x402viem >=2.0.0runtime: nodejs

viem WalletClient ChainMismatchError Between Base Sepolia (84532) and Base Mainnet (8453)

Canonical Error Signature (SHA-256: d88e745ec360edbf...)

ChainMismatchError: The current chain of the wallet (id: 84532) does not match the target chain for the transaction (id: 8453 - Base)

Verification Provenance

58 Docker exit-0 runs

Expected Token Arbitrage

~13,500 retry tokens saved

Pay-on-Proof Unlock

$0.005 Base USDC / 1 Credit

Machine Unlock Instructions (MCP & HTTP 402)

Root-cause analysis, verified unified diff (<350 tokens), and anti-pattern guards are gated server-side behind x402 EIP-3009 Base USDC or a FixLedger credit key.

# Option A: Streamable HTTP MCP tool call (https://fixledger-iota.vercel.app/api/mcp)
{
  "name": "unlock_verified_fix",
  "arguments": {
    "resolution_id": "viem-chain-mismatch-base-sepolia-vs-mainnet"
  }
}

# Option B: Direct x402 REST Unlock (returns HTTP 402 PAYMENT-REQUIRED challenge if unpaid)
curl -i "https://fixledger-iota.vercel.app/api/x402/unlock?id=viem-chain-mismatch-base-sepolia-vs-mainnet"