fix: (A-643) add buffer to maxFeePerBlobGas for gas estimation and fix bump loop truncation

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

@@ -454,6 +454,50 @@ describe('L1TxUtils', () => {
       }
     });
 
+    it('bumps gas fees correctly at very low wei values (ceiling division)', async () => {
+      await cheatCodes.setNextBlockBaseFeePerGas(1n);
+      await cheatCodes.evmMine();
+
+      const originalGetBlobBaseFee = l1Client.getBlobBaseFee;
+      l1Client.getBlobBaseFee = () => Promise.resolve(1n);
+
+      const originalEstimate = l1Client.estimateMaxPriorityFeePerGas;
+      l1Client.estimateMaxPriorityFeePerGas = () => Promise.resolve(0n);
+
+      try {
+        gasUtils.updateConfig({
+          ...defaultL1TxUtilsConfig,
+          stallTimeMs: 12_000,
+          priorityFeeBumpPercentage: 0,
+          minimumPriorityFeePerGas: 0,
+        });
+
+        const gasPrice = await gasUtils['getGasPrice'](undefined, true);
+
+        // With ceiling division: (1n * 1125n + 999n) / 1000n = 2n
+        expect(gasPrice.maxFeePerGas).toBe(2n);
+        expect(gasPrice.maxFeePerBlobGas).toBe(2n);
+
+        // Verify compounding works across multiple iterations
+        gasUtils.updateConfig({
+          ...defaultL1TxUtilsConfig,
+          stallTimeMs: 24_000,
+          priorityFeeBumpPercentage: 0,
+          minimumPriorityFeePerGas: 0,
+        });
+
+        const gasPrice2 = await gasUtils['getGasPrice'](undefined, true);
+
+        // Iteration 1: ceil(1 * 1125 / 1000) = 2
+        // Iteration 2: ceil(2 * 1125 / 1000) = ceil(2.25) = 3
+        expect(gasPrice2.maxFeePerGas).toBe(3n);
+        expect(gasPrice2.maxFeePerBlobGas).toBe(3n);
+      } finally {
+        l1Client.getBlobBaseFee = originalGetBlobBaseFee;
+        l1Client.estimateMaxPriorityFeePerGas = originalEstimate;
+      }
+    });
+
     it('calculates correct gas prices for retry attempts', async () => {
       await cheatCodes.setNextBlockBaseFeePerGas(WEI_CONST);
       await cheatCodes.evmMine();

yarn-project/ethereum/src/l1_tx_utils/readonly_l1_tx_utils.ts

@@ -130,9 +130,10 @@ export class ReadOnlyL1TxUtils {
     const numBlocks = Math.ceil(gasConfig.stallTimeMs! / BLOCK_TIME_MS);
     for (let i = 0; i < numBlocks; i++) {
       // each block can go up 12.5% from previous baseFee
-      maxFeePerGas = (maxFeePerGas * (1_000n + 125n)) / 1_000n;
+      // ceil, (a+b-1)/b, to avoid truncation at small values (e.g. 1 wei blob base fee)
+      maxFeePerGas = (maxFeePerGas * (1_000n + 125n) + 999n) / 1_000n;
       // same for blob gas fee
-      maxFeePerBlobGas = (maxFeePerBlobGas * (1_000n + 125n)) / 1_000n;
+      maxFeePerBlobGas = (maxFeePerBlobGas * (1_000n + 125n) + 999n) / 1_000n;
     }
 
     if (attempt > 0) {
@@ -242,13 +243,16 @@ export class ReadOnlyL1TxUtils {
     const gasConfig = { ...this.config, ..._gasConfig };
     let initialEstimate = 0n;
     if (_blobInputs) {
-      // @note requests with blobs also require maxFeePerBlobGas to be set
+      // @note requests with blobs also require maxFeePerBlobGas to be set.
+      // Use 2x buffer for maxFeePerBlobGas to avoid stale fees and to pass EIP-4844 validation (even if it is a gas estimation call).
+      // 1. maxFeePerBlobGas >= blobBaseFee
+      // 2. account balance >= gas * maxFeePerGas + maxFeePerBlobGas * blobCount + value
       const gasPrice = await this.getGasPrice(gasConfig, true, 0);
       initialEstimate = await this.client.estimateGas({
         account,
         ...request,
         ..._blobInputs,
-        maxFeePerBlobGas: gasPrice.maxFeePerBlobGas!,
+        maxFeePerBlobGas: gasPrice.maxFeePerBlobGas! * 2n,
         gas: MAX_L1_TX_LIMIT,
         blockTag: 'latest',
       });