JVz

works fine, dont forget to change logger to console output or logger of your choice and community to your node-steamcommunity instance
 
let tradeOfferAcknowledged = false; const acknowledgeTradeOffer = function(sessionId=null, callback) { try { if (tradeOfferAcknowledged) { const error = new Error('Trade offer has already been acknowledged'); logger.warn('Attempt to acknowledge trade offer that was already acknowledged'); if (callback) callback(error); return; } if (!community) { const error = new Error('Community not initialized'); logger.error('Cannot acknowledge trade offer - community not initialized'); if (callback) callback(error); return; } if (!sessionId) { sessionId = community.getSessionID(); } const options = { uri: 'https://steamcommunity.com/trade/new/acknowledge', method: 'POST', form: { sessionid: sessionId, message: 1 } }; logger.info('Acknowledging trade offer'); community.httpRequest(options, (err, response, body) => { if (err) { logger.error(`Error acknowledging trade offer: ${err}`); if (callback) callback(err); return; } // Check if response indicates success (currently Steam returns [] on success) if (response && response.statusCode === 200) { tradeOfferAcknowledged = true; logger.info(`Trade offer acknowledged successfully. Response: ${body}`); if (callback) callback(null, body); } else { const error = new Error(`Unexpected response from Steam: ${response ? response.statusCode : 'unknown'}`); logger.error(`Failed to acknowledge trade offer: ${error.message}. Response body: ${body}`); if (callback) callback(error); } }, 'acknowledgeTradeOffer'); } catch (error) { logger.error(`Error acknowledging trade offer: ${error}`); if (callback) callback(error); } };

Yes, error 16 is a well-known cause for headache.

That's correct.
That's incorrect. They will still be auto-canceled per your options.