.Comparison(repository.IDField(), builder.Gt, oid)
 		} else {
-			t.logger.Warn("ignoring invalid transfer cursor", zap.String("cursor", cursor), zap.Error(err))
+			t.logger.Warn("Ignoring invalid transfer cursor", zap.String("cursor", cursor), zap.Error(err))
 		}
 	}
 

api/gateway/chain/storage/mongo/store/wallets.go

@@ -56,7 +56,7 @@ func NewWallets(logger mlogger.Logger, db *mongo.Database) (*Wallets, error) {
 	}
 	for _, def := range walletIndexes {
 		if err := walletRepo.CreateIndex(def); err != nil {
-			logger.Error("failed to ensure wallet index", zap.String("collection", walletRepo.Collection()), zap.Error(err))
+			logger.Error("Failed to ensure wallet index", zap.String("collection", walletRepo.Collection()), zap.Error(err))
 			return nil, err
 		}
 	}
@@ -70,13 +70,13 @@ func NewWallets(logger mlogger.Logger, db *mongo.Database) (*Wallets, error) {
 	}
 	for _, def := range balanceIndexes {
 		if err := balanceRepo.CreateIndex(def); err != nil {
-			logger.Error("failed to ensure wallet balance index", zap.String("collection", balanceRepo.Collection()), zap.Error(err))
+			logger.Error("Failed to ensure wallet balance index", zap.String("collection", balanceRepo.Collection()), zap.Error(err))
 			return nil, err
 		}
 	}
 
 	childLogger := logger.Named("wallets")
-	childLogger.Debug("wallet stores initialised")
+	childLogger.Debug("Wallet stores initialised")
 
 	return &Wallets{
 		logger:      childLogger,
@@ -99,24 +99,49 @@ func (w *Wallets) Create(ctx context.Context, wallet *model.ManagedWallet) (*mod
 	if strings.TrimSpace(wallet.IdempotencyKey) == "" {
 		return nil, merrors.InvalidArgument("walletsStore: empty idempotencyKey")
 	}
+	fields := []zap.Field{
+		zap.String("wallet_ref", wallet.WalletRef),
+		zap.String("idempotency_key", wallet.IdempotencyKey),
+	}
+	if wallet.OrganizationRef != "" {
+		fields = append(fields, zap.String("organization_ref", wallet.OrganizationRef))
+	}
+	if wallet.OwnerRef != "" {
+		fields = append(fields, zap.String("owner_ref", wallet.OwnerRef))
+	}
+	if wallet.Network != "" {
+		fields = append(fields, zap.String("network", wallet.Network))
+	}
+	if wallet.TokenSymbol != "" {
+		fields = append(fields, zap.String("token_symbol", wallet.TokenSymbol))
+	}
 	if err := w.walletRepo.Insert(ctx, wallet, repository.Filter("idempotencyKey", wallet.IdempotencyKey)); err != nil {
 		if errors.Is(err, merrors.ErrDataConflict) {
-			w.logger.Debug("wallet already exists", zap.String("wallet_ref", wallet.WalletRef), zap.String("idempotency_key", wallet.IdempotencyKey))
+			w.logger.Debug("Wallet already exists", fields...)
 			return wallet, nil
 		}
+		w.logger.Warn("Wallet create failed", append(fields, zap.Error(err))...)
 		return nil, err
 	}
-	w.logger.Debug("wallet created", zap.String("wallet_ref", wallet.WalletRef))
+	w.logger.Debug("Wallet created", fields...)
 	return wallet, nil
 }
 
-func (w *Wallets) Get(ctx context.Context, walletRef string) (*model.ManagedWallet, error) {
-	walletRef = strings.TrimSpace(walletRef)
-	if walletRef == "" {
+func (w *Wallets) Get(ctx context.Context, walletID string) (*model.ManagedWallet, error) {
+	walletID = strings.TrimSpace(walletID)
+	if walletID == "" {
 		return nil, merrors.InvalidArgument("walletsStore: empty walletRef")
 	}
+	fields := []zap.Field{
+		zap.String("wallet_id", walletID),
+	}
 	wallet := &model.ManagedWallet{}
-	if err := w.walletRepo.FindOneByFilter(ctx, repository.Filter("walletRef", walletRef), wallet); err != nil {
+	if err := w.walletRepo.FindOneByFilter(ctx, repository.Filter("walletRef", walletID), wallet); err != nil {
+		if errors.Is(err, merrors.ErrNoData) {
+			w.logger.Debug("Wallet not found", fields...)
+		} else {
+			w.logger.Warn("Wallet lookup failed", append(fields, zap.Error(err))...)
+		}
 		return nil, err
 	}
 	return wallet, nil
@@ -124,29 +149,38 @@ func (w *Wallets) Get(ctx context.Context, walletRef string) (*model.ManagedWall
 
 func (w *Wallets) List(ctx context.Context, filter model.ManagedWalletFilter) (*model.ManagedWalletList, error) {
 	query := repository.Query()
+	fields := make([]zap.Field, 0, 6)
 
 	if org := strings.TrimSpace(filter.OrganizationRef); org != "" {
 		query = query.Filter(repository.Field("organizationRef"), org)
+		fields = append(fields, zap.String("organization_ref", org))
 	}
 	if owner := strings.TrimSpace(filter.OwnerRef); owner != "" {
 		query = query.Filter(repository.Field("ownerRef"), owner)
+		fields = append(fields, zap.String("owner_ref", owner))
 	}
 	if network := strings.TrimSpace(filter.Network); network != "" {
-		query = query.Filter(repository.Field("network"), strings.ToLower(network))
+		normalized := strings.ToLower(network)
+		query = query.Filter(repository.Field("network"), normalized)
+		fields = append(fields, zap.String("network", normalized))
 	}
 	if token := strings.TrimSpace(filter.TokenSymbol); token != "" {
-		query = query.Filter(repository.Field("tokenSymbol"), strings.ToUpper(token))
+		normalized := strings.ToUpper(token)
+		query = query.Filter(repository.Field("tokenSymbol"), normalized)
+		fields = append(fields, zap.String("token_symbol", normalized))
 	}
 
 	if cursor := strings.TrimSpace(filter.Cursor); cursor != "" {
 		if oid, err := primitive.ObjectIDFromHex(cursor); err == nil {
 			query = query.Comparison(repository.IDField(), builder.Gt, oid)
+			fields = append(fields, zap.String("cursor", cursor))
 		} else {
-			w.logger.Warn("ignoring invalid wallet cursor", zap.String("cursor", cursor), zap.Error(err))
+			w.logger.Warn("Ignoring invalid wallet cursor", zap.String("cursor", cursor), zap.Error(err))
 		}
 	}
 
 	limit := sanitizeWalletLimit(filter.Limit)
+	fields = append(fields, zap.Int64("limit", limit))
 	fetchLimit := limit + 1
 	query = query.Sort(repository.IDField(), true).Limit(&fetchLimit)
 
@@ -160,8 +194,10 @@ func (w *Wallets) List(ctx context.Context, filter model.ManagedWalletFilter) (*
 		return nil
 	}
 
-	if err := w.walletRepo.FindManyByFilter(ctx, query, decoder); err != nil && !errors.Is(err, merrors.ErrNoData) {
-		return nil, err
+	listErr := w.walletRepo.FindManyByFilter(ctx, query, decoder)
+	if listErr != nil && !errors.Is(listErr, merrors.ErrNoData) {
+		w.logger.Warn("Wallet list failed", append(fields, zap.Error(listErr))...)
+		return nil, listErr
 	}
 
 	nextCursor := ""
@@ -171,10 +207,21 @@ func (w *Wallets) List(ctx context.Context, filter model.ManagedWalletFilter) (*
 		wallets = wallets[:len(wallets)-1]
 	}
 
-	return &model.ManagedWalletList{
+	result := &model.ManagedWalletList{
 		Items:      wallets,
 		NextCursor: nextCursor,
-	}, nil
+	}
+
+	fields = append(fields,
+		zap.Int("count", len(result.Items)),
+		zap.String("next_cursor", result.NextCursor),
+	)
+	if errors.Is(listErr, merrors.ErrNoData) {
+		w.logger.Debug("Wallet list empty", fields...)
+	} else {
+		w.logger.Debug("Wallet list fetched", fields...)
+	}
+	return result, nil
 }
 
 func (w *Wallets) SaveBalance(ctx context.Context, balance *model.WalletBalance) error {
@@ -188,6 +235,7 @@ func (w *Wallets) SaveBalance(ctx context.Context, balance *model.WalletBalance)
 	if balance.CalculatedAt.IsZero() {
 		balance.CalculatedAt = time.Now().UTC()
 	}
+	fields := []zap.Field{zap.String("wallet_ref", balance.WalletRef)}
 
 	existing := &model.WalletBalance{}
 	err := w.balanceRepo.FindOneByFilter(ctx, repository.Filter("walletRef", balance.WalletRef), existing)
@@ -198,28 +246,40 @@ func (w *Wallets) SaveBalance(ctx context.Context, balance *model.WalletBalance)
 		existing.PendingOutbound = balance.PendingOutbound
 		existing.CalculatedAt = balance.CalculatedAt
 		if err := w.balanceRepo.Update(ctx, existing); err != nil {
+			w.logger.Warn("Wallet balance update failed", append(fields, zap.Error(err))...)
 			return err
 		}
+		w.logger.Debug("Wallet balance updated", fields...)
 		return nil
 	case errors.Is(err, merrors.ErrNoData):
 		if err := w.balanceRepo.Insert(ctx, balance, repository.Filter("walletRef", balance.WalletRef)); err != nil {
+			w.logger.Warn("Wallet balance create failed", append(fields, zap.Error(err))...)
 			return err
 		}
+		w.logger.Debug("Wallet balance created", fields...)
 		return nil
 	default:
+		w.logger.Warn("Wallet balance lookup failed", append(fields, zap.Error(err))...)
 		return err
 	}
 }
 
-func (w *Wallets) GetBalance(ctx context.Context, walletRef string) (*model.WalletBalance, error) {
-	walletRef = strings.TrimSpace(walletRef)
-	if walletRef == "" {
+func (w *Wallets) GetBalance(ctx context.Context, walletID string) (*model.WalletBalance, error) {
+	walletID = strings.TrimSpace(walletID)
+	if walletID == "" {
 		return nil, merrors.InvalidArgument("walletsStore: empty walletRef")
 	}
+	fields := []zap.Field{zap.String("wallet_ref", walletID)}
 	balance := &model.WalletBalance{}
-	if err := w.balanceRepo.FindOneByFilter(ctx, repository.Filter("walletRef", walletRef), balance); err != nil {
+	if err := w.balanceRepo.FindOneByFilter(ctx, repository.Filter("walletRef", walletID), balance); err != nil {
+		if errors.Is(err, merrors.ErrNoData) {
+			w.logger.Debug("Wallet balance not found", fields...)
+		} else {
+			w.logger.Warn("Wallet balance lookup failed", append(fields, zap.Error(err))...)
+		}
 		return nil, err
 	}
+	w.logger.Debug("Wallet balance fetched", fields...)
 	return balance, nil
 }
 

api/gateway/mntx/client/client.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/tech/sendico/pkg/merrors"
 	mntxv1 "github.com/tech/sendico/pkg/proto/gateway/mntx/v1"
+	"go.uber.org/zap"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 )
@@ -23,6 +24,7 @@ type gatewayClient struct {
 	conn   *grpc.ClientConn
 	client mntxv1.MntxGatewayServiceClient
 	cfg    Config
+	logger *zap.Logger
 }
 
 // New dials the Monetix gateway.
@@ -47,6 +49,7 @@ func New(ctx context.Context, cfg Config, opts ...grpc.DialOption) (Client, erro
 		conn:   conn,
 		client: mntxv1.NewMntxGatewayServiceClient(conn),
 		cfg:    cfg,
+		logger: cfg.Logger,
 	}, nil
 }
 
@@ -57,28 +60,39 @@ func (g *gatewayClient) Close() error {
 	return nil
 }
 
-func (g *gatewayClient) callContext(ctx context.Context) (context.Context, context.CancelFunc) {
+func (g *gatewayClient) callContext(ctx context.Context, method string) (context.Context, context.CancelFunc) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
 	timeout := g.cfg.CallTimeout
 	if timeout <= 0 {
 		timeout = 5 * time.Second
 	}
+	fields := []zap.Field{
+		zap.String("method", method),
+		zap.Duration("timeout", timeout),
+	}
+	if deadline, ok := ctx.Deadline(); ok {
+		fields = append(fields, zap.Time("parent_deadline", deadline), zap.Duration("parent_deadline_in", time.Until(deadline)))
+	}
+	g.logger.Info("Mntx gateway client call timeout applied", fields...)
 	return context.WithTimeout(ctx, timeout)
 }
 
 func (g *gatewayClient) CreateCardPayout(ctx context.Context, req *mntxv1.CardPayoutRequest) (*mntxv1.CardPayoutResponse, error) {
-	ctx, cancel := g.callContext(ctx)
+	ctx, cancel := g.callContext(ctx, "CreateCardPayout")
 	defer cancel()
 	return g.client.CreateCardPayout(ctx, req)
 }
 
 func (g *gatewayClient) CreateCardTokenPayout(ctx context.Context, req *mntxv1.CardTokenPayoutRequest) (*mntxv1.CardTokenPayoutResponse, error) {
-	ctx, cancel := g.callContext(ctx)
+	ctx, cancel := g.callContext(ctx, "CreateCardTokenPayout")
 	defer cancel()
 	return g.client.CreateCardTokenPayout(ctx, req)
 }
 
 func (g *gatewayClient) GetCardPayoutStatus(ctx context.Context, req *mntxv1.GetCardPayoutStatusRequest) (*mntxv1.GetCardPayoutStatusResponse, error) {
-	ctx, cancel := g.callContext(ctx)
+	ctx, cancel := g.callContext(ctx, "GetCardPayoutStatus")
 	defer cancel()
 	return g.client.GetCardPayoutStatus(ctx, req)
 }

api/gateway/mntx/client/config.go

@@ -1,12 +1,17 @@
 package client
 
-import "time"
+import (
+	"time"
+
+	"go.uber.org/zap"
+)
 
 // Config holds Monetix gateway client settings.
 type Config struct {
 	Address     string
 	DialTimeout time.Duration
 	CallTimeout time.Duration
+	Logger      *zap.Logger
 }
 
 func (c *Config) setDefaults() {
@@ -16,4 +21,7 @@ func (c *Config) setDefaults() {
 	if c.CallTimeout <= 0 {
 		c.CallTimeout = 10 * time.Second
 	}
+	if c.Logger == nil {
+		c.Logger = zap.NewNop()
+	}
 }

api/gateway/mntx/config.yml

@@ -26,7 +26,7 @@ monetix:
   base_url_env: MONETIX_BASE_URL
   project_id_env: MONETIX_PROJECT_ID
   secret_key_env: MONETIX_SECRET_KEY
-  allowed_currencies: ["USD", "EUR"]
+  allowed_currencies: ["RUB"]
   require_customer_address: false
   request_timeout_seconds: 15
   status_success: "success"

api/gateway/mntx/go.mod

@@ -11,8 +11,8 @@ require (
 	github.com/shopspring/decimal v1.4.0
 	github.com/tech/sendico/pkg v0.1.0
 	go.uber.org/zap v1.27.1
-	google.golang.org/grpc v1.77.0
-	google.golang.org/protobuf v1.36.10
+	google.golang.org/grpc v1.78.0
+	google.golang.org/protobuf v1.36.11
 	gopkg.in/yaml.v3 v3.0.1
 )
 
@@ -30,7 +30,7 @@ require (
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/montanaflynn/stats v0.7.1 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
-	github.com/nats-io/nats.go v1.47.0 // indirect
+	github.com/nats-io/nats.go v1.48.0 // indirect
 	github.com/nats-io/nkeys v0.4.12 // indirect
 	github.com/nats-io/nuid v1.0.1 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
@@ -50,5 +50,5 @@ require (
 	golang.org/x/sync v0.19.0 // indirect
 	golang.org/x/sys v0.39.0 // indirect
 	golang.org/x/text v0.32.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b // indirect
 )

api/gateway/mntx/go.sum

@@ -95,8 +95,8 @@ github.com/morikuni/aec v1.0.0 h1:nP9CBfwrvYnBRgY6qfDQkygYDmYwOilePFkwzv4dU8A=
 github.com/morikuni/aec v1.0.0/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7PXmsc=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
-github.com/nats-io/nats.go v1.47.0 h1:YQdADw6J/UfGUd2Oy6tn4Hq6YHxCaJrVKayxxFqYrgM=
-github.com/nats-io/nats.go v1.47.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
+github.com/nats-io/nats.go v1.48.0 h1:pSFyXApG+yWU/TgbKCjmm5K4wrHu86231/w84qRVR+U=
+github.com/nats-io/nats.go v1.48.0/go.mod h1:iRWIPokVIFbVijxuMQq4y9ttaBTMe0SFdlZfMDd+33g=
 github.com/nats-io/nkeys v0.4.12 h1:nssm7JKOG9/x4J8II47VWCL1Ds29avyiQDRn0ckMvDc=
 github.com/nats-io/nkeys v0.4.12/go.mod h1:MT59A1HYcjIcyQDJStTfaOY6vhy9XTUjOFo+SVsvpBg=
 github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
@@ -214,12 +214,12 @@ golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
 gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 h1:gRkg/vSppuSQoDjxyiGfN4Upv/h/DQmIR10ZU8dh4Ww=
-google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217/go.mod h1:7i2o+ce6H/6BluujYR+kqX3GKH+dChPTQU19wjRPiGk=
-google.golang.org/grpc v1.77.0 h1:wVVY6/8cGA6vvffn+wWK5ToddbgdU3d8MNENr4evgXM=
-google.golang.org/grpc v1.77.0/go.mod h1:z0BY1iVj0q8E1uSQCjL9cppRj+gnZjzDnzV0dHhrNig=
-google.golang.org/protobuf v1.36.10 h1:AYd7cD/uASjIL6Q9LiTjz8JLcrh/88q5UObnmY3aOOE=
-google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b h1:Mv8VFug0MP9e5vUxfBcE3vUkV6CImK3cMNMIDFjmzxU=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20251222181119-0a764e51fe1b/go.mod h1:j9x/tPzZkyxcgEFkiKEEGxfvyumM01BEtsW8xzOahRQ=
+google.golang.org/grpc v1.78.0 h1:K1XZG/yGDJnzMdd/uZHAkVqJE+xIDOcmdSFZkBUicNc=
+google.golang.org/grpc v1.78.0/go.mod h1:I47qjTo4OKbMkjA/aOOwxDIiPSBofUtQUI5EfpWvW7U=
+google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
+google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

api/gateway/mntx/internal/server/internal/serverimp.go

@@ -95,22 +95,49 @@ func (i *Imp) Shutdown() {
 }
 
 func (i *Imp) Start() error {
+	i.logger.Info("Starting Monetix gateway", zap.String("config_file", i.file), zap.Bool("debug", i.debug))
+
 	cfg, err := i.loadConfig()
 	if err != nil {
 		return err
 	}
 	i.config = cfg
 
+	i.logger.Info("Configuration loaded",
+		zap.String("grpc_address", cfg.GRPC.Address),
+		zap.String("metrics_address", cfg.Metrics.Address),
+	)
+
 	monetixCfg, err := i.resolveMonetixConfig(cfg.Monetix)
 	if err != nil {
+		i.logger.Error("Failed to resolve Monetix configuration", zap.Error(err))
 		return err
 	}
 
 	callbackCfg, err := i.resolveCallbackConfig(cfg.HTTP.Callback)
 	if err != nil {
+		i.logger.Error("Failed to resolve callback configuration", zap.Error(err))
 		return err
 	}
 
+	i.logger.Info("Monetix configuration resolved",
+		zap.Bool("base_url_set", strings.TrimSpace(monetixCfg.BaseURL) != ""),
+		zap.Int64("project_id", monetixCfg.ProjectID),
+		zap.Bool("secret_key_set", strings.TrimSpace(monetixCfg.SecretKey) != ""),
+		zap.Int("allowed_currencies", len(monetixCfg.AllowedCurrencies)),
+		zap.Bool("require_customer_address", monetixCfg.RequireCustomerAddress),
+		zap.Duration("request_timeout", monetixCfg.RequestTimeout),
+		zap.String("status_success", monetixCfg.SuccessStatus()),
+		zap.String("status_processing", monetixCfg.ProcessingStatus()),
+	)
+
+	i.logger.Info("Callback configuration resolved",
+		zap.String("address", callbackCfg.Address),
+		zap.String("path", callbackCfg.Path),
+		zap.Int("allowed_cidrs", len(callbackCfg.AllowedCIDRs)),
+		zap.Int64("max_body_bytes", callbackCfg.MaxBodyBytes),
+	)
+
 	serviceFactory := func(logger mlogger.Logger, _ struct{}, producer msg.Producer) (grpcapp.Service, error) {
 		svc := mntxservice.NewService(logger,
 			mntxservice.WithProducer(producer),
@@ -137,7 +164,7 @@ func (i *Imp) Start() error {
 func (i *Imp) loadConfig() (*config, error) {
 	data, err := os.ReadFile(i.file)
 	if err != nil {
-		i.logger.Error("could not read configuration file", zap.String("config_file", i.file), zap.Error(err))
+		i.logger.Error("Could not read configuration file", zap.String("config_file", i.file), zap.Error(err))
 		return nil, err
 	}
 
@@ -145,7 +172,7 @@ func (i *Imp) loadConfig() (*config, error) {
 		Config: &grpcapp.Config{},
 	}
 	if err := yaml.Unmarshal(data, cfg); err != nil {
-		i.logger.Error("failed to parse configuration", zap.Error(err))
+		i.logger.Error("Failed to parse configuration", zap.Error(err))
 		return nil, err
 	}
 
@@ -245,7 +272,7 @@ func (i *Imp) resolveCallbackConfig(cfg callbackConfig) (callbackRuntimeConfig,
 		}
 		_, block, err := net.ParseCIDR(clean)
 		if err != nil {
-			i.logger.Warn("invalid callback allowlist CIDR skipped", zap.String("cidr", clean), zap.Error(err))
+			i.logger.Warn("Invalid callback allowlist CIDR skipped", zap.String("cidr", clean), zap.Error(err))
 			continue
 		}
 		cidrs = append(cidrs, block)
@@ -270,20 +297,36 @@ func (i *Imp) startHTTPCallbackServer(svc *mntxservice.Service, cfg callbackRunt
 
 	router := chi.NewRouter()
 	router.Post(cfg.Path, func(w http.ResponseWriter, r *http.Request) {
+		log := i.logger.Named("callback_http")
+		log.Debug("Callback request received",
+			zap.String("remote_addr", strings.TrimSpace(r.RemoteAddr)),
+			zap.String("path", r.URL.Path),
+			zap.String("method", r.Method),
+		)
+
 		if len(cfg.AllowedCIDRs) > 0 && !clientAllowed(r, cfg.AllowedCIDRs) {
+			ip := clientIPFromRequest(r)
+			remoteIP := ""
+			if ip != nil {
+				remoteIP = ip.String()
+			}
+			log.Warn("Callback rejected by CIDR allowlist", zap.String("remote_ip", remoteIP))
 			http.Error(w, "forbidden", http.StatusForbidden)
 			return
 		}
 		body, err := io.ReadAll(io.LimitReader(r.Body, cfg.MaxBodyBytes))
 		if err != nil {
+			log.Warn("Callback body read failed", zap.Error(err))
 			http.Error(w, "failed to read body", http.StatusBadRequest)
 			return
 		}
 		status, err := svc.ProcessMonetixCallback(r.Context(), body)
 		if err != nil {
+			log.Warn("Callback processing failed", zap.Error(err), zap.Int("status", status))
 			http.Error(w, err.Error(), status)
 			return
 		}
+		log.Debug("Callback processed", zap.Int("status", status))
 		w.WriteHeader(status)
 	})
 
@@ -301,7 +344,7 @@ func (i *Imp) startHTTPCallbackServer(svc *mntxservice.Service, cfg callbackRunt
 
 	go func() {
 		if err := server.Serve(ln); err != nil && !errors.Is(err, http.ErrServerClosed) {
-			i.logger.Error("Monetix callback server stopped with error", zap.Error(err))
+			i.logger.Warn("Monetix callback server stopped with error", zap.Error(err))
 		}
 	}()
 

api/gateway/mntx/internal/server/internal/serverimp_test.go

@@ -0,0 +1,52 @@
+package serverimp
+
+import (
+	"net"
+	"net/http"
+	"testing"
+)
+
+func TestClientIPFromRequest(t *testing.T) {
+	req := &http.Request{
+		Header:     http.Header{"X-Forwarded-For": []string{"1.2.3.4, 5.6.7.8"}},
+		RemoteAddr: "9.8.7.6:1234",
+	}
+	ip := clientIPFromRequest(req)
+	if ip == nil || ip.String() != "1.2.3.4" {
+		t.Fatalf("expected forwarded ip, got %v", ip)
+	}
+
+	req = &http.Request{RemoteAddr: "9.8.7.6:1234"}
+	ip = clientIPFromRequest(req)
+	if ip == nil || ip.String() != "9.8.7.6" {
+		t.Fatalf("expected remote addr ip, got %v", ip)
+	}
+
+	req = &http.Request{RemoteAddr: "invalid"}
+	ip = clientIPFromRequest(req)
+	if ip != nil {
+		t.Fatalf("expected nil ip, got %v", ip)
+	}
+}
+
+func TestClientAllowed(t *testing.T) {
+	_, cidr, err := net.ParseCIDR("10.0.0.0/8")
+	if err != nil {
+		t.Fatalf("failed to parse cidr: %v", err)
+	}
+
+	allowedReq := &http.Request{RemoteAddr: "10.1.2.3:1234"}
+	if !clientAllowed(allowedReq, []*net.IPNet{cidr}) {
+		t.Fatalf("expected allowed request")
+	}
+
+	deniedReq := &http.Request{RemoteAddr: "8.8.8.8:1234"}
+	if clientAllowed(deniedReq, []*net.IPNet{cidr}) {
+		t.Fatalf("expected denied request")
+	}
+
+	openReq := &http.Request{RemoteAddr: "8.8.8.8:1234"}
+	if !clientAllowed(openReq, nil) {
+		t.Fatalf("expected allow when no cidrs are configured")
+	}
+}

api/gateway/mntx/internal/service/gateway/callback.go

@@ -10,6 +10,7 @@ import (
 	clockpkg "github.com/tech/sendico/pkg/clock"
 	"github.com/tech/sendico/pkg/merrors"
 	mntxv1 "github.com/tech/sendico/pkg/proto/gateway/mntx/v1"
+	"go.uber.org/zap"
 	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
@@ -66,9 +67,12 @@ type monetixCallback struct {
 
 // ProcessMonetixCallback ingests Monetix provider callbacks and updates payout state.
 func (s *Service) ProcessMonetixCallback(ctx context.Context, payload []byte) (int, error) {
+	log := s.logger.Named("callback")
 	if s.card == nil {
+		log.Warn("Card payout processor not initialised")
 		return http.StatusInternalServerError, merrors.Internal("card payout processor not initialised")
 	}
+	log.Debug("Callback processing requested", zap.Int("payload_bytes", len(payload)))
 	return s.card.ProcessCallback(ctx, payload)
 }
 

api/gateway/mntx/internal/service/gateway/callback_test.go

@@ -0,0 +1,130 @@
+package gateway
+
+import (
+	"testing"
+	"time"
+
+	"github.com/tech/sendico/gateway/mntx/internal/service/monetix"
+	mntxv1 "github.com/tech/sendico/pkg/proto/gateway/mntx/v1"
+)
+
+type fixedClock struct {
+	now time.Time
+}
+
+func (f fixedClock) Now() time.Time {
+	return f.now
+}
+
+func baseCallback() monetixCallback {
+	cb := monetixCallback{
+		ProjectID: 42,
+	}
+	cb.Payment.ID = "payout-1"
+	cb.Payment.Status = "success"
+	cb.Payment.Sum.Amount = 5000
+	cb.Payment.Sum.Currency = "usd"
+	cb.Customer.ID = "cust-1"
+	cb.Operation.Status = "success"
+	cb.Operation.Code = ""
+	cb.Operation.Message = "ok"
+	cb.Operation.RequestID = "req-1"
+	cb.Operation.Provider.PaymentID = "prov-1"
+	return cb
+}
+
+func TestMapCallbackToState_StatusMapping(t *testing.T) {
+	now := time.Date(2024, 1, 2, 3, 4, 5, 0, time.UTC)
+	cfg := monetix.DefaultConfig()
+
+	cases := []struct {
+		name           string
+		paymentStatus  string
+		operationStatus string
+		code           string
+		expectedStatus mntxv1.PayoutStatus
+		expectedOutcome string
+	}{
+		{
+			name:            "success",
+			paymentStatus:   "success",
+			operationStatus: "success",
+			code:            "0",
+			expectedStatus:  mntxv1.PayoutStatus_PAYOUT_STATUS_PROCESSED,
+			expectedOutcome: monetix.OutcomeSuccess,
+		},
+		{
+			name:            "processing",
+			paymentStatus:   "processing",
+			operationStatus: "success",
+			code:            "",
+			expectedStatus:  mntxv1.PayoutStatus_PAYOUT_STATUS_PENDING,
+			expectedOutcome: monetix.OutcomeProcessing,
+		},
+		{
+			name:            "decline",
+			paymentStatus:   "failed",
+			operationStatus: "failed",
+			code:            "1",
+			expectedStatus:  mntxv1.PayoutStatus_PAYOUT_STATUS_FAILED,
+			expectedOutcome: monetix.OutcomeDecline,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			cb := baseCallback()
+			cb.Payment.Status = tc.paymentStatus
+			cb.Operation.Status = tc.operationStatus
+			cb.Operation.Code = tc.code
+
+			state, outcome := mapCallbackToState(fixedClock{now: now}, cfg, cb)
+			if state.Status != tc.expectedStatus {
+				t.Fatalf("expected status %v, got %v", tc.expectedStatus, state.Status)
+			}
+			if outcome != tc.expectedOutcome {
+				t.Fatalf("expected outcome %q, got %q", tc.expectedOutcome, outcome)
+			}
+			if state.Currency != "USD" {
+				t.Fatalf("expected currency USD, got %q", state.Currency)
+			}
+			if !state.UpdatedAt.AsTime().Equal(now) {
+				t.Fatalf("expected updated_at %v, got %v", now, state.UpdatedAt.AsTime())
+			}
+		})
+	}
+}
+
+func TestFallbackProviderPaymentID(t *testing.T) {
+	cb := baseCallback()
+	if got := fallbackProviderPaymentID(cb); got != "prov-1" {
+		t.Fatalf("expected provider payment id, got %q", got)
+	}
+	cb.Operation.Provider.PaymentID = ""
+	if got := fallbackProviderPaymentID(cb); got != "req-1" {
+		t.Fatalf("expected request id fallback, got %q", got)
+	}
+	cb.Operation.RequestID = ""
+	if got := fallbackProviderPaymentID(cb); got != "payout-1" {
+		t.Fatalf("expected payment id fallback, got %q", got)
+	}
+}
+
+func TestVerifyCallbackSignature(t *testing.T) {
+	secret := "secret"
+	cb := baseCallback()
+
+	sig, err := monetix.SignPayload(cb, secret)
+	if err != nil {
+		t.Fatalf("failed to sign payload: %v", err)
+	}
+	cb.Signature = sig
+	if err := verifyCallbackSignature(cb, secret); err != nil {
+		t.Fatalf("expected valid signature, got %v", err)
+	}
+
+	cb.Signature = "invalid"
+	if err := verifyCallbackSignature(cb, secret); err == nil {
+		t.Fatalf("expected signature mismatch error")
+	}
+}

api/gateway/mntx/internal/service/gateway/card_payout_handlers.go

@@ -9,6 +9,7 @@ import (
 	"github.com/tech/sendico/pkg/merrors"
 	"github.com/tech/sendico/pkg/mservice"
 	mntxv1 "github.com/tech/sendico/pkg/proto/gateway/mntx/v1"
+	"go.uber.org/zap"
 	"google.golang.org/protobuf/proto"
 )
 
@@ -17,14 +18,24 @@ func (s *Service) CreateCardPayout(ctx context.Context, req *mntxv1.CardPayoutRe
 }
 
 func (s *Service) handleCreateCardPayout(ctx context.Context, req *mntxv1.CardPayoutRequest) gsresponse.Responder[mntxv1.CardPayoutResponse] {
+	log := s.logger.Named("card_payout")
+	log.Info("Create card payout request received",
+		zap.String("payout_id", strings.TrimSpace(req.GetPayoutId())),
+		zap.String("customer_id", strings.TrimSpace(req.GetCustomerId())),
+		zap.Int64("amount_minor", req.GetAmountMinor()),
+		zap.String("currency", strings.ToUpper(strings.TrimSpace(req.GetCurrency()))),
+	)
 	if s.card == nil {
+		log.Warn("Card payout processor not initialised")
 		return gsresponse.Internal[mntxv1.CardPayoutResponse](s.logger, mservice.MntxGateway, merrors.Internal("card payout processor not initialised"))
 	}
 
 	resp, err := s.card.Submit(ctx, req)
 	if err != nil {
+		log.Warn("Card payout submission failed", zap.Error(err))
 		return gsresponse.Auto[mntxv1.CardPayoutResponse](s.logger, mservice.MntxGateway, err)
 	}
+	log.Info("Card payout submission completed", zap.String("payout_id", resp.GetPayout().GetPayoutId()), zap.Bool("accepted", resp.GetAccepted()))
 	return gsresponse.Success(resp)
 }
 
@@ -33,14 +44,24 @@ func (s *Service) CreateCardTokenPayout(ctx context.Context, req *mntxv1.CardTok
 }
 
 func (s *Service) handleCreateCardTokenPayout(ctx context.Context, req *mntxv1.CardTokenPayoutRequest) gsresponse.Responder[mntxv1.CardTokenPayoutResponse] {
+	log := s.logger.Named("card_token_payout")
+	log.Info("Create card token payout request received",
+		zap.String("payout_id", strings.TrimSpace(req.GetPayoutId())),
+		zap.String("customer_id", strings.TrimSpace(req.GetCustomerId())),
+		zap.Int64("amount_minor", req.GetAmountMinor()),
+		zap.String("currency", strings.ToUpper(strings.TrimSpace(req.GetCurrency()))),
+	)
 	if s.card == nil {
+		log.Warn("Card payout processor not initialised")
 		return gsresponse.Internal[mntxv1.CardTokenPayoutResponse](s.logger, mservice.MntxGateway, merrors.Internal("card payout processor not initialised"))
 	}
 
 	resp, err := s.card.SubmitToken(ctx, req)
 	if err != nil {
+		log.Warn("Card token payout submission failed", zap.Error(err))
 		return gsresponse.Auto[mntxv1.CardTokenPayoutResponse](s.logger, mservice.MntxGateway, err)
 	}
+	log.Info("Card token payout submission completed", zap.String("payout_id", resp.GetPayout().GetPayoutId()), zap.Bool("accepted", resp.GetAccepted()))
 	return gsresponse.Success(resp)
 }
 
@@ -49,14 +70,22 @@ func (s *Service) CreateCardToken(ctx context.Context, req *mntxv1.CardTokenizeR
 }
 
 func (s *Service) handleCreateCardToken(ctx context.Context, req *mntxv1.CardTokenizeRequest) gsresponse.Responder[mntxv1.CardTokenizeResponse] {
+	log := s.logger.Named("card_tokenize")
+	log.Info("Create card token request received",
+		zap.String("request_id", strings.TrimSpace(req.GetRequestId())),
+		zap.String("customer_id", strings.TrimSpace(req.GetCustomerId())),
+	)
 	if s.card == nil {
+		log.Warn("Card payout processor not initialised")
 		return gsresponse.Internal[mntxv1.CardTokenizeResponse](s.logger, mservice.MntxGateway, merrors.Internal("card payout processor not initialised"))
 	}
 
 	resp, err := s.card.Tokenize(ctx, req)
 	if err != nil {
+		log.Warn("Card tokenization failed", zap.Error(err))
 		return gsresponse.Auto[mntxv1.CardTokenizeResponse](s.logger, mservice.MntxGateway, err)
 	}
+	log.Info("Card tokenization completed", zap.String("request_id", resp.GetRequestId()), zap.Bool("success", resp.GetSuccess()))
 	return gsresponse.Success(resp)
 }
 
@@ -65,14 +94,19 @@ func (s *Service) GetCardPayoutStatus(ctx context.Context, req *mntxv1.GetCardPa
 }
 
 func (s *Service) handleGetCardPayoutStatus(_ context.Context, req *mntxv1.GetCardPayoutStatusRequest) gsresponse.Responder[mntxv1.GetCardPayoutStatusResponse] {
+	log := s.logger.Named("card_payout_status")
+	log.Info("Get card payout status request received", zap.String("payout_id", strings.TrimSpace(req.GetPayoutId())))
 	if s.card == nil {
+		log.Warn("Card payout processor not initialised")
 		return gsresponse.Internal[mntxv1.GetCardPayoutStatusResponse](s.logger, mservice.MntxGateway, merrors.Internal("card payout processor not initialised"))
 	}
 
 	state, err := s.card.Status(context.Background(), req.GetPayoutId())
 	if err != nil {
+		log.Warn("Card payout status lookup failed", zap.Error(err))
 		return gsresponse.Auto[mntxv1.GetCardPayoutStatusResponse](s.logger, mservice.MntxGateway, err)
 	}
+	log.Info("Card payout status retrieved", zap.String("payout_id", state.GetPayoutId()), zap.String("status", state.GetStatus().String()))
 	return gsresponse.Success(&mntxv1.GetCardPayoutStatusResponse{Payout: state})
 }
 

api/gateway/mntx/internal/service/gateway/card_payout_validation_test.go

@@ -0,0 +1,103 @@
+package gateway
+
+import (
+	"testing"
+
+	"github.com/tech/sendico/gateway/mntx/internal/service/monetix"
+	mntxv1 "github.com/tech/sendico/pkg/proto/gateway/mntx/v1"
+)
+
+func TestValidateCardPayoutRequest_Valid(t *testing.T) {
+	cfg := testMonetixConfig()
+	req := validCardPayoutRequest()
+	if err := validateCardPayoutRequest(req, cfg); err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+}
+
+func TestValidateCardPayoutRequest_Errors(t *testing.T) {
+	baseCfg := testMonetixConfig()
+	cases := []struct {
+		name     string
+		mutate   func(*mntxv1.CardPayoutRequest)
+		config   func(monetix.Config) monetix.Config
+		expected string
+	}{
+		{
+			name:     "missing_payout_id",
+			mutate:   func(r *mntxv1.CardPayoutRequest) { r.PayoutId = "" },
+			expected: "missing_payout_id",
+		},
+		{
+			name:     "missing_customer_id",
+			mutate:   func(r *mntxv1.CardPayoutRequest) { r.CustomerId = "" },
+			expected: "missing_customer_id",
+		},
+		{
+			name:     "missing_customer_ip",
+			mutate:   func(r *mntxv1.CardPayoutRequest) { r.CustomerIp = "" },
+			expected: "missing_customer_ip",
+		},
+		{
+			name:     "invalid_amount",
+			mutate:   func(r *mntxv1.CardPayoutRequest) { r.AmountMinor = 0 },
+			expected: "invalid_amount",
+		},
+		{
+			name:     "missing_currency",
+			mutate:   func(r *mntxv1.CardPayoutRequest) { r.Currency = "" },
+			expected: "missing_currency",
+		},
+		{
+			name:   "unsupported_currency",
+			mutate: func(r *mntxv1.CardPayoutRequest) { r.Currency = "EUR" },
+			config: func(cfg monetix.Config) monetix.Config {
+				cfg.AllowedCurrencies = []string{"USD"}
+				return cfg
+			},
+			expected: "unsupported_currency",
+		},
+		{
+			name:     "missing_card_pan",
+			mutate:   func(r *mntxv1.CardPayoutRequest) { r.CardPan = "" },
+			expected: "missing_card_pan",
+		},
+		{
+			name:     "missing_card_holder",
+			mutate:   func(r *mntxv1.CardPayoutRequest) { r.CardHolder = "" },
+			expected: "missing_card_holder",
+		},
+		{
+			name:     "invalid_expiry_month",
+			mutate:   func(r *mntxv1.CardPayoutRequest) { r.CardExpMonth = 13 },
+			expected: "invalid_expiry_month",
+		},
+		{
+			name:     "invalid_expiry_year",
+			mutate:   func(r *mntxv1.CardPayoutRequest) { r.CardExpYear = 0 },
+			expected: "invalid_expiry_year",
+		},
+		{
+			name:   "missing_customer_country_when_required",
+			mutate: func(r *mntxv1.CardPayoutRequest) { r.CustomerCountry = "" },
+			config: func(cfg monetix.Config) monetix.Config {
+				cfg.RequireCustomerAddress = true
+				return cfg
+			},
+			expected: "missing_customer_country",
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			req := validCardPayoutRequest()
+			tc.mutate(req)
+			cfg := baseCfg
+			if tc.config != nil {
+				cfg = tc.config(cfg)
+			}
+			err := validateCardPayoutRequest(req, cfg)
+			requireReason(t, err, tc.expected)
+		})
+	}
+}

api/gateway/mntx/internal/service/gateway/card_processor.go

@@ -45,14 +45,20 @@ func (p *cardPayoutProcessor) Submit(ctx context.Context, req *mntxv1.CardPayout
 	if p == nil {
 		return nil, merrors.Internal("card payout processor not initialised")
 	}
+	p.logger.Info("Submitting card payout",
+		zap.String("payout_id", strings.TrimSpace(req.GetPayoutId())),
+		zap.String("customer_id", strings.TrimSpace(req.GetCustomerId())),
+		zap.Int64("amount_minor", req.GetAmountMinor()),
+		zap.String("currency", strings.ToUpper(strings.TrimSpace(req.GetCurrency()))),
+	)
 	if strings.TrimSpace(p.config.BaseURL) == "" || strings.TrimSpace(p.config.SecretKey) == "" {
-		p.logger.Warn("monetix configuration is incomplete for payout submission")
+		p.logger.Warn("Monetix configuration is incomplete for payout submission")
 		return nil, merrors.Internal("monetix configuration is incomplete")
 	}
 
 	req = sanitizeCardPayoutRequest(req)
 	if err := validateCardPayoutRequest(req, p.config); err != nil {
-		p.logger.Warn("card payout validation failed",
+		p.logger.Warn("Card payout validation failed",
 			zap.String("payout_id", req.GetPayoutId()),
 			zap.String("customer_id", req.GetCustomerId()),
 			zap.Error(err),
@@ -65,7 +71,7 @@ func (p *cardPayoutProcessor) Submit(ctx context.Context, req *mntxv1.CardPayout
 		projectID = p.config.ProjectID
 	}
 	if projectID == 0 {
-		p.logger.Warn("monetix project_id is not configured", zap.String("payout_id", req.GetPayoutId()))
+		p.logger.Warn("Monetix project_id is not configured", zap.String("payout_id", req.GetPayoutId()))
 		return nil, merrors.Internal("monetix project_id is not configured")
 	}
 
@@ -95,7 +101,7 @@ func (p *cardPayoutProcessor) Submit(ctx context.Context, req *mntxv1.CardPayout
 		state.ProviderMessage = err.Error()
 		state.UpdatedAt = timestamppb.New(p.clock.Now())
 		p.store.Save(state)
-		p.logger.Warn("monetix payout submission failed",
+		p.logger.Warn("Monetix payout submission failed",
 			zap.String("payout_id", req.GetPayoutId()),
 			zap.String("customer_id", req.GetCustomerId()),
 			zap.Error(err),
@@ -122,6 +128,13 @@ func (p *cardPayoutProcessor) Submit(ctx context.Context, req *mntxv1.CardPayout
 		ErrorMessage:      result.ErrorMessage,
 	}
 
+	p.logger.Info("Card payout submission stored",
+		zap.String("payout_id", state.GetPayoutId()),
+		zap.String("status", state.GetStatus().String()),
+		zap.Bool("accepted", result.Accepted),
+		zap.String("provider_request_id", result.ProviderRequestID),
+	)
+
 	return resp, nil
 }
 
@@ -129,14 +142,20 @@ func (p *cardPayoutProcessor) SubmitToken(ctx context.Context, req *mntxv1.CardT
 	if p == nil {
 		return nil, merrors.Internal("card payout processor not initialised")
 	}
+	p.logger.Info("Submitting card token payout",
+		zap.String("payout_id", strings.TrimSpace(req.GetPayoutId())),
+		zap.String("customer_id", strings.TrimSpace(req.GetCustomerId())),
+		zap.Int64("amount_minor", req.GetAmountMinor()),
+		zap.String("currency", strings.ToUpper(strings.TrimSpace(req.GetCurrency()))),
+	)
 	if strings.TrimSpace(p.config.BaseURL) == "" || strings.TrimSpace(p.config.SecretKey) == "" {
-		p.logger.Warn("monetix configuration is incomplete for token payout submission")
+		p.logger.Warn("Monetix configuration is incomplete for token payout submission")
 		return nil, merrors.Internal("monetix configuration is incomplete")
 	}
 
 	req = sanitizeCardTokenPayoutRequest(req)
 	if err := validateCardTokenPayoutRequest(req, p.config); err != nil {
-		p.logger.Warn("card token payout validation failed",
+		p.logger.Warn("Card token payout validation failed",
 			zap.String("payout_id", req.GetPayoutId()),
 			zap.String("customer_id", req.GetCustomerId()),
 			zap.Error(err),
@@ -149,7 +168,7 @@ func (p *cardPayoutProcessor) SubmitToken(ctx context.Context, req *mntxv1.CardT
 		projectID = p.config.ProjectID
 	}
 	if projectID == 0 {
-		p.logger.Warn("monetix project_id is not configured", zap.String("payout_id", req.GetPayoutId()))
+		p.logger.Warn("Monetix project_id is not configured", zap.String("payout_id", req.GetPayoutId()))
 		return nil, merrors.Internal("monetix project_id is not configured")
 	}
 
@@ -179,7 +198,7 @@ func (p *cardPayoutProcessor) SubmitToken(ctx context.Context, req *mntxv1.CardT
 		state.ProviderMessage = err.Error()
 		state.UpdatedAt = timestamppb.New(p.clock.Now())
 		p.store.Save(state)
-		p.logger.Warn("monetix token payout submission failed",
+		p.logger.Warn("Monetix token payout submission failed",
 			zap.String("payout_id", req.GetPayoutId()),
 			zap.String("customer_id", req.GetCustomerId()),
 			zap.Error(err),
@@ -206,6 +225,13 @@ func (p *cardPayoutProcessor) SubmitToken(ctx context.Context, req *mntxv1.CardT
 		ErrorMessage:      result.ErrorMessage,
 	}
 
+	p.logger.Info("Card token payout submission stored",
+		zap.String("payout_id", state.GetPayoutId()),
+		zap.String("status", state.GetStatus().String()),
+		zap.Bool("accepted", result.Accepted),
+		zap.String("provider_request_id", result.ProviderRequestID),
+	)
+
 	return resp, nil
 }
 
@@ -213,9 +239,13 @@ func (p *cardPayoutProcessor) Tokenize(ctx context.Context, req *mntxv1.CardToke
 	if p == nil {
 		return nil, merrors.Internal("card payout processor not initialised")
 	}
+	p.logger.Info("Submitting card tokenization",
+		zap.String("request_id", strings.TrimSpace(req.GetRequestId())),
+		zap.String("customer_id", strings.TrimSpace(req.GetCustomerId())),
+	)
 	cardInput, err := validateCardTokenizeRequest(req, p.config)
 	if err != nil {
-		p.logger.Warn("card tokenization validation failed",
+		p.logger.Warn("Card tokenization validation failed",
 			zap.String("request_id", req.GetRequestId()),
 			zap.String("customer_id", req.GetCustomerId()),
 			zap.Error(err),
@@ -228,7 +258,7 @@ func (p *cardPayoutProcessor) Tokenize(ctx context.Context, req *mntxv1.CardToke
 		projectID = p.config.ProjectID
 	}
 	if projectID == 0 {
-		p.logger.Warn("monetix project_id is not configured", zap.String("request_id", req.GetRequestId()))
+		p.logger.Warn("Monetix project_id is not configured", zap.String("request_id", req.GetRequestId()))
 		return nil, merrors.Internal("monetix project_id is not configured")
 	}
 
@@ -238,7 +268,7 @@ func (p *cardPayoutProcessor) Tokenize(ctx context.Context, req *mntxv1.CardToke
 	apiReq := buildCardTokenizeRequest(projectID, req, cardInput)
 	result, err := client.CreateCardTokenization(ctx, apiReq)
 	if err != nil {
-		p.logger.Warn("monetix tokenization request failed",
+		p.logger.Warn("Monetix tokenization request failed",
 			zap.String("request_id", req.GetRequestId()),
 			zap.String("customer_id", req.GetCustomerId()),
 			zap.Error(err),
@@ -258,6 +288,12 @@ func (p *cardPayoutProcessor) Tokenize(ctx context.Context, req *mntxv1.CardToke
 	resp.ExpiryYear = result.ExpiryYear
 	resp.CardBrand = result.CardBrand
 
+	p.logger.Info("Card tokenization completed",
+		zap.String("request_id", resp.GetRequestId()),
+		zap.Bool("success", resp.GetSuccess()),
+		zap.String("provider_request_id", result.ProviderRequestID),
+	)
+
 	return resp, nil
 }
 
@@ -267,16 +303,18 @@ func (p *cardPayoutProcessor) Status(_ context.Context, payoutID string) (*mntxv
 	}
 
 	id := strings.TrimSpace(payoutID)
+	p.logger.Info("Card payout status requested", zap.String("payout_id", id))
 	if id == "" {
-		p.logger.Warn("payout status requested with empty payout_id")
+		p.logger.Warn("Payout status requested with empty payout_id")
 		return nil, merrors.InvalidArgument("payout_id is required", "payout_id")
 	}
 
 	state, ok := p.store.Get(id)
 	if !ok || state == nil {
-		p.logger.Warn("payout status not found", zap.String("payout_id", id))
+		p.logger.Warn("Payout status not found", zap.String("payout_id", id))
 		return nil, merrors.NoData("payout not found")
 	}
+	p.logger.Info("Card payout status resolved", zap.String("payout_id", state.GetPayoutId()), zap.String("status", state.GetStatus().String()))
 	return state, nil
 }
 
@@ -284,18 +322,19 @@ func (p *cardPayoutProcessor) ProcessCallback(ctx context.Context, payload []byt
 	if p == nil {
 		return http.StatusInternalServerError, merrors.Internal("card payout processor not initialised")
 	}
+	p.logger.Debug("Processing Monetix callback", zap.Int("payload_bytes", len(payload)))
 	if len(payload) == 0 {
-		p.logger.Warn("received empty Monetix callback payload")
+		p.logger.Warn("Received empty Monetix callback payload")
 		return http.StatusBadRequest, merrors.InvalidArgument("callback body is empty")
 	}
 	if strings.TrimSpace(p.config.SecretKey) == "" {
-		p.logger.Warn("monetix secret key is not configured; cannot verify callback")
+		p.logger.Warn("Monetix secret key is not configured; cannot verify callback")
 		return http.StatusInternalServerError, merrors.Internal("monetix secret key is not configured")
 	}
 
 	var cb monetixCallback
 	if err := json.Unmarshal(payload, &cb); err != nil {
-		p.logger.Warn("failed to unmarshal Monetix callback", zap.Error(err))
+		p.logger.Warn("Failed to unmarshal Monetix callback", zap.Error(err))
 		return http.StatusBadRequest, err
 	}
 
@@ -304,7 +343,12 @@ func (p *cardPayoutProcessor) ProcessCallback(ctx context.Context, payload []byt
 		return http.StatusBadRequest, merrors.InvalidArgument("signature is missing")
 	}
 	if err := verifyCallbackSignature(cb, p.config.SecretKey); err != nil {
-		p.logger.Warn("Monetix callback signature check failed", zap.Error(err))
+		p.logger.Warn("Monetix callback signature check failed",
+			zap.String("payout_id", cb.Payment.ID),
+			zap.String("signature", cb.Signature),
+			zap.String("payload", string(payload)),
+			zap.Error(err),
+		)
 		return http.StatusForbidden, err
 	}
 
@@ -337,16 +381,16 @@ func (p *cardPayoutProcessor) emitCardPayoutEvent(state *mntxv1.CardPayoutState)
 	event := &mntxv1.CardPayoutStatusChangedEvent{Payout: state}
 	payload, err := protojson.Marshal(event)
 	if err != nil {
-		p.logger.Warn("failed to marshal payout callback event", zap.Error(err))
+		p.logger.Warn("Failed to marshal payout callback event", zap.Error(err))
 		return
 	}
 
 	env := messaging.CreateEnvelope(string(mservice.MntxGateway), model.NewNotification(mservice.MntxGateway, nm.NAUpdated))
 	if _, err := env.Wrap(payload); err != nil {
-		p.logger.Warn("failed to wrap payout callback event payload", zap.Error(err))
+		p.logger.Warn("Failed to wrap payout callback event payload", zap.Error(err))
 		return
 	}
 	if err := p.producer.SendMessage(env); err != nil {
-		p.logger.Warn("failed to publish payout callback event", zap.Error(err))
+		p.logger.Warn("Failed to publish payout callback event", zap.Error(err))
 	}
 }

api/gateway/mntx/internal/service/gateway/card_processor_test.go

@@ -0,0 +1,149 @@
+package gateway
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/tech/sendico/gateway/mntx/internal/service/monetix"
+	clockpkg "github.com/tech/sendico/pkg/clock"
+	"github.com/tech/sendico/pkg/merrors"
+	mntxv1 "github.com/tech/sendico/pkg/proto/gateway/mntx/v1"
+	"go.uber.org/zap"
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+type roundTripperFunc func(*http.Request) (*http.Response, error)
+
+func (f roundTripperFunc) RoundTrip(r *http.Request) (*http.Response, error) {
+	return f(r)
+}
+
+type staticClock struct {
+	now time.Time
+}
+
+func (s staticClock) Now() time.Time {
+	return s.now
+}
+
+func TestCardPayoutProcessor_Submit_Success(t *testing.T) {
+	cfg := monetix.Config{
+		BaseURL:           "https://monetix.test",
+		SecretKey:         "secret",
+		ProjectID:         99,
+		AllowedCurrencies: []string{"RUB"},
+	}
+
+	existingCreated := timestamppb.New(time.Date(2020, 2, 3, 0, 0, 0, 0, time.UTC))
+	store := newCardPayoutStore()
+	store.Save(&mntxv1.CardPayoutState{
+		PayoutId:  "payout-1",
+		CreatedAt: existingCreated,
+	})
+
+	httpClient := &http.Client{
+		Transport: roundTripperFunc(func(r *http.Request) (*http.Response, error) {
+			resp := monetix.APIResponse{}
+			resp.Operation.RequestID = "req-123"
+			body, _ := json.Marshal(resp)
+			return &http.Response{
+				StatusCode: http.StatusOK,
+				Body:       io.NopCloser(bytes.NewReader(body)),
+				Header:     http.Header{"Content-Type": []string{"application/json"}},
+			}, nil
+		}),
+	}
+
+	now := time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC)
+	processor := newCardPayoutProcessor(zap.NewNop(), cfg, staticClock{now: now}, store, httpClient, nil)
+
+	req := validCardPayoutRequest()
+	req.ProjectId = 0
+
+	resp, err := processor.Submit(context.Background(), req)
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if !resp.GetAccepted() {
+		t.Fatalf("expected accepted payout response")
+	}
+	if resp.GetPayout().GetProjectId() != cfg.ProjectID {
+		t.Fatalf("expected project id %d, got %d", cfg.ProjectID, resp.GetPayout().GetProjectId())
+	}
+	if resp.GetPayout().GetStatus() != mntxv1.PayoutStatus_PAYOUT_STATUS_PENDING {
+		t.Fatalf("expected pending status, got %v", resp.GetPayout().GetStatus())
+	}
+	if !resp.GetPayout().GetCreatedAt().AsTime().Equal(existingCreated.AsTime()) {
+		t.Fatalf("expected created_at preserved, got %v", resp.GetPayout().GetCreatedAt().AsTime())
+	}
+
+	stored, ok := store.Get(req.GetPayoutId())
+	if !ok || stored == nil {
+		t.Fatalf("expected payout state stored")
+	}
+	if stored.GetProviderPaymentId() == "" {
+		t.Fatalf("expected provider payment id")
+	}
+}
+
+func TestCardPayoutProcessor_Submit_MissingConfig(t *testing.T) {
+	cfg := monetix.Config{
+		AllowedCurrencies: []string{"RUB"},
+	}
+	processor := newCardPayoutProcessor(zap.NewNop(), cfg, clockpkg.NewSystem(), newCardPayoutStore(), &http.Client{}, nil)
+
+	_, err := processor.Submit(context.Background(), validCardPayoutRequest())
+	if err == nil {
+		t.Fatalf("expected error")
+	}
+	if !errors.Is(err, merrors.ErrInternal) {
+		t.Fatalf("expected internal error, got %v", err)
+	}
+}
+
+func TestCardPayoutProcessor_ProcessCallback(t *testing.T) {
+	cfg := monetix.Config{
+		SecretKey:         "secret",
+		StatusSuccess:     "success",
+		StatusProcessing:  "processing",
+		AllowedCurrencies: []string{"RUB"},
+	}
+	store := newCardPayoutStore()
+	processor := newCardPayoutProcessor(zap.NewNop(), cfg, staticClock{now: time.Date(2024, 1, 2, 3, 4, 5, 0, time.UTC)}, store, &http.Client{}, nil)
+
+	cb := baseCallback()
+	cb.Payment.Sum.Currency = "RUB"
+	cb.Signature = ""
+	sig, err := monetix.SignPayload(cb, cfg.SecretKey)
+	if err != nil {
+		t.Fatalf("failed to sign callback: %v", err)
+	}
+	cb.Signature = sig
+
+	payload, err := json.Marshal(cb)
+	if err != nil {
+		t.Fatalf("failed to marshal callback: %v", err)
+	}
+
+	status, err := processor.ProcessCallback(context.Background(), payload)
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if status != http.StatusOK {
+		t.Fatalf("expected status ok, got %d", status)
+	}
+
+	state, ok := store.Get(cb.Payment.ID)
+	if !ok || state == nil {
+		t.Fatalf("expected payout state stored")
+	}
+	if state.GetStatus() != mntxv1.PayoutStatus_PAYOUT_STATUS_PROCESSED {
+		t.Fatalf("expected processed status, got %v", state.GetStatus())
+	}
+}

api/gateway/mntx/internal/service/gateway/card_token_validation_test.go

@@ -0,0 +1,93 @@
+package gateway
+
+import (
+	"testing"
+
+	"github.com/tech/sendico/gateway/mntx/internal/service/monetix"
+	mntxv1 "github.com/tech/sendico/pkg/proto/gateway/mntx/v1"
+)
+
+func TestValidateCardTokenPayoutRequest_Valid(t *testing.T) {
+	cfg := testMonetixConfig()
+	req := validCardTokenPayoutRequest()
+	if err := validateCardTokenPayoutRequest(req, cfg); err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+}
+
+func TestValidateCardTokenPayoutRequest_Errors(t *testing.T) {
+	baseCfg := testMonetixConfig()
+	cases := []struct {
+		name     string
+		mutate   func(*mntxv1.CardTokenPayoutRequest)
+		config   func(monetix.Config) monetix.Config
+		expected string
+	}{
+		{
+			name:     "missing_payout_id",
+			mutate:   func(r *mntxv1.CardTokenPayoutRequest) { r.PayoutId = "" },
+			expected: "missing_payout_id",
+		},
+		{
+			name:     "missing_customer_id",
+			mutate:   func(r *mntxv1.CardTokenPayoutRequest) { r.CustomerId = "" },
+			expected: "missing_customer_id",
+		},
+		{
+			name:     "missing_customer_ip",
+			mutate:   func(r *mntxv1.CardTokenPayoutRequest) { r.CustomerIp = "" },
+			expected: "missing_customer_ip",
+		},
+		{
+			name:     "invalid_amount",
+			mutate:   func(r *mntxv1.CardTokenPayoutRequest) { r.AmountMinor = 0 },
+			expected: "invalid_amount",
+		},
+		{
+			name:     "missing_currency",
+			mutate:   func(r *mntxv1.CardTokenPayoutRequest) { r.Currency = "" },
+			expected: "missing_currency",
+		},
+		{
+			name:   "unsupported_currency",
+			mutate: func(r *mntxv1.CardTokenPayoutRequest) { r.Currency = "EUR" },
+			config: func(cfg monetix.Config) monetix.Config {
+				cfg.AllowedCurrencies = []string{"USD"}
+				return cfg
+			},
+			expected: "unsupported_currency",
+		},
+		{
+			name:     "missing_card_token",
+			mutate:   func(r *mntxv1.CardTokenPayoutRequest) { r.CardToken = "" },
+			expected: "missing_card_token",
+		},
+		{
+			name:   "missing_customer_city_when_required",
+			mutate: func(r *mntxv1.CardTokenPayoutRequest) {
+				r.CustomerCountry = "US"
+				r.CustomerCity = ""
+				r.CustomerAddress = "Main St"
+				r.CustomerZip = "12345"
+			},
+			config: func(cfg monetix.Config) monetix.Config {
+				cfg.RequireCustomerAddress = true
+				return cfg
+			},
+			expected: "missing_customer_city",
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			req := validCardTokenPayoutRequest()
+			tc.mutate(req)
+			cfg := baseCfg
+			if tc.config != nil {
+				cfg = tc.config(cfg)
+			}
+			err := validateCardTokenPayoutRequest(req, cfg)
+			requireReason(t, err, tc.expected)
+		})
+	}
+}

api/gateway/mntx/internal/service/gateway/card_tokenize_validation_test.go

@@ -0,0 +1,76 @@
+package gateway
+
+import (
+	"testing"
+	"time"
+
+	mntxv1 "github.com/tech/sendico/pkg/proto/gateway/mntx/v1"
+)
+
+func TestValidateCardTokenizeRequest_ValidTopLevel(t *testing.T) {
+	cfg := testMonetixConfig()
+	req := validCardTokenizeRequest()
+	if _, err := validateCardTokenizeRequest(req, cfg); err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+}
+
+func TestValidateCardTokenizeRequest_ValidNestedCard(t *testing.T) {
+	cfg := testMonetixConfig()
+	req := validCardTokenizeRequest()
+	req.Card = &mntxv1.CardDetails{
+		Pan:        "4111111111111111",
+		ExpMonth:   req.CardExpMonth,
+		ExpYear:    req.CardExpYear,
+		CardHolder: req.CardHolder,
+		Cvv:        req.CardCvv,
+	}
+	req.CardPan = ""
+	req.CardExpMonth = 0
+	req.CardExpYear = 0
+	req.CardHolder = ""
+	req.CardCvv = ""
+
+	if _, err := validateCardTokenizeRequest(req, cfg); err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+}
+
+func TestValidateCardTokenizeRequest_Expired(t *testing.T) {
+	cfg := testMonetixConfig()
+	req := validCardTokenizeRequest()
+	now := time.Now().UTC()
+	req.CardExpMonth = uint32(now.Month())
+	req.CardExpYear = uint32(now.Year() - 1)
+
+	_, err := validateCardTokenizeRequest(req, cfg)
+	requireReason(t, err, "expired_card")
+}
+
+func TestValidateCardTokenizeRequest_MissingCvv(t *testing.T) {
+	cfg := testMonetixConfig()
+	req := validCardTokenizeRequest()
+	req.CardCvv = ""
+
+	_, err := validateCardTokenizeRequest(req, cfg)
+	requireReason(t, err, "missing_cvv")
+}
+
+func TestValidateCardTokenizeRequest_MissingCardPan(t *testing.T) {
+	cfg := testMonetixConfig()
+	req := validCardTokenizeRequest()
+	req.CardPan = ""
+
+	_, err := validateCardTokenizeRequest(req, cfg)
+	requireReason(t, err, "missing_card_pan")
+}
+
+func TestValidateCardTokenizeRequest_AddressRequired(t *testing.T) {
+	cfg := testMonetixConfig()
+	cfg.RequireCustomerAddress = true
+	req := validCardTokenizeRequest()
+	req.CustomerCountry = ""
+
+	_, err := validateCardTokenizeRequest(req, cfg)
+	requireReason(t, err, "missing_customer_country")
+}

api/gateway/mntx/internal/service/gateway/metrics.go

@@ -164,11 +164,3 @@ func statusLabel(err error) string {
 		return "error"
 	}
 }
-
-func normalizeCallbackStatus(status string) string {
-	status = strings.TrimSpace(status)
-	if status == "" {
-		return "unknown"
-	}
-	return strings.ToLower(status)
-}

api/gateway/mntx/internal/service/gateway/payout_get.go

@@ -9,6 +9,7 @@ import (
 	"github.com/tech/sendico/pkg/merrors"
 	"github.com/tech/sendico/pkg/mservice"
 	mntxv1 "github.com/tech/sendico/pkg/proto/gateway/mntx/v1"
+	"go.uber.org/zap"
 )
 
 func (s *Service) GetPayout(ctx context.Context, req *mntxv1.GetPayoutRequest) (*mntxv1.GetPayoutResponse, error) {
@@ -17,14 +18,19 @@ func (s *Service) GetPayout(ctx context.Context, req *mntxv1.GetPayoutRequest) (
 
 func (s *Service) handleGetPayout(_ context.Context, req *mntxv1.GetPayoutRequest) gsresponse.Responder[mntxv1.GetPayoutResponse] {
 	ref := strings.TrimSpace(req.GetPayoutRef())
+	log := s.logger.Named("payout")
+	log.Info("Get payout request received", zap.String("payout_ref", ref))
 	if ref == "" {
+		log.Warn("Get payout request missing payout_ref")
 		return gsresponse.InvalidArgument[mntxv1.GetPayoutResponse](s.logger, mservice.MntxGateway, merrors.InvalidArgument("payout_ref is required", "payout_ref"))
 	}
 
 	payout, ok := s.store.Get(ref)
 	if !ok {
+		log.Warn("Payout not found", zap.String("payout_ref", ref))
 		return gsresponse.NotFound[mntxv1.GetPayoutResponse](s.logger, mservice.MntxGateway, merrors.NoData(fmt.Sprintf("payout %s not found", ref)))
 	}
 
+	log.Info("Payout retrieved", zap.String("payout_ref", ref), zap.String("status", payout.GetStatus().String()))
 	return gsresponse.Success(&mntxv1.GetPayoutResponse{Payout: payout})
 }