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.

Networks

Both networks have a block explorer with an API and contract verification (mainnet API: https://block-explorer-api.mainnet.battlechain.com/api, testnet API: https://block-explorer-api.testnet.battlechain.com/api). The mock dependency contracts (tokens, Chainlink, Uniswap, etc.) are testnet-only. battlechain-lib tooling defaults to testnet; set NETWORK=mainnet to target mainnet.

Mainnet core contracts (chain 626)

Mainnet CreateX was deployed by Cyfrin and is NOT at the well-known 0xba5Ed... address. battlechain-lib resolves the correct address per chain — do not hardcode 0xba5Ed... on BattleChain.

Mainnet Safe contracts (chain 626)

Real Safe contracts, deployed by Cyfrin (not the Safe team):

For testnet contract addresses, fetch the full docs (below).

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

Key helpers

Cross-chain behavior

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

Attack mode approval

requestAttackMode moves the agreement to ATTACKREQUESTED; the registry moderator must approve it to reach UNDERATTACK.

• Testnet (627): the moderator is the permissionless MockRegistryModerator at 0x3DdA228A38b4d7438bBF5D5137c8D1090DcaF6bF — anyone can approve their own attack request instantly:

``bash cast send 0x3DdA228A38b4d7438bBF5D5137c8D1090DcaF6bF \ "approveAttack(address)" <AGREEMENT_ADDRESS> \ --rpc-url https://testnet.battlechain.com --account <your-account> ``

• Mainnet (626): approval is a controlled DAO action by the Registry Moderator (0x445d5685c4Ae71550Da0716b82B434AEA140E0c7).

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. Verification works on both networks — testnet (chain 627) and mainnet (chain 626). The examples below target testnet; for mainnet, swap in chain ID 626, verifier URL https://block-explorer-api.mainnet.battlechain.com/api, and RPC https://mainnet.battlechain.com. 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:

The targets are network-aware: they default to testnet, and NETWORK=mainnet switches the RPC and explorer API to mainnet.

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

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 \
    --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

Hardhat

Coming soon...