feat(sdk-coin-starknet): add Poseidon V3 INVOKE transaction hash computation

The TransferBuilder now computes the signableHex (Poseidon hash) locally
using @scure/starknet primitives, enabling wallet-platform to build
Starknet transactions without delegating to IMS.

New utils: encodeShortString, getSelectorFromName, compileExecuteCalldata,
calculateInvokeTransactionHash. Hash validated against known Sepolia tx
0x739a72831c7f53634a2ffc94b78b61985e3cdffbad09ab20a1480e1bec9bdf2.

CECHO-1165

TICKET: CECHO-1165

Author: shubham-damkondwar

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

@@ -17,3 +17,14 @@ export const ADDR_BOUND = 2n ** 251n - 256n;
 export const CONTRACT_ADDRESS_PREFIX = 0x535441524b4e45545f434f4e54524143545f41444452455353n;
 
 export const DEFAULT_SEED_SIZE_BYTES = 16;
+
+// V3 transaction hash prefix: encodeShortString("invoke")
+export const INVOKE_TX_PREFIX = 0x696e766f6b65n;
+
+// V3 transaction version
+export const TRANSACTION_VERSION_3 = 3n;
+
+// Resource bound type names (short-string encoded felts)
+export const L1_GAS_NAME = 0x4c315f474153n; // "L1_GAS"
+export const L2_GAS_NAME = 0x4c325f474153n; // "L2_GAS"
+export const L1_DATA_GAS_NAME = 0x4c315f44415441n; // "L1_DATA" — NOT "L1_DATA_GAS"

modules/sdk-coin-starknet/src/lib/iface.ts

@@ -30,6 +30,24 @@ export interface StarknetTransactionData {
   transactionType: StarknetTransactionType;
   signature?: string[];
   transactionHash?: string;
+  tip?: string;
+  nonceDataAvailabilityMode?: number;
+  feeDataAvailabilityMode?: number;
+  compiledCalldata?: string[];
+}
+
+export interface InvokeTransactionHashParams {
+  senderAddress: string;
+  compiledCalldata: string[];
+  chainId: string;
+  nonce: string;
+  resourceBounds: StarknetResourceBounds;
+  tip?: string;
+  nonceDataAvailabilityMode?: number;
+  feeDataAvailabilityMode?: number;
+  paymasterData?: string[];
+  accountDeploymentData?: string[];
+  proofFacts?: string[];
 }
 
 export interface ParsedTransferData {

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

@@ -23,6 +23,13 @@ export class Transaction extends BaseTransaction {
 
   set starknetTransactionData(data: StarknetTransactionData) {
     this._starknetTransactionData = data;
+    if (data.transactionHash) {
+      this._id = data.transactionHash;
+    }
+  }
+
+  get signableHex(): string {
+    return this._starknetTransactionData?.transactionHash || '';
   }
 
   get signedTransaction(): string | undefined {
@@ -47,6 +54,11 @@ export class Transaction extends BaseTransaction {
         transactionType: parsed.transactionType || StarknetTransactionType.INVOKE,
         signature: parsed.signature,
         transactionHash: parsed.transactionHash,
+        resourceBounds: parsed.resourceBounds,
+        tip: parsed.tip,
+        compiledCalldata: parsed.compiledCalldata,
+        nonceDataAvailabilityMode: parsed.nonceDataAvailabilityMode,
+        feeDataAvailabilityMode: parsed.feeDataAvailabilityMode,
       };
 
       if (parsed.signature && parsed.signature.length > 0) {

modules/sdk-coin-starknet/src/lib/transactionBuilder.ts

@@ -8,17 +8,27 @@ import {
 } from '@bitgo/sdk-core';
 import { BaseCoin as CoinConfig } from '@bitgo/statics';
 import BigNumber from 'bignumber.js';
-import { StarknetTransactionData, StarknetTransactionType, StarknetCall } from './iface';
+import { StarknetTransactionData, StarknetTransactionType, StarknetCall, StarknetResourceBounds } from './iface';
 import { Transaction } from './transaction';
 import utils from './utils';
 
+function defaultResourceBounds(): StarknetResourceBounds {
+  return {
+    l2_gas: { max_amount: '0x1c9c380', max_price_per_unit: '0x174876e800' },
+    l1_gas: { max_amount: '0x0', max_price_per_unit: '0x5af3107a4000' },
+    l1_data_gas: { max_amount: '0x3e8', max_price_per_unit: '0x2540be400' },
+  };
+}
+
 export abstract class TransactionBuilder extends BaseTransactionBuilder {
   protected _transaction: Transaction;
   protected _sender?: string;
   protected _publicKey?: string;
   protected _calls: StarknetCall[] = [];
   protected _nonce?: string;
   protected _chainId?: string;
+  protected _resourceBounds: StarknetResourceBounds = defaultResourceBounds();
+  protected _tip = '0x0';
 
   constructor(_coinConfig: Readonly<CoinConfig>) {
     super(_coinConfig);
@@ -55,6 +65,16 @@ export abstract class TransactionBuilder extends BaseTransactionBuilder {
     return this;
   }
 
+  public resourceBounds(rb: StarknetResourceBounds): this {
+    this._resourceBounds = rb;
+    return this;
+  }
+
+  public tip(tip: string): this {
+    this._tip = tip;
+    return this;
+  }
+
   /** @inheritdoc */
   get transaction(): Transaction {
     return this._transaction;
@@ -72,6 +92,12 @@ export abstract class TransactionBuilder extends BaseTransactionBuilder {
     this._calls = data.calls || [];
     this._nonce = data.nonce;
     this._chainId = data.chainId;
+    if (data.resourceBounds) {
+      this._resourceBounds = data.resourceBounds;
+    }
+    if (data.tip) {
+      this._tip = data.tip;
+    }
   }
 
   /** @inheritdoc */
@@ -128,12 +154,30 @@ export abstract class TransactionBuilder extends BaseTransactionBuilder {
 
   /** @inheritdoc */
   protected async buildImplementation(): Promise<Transaction> {
+    const sender = this._sender as string;
+    const chainId = this._chainId as string;
+    const nonce = this._nonce as string;
+    const compiledCalldata = utils.compileExecuteCalldata(this._calls);
+
+    const transactionHash = utils.calculateInvokeTransactionHash({
+      senderAddress: sender,
+      compiledCalldata,
+      chainId,
+      nonce,
+      resourceBounds: this._resourceBounds,
+      tip: this._tip,
+    });
+
     const data: StarknetTransactionData = {
-      senderAddress: this._sender!,
+      senderAddress: sender,
       calls: this._calls,
-      nonce: this._nonce!,
-      chainId: this._chainId!,
+      nonce,
+      chainId,
       transactionType: this.transactionType,
+      resourceBounds: this._resourceBounds,
+      tip: this._tip,
+      transactionHash,
+      compiledCalldata,
     };
 
     this._transaction.starknetTransactionData = data;

modules/sdk-coin-starknet/src/lib/utils.ts

@@ -1,6 +1,17 @@
-import { computeHashOnElements } from '@scure/starknet';
-import { FELT_MAX, MASK_128, OZ_ETH_ACCOUNT_CLASS_HASH, ADDR_BOUND, CONTRACT_ADDRESS_PREFIX } from './constants';
-import { StarknetTransactionData, StarknetCall, ParsedTransferData } from './iface';
+import { computeHashOnElements, poseidonHashMany, keccak } from '@scure/starknet';
+import {
+  FELT_MAX,
+  MASK_128,
+  OZ_ETH_ACCOUNT_CLASS_HASH,
+  ADDR_BOUND,
+  CONTRACT_ADDRESS_PREFIX,
+  INVOKE_TX_PREFIX,
+  TRANSACTION_VERSION_3,
+  L1_GAS_NAME,
+  L2_GAS_NAME,
+  L1_DATA_GAS_NAME,
+} from './constants';
+import { StarknetTransactionData, StarknetCall, ParsedTransferData, InvokeTransactionHashParams } from './iface';
 import { ecc } from '@bitgo/secp256k1';
 
 /**
@@ -198,6 +209,106 @@ export function validateRawTransaction(tx: StarknetTransactionData): void {
   }
 }
 
+/**
+ * Encode an ASCII string (max 31 chars) as a felt252.
+ */
+export function encodeShortString(str: string): bigint {
+  if (str.length > 31) {
+    throw new Error(`Short string too long: ${str.length} > 31`);
+  }
+  for (let i = 0; i < str.length; i++) {
+    const code = str.charCodeAt(i);
+    if (code > 127) {
+      throw new Error(`Non-ASCII character at index ${i}: code ${code}`);
+    }
+  }
+  let result = 0n;
+  for (let i = 0; i < str.length; i++) {
+    result = (result << 8n) | BigInt(str.charCodeAt(i));
+  }
+  return result;
+}
+
+/**
+ * Compute the Starknet function selector: keccak256(name) masked to 250 bits.
+ * @scure/starknet's keccak() already applies the 250-bit mask.
+ */
+export function getSelectorFromName(name: string): bigint {
+  return keccak(Buffer.from(name, 'ascii'));
+}
+
+/**
+ * Compile calls into the Cairo 1 multicall __execute__ calldata format.
+ * Format: [num_calls, to_0, selector_0, data_len_0, ...data_0, to_1, ...]
+ */
+export function compileExecuteCalldata(calls: StarknetCall[]): string[] {
+  const result: string[] = [];
+  result.push('0x' + BigInt(calls.length).toString(16));
+  for (const call of calls) {
+    result.push(call.contractAddress);
+    result.push('0x' + getSelectorFromName(call.entrypoint).toString(16));
+    result.push('0x' + BigInt(call.calldata.length).toString(16));
+    result.push(...call.calldata);
+  }
+  return result;
+}
+
+function encodeResourceBound(typeName: bigint, maxAmount: string, maxPricePerUnit: string): bigint {
+  return (typeName << 192n) | (BigInt(maxAmount) << 128n) | BigInt(maxPricePerUnit);
+}
+
+/**
+ * Compute the Poseidon V3 INVOKE transaction hash per SNIP-8.
+ */
+export function calculateInvokeTransactionHash(params: InvokeTransactionHashParams): string {
+  const {
+    senderAddress,
+    compiledCalldata,
+    chainId,
+    nonce,
+    resourceBounds,
+    tip = '0x0',
+    nonceDataAvailabilityMode = 0,
+    feeDataAvailabilityMode = 0,
+    paymasterData = [],
+    accountDeploymentData = [],
+    proofFacts,
+  } = params;
+
+  const feeFieldHash = poseidonHashMany([
+    BigInt(tip),
+    encodeResourceBound(L1_GAS_NAME, resourceBounds.l1_gas.max_amount, resourceBounds.l1_gas.max_price_per_unit),
+    encodeResourceBound(L2_GAS_NAME, resourceBounds.l2_gas.max_amount, resourceBounds.l2_gas.max_price_per_unit),
+    encodeResourceBound(
+      L1_DATA_GAS_NAME,
+      resourceBounds.l1_data_gas.max_amount,
+      resourceBounds.l1_data_gas.max_price_per_unit
+    ),
+  ]);
+
+  const daMode = (BigInt(nonceDataAvailabilityMode) << 32n) | BigInt(feeDataAvailabilityMode);
+
+  const hashFields: bigint[] = [
+    INVOKE_TX_PREFIX,
+    TRANSACTION_VERSION_3,
+    BigInt(senderAddress),
+    feeFieldHash,
+    poseidonHashMany(paymasterData.map(BigInt)),
+    BigInt(chainId),
+    BigInt(nonce),
+    daMode,
+    poseidonHashMany(accountDeploymentData.map(BigInt)),
+    poseidonHashMany(compiledCalldata.map(BigInt)),
+  ];
+
+  if (proofFacts && proofFacts.length > 0) {
+    hashFields.push(poseidonHashMany(proofFacts.map(BigInt)));
+  }
+
+  const hash = poseidonHashMany(hashFields);
+  return '0x' + hash.toString(16);
+}
+
 export default {
   isValidAddress,
   isValidPublicKey,
@@ -212,4 +323,8 @@ export default {
   parseTransferCall,
   generateKeyPair,
   validateRawTransaction,
+  encodeShortString,
+  getSelectorFromName,
+  compileExecuteCalldata,
+  calculateInvokeTransactionHash,
 };

modules/sdk-coin-starknet/test/resources/starknet.ts

@@ -84,3 +84,34 @@ export const TEST_AMOUNTS = {
   medium: '10000000000000000000',
   large: '999999999999999999999999',
 };
+
+export const SandboxTransferData = {
+  senderAddress: '0x1559292d3f9ea355458f83adf235b400e79786af5dc5e3b50f5505caa2bdc84',
+  receiverAddress: '0x4a1e86ae265e6e6ecbea5be7f67117c3540f8aaf2ad7f1cfec33c53080f05af',
+  amount: '1000000000000000000',
+  chainId: '0x534e5f5345504f4c4941',
+  tokenContract: '0x04718f5a0fc34cc1af16a1cdee98ffb20c31f5cd61d6ab07201858f4287c938d',
+  resourceBounds: {
+    l2_gas: { max_amount: '0x1c9c380', max_price_per_unit: '0x174876e800' },
+    l1_gas: { max_amount: '0x0', max_price_per_unit: '0x5af3107a4000' },
+    l1_data_gas: { max_amount: '0x3e8', max_price_per_unit: '0x2540be400' },
+  },
+};
+
+// Known-good tx from coins-sandbox/strkMPC/transferLocal.ts (block 9537253, Sepolia)
+// All inputs from the sandbox script; nonce confirmed via Voyager explorer.
+export const KnownGoodInvokeTx = {
+  senderAddress: '0x1559292d3f9ea355458f83adf235b400e79786af5dc5e3b50f5505caa2bdc84',
+  receiverAddress: '0x4a1e86ae265e6e6ecbea5be7f67117c3540f8aaf2ad7f1cfec33c53080f05af',
+  amount: '1000000000000000000',
+  tokenContract: '0x04718f5a0fc34cc1af16a1cdee98ffb20c31f5cd61d6ab07201858f4287c938d',
+  nonce: '0x8',
+  chainId: '0x534e5f5345504f4c4941',
+  tip: '0x0',
+  resourceBounds: {
+    l2_gas: { max_amount: '0x1c9c380', max_price_per_unit: '0x174876e800' },
+    l1_gas: { max_amount: '0x0', max_price_per_unit: '0x5af3107a4000' },
+    l1_data_gas: { max_amount: '0x3e8', max_price_per_unit: '0x2540be400' },
+  },
+  expectedTxHash: '0x739a72831c7f53634a2ffc94b78b61985e3cdffbad09ab20a1480e1bec9bdf2',
+};