feat(gl): add standalone ledger authority mode

infrastructure/postgres/settlement_repository.go

@@ -23,6 +23,14 @@ func NewSettlementRepository(database Database) *SettlementRepository {
 	return &SettlementRepository{database: database}
 }
 
+// Existing normal-mode Wallet clients require SettlementReady; a GL-only
+// cutover must not let them continue admitting blockchain-dependent effects.
+func (r *SettlementRepository) SettlementAllowed(ctx context.Context) (bool, error) {
+	var mode string
+	err := r.database.QueryRow(ctx, "SELECT mode FROM ledger_operating_state WHERE singleton").Scan(&mode)
+	return mode == string(ledger.ModeNormal), err
+}
+
 func (r *SettlementRepository) Stats(ctx context.Context) (ledger.SettlementStats, error) {
 	var stats ledger.SettlementStats
 	err := r.database.QueryRow(ctx, `SELECT
@@ -60,6 +68,9 @@ func (r *SettlementRepository) Enqueue(ctx context.Context, s ledger.Settlement)
 		existing, err := r.Get(ctx, inserted, "")
 		return existing, true, err
 	}
+	if classified := authorityError(err); classified != nil {
+		return ledger.Settlement{}, false, classified
+	}
 	return ledger.Settlement{}, false, fmt.Errorf("enqueue settlement: %w", err)
 }
 
@@ -78,6 +89,13 @@ func (r *SettlementRepository) ClaimDue(ctx context.Context, workerID string, li
 		return nil, err
 	}
 	defer tx.Rollback(ctx)
+	var mode string
+	if err := tx.QueryRow(ctx, "SELECT mode FROM ledger_operating_state WHERE singleton FOR SHARE").Scan(&mode); err != nil {
+		return nil, err
+	}
+	if mode == string(ledger.ModeGLOnly) {
+		return nil, nil
+	}
 	if _, err := tx.Exec(ctx, `UPDATE kuknos_settlements SET locked_at=NULL, locked_by='', updated_at=clock_timestamp() WHERE locked_at < clock_timestamp() - interval '10 minutes'`); err != nil {
 		return nil, fmt.Errorf("release stale settlement locks: %w", err)
 	}