feat(sdk-coin-ton): add setFullWithdrawalMessage() for full unstake

Implements the full-withdrawal path for TON single nominator contracts
via text comment "w". When present, the contract drains
balance - gas - MIN_TON_FOR_STORAGE automatically.

- Add SINGLE_NOMINATOR_WITHDRAW_ALL_COMMENT = 'w' constant
- Add setFullWithdrawalMessage() to SingleNominatorWithdrawBuilder
- Detect "w" comment in transaction parser to set SingleNominatorWithdraw type
- Add unit tests for full withdrawal build and round-trip

Full withdrawal is inferred by transactionType === SingleNominatorWithdraw
&& !withdrawAmount, mirroring TonWhales handling.

SC-6175

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

TICKET: SC-6175

Author: feng-bitgo

modules/sdk-coin-ton/src/lib/constants.ts

@@ -6,3 +6,4 @@ export const VESTING_CONTRACT_CODE_B64 =
   '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';
 export const TON_WHALES_DEPOSIT_OPCODE = '2077040623';
 export const TON_WHALES_WITHDRAW_OPCODE = '3665837821';
+export const SINGLE_NOMINATOR_WITHDRAW_ALL_COMMENT = 'w';

modules/sdk-coin-ton/src/lib/singleNominatorWithdrawBuilder.ts

@@ -2,6 +2,7 @@ import { BaseCoin as CoinConfig } from '@bitgo/statics';
 import { Recipient, TransactionType } from '@bitgo/sdk-core';
 import { TransactionBuilder } from './transactionBuilder';
 import { Transaction } from './transaction';
+import { SINGLE_NOMINATOR_WITHDRAW_ALL_COMMENT } from './constants';
 
 export class SingleNominatorWithdrawBuilder extends TransactionBuilder {
   constructor(_coinConfig: Readonly<CoinConfig>) {
@@ -23,6 +24,16 @@ export class SingleNominatorWithdrawBuilder extends TransactionBuilder {
     return this;
   }
 
+  /**
+   * Sets the message to withdraw everything from the single nominator contract.
+   * Uses a plain transfer with text comment "w" which instructs the contract to
+   * drain balance - gas - MIN_TON_FOR_STORAGE automatically.
+   */
+  setFullWithdrawalMessage(): SingleNominatorWithdrawBuilder {
+    this.transaction.message = SINGLE_NOMINATOR_WITHDRAW_ALL_COMMENT;
+    return this;
+  }
+
   setMessage(msg: string): SingleNominatorWithdrawBuilder {
     throw new Error('Method not implemented.');
   }

modules/sdk-coin-ton/src/lib/transaction.ts

@@ -12,6 +12,7 @@ import {
   VESTING_CONTRACT_WALLET_ID,
   TON_WHALES_DEPOSIT_OPCODE,
   TON_WHALES_WITHDRAW_OPCODE,
+  SINGLE_NOMINATOR_WITHDRAW_ALL_COMMENT,
 } from './constants';
 
 export class Transaction extends BaseTransaction {
@@ -359,6 +360,8 @@ export class Transaction extends BaseTransaction {
             this.transactionType = TransactionType.TonWhalesVestingDeposit;
           } else if (payload === 'Withdraw') {
             this.transactionType = TransactionType.TonWhalesVestingWithdrawal;
+          } else if (payload === SINGLE_NOMINATOR_WITHDRAW_ALL_COMMENT) {
+            this.transactionType = TransactionType.SingleNominatorWithdraw;
           }
         } else if (opcode === 4096) {
           const queryId = order.loadUint(64).toNumber();

modules/sdk-coin-ton/test/unit/singleNominatorWithdrawBuilder.ts

@@ -132,6 +132,68 @@ describe('Ton Single Nominator Withdraw Builder', () => {
     should.equal(txBounceable.toJson().withdrawAmount, singleNominatorWithdrawAmount);
   });
 
+  it('should build a full withdrawal tx using setFullWithdrawalMessage', async function () {
+    const txBuilder = factory.getSingleNominatorWithdrawBuilder();
+    txBuilder.sender(testData.sender.address);
+    txBuilder.sequenceNumber(0);
+    txBuilder.publicKey(testData.sender.publicKey);
+    txBuilder.expireTime(1234567890);
+    txBuilder.send(testData.recipients[0]);
+    txBuilder.setFullWithdrawalMessage();
+    const tx = await txBuilder.build();
+    should.equal(tx.type, TransactionType.SingleNominatorWithdraw);
+    should.equal(tx.toJson().bounceable, false);
+    should.equal(tx.toJson().withdrawAmount, undefined);
+    tx.inputs.length.should.equal(1);
+    tx.inputs[0].should.deepEqual({
+      address: testData.sender.address,
+      value: testData.recipients[0].amount,
+      coin: 'tton',
+    });
+    tx.outputs.length.should.equal(1);
+    tx.outputs[0].should.deepEqual({
+      address: testData.recipients[0].address,
+      value: testData.recipients[0].amount,
+      coin: 'tton',
+    });
+    const rawTx = tx.toBroadcastFormat();
+    // Verify the raw transaction can be parsed back as a full withdrawal
+    // Full withdrawal is inferred by: transactionType === SingleNominatorWithdraw && !withdrawAmount
+    const txBuilder2 = factory.from(rawTx);
+    const tx2 = await txBuilder2.build();
+    should.equal(tx2.type, TransactionType.SingleNominatorWithdraw);
+    should.equal(tx2.toJson().withdrawAmount, undefined);
+    should.equal(tx2.toBroadcastFormat(), rawTx);
+  });
+
+  it('should build a signed full withdrawal tx using add signature', async function () {
+    const keyPair = new KeyPair({ prv: testData.privateKeys.prvKey1 });
+    const publicKey = keyPair.getKeys().pub;
+    const address = await utils.default.getAddressFromPublicKey(publicKey);
+    const txBuilder = factory.getSingleNominatorWithdrawBuilder();
+    txBuilder.sender(address);
+    txBuilder.sequenceNumber(0);
+    txBuilder.publicKey(publicKey);
+    const expireAt = Math.floor(Date.now() / 1e3) + 60 * 60 * 24 * 7;
+    txBuilder.expireTime(expireAt);
+    txBuilder.send(testData.recipients[0]);
+    txBuilder.setFullWithdrawalMessage();
+    const tx = await txBuilder.build();
+    should.equal(tx.type, TransactionType.SingleNominatorWithdraw);
+    should.equal(tx.toJson().withdrawAmount, undefined);
+    const signable = tx.signablePayload;
+    const signature = keyPair.signMessageinUint8Array(signable);
+    txBuilder.addSignature(keyPair.getKeys(), Buffer.from(signature));
+    const signedTx = await txBuilder.build();
+    const builder2 = factory.from(signedTx.toBroadcastFormat());
+    const tx2 = await builder2.build();
+    const signature2 = keyPair.signMessageinUint8Array(tx2.signablePayload);
+    should.equal(Buffer.from(signature).toString('hex'), Buffer.from(signature2).toString('hex'));
+    should.equal(tx.toBroadcastFormat(), tx2.toBroadcastFormat());
+    should.equal(tx2.type, TransactionType.SingleNominatorWithdraw);
+    should.equal(tx2.toJson().withdrawAmount, undefined);
+  });
+
   xit('should build a signed withdraw tx and submit onchain', async function () {
     const tonweb = new TonWeb(new TonWeb.HttpProvider('https://testnet.toncenter.com/api/v2/jsonRPC'));
     const keyPair = new KeyPair({ prv: testData.privateKeys.prvKey1 });