feat: PoC redeem frontrun protection

packages/sui-indexer/src/redeem-service.ts

@@ -326,9 +326,6 @@ export class RedeemService {
 		const availableUtxos = await this.storage.getAvailableUtxos(req.setup_id);
 		const selectedUtxos = selectUtxos(availableUtxos, req.amount);
 
-		// TODO: we should continue only if our solution is better than the existing one - in case
-		//   someone frontrun us.
-
 		if (!selectedUtxos) {
 			logger.warn({
 				msg: "Insufficient UTXOs for request",
@@ -338,14 +335,26 @@ export class RedeemService {
 			return;
 		}
 
-		try {
-			const client = this.getSuiClient(req.sui_network);
-			const txDigest = await client.proposeRedeemUtxos({
+		const client = this.getSuiClient(req.sui_network);
+		const proposalArgs = {
+			redeemId: req.redeem_id,
+			utxoIds: selectedUtxos.map((u) => u.nbtc_utxo_id),
+			nbtcPkg: req.nbtc_pkg,
+			nbtcContract: req.nbtc_contract,
+		};
+
+		const wouldSucceed = await client.dryRunProposeUtxos(proposalArgs);
+		if (!wouldSucceed) {
+			logger.info({
+				msg: "Dry-run failed, existing proposal is better or equal",
 				redeemId: req.redeem_id,
-				utxoIds: selectedUtxos.map((u) => u.nbtc_utxo_id),
-				nbtcPkg: req.nbtc_pkg,
-				nbtcContract: req.nbtc_contract,
+				ourUtxoCount: selectedUtxos.length,
 			});
+			return;
+		}
+
+		try {
+			const txDigest = await client.proposeRedeemUtxos(proposalArgs);
 
 			logger.info({
 				msg: "Proposed UTXOs for redeem request",

packages/sui-indexer/src/redeem-sui-client.ts

@@ -21,6 +21,7 @@ export interface SuiClientCfg {
 export interface SuiClient {
 	ikaClient(): IkaClient;
 	proposeRedeemUtxos(args: ProposeRedeemCall): Promise<string>;
+	dryRunProposeUtxos(args: ProposeRedeemCall): Promise<boolean>;
 	solveRedeemRequest(args: SolveRedeemCall): Promise<string>;
 	finalizeRedeem(args: FinalizeRedeemCall): Promise<string>;
 	requestIkaPresigns(count: number): Promise<string[]>;
@@ -142,6 +143,28 @@ class SuiClientImp implements SuiClient {
 		return result.digest;
 	}
 
+	async dryRunProposeUtxos(args: ProposeRedeemCall): Promise<boolean> {
+		const tx = new Transaction();
+
+		tx.add(
+			nBTCContractModule.proposeUtxos({
+				package: args.nbtcPkg,
+				arguments: {
+					contract: args.nbtcContract,
+					redeemId: args.redeemId,
+					utxoIds: args.utxoIds.map((u) => BigInt(u)),
+				},
+			}),
+		);
+
+		const result = await this.#sui.devInspectTransactionBlock({
+			transactionBlock: tx,
+			sender: this.signer.toSuiAddress(),
+		});
+
+		return !result.error;
+	}
+
 	async solveRedeemRequest(args: SolveRedeemCall): Promise<string> {
 		const tx = new Transaction();