feat(fast-inbox): drop archiver inHash cross-check and TXE message padding (A-1384)

- Archiver l1_synchronizer stops cross-checking the (now-zero) checkpoint inHash;
  the consensus Inbox rolling hash is verified on L1 at propose (AZIP-22 Fast Inbox).
- TXE appends real message leaves unpadded at compact indices (synchronizer,
  block_creation) and stops padding empty blocks to a full subtree.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: spalladino

yarn-project/archiver/src/modules/l1_synchronizer.ts

@@ -30,7 +30,6 @@ import {
   PublishedCheckpoint,
 } from '@aztec/stdlib/checkpoint';
 import { type L1RollupConstants, getEpochAtSlot, getSlotAtNextL1Block } from '@aztec/stdlib/epoch-helpers';
-import { computeInHashFromL1ToL2Messages } from '@aztec/stdlib/messaging';
 import type { CoordinationSignatureContext } from '@aztec/stdlib/p2p';
 import { type Traceable, type Tracer, execInSpan, trackSpan } from '@aztec/telemetry-client';
 
@@ -1013,25 +1012,8 @@ export class ArchiverL1Synchronizer implements Traceable {
       for (const calldataCheckpoint of checkpointsToIngest) {
         const published = publishedByNumber.get(calldataCheckpoint.checkpointNumber)!;
 
-        // Check the inHash of the checkpoint against the l1->l2 messages.
-        // The messages should've been synced up to the currentL1BlockNumber and must be available for the published
-        // checkpoints we just retrieved.
-        const l1ToL2Messages = await this.stores.messages.getL1ToL2Messages(published.checkpoint.number);
-        const computedInHash = computeInHashFromL1ToL2Messages(l1ToL2Messages);
-        const publishedInHash = published.checkpoint.header.inHash;
-        if (!computedInHash.equals(publishedInHash)) {
-          this.log.fatal(`Mismatch inHash for checkpoint ${published.checkpoint.number}`, {
-            checkpointHash: published.checkpoint.hash(),
-            l1BlockNumber: published.l1.blockNumber,
-            computedInHash,
-            publishedInHash,
-          });
-          // Throwing an error since this is most likely caused by a bug.
-          throw new Error(
-            `Mismatch inHash for checkpoint ${published.checkpoint.number}. Expected ${computedInHash} but got ${publishedInHash}`,
-          );
-        }
-
+        // The legacy inHash cross-check is dead post-flip (the header carries zero): the consensus Inbox rolling hash
+        // is verified on L1 at propose, so no equivalent check is needed here (AZIP-22 Fast Inbox).
         validCheckpoints.push(published);
         this.log.debug(
           `Ingesting new checkpoint ${published.checkpoint.number} with ${published.checkpoint.blocks.length} blocks`,

yarn-project/txe/src/oracle/txe_oracle_top_level_context.ts

@@ -1,8 +1,4 @@
-import {
-  CONTRACT_INSTANCE_REGISTRY_CONTRACT_ADDRESS,
-  MAX_PRIVATE_LOGS_PER_TX,
-  NUMBER_OF_L1_L2_MESSAGES_PER_ROLLUP,
-} from '@aztec/constants';
+import { CONTRACT_INSTANCE_REGISTRY_CONTRACT_ADDRESS, MAX_PRIVATE_LOGS_PER_TX } from '@aztec/constants';
 import { BlockNumber } from '@aztec/foundation/branded-types';
 import { Schnorr } from '@aztec/foundation/crypto/schnorr';
 import { Fr } from '@aztec/foundation/curves/bn254';
@@ -658,8 +654,7 @@ export class TXEOracleTopLevelContext implements IMiscOracle, ITxeExecutionOracl
 
     txEffect.txHash = new TxHash(new Fr(blockNumber));
 
-    const l1ToL2Messages = Array(NUMBER_OF_L1_L2_MESSAGES_PER_ROLLUP).fill(0).map(Fr.zero);
-    await forkedWorldTrees.appendLeaves(MerkleTreeId.L1_TO_L2_MESSAGE_TREE, l1ToL2Messages);
+    // Post-flip TXE blocks carry no L1-to-L2 messages, so the message tree is left unadvanced (AZIP-22 Fast Inbox).
 
     const l2Block = await makeTXEBlock(forkedWorldTrees, globals, [txEffect]);
 
@@ -823,8 +818,7 @@ export class TXEOracleTopLevelContext implements IMiscOracle, ITxeExecutionOracl
 
     txEffect.txHash = new TxHash(new Fr(blockNumber));
 
-    const l1ToL2Messages = Array(NUMBER_OF_L1_L2_MESSAGES_PER_ROLLUP).fill(0).map(Fr.zero);
-    await forkedWorldTrees.appendLeaves(MerkleTreeId.L1_TO_L2_MESSAGE_TREE, l1ToL2Messages);
+    // Post-flip TXE blocks carry no L1-to-L2 messages, so the message tree is left unadvanced (AZIP-22 Fast Inbox).
 
     const l2Block = await makeTXEBlock(forkedWorldTrees, globals, [txEffect]);
 

yarn-project/txe/src/state_machine/synchronizer.ts

@@ -1,6 +1,4 @@
-import { NUMBER_OF_L1_L2_MESSAGES_PER_ROLLUP } from '@aztec/constants';
 import { BlockNumber } from '@aztec/foundation/branded-types';
-import { padArrayEnd } from '@aztec/foundation/collection';
 import { Fr } from '@aztec/foundation/curves/bn254';
 import { AvmSimulatorPool } from '@aztec/simulator/server';
 import type { BlockHash, L2Block } from '@aztec/stdlib/block';
@@ -35,14 +33,8 @@ export class TXESynchronizer implements WorldStateSynchronizer {
   }
 
   public async handleL2Block(block: L2Block, l1ToL2Messages: Fr[] = []) {
-    // Pad the bundle only for a first-in-checkpoint block, matching how the circuits (and native world state) build the
-    // message tree. TXE mines one block per checkpoint, so this is always the first block, but keep the condition
-    // explicit so the caller matches the per-block message-insertion semantics of handleL2BlockAndMessages.
-    const messages =
-      block.indexWithinCheckpoint === 0
-        ? padArrayEnd<Fr, number>(l1ToL2Messages, Fr.ZERO, NUMBER_OF_L1_L2_MESSAGES_PER_ROLLUP)
-        : l1ToL2Messages;
-    await this.nativeWorldStateService.handleL2BlockAndMessages(block, messages);
+    // Append the block's real message leaves unpadded at compact indices (AZIP-22 Fast Inbox).
+    await this.nativeWorldStateService.handleL2BlockAndMessages(block, l1ToL2Messages);
 
     this.blockNumber = block.header.globalVariables.blockNumber;
   }

yarn-project/txe/src/utils/block_creation.ts

@@ -1,9 +1,4 @@
-import {
-  MAX_NOTE_HASHES_PER_TX,
-  MAX_NULLIFIERS_PER_TX,
-  NULLIFIER_SUBTREE_HEIGHT,
-  NUMBER_OF_L1_L2_MESSAGES_PER_ROLLUP,
-} from '@aztec/constants';
+import { MAX_NOTE_HASHES_PER_TX, MAX_NULLIFIERS_PER_TX, NULLIFIER_SUBTREE_HEIGHT } from '@aztec/constants';
 import { BlockNumber, CheckpointNumber, IndexWithinCheckpoint } from '@aztec/foundation/branded-types';
 import { padArrayEnd } from '@aztec/foundation/collection';
 import { Fr } from '@aztec/foundation/curves/bn254';
@@ -36,10 +31,8 @@ export async function insertTxEffectIntoWorldTrees(
     NULLIFIER_SUBTREE_HEIGHT,
   );
 
-  await worldTrees.appendLeaves(
-    MerkleTreeId.L1_TO_L2_MESSAGE_TREE,
-    padArrayEnd<Fr, number>(l1ToL2Messages, Fr.ZERO, NUMBER_OF_L1_L2_MESSAGES_PER_ROLLUP),
-  );
+  // Append the block's real message leaves unpadded at compact indices (AZIP-22 Fast Inbox).
+  await worldTrees.appendLeaves(MerkleTreeId.L1_TO_L2_MESSAGE_TREE, l1ToL2Messages);
 
   // We do not need to add public data writes because we apply them as we go.
 }