test

    // Loss detection + PTO probes: retransmit lost/stale packets so the

    // peer can make progress even when the caller is not sending new data.

    // Unlike the checkLossAndRetransmit() calls after processing an ACK

    // frame or a pumpIncoming() batch (which run because something new

    // just happened, so they always run immediately), this call site is

    // purely opportunistic polling — a caller looping on pumpNetwork() can

    // invoke it enormously more often than the RTT/PTO-scale checks inside

    // are useful (measured ~1 call per 3us under load, vs. PTO thresholds

    // of tens of ms at minimum: see the +0.025s term and 0.5s initial _rto

    // above). Throttle only *this* call site so a busy poll loop doesn't

    // pay for a full _sent_packets scan on every iteration; the ACK- and

    // batch-triggered call sites are untouched and still fire promptly.

    {

        std::lock_guard<std::recursive_mutex> lock(quic_mtx());

        auto now = std::chrono::steady_clock::now();

        if (now - _last_pump_loss_scan >= _pump_loss_scan_interval) {

            _last_pump_loss_scan = now;

            checkLossAndRetransmit();

        }

    }

}

// ============================================================================

// Stream Data Receive (for specific stream)

		static constexpr double   TIME_THRESHOLD   = 9.0/8; // RFC 9002 kTimeThreshold

		int _pto_count = 0;           // PTO back-off counter (RFC 9002 §6.2)

		// Throttle for pumpNetwork()'s opportunistic checkLossAndRetransmit()

		// call only (see pumpNetwork) — NOT used by the ACK-frame or

		// pumpIncoming() call sites, which must stay untouched since they

		// run precisely because something new arrived. Per-instance so

		// servicing multiple connections on one thread can't make one

		// connection's polling suppress another's.

		std::chrono::steady_clock::time_point _last_pump_loss_scan{};

		static constexpr std::chrono::microseconds _pump_loss_scan_interval{50};

		// Flow control batching: avoid sending duplicate MAX_DATA/MAX_STREAM_DATA

		bool _pending_max_data = false;

		uint64_t _pending_max_data_value = 0;