Arc fundamentals

Arc is an EVM-compatible Layer 1 built for programmable money. ArcSet currently targets Arc Testnet and treats Arc’s USDC-native model as an accounting invariant, not a cosmetic chain setting.

Network profile

ArcSet imports arcTestnet from viem/chains and configures it as the only Wagmi and Privy chain. Server balance reads try the server override, public primary endpoint, and checked-in provider fallbacks in order.

One USDC balance, two interfaces

Arc exposes the same underlying USDC balance through two representations:

They are not two assets. ArcSet never adds them, shows them as separate holdings, or offers a conversion between them. The raw values differ by 10^12, so comparing them without converting produces incorrect accounting.

// Application balance and approval display
formatUnits(usdcBalanceOf, 6)

// Raw gas or msg.value accounting only
formatUnits(nativeBalance, 18)

The ERC-20 view truncates values smaller than one micro-USDC. A zero ERC-20 balanceOf result therefore does not prove the native balance is mathematically zero.

EVM differences

Arc targets the Osaka EVM baseline, but several behaviors differ from Ethereum.

Gas and fee market

• fees are paid in native USDC with 18-decimal precision;
• the testnet minimum base fee is 20 Gwei;
• transactions below the fee floor can be dropped without a receipt;
• the next base fee is published in the parent header extra_data;
• base and priority fees are credited to the block beneficiary rather than burned;
• the application shows fee values as USDC, never ETH.

Value transfers

• non-zero transfers to address(0) revert;
• transfers to or from blocklisted accounts revert and consume gas;
• sending value to a previously self-destructed account can revert;
• a contract forwarding native USDC is not guaranteed to succeed;
• a transfer that completely drains a brand-new, zero-nonce account is a documented testnet limitation.

Opcodes and block data

• PREVRANDAO returns zero and must not be used for randomness;
• blob transactions are not supported;
• withdrawals are always empty;
• the EIP-4788 beacon-roots contract is omitted;
• sub-second blocks can share timestamps, so use block numbers for ordering;
• SELFDESTRUCT follows EIP-6780 plus Arc’s native-value restrictions.

USDC events and indexing

Native USDC movements emit standard Transfer logs from Arc’s system emitter using 18 decimals. An ERC-20 transfer() can also emit the familiar event from the 6-decimal USDC interface.

An indexer must choose one canonical source. Counting both event streams double-counts ERC-20 transfers. ArcSet’s product model specifies the system emitter for a future complete transaction indexer, while the current application reads supported balances directly and stores only wallet-local execution attribution.

Contract addresses

The tables below are rendered from the application’s centralized configuration and current Circle reference deployment.

Funding and wallet setup

For the current testnet application:

1. sign in through Privy;
2. let Privy create the embedded EVM wallet;
3. switch to Arc Testnet if required;
4. copy the embedded address from the account menu;
5. request Arc Testnet USDC from the Circle faucet or send testnet USDC directly;
6. refresh the balance before requesting a quote.

There is no separate ETH funding step. USDC funds both application actions and network fees.

Canonical Arc references

• Arc RPC endpoints
• Connect to Arc
• Stablecoin native model
• EVM differences
• Gas and fees
• Contract addresses