feat: add durable Kuknos settlement coordination

application/health/service.go

@@ -1,23 +1,41 @@
 // Package health provides the service readiness use case.
 package health
 
-import "context"
+import (
+	"context"
+
+	"gl/domain/ledger"
+)
 
 type Database interface {
 	Ping(context.Context) error
 }
 
+type SettlementMonitor interface {
+	Stats(context.Context) (ledger.SettlementStats, error)
+}
+
 type Status struct {
-	Serving       bool
-	DatabaseReady bool
+	Serving           bool
+	DatabaseReady     bool
+	SettlementEnabled bool
+	SettlementReady   bool
+	SettlementStats   ledger.SettlementStats
 }
 
 type Service struct {
-	database Database
+	database          Database
+	settlement        SettlementMonitor
+	settlementEnabled bool
 }
 
-func NewService(database Database) *Service {
-	return &Service{database: database}
+func NewService(database Database, settlement ...SettlementMonitor) *Service {
+	service := &Service{database: database}
+	if len(settlement) > 0 && settlement[0] != nil {
+		service.settlement = settlement[0]
+		service.settlementEnabled = true
+	}
+	return service
 }
 
 func (s *Service) Check(ctx context.Context) Status {
@@ -26,5 +44,13 @@ func (s *Service) Check(ctx context.Context) Status {
 		status.DatabaseReady = s.database.Ping(ctx) == nil
 	}
 	status.Serving = status.DatabaseReady
+	status.SettlementEnabled = s.settlementEnabled
+	if status.DatabaseReady && s.settlementEnabled {
+		stats, err := s.settlement.Stats(ctx)
+		if err == nil {
+			status.SettlementStats = stats
+			status.SettlementReady = true
+		}
+	}
 	return status
 }

application/health/service_test.go

@@ -4,12 +4,23 @@ import (
 	"context"
 	"errors"
 	"testing"
+
+	"gl/domain/ledger"
 )
 
 type databaseStub struct{ err error }
 
 func (s databaseStub) Ping(context.Context) error { return s.err }
 
+type settlementStub struct {
+	stats ledger.SettlementStats
+	err   error
+}
+
+func (s settlementStub) Stats(context.Context) (ledger.SettlementStats, error) {
+	return s.stats, s.err
+}
+
 func TestCheckReportsDatabaseReadiness(t *testing.T) {
 	for _, tc := range []struct {
 		name  string
@@ -28,3 +39,25 @@ func TestCheckReportsDatabaseReadiness(t *testing.T) {
 		})
 	}
 }
+
+func TestCheckReportsSettlementBacklog(t *testing.T) {
+	monitor := settlementStub{stats: ledger.SettlementStats{Pending: 2, Retryable: 3, OldestPendingSeconds: 60}}
+	got := NewService(databaseStub{}, monitor).Check(context.Background())
+	if !got.Serving || !got.DatabaseReady || !got.SettlementEnabled || !got.SettlementReady || got.SettlementStats != monitor.stats {
+		t.Fatalf("unexpected status: %+v", got)
+	}
+}
+
+func TestCheckExposesManualReviewWithoutStoppingSettlementQueue(t *testing.T) {
+	got := NewService(databaseStub{}, settlementStub{stats: ledger.SettlementStats{ManualReview: 1}}).Check(context.Background())
+	if !got.Serving || !got.SettlementReady || got.SettlementStats.ManualReview != 1 {
+		t.Fatalf("unexpected status: %+v", got)
+	}
+}
+
+func TestCheckReportsSettlementQueryFailure(t *testing.T) {
+	got := NewService(databaseStub{}, settlementStub{err: errors.New("query failed")}).Check(context.Background())
+	if !got.Serving || got.SettlementReady {
+		t.Fatalf("unexpected status: %+v", got)
+	}
+}