feat(evm): EIP-2612 permit signing helper (Node SDK + Rust CLI)

[teyrebaz33]

Summary

Adds a purpose-built signPermit helper that eliminates the boilerplate currently required to sign EIP-2612 permits via OWS. Closes #132

What's included

Node SDK — signPermit()

import { signPermit } from '@open-wallet-standard/core/evm/permit';

const sig = await signPermit(ownerAddress, 'eip155:8453', {
  token:    '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913', // USDC on Base
  spender:  '0xYourProtocol',
  value:    '1000000',
  deadline: Math.floor(Date.now() / 1000) + 3600,
}, owsSignTypedData);
// → { v, r, s, signature, typedData }

CLI — ows sign permit

ows sign permit   --wallet my-wallet   --chain  eip155:8453   --token  0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913   --spender 0xYourProtocol   --value  1000000   --deadline 1800000000   --json

Domain resolution

The hard part of EIP-2612 is getting the domain separator right. signPermit resolves it in three stages:

1. eip712Domain() (EIP-5267) — self-describing; works for USDC v2.2+, OZ ERC20Permit 5.x
2. Well-known override table — USDC ("2"), DAI ("1"), Base USDT
3. name() + default version "1" — generic fallback

Tokens that omit version from their domain are handled correctly — the EIP712Domain type array is built dynamically.

Tests

✔ returns correct v / r / s from mock signature
✔ builds correct EIP-712 typed data structure
✔ resolves domain via eip712Domain()
✔ falls back to name() + override when eip712Domain() reverts
✔ auto-fetches nonce when not supplied
✔ uses supplied nonce without RPC call
✔ omits version field in EIP712Domain when token has no version
✔ chainId matches CAIP-2 chain segment
✔ throws when token name is empty and no override exists
✔ throws when RPC is unreachable
✔ DAI fallback domain version is 1
✔ Ethereum USDC fallback domain version is 2

12 passed, 0 failed — fully offline, no network required

Files changed

File	Description
bindings/node/src/evm/permit.mjs	SDK function
bindings/node/__test__/permit.spec.mjs	12 offline tests
docs/examples/eip2612-permit.md	Usage guide
ows/crates/ows-lib/src/ops.rs	sign_permit() Rust implementation
ows/crates/ows-lib/src/types.rs	PermitParams, PermitSignResult types
ows/crates/ows-lib/Cargo.toml	Added ureq for sync HTTP
ows/crates/ows-cli/src/commands/sign_permit.rs	CLI command handler
ows/crates/ows-cli/src/commands/mod.rs	Module registration
ows/crates/ows-cli/src/main.rs	Permit subcommand + handler

Checklist

• Node SDK signPermit()
• CLI ows sign permit
• 12 offline tests, all passing
• Rust workspace builds without errors
• Documentation
• Follows existing code patterns (sign_message, sign_transaction)

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Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	cargo/​ureq@​2.12.1

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[0xultravioleta]

Thanks for this. The EIP-712 structure looks right, and reusing the existing typed-data signing path for the permit is the correct call. The concern is what it pulls in around the signing flow on the Rust side.

This adds a new HTTP client (ureq) into ows-lib, the FFI library crate that sits right next to key handling and today has no HTTP dependencies at all, and it calls hardcoded third-party RPC endpoints from the permit flow by default. That crate should not be opening network connections, and definitely not to endpoints baked into the source. Could you move the network calls out of ows-lib, to the CLI or binding layer, or make the RPC endpoint an explicit, required argument so nothing is contacted implicitly and nothing is hardcoded?

One more: the hand-rolled ABI decode silently returns 0 for a nonce at or above 2^64 (the parse overflows and falls back to 0), so an oversized nonce would produce a wrong value and an invalid signature with no error raised. Please use the existing ABI decoding rather than a hand-rolled one so large values are handled correctly.

Once the network surface is out of ows-lib and the decode is fixed, this is in good shape. Final sign-off is @njdawn's.