BattleChain Development Standards

Instructions for working with BattleChain, from the Cyfrin security team.

What is BattleChain

BattleChain is a ZKSync-based L2 blockchain that inserts a battle-testing phase between testnet and mainnet: Dev -> Testnet -> BattleChain -> Mainnet. Protocols deploy audited contracts with real funds, whitehats legally attack them for bounties under Safe Harbor agreements, and surviving contracts promote to production.

Full Documentation

For up-to-date contract addresses, function signatures, struct definitions, enums, state transitions, bounty calculation rules, Safe Harbor agreement details, and all other technical reference material, fetch the full docs:

https://docs.battlechain.com/llms-full.txt

Always fetch this URL when you need BattleChain technical details. The docs are the single source of truth and stay current as the protocol evolves.

Deployment

Projects deploying to BattleChain (or any EVM chain) should use cyfrin/battlechain-lib:

forge install cyfrin/battlechain-lib

Add the remapping to foundry.toml:

remappings = ["battlechain-lib/=lib/battlechain-lib/src/"]

Inheritance hierarchy

Contract	Use when you need
BCScript	Full lifecycle: deploy + agreement + attack mode
BCDeploy	Deploy only (via CreateX on any chain, BattleChainDeployer on BC)
BCSafeHarbor	Agreement creation only

Key helpers

Helper	What it does
bcDeployCreate(bytecode)	Deploy via BattleChainDeployer on BattleChain, CreateX on 190+ other chains
bcDeployCreate2(salt, bytecode)	Deterministic deploy — same address across chains
bcDeployCreate3(salt, bytecode)	Address depends only on salt, not bytecode
defaultAgreementDetails(name, contacts, contracts, recovery)	Builds agreement with correct scope and URI per chain
createAndAdoptAgreement(details, owner, salt)	Create + 14-day commitment + adopt in one call
requestAttackMode(agreement)	Enter attack mode (BattleChain only — reverts on other chains)
_isBattleChain()	Runtime check: true on chain IDs 626, 627, 624
getDeployedContracts()	All addresses deployed this session via bcDeploy*

Cross-chain behavior

	BattleChain (626/627/624)	Other EVM chains (190+)
bcDeployCreate*	BattleChainDeployer (CreateX + AttackRegistry)	CreateX (0xba5Ed...) directly
defaultAgreementDetails	BattleChain scope + BATTLECHAIN_SAFE_HARBOR_URI	Current chain CAIP-2 scope + SAFE_HARBOR_V3_URI
requestAttackMode	Works	Reverts with BCSafeHarbor__NotBattleChain
createAndAdoptAgreement	Works	Works (requires registry/factory on that chain)

Only requestAttackMode is BattleChain-specific. Everything else works on any supported chain.

Foundry

When working with foundry scripts, as of today, you need to pass a flag to skip simulations, for example:

forge script scripts/Deploy.s.sol --skip-simulation

Otherwise, you'll run into errors about gas estimation. You can also combine this with -g:

forge script scripts/Deploy.s.sol --skip-simulation -g 300

If the issues persist. If using a justfile or makefile please add these flags to the targets in those files.

Verification

BattleChain uses a custom block explorer API for contract verification. The battlechain-lib ships a reusable justfile module with verification targets.

Install verification targets

Add to your justfile:

import "lib/battlechain-lib/battlechain.just"

This gives you:

Target	Usage
bc-verify <addr> <path:name>	Verify a single contract
bc-verify-broadcast <script>	Verify all contracts from a broadcast file (handles CreateX/BCDeploy factory creates)
bc-deploy <script> <account> <sender>	Deploy with standard BC flags
bc-deploy-verify <script> <account> <sender>	Deploy + verify in one step

Verify manually

forge verify-contract <ADDRESS> src/MyVault.sol:MyVault \
    --chain-id 627 \
    --verifier-url https://block-explorer-api.testnet.battlechain.com/api \
    --verifier custom \
    --etherscan-api-key "1234" \
    --rpc-url https://testnet.battlechain.com:3051

The API key is not validated — any non-empty string works.

Verify during deployment

Add --verify to your forge script call:

forge script script/Deploy.s.sol \
    --rpc-url https://testnet.battlechain.com:3051 \
    --broadcast --skip-simulation -g 300 \
    --verify \
    --verifier-url https://block-explorer-api.testnet.battlechain.com/api \
    --verifier custom \
    --etherscan-api-key 1234

This verifies contracts as they're deployed. For factory-deployed contracts (via CreateX/BCDeploy), use bc-verify-broadcast after deployment instead.

Troubleshooting

AnyTxType(2) transaction can't be built due to missing keys: ["gas_limit"]

This error means a contract exceeds the EVM contract size limit (24,576 bytes). Forge can't estimate gas for an oversized contract, so the deploy transaction fails to build.

Diagnose: Check contract sizes after compiling:

forge build --sizes

Any contract over 24,576 bytes will fail to deploy.

Fix options:

1. Split the contract into smaller pieces (libraries, separate contracts)
2. Enable the optimizer with more runs: optimizer = true and optimizer_runs = 200 in foundry.toml
3. Use --via-ir for deeper optimization (slower compile, smaller output)
4. Extract constants and large string literals into separate libraries

BattleChain does not support EIP-1559

Every forge script and cast send call must include --legacy. Without it, transactions are rejected.

Hardhat

Coming soon...