Add Arc support

[j0ntz]

CHANGELOG

Does this branch warrant an entry to the CHANGELOG?

• Yes
• No

Dependencies

none

Description

Adds Arc (arc), Circle's EVM chain 5042 with USDC as its gas token. History comes from the existing Alchemy key.

Asana: https://app.asana.com/0/1215088146871429/1218563157181138

Arc's native balance is USDC at 18 decimals, and 0x3600000000000000000000000000000000000000 is an ERC-20 view of that same balance at 6 decimals. A transfer through that contract moves native USDC, but Alchemy reports it only as an erc20 row on 0x3600, never as external or internal. Bridges deliver this way. The LI.FI funding receive in testing (0x223aa302…) exists on Alchemy only as a 0x3600 row; without the handling below, the wallet showed the balance with an empty history.

• nativeErc20Interface: a new network option naming that contract and its precision. A native Alchemy sync also reads the contract's transfers in both directions, scales them to 18 decimals, and sums them with the transaction's other native rows. scaleInterfaceTransfers is unit-tested with a real Arc transaction's values.
• No 0x3600 token: listed as a token, it would show the same money twice.
• History source: Alchemy only. Etherscan V2 serves chain 5042, but its lists miss interface transfers, and a fallback there would store incomplete history.
• Built-in tokens: EURC and cirBTC, each checked against the contract's name, symbol and decimals. USYC is left out (permissioned yield token).
• Fees: the base fee holds near 20 gwei, about $0.0004 per transfer; priority fee floor 1 gwei.

Tested on the iOS sim with this branch's bundle (screenshots below): wallet creation, a LI.FI swap into Arc, a LI.FI swap out of Arc (approval plus swap), and a plain send. Each was checked against Alchemy and the chain.

Companion PRs: jon/arc-chain in edge-react-gui, edge-exchange-plugins and edge-rates-server.

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Note

Medium Risk
Shared EVM history adapters gain new merge paths that affect reported native amounts and fees; mistakes would show wrong history, though behavior is gated on the new optional network flag and covered by tests.

Overview
Adds Arc (arc, EVM chain 5042) as a USDC-native wallet plugin (Alchemy/RPC/Etherscan V2 adapters, built-in EURC and cirBTC, explorers and fees tuned for Arc). The native USDC interface at 0x3600…0000 is intentionally not a separate token so balances are not double-counted.

Introduces optional nativeErc20Interface on EVM network info for chains where native value moves only through an ERC-20 view at different decimals. Alchemy and EvmScan native history sync now also pull those contract transfers, scale amounts to native units, and merge them with regular/internal rows (EvmScan zeroes interface row gas so fees are not duplicated). EvmScan URL selection for token vs regular lists now keys off contractAddress rather than tokenId.

Unit tests cover scaling/merging for both adapters using real Arc-style transaction data.

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Test evidence

4856604 Add Arc support	arc in create wallet	arc balance after funding	arc history send swap approval receive
	arc wallet usdc symbol	arc send confirm	arc send result
	arc history after keyless resync

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[j0ntz]

Description update for 4856604: the "History source" bullet above is superseded. Arc's history comes from Alchemy with Etherscan V2 as the fallback, and Etherscan is the only source in a build without an Alchemy key. Both adapters fold in transfers through the 0x3600 interface: the evmscan native sync reads the interface's tokentx rows, restates them in native units, and zeroes their gas price so the merge with the signer's txlist row counts the fee once (asNativeInterfaceTransaction, tested with the real rows of Arc tx 0xf4a07658…).