feat(sdk-coin-sol): add WASM-based transaction parsing via @bitgo/wasm-solana by lcovar · Pull Request #7957 · BitGo/BitGoJS

lcovar · 2026-01-21T22:01:45Z

This PR introduces WASM-based transaction parsing as an alternative to
the legacy @solana/web3.js approach. The WASM implementation provides
cleaner parsing with zero web3.js dependencies for transaction decoding.

Key changes:

Add WasmTransaction class (~150 lines vs 800+ in legacy Transaction)
Add wasmInstructionMapper to convert WASM parsed instructions to SDK format
Add wasmInstructionCombiner to derive transaction types from instructions
Update sol.ts to extract transaction IDs using WASM parsing
Add comprehensive tests including Jito staking verification

Dependencies:

@bitgo/wasm-solana@2.0.0
Webpack alias added for browser builds

modules/sdk-coin-sol/src/sol.ts

OttoAllmendinger

we can move towards bigint a little bit more

where external interfaces force us to string keep it

OttoAllmendinger · 2026-02-11T08:15:47Z

modules/sdk-coin-sol/src/lib/wasm/transaction.ts

+    ];
+
+    const outputs: { address: string; amount: string; memo?: string }[] = [];
+    let outputAmount = '0';


Suggested change

let outputAmount = '0';

let outputAmount = 0n;

OttoAllmendinger · 2026-02-11T08:16:10Z

modules/sdk-coin-sol/src/lib/wasm/transaction.ts

+            address: instr.params.toAddress,
+            amount: instr.params.amount,
+          });
+          outputAmount = (BigInt(outputAmount) + BigInt(instr.params.amount)).toString();


let's avoid the internal bigint casts - why is instr.params.amount not a bigint already?

modules/sdk-coin-sol/src/lib/wasmInstructionMapper.ts

OttoAllmendinger · 2026-02-11T08:17:44Z

modules/sdk-coin-sol/src/sol.ts

+    // Derive outputs and tokenEnablements from combined instructions
+    const outputs: TransactionRecipient[] = [];
+    const tokenEnablements: ITokenEnablement[] = [];
+    let outputAmount = new BigNumber(0);


yet another way to sum up things... use bigint instead

OttoAllmendinger · 2026-02-11T09:43:47Z

modules/sdk-coin-sol/src/lib/wasm/transaction.ts

+
+  /** Transaction ID (first signature, base58 encoded) */
+  get id(): string {
+    if (!this._wasmTransaction) return UNAVAILABLE_TEXT;


I'm guessing the interface forces us to do this ugliness?

Unfortunately yes, base class forces the return type of string while _id can be string | undefined so it's a bit silly. We have to return a string, i guess we can return an empty string.

Seeing what it would take to update the base class to accept undefined as a return type. It would cause some breaking changes though but lets see. 🤖

Fixing the interface could spiral out of control very quickly, so let's leave it. I just need to know what is hard to change and what is easy to change. You can use the override keyword in typescript to signal that a method or getter implements a base method.

OttoAllmendinger

counting on you claude

OttoAllmendinger · 2026-02-13T08:48:06Z

modules/sdk-coin-sol/src/sol.ts

+    let outputAmount = 0n;
+
+    for (const instr of combinedInstructions) {
+      switch (instr.type) {
+        case InstructionBuilderTypes.Transfer:
+          outputs.push({
+            address: instr.params.toAddress,
+            amount: instr.params.amount,
+          });
+          outputAmount += BigInt(instr.params.amount);
+          break;
+
+        case InstructionBuilderTypes.TokenTransfer:
+          outputs.push({
+            address: instr.params.toAddress,
+            amount: instr.params.amount,
+            tokenName: findTokenName(instr.params.tokenAddress ?? '', undefined, true),
+          });
+          break;
+
+        case InstructionBuilderTypes.CreateNonceAccount:
+          outputs.push({
+            address: instr.params.nonceAddress,
+            amount: instr.params.amount,
+          });
+          outputAmount += BigInt(instr.params.amount);
+          break;
+
+        case InstructionBuilderTypes.StakingActivate:
+          outputs.push({
+            address: instr.params.stakingAddress,
+            amount: instr.params.amount,
+          });
+          outputAmount += BigInt(instr.params.amount);
+          break;
+
+        case InstructionBuilderTypes.StakingWithdraw:
+          outputs.push({
+            address: instr.params.fromAddress,
+            amount: instr.params.amount,
+          });
+          outputAmount += BigInt(instr.params.amount);
+          break;
+
+        case InstructionBuilderTypes.CreateAssociatedTokenAccount:
+          tokenEnablements.push({
+            address: instr.params.ataAddress,
+            tokenName: findTokenName(instr.params.mintAddress, undefined, true),
+            tokenAddress: instr.params.mintAddress,
+          });
+          break;
+      }
+    }


this whole thing gives me a deja vue

@claude can we consolidate here

🤖 Claude here.

Yes, this output extraction loop is duplicated in three places:

Transaction.explainTransaction() (transaction.ts:525-587) using BigNumber

WasmTransaction.explainTransaction() (wasm/transaction.ts:206-240) using bigint

Sol.explainTransactionWithWasm() (sol.ts:810-860) using bigint

Proposal: extract a shared free function in a new lib/explainUtil.ts:

interface ExplainedOutputs { outputs: TransactionRecipient[]; tokenEnablements: ITokenEnablement[]; outputAmount: bigint; memo?: string; } function extractOutputsFromInstructions(instructions: InstructionParams[]): ExplainedOutputs { const outputs: TransactionRecipient[] = []; const tokenEnablements: ITokenEnablement[] = []; let outputAmount = 0n; let memo: string | undefined; for (const instr of instructions) { switch (instr.type) { case InstructionBuilderTypes.Transfer: outputs.push({ address: instr.params.toAddress, amount: instr.params.amount }); outputAmount += BigInt(instr.params.amount); break; case InstructionBuilderTypes.TokenTransfer: outputs.push({ address: instr.params.toAddress, amount: instr.params.amount, tokenName: instr.params.tokenName, }); break; case InstructionBuilderTypes.CreateNonceAccount: outputs.push({ address: instr.params.nonceAddress, amount: instr.params.amount }); outputAmount += BigInt(instr.params.amount); break; case InstructionBuilderTypes.StakingActivate: outputs.push({ address: instr.params.stakingAddress, amount: instr.params.amount }); outputAmount += BigInt(instr.params.amount); break; case InstructionBuilderTypes.StakingWithdraw: outputs.push({ address: instr.params.fromAddress, amount: instr.params.amount }); outputAmount += BigInt(instr.params.amount); break; case InstructionBuilderTypes.CreateAssociatedTokenAccount: tokenEnablements.push({ address: instr.params.ataAddress, tokenName: instr.params.tokenName, tokenAddress: instr.params.mintAddress, }); break; case InstructionBuilderTypes.Memo: memo = instr.params.memo; break; } } return { outputs, tokenEnablements, outputAmount, memo }; }

All three call sites then become thin wrappers that call this, eliminating the duplication. The legacy Transaction.explainTransaction() can convert the bigint result to BigNumber at the boundary if needed (or migrate to bigint too).

OttoAllmendinger · 2026-02-13T08:48:38Z

modules/sdk-coin-sol/src/sol.ts

+    // Calculate fee: lamportsPerSignature * numSignatures + (rent * numATAs)
+    const lamportsPerSignature = parseInt(params.feeInfo?.fee || '0', 10);
+    const rentPerAta = parseInt(params.tokenAccountRentExemptAmount || '0', 10);


@claude suggest a inner func that has a nicer signature with already parsed args

don't we want bigint for amounts anyway?

🤖 Claude here.

Yes, bigint for amounts. The ExplainTransactionOptions.feeInfo.fee and tokenAccountRentExemptAmount come in as string from the external interface (TransactionFee.fee is string in sdk-core), so we should convert exactly once at the boundary.

Proposal — parse external args at the top, then pass typed values into a pure inner function:

interface WasmExplainArgs { combinedInstructions: InstructionParams[]; transactionType: TransactionType; memo?: string; nonce: string; durableNonce?: DurableNonceParams; numSignatures: number; signatures: Uint8Array[]; lamportsPerSignature: bigint; rentPerAta: bigint; } function buildWasmExplanation(args: WasmExplainArgs): SolLibTransactionExplanation { const { outputs, tokenEnablements, outputAmount } = extractOutputsFromInstructions(args.combinedInstructions); const signatureFee = args.lamportsPerSignature * BigInt(args.numSignatures); const rentFee = args.rentPerAta * BigInt(tokenEnablements.length); const totalFee = (signatureFee + rentFee).toString(); const txId = getTransactionId(args.signatures); return { displayOrder: [ ... ], id: txId, type: TransactionType[args.transactionType], changeOutputs: [], changeAmount: '0', outputAmount: outputAmount.toString(), outputs, fee: { fee: totalFee, feeRate: Number(args.lamportsPerSignature) }, memo: args.memo, blockhash: args.nonce, durableNonce: args.durableNonce, tokenEnablements, }; }

Then explainTransactionWithWasm becomes a thin adapter:

explainTransactionWithWasm(params: ExplainTransactionOptions): SolLibTransactionExplanation { const txBytes = Buffer.from(params.txBase64, 'base64'); const wasmTx = WasmTransaction.fromBytes(txBytes); const parsed = wasmParseTransaction(txBytes); const { instructions, transactionType } = combineWasmInstructionsFromBytes(txBytes); const memo = parsed.instructionsData.find((i) => i.type === 'Memo')?.memo; return buildWasmExplanation({ combinedInstructions: instructions, transactionType, memo, nonce: parsed.nonce, durableNonce: parsed.durableNonce, numSignatures: parsed.numSignatures, signatures: wasmTx.signatures, lamportsPerSignature: BigInt(params.feeInfo?.fee || '0'), rentPerAta: BigInt(params.tokenAccountRentExemptAmount || '0'), }); }

String → bigint conversion happens once at the boundary, all arithmetic is native bigint, and .toString() only at the final return where the external interface requires string.

OttoAllmendinger · 2026-02-13T08:49:13Z

modules/sdk-coin-sol/src/sol.ts

+    const totalFee = (signatureFee + rentFee).toString();
+
+    // Get transaction id from first signature (base58 encoded) or UNAVAILABLE
+    let txId = 'UNAVAILABLE';


this needs to be a higher level const

🤖 Claude here.

Agreed — should use the existing UNAVAILABLE_TEXT constant from lib/constants.ts instead of a string literal. Same constant is already used in WasmTransaction for the same purpose.

OttoAllmendinger · 2026-02-13T08:49:30Z

modules/sdk-coin-sol/src/sol.ts

+  private mapTransactionTypeToString(type: TransactionType): string {
+    switch (type) {
+      case TransactionType.Send:
+        return 'Send';
+      case TransactionType.WalletInitialization:
+        return 'WalletInitialization';
+      case TransactionType.StakingActivate:
+        return 'StakingActivate';
+      case TransactionType.StakingDeactivate:
+        return 'StakingDeactivate';
+      case TransactionType.StakingWithdraw:
+        return 'StakingWithdraw';
+      case TransactionType.StakingDelegate:
+        return 'StakingDelegate';
+      case TransactionType.StakingAuthorize:
+        return 'StakingAuthorize';
+      case TransactionType.AssociatedTokenAccountInitialization:
+        return 'AssociatedTokenAccountInitialization';
+      case TransactionType.CloseAssociatedTokenAccount:
+        return 'CloseAssociatedTokenAccount';
+      case TransactionType.CustomTx:
+        return 'CustomTx';
+      default:
+        return 'Send';
+    }


this should not be a coin method

🤖 Claude here.

Agreed. TransactionType is a numeric enum, so TypeScript's reverse mapping already gives us string names. The entire mapTransactionTypeToString method can be replaced with:

TransactionType[transactionType]

This is exactly what the legacy Transaction class does at transaction.ts:645:

type: TransactionType[this.type].toString(),

No switch statement or coin method needed. This should be a standalone expression, not a method on Sol.

…m-solana - Add WasmTransaction class for WASM-only tx parsing (no @solana/web3.js) - Add wasmInstructionMapper/Combiner for converting WASM instructions to BitGoJS format - Add standalone explainSolTransaction() with shared extractOutputsFromInstructions util - Use bigint for fee calculation, UNAVAILABLE_TEXT constant, override on id getter - Fix falsy-zero bug in determineTransactionType (TransactionType.Send = 0 is falsy) BTC-0 TICKET: BTC-0

lcovar force-pushed the BTC-0-draft-example-sol-decoding branch 27 times, most recently from d32c089 to bb885ad Compare January 28, 2026 18:16

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lcovar marked this pull request as ready for review February 10, 2026 19:39

lcovar requested review from a team as code owners February 10, 2026 19:39

lcovar requested review from Marzooqa and deepesh-bitgo February 10, 2026 19:39

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lcovar commented Jan 21, 2026 •

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