Allow validated credit creation transactions

Sources/blocks/Domain/Block.swift

@@ -396,9 +396,21 @@ public struct Block {
          Add Booker Fee Transaction into Block.
          */
         if self.transactions.count <= Block.maxTransactionsInABlock {
-            if let signer = node.signer(), let publicKeyAsBase64String = signer.publicKeyForSignature?.rawRepresentation.base64String, let publicKey = publicKeyAsBase64String as? PublicKey {
-                let claimObject = ClaimOnPay.Object(destination: "")
-                if let bookerFeeTransaction = TransactionType.pay.construct(claim: ClaimOnPay.bookerFee, claimObject: claimObject, makerDhtAddressAsHexString: self.maker, publicKey: publicKey, book: node.book, signer: signer, peerSigner: signer, creditOnRight: ClaimOnPay.bookerFee.fee),
+            if let signer = node.signer(), let publicKey = signer.publicKeyAsData {
+                let claimObject = ClaimOnPay.Object(destination: self.maker)
+                if let bookerFeeTransaction = TransactionType.pay.construct(
+                    claim: ClaimOnPay.bookerFee,
+                    claimObject: claimObject,
+                    makerDhtAddressAsHexString: self.maker,
+                    publicKey: publicKey,
+                    book: node.book,
+                    signer: signer,
+                    peerSigner: signer,
+                    debitOnLeft: ClaimOnPay.bookerFee.fee,
+                    creditOnRight: ClaimOnPay.bookerFee.fee,
+                    withdrawalDhtAddressOnLeft: Signer.moneySupplyUnMoverAccount,
+                    depositDhtAddressOnRight: self.maker.toString
+                ),
                     let bookerFeeTransactionSignature = bookerFeeTransaction.signature,
                     let transactionId = bookerFeeTransaction.transactionId,
                     let bookerFeeTransactionPublicKey = bookerFeeTransaction.publicKey,

Sources/blocks/Domain/Transaction.swift

@@ -376,6 +376,15 @@ public extension Transaction {
             /*
              Check Account Balance.
              */
+            if self.isCreditCreation {
+                guard self.isAllowedCreditCreationClaim else {
+                    Log("Invalid Claim for Credit Creation Transaction.")
+                    return false
+                }
+                Log("Credit Creation Transaction skips maker balance check.")
+                return true
+            }
+
             //transactionの送金金額＋手数料　<= balance
             Log()
             let balancedAmount = self.book.balance(dhtAddressAsHexString: self.makerDhtAddressAsHexString)
@@ -483,6 +492,21 @@ public extension Transaction {
         return (false, nil)
     }
 
+    var isCreditCreation: Bool {
+        self.withdrawalDhtAddressOnLeft.equal(Signer.moneySupplyUnMoverAccount)
+    }
+
+    var isAllowedCreditCreationClaim: Bool {
+        switch self.claim.rawValue {
+        case ClaimOnPay.bookerFee.rawValue,
+             ClaimOnPerson.demandBasicIncome.rawValue,
+             ClaimOnPerson.born.rawValue:
+            return true
+        default:
+            return false
+        }
+    }
+
 //    static func == (lhs: any Transaction, rhs: any Transaction) -> Bool {
     static func == (lhs: Self, rhs: Self) -> Bool {
         guard let lhsTransactionId = lhs.transactionId, let rhsTransactionId = rhs.transactionId else {

Tests/blocksTests/CreditCreationValidationTest.swift

@@ -0,0 +1,62 @@
+//
+//  CreditCreationValidationTest.swift
+//  blocksTests
+//
+//  Created by Codex on 2026/05/24.
+//
+
+import XCTest
+@testable import blocks
+import overlayNetwork
+
+final class CreditCreationValidationTest: XCTestCase {
+
+    func testBookerFeeCreditCreationValidatesWithoutExistingBalance() throws {
+        let signer = Signer(newPrivateKeyOn: "booker-account" as OverlayNetworkAddressAsHexString)
+        guard let publicKey = signer.publicKeyAsData else {
+            XCTFail("Signer should have a public key.")
+            return
+        }
+        let fee = ClaimOnPay.bookerFee.fee
+        let transaction = Pay(
+            claim: ClaimOnPay.bookerFee,
+            claimObject: ClaimOnPay.Object(destination: "booker-account"),
+            makerDhtAddressAsHexString: "booker-account",
+            publicKey: publicKey,
+            book: Book(signature: Data.DataNull),
+            signer: signer,
+            transactionId: "BK-booker-fee",
+            date: Date(timeIntervalSince1970: 1_700_000_000),
+            debitOnLeft: fee,
+            creditOnRight: fee,
+            withdrawalDhtAddressOnLeft: Signer.moneySupplyUnMoverAccount,
+            depositDhtAddressOnRight: "booker-account"
+        )
+
+        XCTAssertTrue(transaction.validate(branchChainHash: nil, indexInBranchChain: nil))
+    }
+
+    func testRegularTransactionStillRequiresExistingBalance() throws {
+        let signer = Signer(newPrivateKeyOn: "maker-account" as OverlayNetworkAddressAsHexString)
+        guard let publicKey = signer.publicKeyAsData else {
+            XCTFail("Signer should have a public key.")
+            return
+        }
+        let transaction = Pay(
+            claim: ClaimOnPay.bookerFee,
+            claimObject: ClaimOnPay.Object(destination: "deposit-account"),
+            makerDhtAddressAsHexString: "maker-account",
+            publicKey: publicKey,
+            book: Book(signature: Data.DataNull),
+            signer: signer,
+            transactionId: "BK-regular-payment",
+            date: Date(timeIntervalSince1970: 1_700_000_000),
+            debitOnLeft: Decimal(10),
+            creditOnRight: Decimal(10),
+            withdrawalDhtAddressOnLeft: "maker-account",
+            depositDhtAddressOnRight: "deposit-account"
+        )
+
+        XCTAssertFalse(transaction.validate(branchChainHash: nil, indexInBranchChain: nil))
+    }
+}