From cf7ba72f8df041fd9f212abb96b4abf8e8699770 Mon Sep 17 00:00:00 2001
From: Santiago Palladino <santiago@aztec-labs.com>
Date: Wed, 6 May 2026 12:58:45 -0300
Subject: [PATCH] test(e2e): wait for archiver sync before asserting pipelining

Alternative fix for flake in epochs_mbps.pipeline.

See also
https://gist.github.com/AztecBot/164f3e04bd74f48cafd6505433935421.
---
 .../epochs_mbps.pipeline.parallel.test.ts     | 40 +++++++++++++++----
 1 file changed, 32 insertions(+), 8 deletions(-)

diff --git a/yarn-project/end-to-end/src/e2e_epochs/epochs_mbps.pipeline.parallel.test.ts b/yarn-project/end-to-end/src/e2e_epochs/epochs_mbps.pipeline.parallel.test.ts
index 013324576541..35f3fb1acc40 100644
--- a/yarn-project/end-to-end/src/e2e_epochs/epochs_mbps.pipeline.parallel.test.ts
+++ b/yarn-project/end-to-end/src/e2e_epochs/epochs_mbps.pipeline.parallel.test.ts
@@ -12,6 +12,7 @@ import { asyncMap } from '@aztec/foundation/async-map';
 import { BlockNumber, CheckpointNumber, SlotNumber } from '@aztec/foundation/branded-types';
 import { times, timesAsync } from '@aztec/foundation/collection';
 import { SecretValue } from '@aztec/foundation/config';
+import { retryUntil } from '@aztec/foundation/retry';
 import { bufferToHex } from '@aztec/foundation/string';
 import { executeTimeout } from '@aztec/foundation/timer';
 import { TestContract } from '@aztec/noir-test-contracts.js/Test';
@@ -113,8 +114,25 @@ describe('e2e_epochs/epochs_mbps_pipeline', () => {
     logger.warn(`Test setup completed.`, { validators: validators.map(v => v.attester.toString()) });
   }
 
-  /** Retrieves all checkpoints from the archiver, checks that one has the target block count, and returns its number. */
-  async function assertMultipleBlocksPerSlot(targetBlockCount: number, logger: Logger): Promise<CheckpointNumber> {
+  /**
+   * Waits until the archiver's checkpointed chain tip has reached `targetBlockNumber`, then retrieves all checkpoints,
+   * checks that one has the target block count, and returns its number.
+   */
+  async function assertMultipleBlocksPerSlot(
+    targetBlockCount: number,
+    targetBlockNumber: BlockNumber,
+    logger: Logger,
+  ): Promise<CheckpointNumber> {
+    await retryUntil(
+      async () => {
+        const checkpointed = await archiver.getBlockNumber({ tag: 'checkpointed' });
+        return checkpointed !== undefined && checkpointed >= targetBlockNumber;
+      },
+      `archiver checkpointed block ${targetBlockNumber}`,
+      10,
+      0.1,
+    );
+
     const checkpoints = await archiver.getCheckpoints({ from: CheckpointNumber(1), limit: 50 });
     logger.warn(`Retrieved ${checkpoints.length} checkpoints from archiver`, {
       checkpoints: checkpoints.map(pc => pc.checkpoint.getStats()),
@@ -253,14 +271,19 @@ describe('e2e_epochs/epochs_mbps_pipeline', () => {
 
     // Wait until all txs are mined
     const timeout = test.L2_SLOT_DURATION_IN_S * 5;
-    await executeTimeout(
+    const receipts = await executeTimeout(
       () => Promise.all(txHashes.map(txHash => waitForTx(context.aztecNode, txHash, { timeout }))),
       timeout * 1000,
     );
     logger.warn(`All txs have been mined`);
 
-    // Verify MBPS works with pipelining
-    const multiBlockCheckpoint = await assertMultipleBlocksPerSlot(EXPECTED_BLOCKS_PER_CHECKPOINT, logger);
+    // Verify MBPS works with pipelining; target the highest block number across mined receipts
+    const maxMinedBlockNumber = BlockNumber(Math.max(...receipts.map(r => r.blockNumber ?? 0)));
+    const multiBlockCheckpoint = await assertMultipleBlocksPerSlot(
+      EXPECTED_BLOCKS_PER_CHECKPOINT,
+      maxMinedBlockNumber,
+      logger,
+    );
 
     // Verify the pipelining offset: build slot N vs submission slot N+1
     await assertProposerPipelining(blockProposedEvents, logger);
@@ -348,14 +371,15 @@ describe('e2e_epochs/epochs_mbps_pipeline', () => {
 
     // Wait for a new checkpoint (recovery) - where all txs end up mined
     const timeout = test.L2_SLOT_DURATION_IN_S * 5;
-    await executeTimeout(
+    const receipts = await executeTimeout(
       () => Promise.all(txHashes.map(txHash => waitForTx(context.aztecNode, txHash, { timeout }))),
       timeout * 1000,
     );
     logger.warn(`All txs have been mined`);
 
-    // Verify MBPS works with pipelining
-    await assertMultipleBlocksPerSlot(EXPECTED_BLOCKS_PER_CHECKPOINT, logger);
+    // Verify MBPS works with pipelining; target the highest block number across mined receipts
+    const maxMinedBlockNumber = BlockNumber(Math.max(...receipts.map(r => r.blockNumber ?? 0)));
+    await assertMultipleBlocksPerSlot(EXPECTED_BLOCKS_PER_CHECKPOINT, maxMinedBlockNumber, logger);
 
     // Verify the pipelining offset: build slot N vs submission slot N+1
     await assertProposerPipelining(blockProposedEvents, logger);