feat: opt-in X-Gate-Size-Decimal for futures and delivery (v1.7.0)

[JJ-Cro]

Summary

Gate requires X-Gate-Size-Decimal: 1 on REST and WebSocket futures traffic so size-related fields are returned as decimal strings instead of integers (rounded down). This PR adds an opt-in client flag and widens the affected TypeScript types.

Version: 1.7.0 (minor bump from 1.6.4). The draft update07102026 branch also targets a minor bump; align versions before release if both land.

Changelog

• Add futuresSizeDecimal?: boolean to RestClientOptions and WSClientConfigurableOptions (default false).
• When enabled, send X-Gate-Size-Decimal: 1 on:
  • REST requests whose path starts with /futures/ or /delivery/ (all futures/delivery REST methods in this SDK use those prefixes, including autoorder under /futures/.../autoorder/...).
  • WebSocket HTTP upgrade for perpFuturesUSDTV4, perpFuturesBTCV4, deliveryFuturesUSDTV4, and deliveryFuturesBTCV4.
  • Futures WebSocket API req_header on those connections (login, order place/amend, etc.).
• Introduce FuturesContractSize (number | string) and apply it to futures/delivery size-related request and response fields (and futures WS API order types), with JSDoc noting string values when futuresSizeDecimal is on.
• Unit tests in test/lib/futuresSizeDecimal.test.ts for header scoping and REST behavior.

Type fields updated

FuturesContractSize on:

Futures response: FuturesOrderBook (asks/bids.s), FuturesTrade.size, FuturesCandle.v, FuturesStats (long_liq_size, short_liq_size, open_interest, top_lsr_size, top_long_size, top_short_size, long_taker_size, short_taker_size), LiquidationHistoryRecord (size, order_size, left), FuturesOrder (size, iceberg, left), FuturesPosition.size, FuturesTradingHistoryRecord (size, close_size), FuturesLiquidationHistoryRecord (size, left), FuturesAutoDeleveragingHistoryRecord (trade_size, position_size), FuturesContract / FuturesDeliveryContract (order_size_min, order_size_max, trade_size, position_size), FuturesPriceTriggeredOrder.initial.size, BatchAmendOrderResp (size, iceberg, left).

Futures request: SubmitFuturesOrderReq (size, iceberg), UpdateFuturesOrderReq.size, SubmitFuturesTriggeredOrderReq.initial.size, BatchAmendOrderReq.size, UpdateFuturesPriceTriggeredOrderReq.size.

Delivery response: DeliveryOrderBook (asks/bids.s), DeliveryTrade.size, DeliveryCandle.v, DeliveryTradingHistoryRecord.size, DeliveryLiquidationHistoryRecord (size, left), DeliverySettlementHistoryRecord.size.

Delivery request: SubmitDeliveryFuturesOrderReq (size, iceberg).

Futures WS API: WSAPIFuturesOrderPlaceReq (size, iceberg), WSAPIFuturesOrderAmendReq.size, WSAPIFuturesOrder (size, left, iceberg).

Testing

• npm run lint — pass
• npm run build — pass
• npm test — test/lib/futuresSizeDecimal.test.ts, test/REST/public.test.ts, test/websockets/wsStore.test.ts pass; test/REST/private.test.ts fails without API credentials (7 tests, expected in CI without secrets)

References

• Gate announcement (USDT perpetual size field upgrade)
• Telegram: https://t.me/gateioapi/117108