[SC-3] Deployment Scripts, Base Sepolia Deploy & Rust ↔ Solidity Integration

[iamyxsh]

[SC-3] Deployment Scripts, Base Sepolia Deploy & Rust Backend EIP712 Integration

Labels: smart-contract, integration, priority:high, week-4
Assignee: Yash

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Context

Per the Source of Truth (Sections 10, 11, and Week 3-4 milestone), the FishnetWallet needs deployment scripts for Base Sepolia and an end-to-end integration test proving that permits signed by the Rust backend are accepted by the on-chain contract. The Rust backend already has EIP712 signing logic (crates/server/src/signer.rs) — this issue ensures the two sides match exactly.

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1. Foundry Deployment Script

File: contracts/script/Deploy.s.sol

• Deploy script using Foundry forge script:

  contract DeployFishnetWallet is Script {
      function run() external {
          vm.startBroadcast();
          FishnetWallet wallet = new FishnetWallet(owner, initialSigner);
          vm.stopBroadcast();
          console.log("FishnetWallet deployed at:", address(wallet));
      }
  }

• Accept constructor args via environment variables: OWNER_ADDRESS, SIGNER_ADDRESS
• Output deployed contract address to console and to a JSON file (deployments/base-sepolia.json)
• Verification script — auto-verify on Basescan after deploy:

  forge verify-contract <address> FishnetWallet --chain base-sepolia
  

2. Deploy to Base Sepolia

• Deploy FishnetWallet to Base Sepolia testnet (Chain ID: 84532)
• Fund wallet with testnet ETH for testing
• Verify contract source on BaseScan Sepolia explorer
• Record deployed address in contracts/deployments/base-sepolia.json:

  {
    "network": "base-sepolia",
    "chainId": 84532,
    "fishnetWallet": "0x...",
    "owner": "0x...",
    "signer": "0x...",
    "deployedAt": "2026-..."
  }

• Document deployment steps in contracts/README.md

3. EIP712 Compatibility Verification (Rust ↔ Solidity)

The Rust backend (crates/server/src/signer.rs) already generates EIP712 permit signatures. Ensure the two sides are perfectly aligned:

• PERMIT_TYPEHASH must match exactly:
  • Rust: verify the typehash string in signer.rs matches the Solidity constant
  • Both must produce the same keccak256 hash
• EIP712 Domain must match exactly:
  • name = "Fishnet" (both sides)
  • version = "1" (both sides)
  • chainId — Rust uses the chain from permit request, Solidity uses block.chainid
  • verifyingContract — Rust must use the deployed wallet address, Solidity uses address(this)
• Struct encoding must match:
  • Field order in abi.encode() must match between Rust and Solidity
  • Type sizes must match (uint64 for chainId, uint48 for expiry, etc.)
• Signature format:
  • Rust produces (v, r, s) or 65-byte packed signature
  • Solidity ecrecover expects the correct unpacking

4. End-to-End Integration Test

The Week 4 milestone test: "gateway signs permit, wallet executes swap"

• Test flow:
  1. Rust backend generates a secp256k1 signing key (or uses existing signer)
  2. Deploy FishnetWallet on Base Sepolia with that key's address as fishnetSigner
  3. Construct an onchain intent (e.g., call a test contract's function)
  4. Rust signs the intent as an EIP712 FishnetPermit
  5. Submit the signed permit + calldata to the FishnetWallet contract
  6. Contract verifies signature and executes the call
  7. Verify the target contract's state changed
• Automated script: scripts/integration-test.sh or Rust integration test that:
  • Spins up a local Anvil fork of Base Sepolia
  • Deploys contract
  • Uses Rust signer to produce permit
  • Submits transaction
  • Asserts success
• Document the integration test in contracts/README.md

5. Nonce Management Sync

• Rust nonce counter (nonce_counter table in SQLite) must stay in sync with contract state
• On Rust side: increment nonce after each signed permit
• On contract side: usedNonces[nonce] = true after each execution
• Recovery mechanism: if a permit is signed but never submitted (agent fails), the nonce is "wasted" — this is acceptable, nonces don't need to be sequential
• Startup sync: on Fishnet start, optionally query contract for last known nonce to detect gaps

6. Multi-Chain Preparation

Per Source of Truth: chain_ids = [8453, 42161] (Base + Arbitrum)

• Deployment config supports multiple chains
• deployments/ directory structure:

  contracts/deployments/
  ├── base-sepolia.json     (testnet)
  ├── base-mainnet.json     (future)
  └── arbitrum-sepolia.json (future)
  

• Rust config reads deployed address per chain from config or deployment files
• EIP712 domain separator is chain-specific (different chainId and verifyingContract)

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Acceptance Criteria

• FishnetWallet deployed and verified on Base Sepolia
• Rust-signed EIP712 permits are accepted by the on-chain contract (proven by integration test)
• Typehash, domain separator, and struct encoding match exactly between Rust and Solidity
• Nonce management prevents replays and handles gaps gracefully
• Deployment is documented and reproducible
• Integration test is automated and can run in CI