Seller-assigned account identifier. For upstream-managed account namespaces, this value comes from list_accounts; for seller-defined namespaces without a list_accounts surface, it is supplied out-of-band. Buyer-declared account sellers MAY echo account_id from sync_accounts as an internal handle, but they MUST continue accepting the account's current natural-key AccountRef on subsequent calls. A former key tombstoned by identity reconciliation returns ACCOUNT_MOVED to authorized callers.
Seller-assigned account identifier. For upstream-managed account namespaces, this value comes from list_accounts; for seller-defined namespaces without a list_accounts surface, it is supplied out-of-band. Buyer-declared account sellers MAY echo account_id from sync_accounts as an internal handle, but they MUST continue accepting the account's current natural-key AccountRef on subsequent calls. A former key tombstoned by identity reconciliation returns ACCOUNT_MOVED to authorized callers.