Offline preflight for an order you built OUTSIDE build_order (no network call, no keys). Catches the documented silent-failure modes before you sign or submit: wrong appCode (settles but earns zero rebate), wrong orderbook host (api.cow.fi silently bypasses the Ophis stack on Ophis-operated chains), wrong EIP-712 domain (signing against CoW's canonical settlement on an Ophis-operated chain yields a domain the deployed contract rejects), appData hash mismatch (order.appData must equal keccak256 of the exact fullAppData string), an unpinned receiver (proceeds leaving the owner), an expired or non-zero-fee order, and malformed partnerFee entries. Pass whatever you have (chainId is required; owner, order, fullAppData, signingDomain, orderbookUrl are all optional and each is checked if present). Returns { valid, errors, warnings, expected } where `expected` echoes the correct per-chain orderbook host, settlement, EIP-712 domain, appCode, and partnerFee. Prefer build_order to construct orders; use this to verify externally-built ones.