Add support for Arc Testnet (chainId: 5042002)

[NetWalker108]

Summary

Add Arc Testnet (chainId: 5042002) to Porto's supported Chains so apps, connectors, viem/wagmi integrations, and docs can use the Arc test network. Arc uses USDC as the native gas token (18 decimals).

Network details

• Name: Arc Testnet
• Chain ID: 5042002
• Native currency: USDC (18 decimals)
• RPC endpoints:
  • https://rpc.testnet.arc.network
  • Alternatives:
    • https://rpc.blockdaemon.testnet.arc.network
    • https://rpc.drpc.testnet.arc.network
    • https://rpc.quicknode.testnet.arc.network
• WebSocket endpoints:
  • wss://rpc.testnet.arc.network
  • Alternatives:
    • wss://rpc.drpc.testnet.arc.network
    • wss://rpc.quicknode.testnet.arc.network
• Explorer: https://testnet.arcscan.app
• Faucet: https://faucet.circle.com
• Note: Arc uses USDC as the native gas token; gas fees are denominated in USDC (18 decimals).

Wallet setup (MetaMask)

1. Open MetaMask → Add network → Add a network manually.
2. Fill in:
   • Network name: Arc Testnet
   • New RPC URL: https://rpc.testnet.arc.network
   • Chain ID: 5042002
   • Currency symbol: USDC
   • Explorer URL: https://testnet.arcscan.app
3. Save and switch to Arc.

Tip: If the wallet supports custom gas tokens, ensure display/decimals for USDC (18 decimals) and clearly label fees as USDC.

Suggested code changes

Add a new Chain entry in the repo's Chains list (where other chains are declared). Example viem-compatible Chain object in TypeScript:

// Example: src/viem/chains/arc.ts
import type { Chain } from 'viem';

export const arcTestnet: Chain = {
  id: 5042002,
  name: 'Arc Testnet',
  network: 'arc-testnet',
  nativeCurrency: {
    name: 'USD Coin',
    symbol: 'USDC',
    decimals: 18,
  },
  rpcUrls: {
    default: {
      http: [
        'https://rpc.testnet.arc.network',
        'https://rpc.blockdaemon.testnet.arc.network',
        'https://rpc.drpc.testnet.arc.network',
        'https://rpc.quicknode.testnet.arc.network',
      ],
      webSocket: [
        'wss://rpc.testnet.arc.network',
        'wss://rpc.drpc.testnet.arc.network',
        'wss://rpc.quicknode.testnet.arc.network',
      ],
    },
    public: {
      http: [
        'https://rpc.testnet.arc.network',
      ],
      webSocket: [
        'wss://rpc.testnet.arc.network',
      ],
    },
  },
  blockExplorers: {
    default: { name: 'ArcScan Testnet', url: 'https://testnet.arcscan.app' },
  },
  testnet: true,
};

Where your repo centralizes chains (e.g. src/core/chains.ts, src/viem/chains.ts, or a chains registry), register arcTestnet and export it to be available to connectors, wagmi/viem helpers, and CLI/dev tooling.

If there is a central Chains enum/list, add an entry:

export const Chains = {
  // existing...
  arcTestnet,
};

Additional places to update:

• wagmi connector / Chains mapping (e.g., src/wagmi/connector.ts or similar) so clients can select Arc Testnet.
• Any helper that maps chainId -> chain metadata.
• Docs and examples (apps/docs) showing how to connect to Arc Testnet.
• UI labels: show gas token "USDC" and decimals 18 where native currency is displayed.

Tests

• Add a unit test confirming the chainId 5042002 exists in the chain registry and the nativeCurrency decimals === 18.
• Add a test that validates rpcUrls are non-empty and at least one http url exists.
• Optional: health check integration test (mock) that expects an RPC response shape or ensures webSocket url is present.

Example test ideas:

• src/viem/chains.test.ts
  • assertChainsContain(5042002)
  • assertChainNativeCurrency(5042002, { symbol: 'USDC', decimals: 18 })
  • assertChainHasRpc(5042002)

Docs

• Add a docs page or extend the existing chains/network docs: apps/docs or docs/:
  • Document Arc Testnet details, RPC endpoints, MetaMask setup, and gas/fee caveat (USDC gas).
  • Add the Arc Testnet entry to any UI network switcher docs or network reference pages.

Checklist

• Add TypeScript Chain object (arcTestnet) and export it in chains registry
• Register Arc Testnet in the Chains mapping used by connectors and helpers
• Update wagmi/viem adapter to include Arc Testnet
• Update UI/network switcher and any components that list available networks
• Add unit tests for chain presence and metadata
• Update docs with network details and wallet setup steps
• Add e2e or integration test(s) if applicable (mocked RPC)
• Review and validate RPC endpoints (alternatives included)
• Add note in docs that Arc uses USDC as native gas token (18 decimals)

Acceptance criteria

• The codebase contains a Chain entry for Arc Testnet (id 5042002) matching the network details above.
• Connectors and viem/wagmi helpers can select and use Arc Testnet with the provided RPC or WebSocket URLs.
• Tests cover the presence and basic validation of Arc Testnet chain metadata.
• Documentation includes MetaMask setup, network details, and a clear note that gas is paid in USDC (18 decimals).
• UI/network switcher lists Arc Testnet where other testnets are shown.

Notes / Considerations

• Arc uses a stablecoin (USDC) as the gas token — make sure any logic that assumes an ETH-like gas token name (e.g., 'ETH') is updated to support USDC as nativeCurrency.
• Gas estimation and fee display UI may need adjustments to correctly show decimal/format for USDC (18 decimals) and to label fees appropriately.
• If the codebase makes chain-specific assumptions about gas token behavior (e.g., burning, base fee denominated in native token), confirm compatibility with Arc’s gas model.

[NetWalker108]

Cc @jenpaff @jxom