AztecProtocol · alexghr · May 15, 2026 · May 12, 2026
diff --git a/yarn-project/end-to-end/src/e2e_slashing/attested_invalid_proposal.test.ts b/yarn-project/end-to-end/src/e2e_slashing/attested_invalid_proposal.test.ts
diff --git a/yarn-project/end-to-end/src/fixtures/setup_p2p_test.ts b/yarn-project/end-to-end/src/fixtures/setup_p2p_test.ts
@@ -88,6 +88,10 @@ export type CreateNodeConfig = AztecNodeConfig & {
   dontStartSequencer?: boolean;
   /** Override the private key (instead of deriving from addressIndex). */
   validatorPrivateKey?: `0x${string}`;
+  /** Corrupt only the block proposal at this indexWithinCheckpoint (testing only). */
+  invalidBlockProposalIndexWithinCheckpoint?: number;
+  /** Accept proposal gossip regardless of slot timing (testing only). */
+  skipProposalSlotValidation?: boolean;
 };
 
 /** Creates a P2P enabled instance of Aztec Node Service with a validator. */

diff --git a/yarn-project/p2p/src/config.ts b/yarn-project/p2p/src/config.ts
@@ -229,6 +229,9 @@ export interface P2PConfig
 
   /** Drop incoming block and checkpoint proposals at the libp2p dispatch layer (for testing only) */
   skipIncomingProposals?: boolean;
+
+  /** Accept proposal gossip regardless of slot timing (for testing only). */
+  skipProposalSlotValidation?: boolean;
 }
 
 export const DEFAULT_P2P_PORT = 40400;
@@ -554,6 +557,10 @@ export const p2pConfigMappings: ConfigMappingsType<P2PConfig> = {
     description: 'Drop incoming block and checkpoint proposals at the libp2p dispatch layer (for testing only)',
     ...booleanConfigHelper(false),
   },
+  skipProposalSlotValidation: {
+    description: 'Accept proposal gossip regardless of slot timing (for testing only)',
+    ...booleanConfigHelper(false),
+  },
   minTxPoolAgeMs: {
     env: 'P2P_MIN_TX_POOL_AGE_MS',
     description: 'Minimum age (ms) a transaction must have been in the pool before it is eligible for block building.',

diff --git a/yarn-project/p2p/src/msg_validators/proposal_validator/block_proposal_validator.ts b/yarn-project/p2p/src/msg_validators/proposal_validator/block_proposal_validator.ts
@@ -13,6 +13,7 @@ export class BlockProposalValidator implements P2PValidator<BlockProposal> {
       maxTxsPerBlock?: number;
       maxBlocksPerCheckpoint?: number;
       p2pPropagationTime?: number;
+      skipSlotValidation?: boolean;
       signatureContext: CoordinationSignatureContext;
     },
   ) {

diff --git a/yarn-project/p2p/src/msg_validators/proposal_validator/checkpoint_proposal_validator.ts b/yarn-project/p2p/src/msg_validators/proposal_validator/checkpoint_proposal_validator.ts
@@ -18,6 +18,7 @@ export class CheckpointProposalValidator implements P2PValidator<CheckpointPropo
       maxTxsPerBlock?: number;
       maxBlocksPerCheckpoint?: number;
       p2pPropagationTime?: number;
+      skipSlotValidation?: boolean;
       signatureContext: CoordinationSignatureContext;
     },
   ) {

diff --git a/yarn-project/p2p/src/msg_validators/proposal_validator/proposal_validator.ts b/yarn-project/p2p/src/msg_validators/proposal_validator/proposal_validator.ts
@@ -20,6 +20,7 @@ export class ProposalValidator {
   private maxTxsPerBlock?: number;
   private maxBlocksPerCheckpoint?: number;
   private pipeliningWindow: PipeliningWindow;
+  private skipSlotValidation: boolean;
   private signatureContext: CoordinationSignatureContext;
 
   constructor(
@@ -29,6 +30,7 @@ export class ProposalValidator {
       maxTxsPerBlock?: number;
       maxBlocksPerCheckpoint?: number;
       p2pPropagationTime?: number;
+      skipSlotValidation?: boolean;
       signatureContext: CoordinationSignatureContext;
     },
     loggerName: string,
@@ -38,6 +40,7 @@ export class ProposalValidator {
     this.maxTxsPerBlock = opts.maxTxsPerBlock;
     this.maxBlocksPerCheckpoint = opts.maxBlocksPerCheckpoint;
     this.pipeliningWindow = new PipeliningWindow(epochCache, { p2pPropagationTime: opts.p2pPropagationTime });
+    this.skipSlotValidation = opts.skipSlotValidation ?? false;
     this.signatureContext = opts.signatureContext;
     this.logger = createLogger(loggerName);
   }
@@ -60,7 +63,7 @@ export class ProposalValidator {
       const { targetSlot, nextSlot } = this.epochCache.getTargetAndNextSlot();
 
       const slotNumber = proposal.slotNumber;
-      if (slotNumber !== targetSlot && slotNumber !== nextSlot) {
+      if (!this.skipSlotValidation && slotNumber !== targetSlot && slotNumber !== nextSlot) {
         // When pipelining, accept proposals for the current slot (built in the previous slot)
         // if they're still within the shared proposal acceptance window.
         if (this.pipeliningWindow.acceptsProposal(slotNumber)) {

diff --git a/yarn-project/p2p/src/services/libp2p/libp2p_service.ts b/yarn-project/p2p/src/services/libp2p/libp2p_service.ts
@@ -240,6 +240,7 @@ export class LibP2PService extends WithTracer implements P2PService {
       maxTxsPerBlock: config.validateMaxTxsPerBlock ?? config.validateMaxTxsPerCheckpoint,
       maxBlocksPerCheckpoint: config.maxBlocksPerCheckpoint,
       p2pPropagationTime,
+      skipSlotValidation: config.skipProposalSlotValidation,
       signatureContext: {
         chainId: config.l1ChainId,
         rollupAddress: config.rollupAddress,

diff --git a/yarn-project/sequencer-client/src/config.ts b/yarn-project/sequencer-client/src/config.ts
@@ -191,6 +191,10 @@ export const sequencerConfigMappings: ConfigMappingsType<SequencerConfig> = {
     description: 'Broadcast invalid block proposals with corrupted state (for testing only)',
     ...booleanConfigHelper(DefaultSequencerConfig.broadcastInvalidBlockProposal),
   },
+  invalidBlockProposalIndexWithinCheckpoint: {
+    description: 'Broadcast an invalid block proposal only at this indexWithinCheckpoint (for testing only)',
+    ...optionalNumberConfigHelper(),
+  },
   injectFakeAttestation: {
     description: 'Inject a fake attestation (for testing only)',
     ...booleanConfigHelper(DefaultSequencerConfig.injectFakeAttestation),

diff --git a/yarn-project/sequencer-client/src/sequencer/checkpoint_proposal_job.ts b/yarn-project/sequencer-client/src/sequencer/checkpoint_proposal_job.ts
@@ -879,7 +879,12 @@ export class CheckpointProposalJob implements Traceable {
       usedTxs.forEach(tx => txHashesAlreadyIncluded.add(tx.txHash.toString()));
 
       // Sign the block proposal. This will throw if HA signing fails.
-      const proposal = await this.createBlockProposal(block, inHash, usedTxs, blockProposalOptions);
+      const proposal = await this.createBlockProposal(block, inHash, usedTxs, {
+        ...blockProposalOptions,
+        broadcastInvalidBlockProposal:
+          blockProposalOptions.broadcastInvalidBlockProposal ||
+          block.indexWithinCheckpoint === this.config.invalidBlockProposalIndexWithinCheckpoint,
+      });
 
       // Sync the proposed block to the archiver to make it available, only after we've managed to sign the proposal,
       // so we avoid polluting our archive with a block that would fail.
@@ -1099,6 +1104,9 @@ export class CheckpointProposalJob implements Traceable {
       // `buildSlot` is the wall-clock slot during which the block was actually built.
       this.eventEmitter.emit('block-proposed', {
         blockNumber: block.number,
+        blockHash,
+        checkpointNumber: this.checkpointNumber,
+        indexWithinCheckpoint: block.indexWithinCheckpoint,
         slot: this.targetSlot,
         buildSlot: this.slotNow,
       });

diff --git a/yarn-project/sequencer-client/src/sequencer/events.ts b/yarn-project/sequencer-client/src/sequencer/events.ts
@@ -1,4 +1,5 @@
-import type { BlockNumber, CheckpointNumber, SlotNumber } from '@aztec/foundation/branded-types';
+import type { BlockNumber, CheckpointNumber, IndexWithinCheckpoint, SlotNumber } from '@aztec/foundation/branded-types';
+import type { BlockHash } from '@aztec/stdlib/block';
 
 import type { Action } from '../publisher/sequencer-publisher.js';
 import type { SequencerState } from './utils.js';
@@ -37,7 +38,14 @@ export type SequencerEvents = {
   ['proposer-rollup-check-failed']: (args: { reason: string; slot: SlotNumber }) => void;
   ['block-tx-count-check-failed']: (args: { minTxs: number; availableTxs: number; slot: SlotNumber }) => void;
   ['block-build-failed']: (args: { reason: string; slot: SlotNumber }) => void;
-  ['block-proposed']: (args: { blockNumber: BlockNumber; slot: SlotNumber; buildSlot: SlotNumber }) => void;
+  ['block-proposed']: (args: {
+    blockNumber: BlockNumber;
+    blockHash: BlockHash;
+    checkpointNumber: CheckpointNumber;
+    indexWithinCheckpoint: IndexWithinCheckpoint;
+    slot: SlotNumber;
+    buildSlot: SlotNumber;
+  }) => void;
   ['checkpoint-empty']: (args: { slot: SlotNumber }) => void;
   /**
    * Emitted when the proposer's pre-broadcast `validateBlockHeader` simulation fails. This is a

diff --git a/yarn-project/stdlib/src/interfaces/configs.ts b/yarn-project/stdlib/src/interfaces/configs.ts
@@ -64,6 +64,8 @@ export interface SequencerConfig {
   skipInvalidateBlockAsProposer?: boolean;
   /** Broadcast invalid block proposals with corrupted state (for testing only) */
   broadcastInvalidBlockProposal?: boolean;
+  /** Broadcast an invalid block proposal only at this indexWithinCheckpoint (for testing only) */
+  invalidBlockProposalIndexWithinCheckpoint?: number;
   /** Inject a fake attestation (for testing only) */
   injectFakeAttestation?: boolean;
   /** Inject a malleable attestation with a high-s value (for testing only) */
@@ -121,6 +123,7 @@ export const SequencerConfigSchema = zodFor<SequencerConfig>()(
     secondsBeforeInvalidatingBlockAsCommitteeMember: z.number(),
     secondsBeforeInvalidatingBlockAsNonCommitteeMember: z.number(),
     broadcastInvalidBlockProposal: z.boolean().optional(),
+    invalidBlockProposalIndexWithinCheckpoint: z.number().int().nonnegative().optional(),
     injectFakeAttestation: z.boolean().optional(),
     injectHighSValueAttestation: z.boolean().optional(),
     injectUnrecoverableSignatureAttestation: z.boolean().optional(),
@@ -149,6 +152,7 @@ type SequencerConfigOptionalKeys =
   | 'fakeThrowAfterProcessingTxCount'
   | 'l1PublishingTime'
   | 'txPublicSetupAllowListExtend'
+  | 'invalidBlockProposalIndexWithinCheckpoint'
   | 'minValidTxsPerBlock'
   | 'minBlocksForCheckpoint'
   | 'maxTxsPerBlock'

diff --git a/yarn-project/stdlib/src/interfaces/validator.ts b/yarn-project/stdlib/src/interfaces/validator.ts
@@ -66,6 +66,9 @@ export type ValidatorClientConfig = ValidatorHASignerConfig &
     /** Agree to attest to equivocated checkpoint proposals (for testing purposes only) */
     attestToEquivocatedProposals?: boolean;
 
+    /** Accept proposal validation regardless of slot timing (for testing only) */
+    skipProposalSlotValidation?: boolean;
+
     /** Maximum L2 gas per block for validation. Proposals exceeding this limit are rejected. */
     validateMaxL2BlockGas?: number;
 
@@ -107,6 +110,7 @@ export const ValidatorClientConfigSchema = zodFor<Omit<ValidatorClientConfig, 'v
     skipCheckpointProposalValidation: z.boolean().optional(),
     skipPushProposedBlocksToArchiver: z.boolean().optional(),
     attestToEquivocatedProposals: z.boolean().optional(),
+    skipProposalSlotValidation: z.boolean().optional(),
     validateMaxL2BlockGas: z.number().optional(),
     validateMaxDABlockGas: z.number().optional(),
     validateMaxTxsPerBlock: z.number().optional(),

diff --git a/yarn-project/validator-client/src/config.ts b/yarn-project/validator-client/src/config.ts
@@ -79,6 +79,10 @@ export const validatorClientConfigMappings: ConfigMappingsType<ValidatorClientCo
     description: 'Agree to attest to equivocated checkpoint proposals (for testing purposes only)',
     ...booleanConfigHelper(false),
   },
+  skipProposalSlotValidation: {
+    description: 'Accept proposal validation regardless of slot timing (for testing only)',
+    ...booleanConfigHelper(false),
+  },
   validateMaxL2BlockGas: {
     env: 'VALIDATOR_MAX_L2_BLOCK_GAS',
     description: 'Maximum L2 block gas for validation. Proposals exceeding this limit are rejected.',

diff --git a/yarn-project/validator-client/src/proposal_handler.ts b/yarn-project/validator-client/src/proposal_handler.ts
@@ -203,6 +203,14 @@ export class ProposalHandler {
           return undefined;
         }
 
+        if (this.config.skipCheckpointProposalValidation) {
+          this.log.warn(
+            `Skipping all-nodes checkpoint proposal validation for slot ${proposal.slotNumber}`,
+            proposalInfo,
+          );
+          return undefined;
+        }
+
         const result = await this.handleCheckpointProposal(proposal, proposalInfo);
         if (result.isValid && this.archiver && this.epochCache.isProposerPipeliningEnabled()) {
           const set = await this.setProposedCheckpointFromValidation(proposal);

diff --git a/yarn-project/validator-client/src/validator.ts b/yarn-project/validator-client/src/validator.ts
@@ -213,6 +213,7 @@ export class ValidatorClient extends (EventEmitter as new () => WatcherEmitter)
       txsPermitted: !config.disableTransactions,
       maxTxsPerBlock: config.validateMaxTxsPerBlock,
       maxBlocksPerCheckpoint: config.maxBlocksPerCheckpoint,
+      skipSlotValidation: config.skipProposalSlotValidation,
       signatureContext: {
         chainId: config.l1ChainId,
         rollupAddress: config.rollupAddress,
@@ -876,7 +877,8 @@ export class ValidatorClient extends (EventEmitter as new () => WatcherEmitter)
       proposerAddress,
       {
         ...options,
-        broadcastInvalidBlockProposal: this.config.broadcastInvalidBlockProposal,
+        broadcastInvalidBlockProposal:
+          options.broadcastInvalidBlockProposal || this.config.broadcastInvalidBlockProposal,
       },
     );
     this.lastProposedBlock = newProposal;