Skip dataAvailabilityMode in program output

packages/backend/src/Application.ts

@@ -255,7 +255,8 @@ export class Application {
           : undefined
 
         const perpetualCairoOutputCollector = new PerpetualCairoOutputCollector(
-          ethereumClient
+          ethereumClient,
+          config.starkex
         )
         const rollupStateRepository = new MerkleTreeRepository(
           database,

packages/backend/src/core/PerpetualValidiumSyncService.ts

@@ -56,7 +56,8 @@ export class PerpetualValidiumSyncService implements IDataSyncService {
     for (const stateTransition of stateTransitions) {
       const [perpetualCairoOutput, batch] = await Promise.all([
         this.perpetualCairoOutputCollector.collect(
-          stateTransition.transactionHash
+          stateTransition.transactionHash,
+          stateTransition.blockNumber
         ),
         this.availabilityGatewayClient.getPerpetualBatchData(
           stateTransition.batchId

packages/backend/src/core/collectors/PerpetualCairoOutputCollector.ts

@@ -5,6 +5,7 @@ import {
 import { Hash256 } from '@explorer/types'
 import { BigNumber, utils } from 'ethers'
 
+import { StarkexConfig } from '../../config/starkex/StarkexConfig'
 import { EthereumClient } from '../../peripherals/ethereum/EthereumClient'
 import { toHexData } from '../../utils/toHexData'
 
@@ -13,16 +14,31 @@ const ABI = new utils.Interface([
 ])
 
 export class PerpetualCairoOutputCollector {
-  constructor(private readonly ethereumClient: EthereumClient) {}
+  constructor(
+    private readonly ethereumClient: EthereumClient,
+    private readonly starkexConfig: StarkexConfig
+  ) {}
 
-  async collect(transactionHash: Hash256): Promise<PerpetualCairoOutput> {
+  async collect(
+    transactionHash: Hash256,
+    blockNumber: number
+  ): Promise<PerpetualCairoOutput> {
     const tx = await this.ethereumClient.getTransaction(transactionHash)
     if (!tx) {
       throw new Error('Invalid transaction')
     }
     const decoded = ABI.decodeFunctionData('updateState', tx.data)
     const programOutputValues = decoded.programOutput as BigNumber[]
     const hexData = toHexData(programOutputValues)
-    return decodePerpetualCairoOutput(hexData)
+
+    // This is a fix for Apex Goerli testnet, which switches
+    // to a different program output (one more field) at block 8056029.
+    // See: https://github.com/starkware-libs/stark-perpetual/blob/eaa284683deec190407fece98b96546d10f6ad67/src/services/perpetual/cairo/output/program_output.cairo#L36
+    const skipDataAvailabilityModeField =
+      this.starkexConfig.instanceName === 'ApeX' &&
+      this.starkexConfig.blockchain.chainId === 5 && // it's goerli
+      blockNumber >= 8056029
+
+    return decodePerpetualCairoOutput(hexData, skipDataAvailabilityModeField)
   }
 }

packages/encoding/src/decoding/decodePerpetualCairoOutput.ts

@@ -8,9 +8,16 @@ import { readForcedActions } from './readForcedActions'
 import { readModifications } from './readModifications'
 import { readState } from './readState'
 
-export function decodePerpetualCairoOutput(data: string): PerpetualCairoOutput {
+export function decodePerpetualCairoOutput(
+  data: string,
+  skipDataAvailabilityModeField?: boolean
+): PerpetualCairoOutput {
   const reader = new ByteReader(data)
 
+  if (skipDataAvailabilityModeField) {
+    const _dataAvailabilityMode = reader.readBigInt(32)
+  }
+
   const configurationHash = Hash256(reader.readHex(32))
   const assetConfigHashes = readAssetConfigHashes(reader)
   const oldState = readState(reader)