fix: speed-up attempt blob fee

- use newly calculated `maxFeePerBlobGas` in new TX
- retry fetching blob fees. Blob txs are specifically very important so applying retry mechanism just for those

Fixes https://linear.app/aztec-labs/issue/TMNT-312/details-transaction-gas-price-below-minimum-blob-fee-cap-0-minimum

Author: spypsy

yarn-project/ethereum/src/l1_tx_utils.test.ts

@@ -94,6 +94,78 @@ describe('L1TxUtils', () => {
       });
     });
 
+    it('regression: speed-up of blob tx via L1TxUtils sets non-zero maxFeePerBlobGas', async () => {
+      await cheatCodes.setAutomine(false);
+      await cheatCodes.setIntervalMining(0);
+
+      const baseUtils = createL1TxUtilsFromViemWallet(l1Client, logger, dateProvider, {
+        gasLimitBufferPercentage: 20,
+        maxGwei: 500n,
+        maxAttempts: 1,
+        checkIntervalMs: 50,
+        stallTimeMs: 300,
+      });
+
+      const blobData = new Uint8Array(131072).fill(1);
+      const kzg = Blob.getViemKzgInstance();
+
+      const request = {
+        to: '0x1234567890123456789012345678901234567890' as `0x${string}`,
+        data: '0x' as `0x${string}`,
+        value: 0n,
+      } as const;
+
+      const estimatedGas = await l1Client.estimateGas(request);
+
+      // Send initial blob tx with a valid maxFeePerBlobGas
+      const { txHash } = await baseUtils.sendTransaction(request, undefined, {
+        blobs: [blobData],
+        kzg,
+        maxFeePerBlobGas: 10n * WEI_CONST,
+      });
+
+      // Capture the replacement tx when it is being signed
+      const originalSign = l1Client.signTransaction;
+      const signedTxs: TransactionSerializable[] = [];
+      using _spy = jest.spyOn(l1Client, 'signTransaction').mockImplementation((arg: any) => {
+        signedTxs.push(arg);
+        return originalSign(arg);
+      });
+
+      // Trigger monitor with blob inputs but WITHOUT maxFeePerBlobGas so the bug manifests
+      const monitorPromise = baseUtils.monitorTransaction(
+        request,
+        txHash,
+        new Set(),
+        { gasLimit: estimatedGas },
+        undefined,
+        {
+          blobs: [blobData],
+          kzg,
+        },
+      );
+
+      // Wait until a speed-up is attempted
+      await retryUntil(
+        () => baseUtils['state'] === TxUtilsState.SPEED_UP || signedTxs.length > 0,
+        'waiting for speed-up',
+        40,
+        0.05,
+      );
+
+      // Interrupt to stop the monitor loop and avoid hanging the test
+      baseUtils.interrupt();
+      await expect(monitorPromise).rejects.toThrow();
+
+      // Ensure we captured a replacement tx being signed
+      expect(signedTxs.length).toBeGreaterThan(0);
+      const replacement = signedTxs[signedTxs.length - 1] as any;
+
+      // Assert fix: maxFeePerBlobGas is populated and non-zero on replacement
+      expect(replacement.maxFeePerBlobGas).toBeDefined();
+      expect(replacement.maxFeePerBlobGas!).toBeGreaterThan(0n);
+    }, 20_000);
+
     it('sends and monitors a simple transaction', async () => {
       const { receipt } = await gasUtils.sendAndMonitorTransaction({
         to: '0x1234567890123456789012345678901234567890',

yarn-project/ethereum/src/l1_tx_utils.ts

@@ -279,7 +279,13 @@ export class ReadOnlyL1TxUtils {
     let blobBaseFee = 0n;
     if (isBlobTx) {
       try {
-        blobBaseFee = await this.client.getBlobBaseFee();
+        blobBaseFee = await retry<bigint>(
+          () => this.client.getBlobBaseFee(),
+          'Getting L1 blob base fee',
+          makeBackoff(times(2, () => 1)),
+          this.logger,
+          true,
+        );
         this.logger?.debug('L1 Blob base fee:', { blobBaseFee: formatGwei(blobBaseFee) });
       } catch {
         this.logger?.warn('Failed to get L1 blob base fee', attempt);
@@ -864,14 +870,17 @@ export class L1TxUtils extends ReadOnlyL1TxUtils {
             },
           );
 
-          const txData = {
+          const txData: PrepareTransactionRequestRequest = {
             ...request,
             ...blobInputs,
             nonce,
             gas: params.gasLimit,
             maxFeePerGas: newGasPrice.maxFeePerGas,
             maxPriorityFeePerGas: newGasPrice.maxPriorityFeePerGas,
           };
+          if (isBlobTx && newGasPrice.maxFeePerBlobGas) {
+            (txData as any).maxFeePerBlobGas = newGasPrice.maxFeePerBlobGas;
+          }
           const signedRequest = await this.prepareSignedTransaction(txData);
           const newHash = await this.client.sendRawTransaction({ serializedTransaction: signedRequest });
           if (!isCancelTx) {