fetchNonce: prefer /v2/accounts over extended API for nonce accuracy

[whoabuddy]

Summary

When making rapid sequential transactions, we observed that /v2/accounts/{address} returns more up-to-date nonce values than /extended/v1/address/{address}/nonces. Preferring /v2/accounts in fetchNonce would improve reliability.

Observed Behavior

# Extended API - returned possible_next_nonce: 4636
curl "https://api.mainnet.hiro.so/extended/v1/address/SPWD5Y6Z7SKANZH6C7BK6A81CRKD6B4G2CG4SQ8W/nonces"

# v2/accounts - returned nonce: 4637 (correct)
curl "https://api.mainnet.hiro.so/v2/accounts/SPWD5Y6Z7SKANZH6C7BK6A81CRKD6B4G2CG4SQ8W"

# Nonce 4636 was already used in a confirmed transaction

Current Code

fetchNonce tries the extended API first:

export async function fetchNonce(opts) {
    try {
        return await _getNonceApi(opts);  // /extended/v1/.../nonces
    } catch (e) {}
    // Falls back to /v2/accounts
}

Suggestion

Swap the order to prefer /v2/accounts:

export async function fetchNonce(opts) {
    try {
        const url = `${client.baseUrl}/v2/accounts/${opts.address}?proof=0`;
        const response = await client.fetch(url);
        const json = await response.json();
        return BigInt(json.nonce);
    } catch (e) {}
    return _getNonceApi(opts);  // fallback
}

Environment

• @stacks/transactions: 7.x
• Observed on mainnet

[whoabuddy]

This issue stems from a problem we ran into sending multiple x402 payments through stx402, patching it on our side fixed the issue and wanted to at least share the suggestion back (plus test out generating issues from things we encounter in the wild!)

Related code:

stacks.js/packages/transactions/src/fetch.ts

Lines 93 to 124 in f7523b6

	/**
	* Lookup the nonce for an address from a core node
	* @param opts.address - The Stacks address to look up the next nonce for
	* @param opts.api - Optional API info (`.url` & `.fetch`) used for fetch call
	* @return A promise that resolves to an integer
	*/
	export async function fetchNonce(
	opts: {
	/** The Stacks address to look up the next nonce for */
	address: string;
	} & NetworkClientParam
	): Promise<bigint> {
	// Try API first
	try {
	return await _getNonceApi(opts);
	} catch (e) {}
	const network = networkFrom(opts.network ?? 'mainnet');
	const client = Object.assign({}, clientFromNetwork(network), opts.client);
	const url = `${client.baseUrl}${ACCOUNT_PATH}/${opts.address}?proof=0`;
	const response = await client.fetch(url);
	if (!response.ok) {
	const msg = await response.text().catch(() => '');
	throw new Error(
	`Error fetching nonce. Response ${response.status}: ${response.statusText}. Attempted to fetch ${url} and failed with the message: "${msg}"`
	);
	}
	const json = (await response.json()) as { nonce: string };
	return BigInt(json.nonce);
	}