perf: throttle CONFIG_SND during mass peer login bursts

Widen monitor CONFIG push debounce from 0.3s to 2s when five or more
peers connect within ten seconds, coalescing updates during fast ramps.

src/adn_server/infrastructure/config_push_throttle.py

@@ -0,0 +1,38 @@
+"""Adaptive debounce for CONFIG_SND pushes during mass peer login."""
+
+from __future__ import annotations
+
+import time
+from collections import deque
+
+# Normal peer connect/disconnect: near-realtime monitor update.
+CONFIG_PUSH_DEBOUNCE_NORMAL_SEC = 0.3
+# Many peers logging in at once: coalesce harder (monitor need not be instant).
+CONFIG_PUSH_DEBOUNCE_BURST_SEC = 2.0
+CONFIG_PUSH_BURST_WINDOW_SEC = 10.0
+CONFIG_PUSH_BURST_MIN_CONNECTS = 5
+
+
+class ConfigPushThrottle:
+    """Widen CONFIG_SND debounce when peer connect rate is high."""
+
+    def __init__(self) -> None:
+        self._connect_times: deque[float] = deque()
+
+    def note_peer_connected(self, *, now: float | None = None) -> None:
+        """Record a peer reaching CONNECTION=YES (MASTER login)."""
+        t = time.time() if now is None else now
+        self._connect_times.append(t)
+        self._prune(t)
+
+    def debounce_seconds(self, *, now: float | None = None) -> float:
+        t = time.time() if now is None else now
+        self._prune(t)
+        if len(self._connect_times) >= CONFIG_PUSH_BURST_MIN_CONNECTS:
+            return CONFIG_PUSH_DEBOUNCE_BURST_SEC
+        return CONFIG_PUSH_DEBOUNCE_NORMAL_SEC
+
+    def _prune(self, now: float) -> None:
+        cutoff = now - CONFIG_PUSH_BURST_WINDOW_SEC
+        while self._connect_times and self._connect_times[0] < cutoff:
+            self._connect_times.popleft()

src/adn_server/infrastructure/twisted_adapters/udp_hbp.py

@@ -70,6 +70,7 @@ from ...domain.talker_alias import (
 from ...domain.mesh_routing import MeshEgress, MeshIngress, PeerMeshConfig
 from ..mesh.dmre_v5 import parse_dmre_trailer
 from ..mesh.registry import MeshCodecRegistry
+from ..config_push_throttle import ConfigPushThrottle
 from ..mesh.obp_v1 import (
     build_bcka,
     build_bcve,
@@ -228,6 +229,7 @@ class HBPProtocol(DatagramProtocol):
             self._downlink_index = None
             self._connected_peer_count = 0
             self._config_push_delayed = None
+            self._config_push_throttle = ConfigPushThrottle()
             self._refresh_connected_peer_count()
         else:
             self._peers = {}
@@ -736,7 +738,8 @@ class HBPProtocol(DatagramProtocol):
         """Schedule debounced CONFIG_SND when MASTER peer list or OPTIONS change."""
         if self._config_push_delayed is not None:
             return
-        self._config_push_delayed = reactor.callLater(0.3, self._flush_config_to_monitor)
+        delay = self._config_push_throttle.debounce_seconds()
+        self._config_push_delayed = reactor.callLater(delay, self._flush_config_to_monitor)
 
     def _flush_config_to_monitor(self) -> None:
         self._config_push_delayed = None
@@ -1171,6 +1174,7 @@ class HBPProtocol(DatagramProtocol):
                         logger.info("(%s) Peer %s (%s) has sent repeater configuration, Package ID: %s, Software ID: %s, Desc: %s", self._system, _this_peer["CALLSIGN"], _this_peer["RADIO_ID"], self._peers[_peer_id]["PACKAGE_ID"].decode("utf8", errors="replace").rstrip(), self._peers[_peer_id]["SOFTWARE_ID"].decode("utf8", errors="replace").rstrip(), self._peers[_peer_id]["DESCRIPTION"].decode("utf8", errors="replace").rstrip())
                         self._refresh_connected_peer_count()
                         self._mark_downlink_index_dirty()
+                        self._config_push_throttle.note_peer_connected()
                         self._push_config_to_monitor()
                 else:
                     self.transport.write(b"".join([MSTNAK, _peer_id]), _sockaddr)

tests/infrastructure/test_config_push_throttle.py

@@ -0,0 +1,34 @@
+"""CONFIG_SND adaptive debounce during peer login bursts."""
+
+from __future__ import annotations
+
+from adn_server.infrastructure.config_push_throttle import (
+    CONFIG_PUSH_BURST_MIN_CONNECTS,
+    CONFIG_PUSH_DEBOUNCE_BURST_SEC,
+    CONFIG_PUSH_DEBOUNCE_NORMAL_SEC,
+    ConfigPushThrottle,
+)
+
+
+def test_normal_debounce_with_few_connects() -> None:
+    throttle = ConfigPushThrottle()
+    base = 1_700_000_000.0
+    for i in range(CONFIG_PUSH_BURST_MIN_CONNECTS - 1):
+        throttle.note_peer_connected(now=base + i)
+    assert throttle.debounce_seconds(now=base + 10) == CONFIG_PUSH_DEBOUNCE_NORMAL_SEC
+
+
+def test_burst_debounce_after_many_connects_in_window() -> None:
+    throttle = ConfigPushThrottle()
+    base = 1_700_000_000.0
+    for i in range(CONFIG_PUSH_BURST_MIN_CONNECTS):
+        throttle.note_peer_connected(now=base + i * 0.5)
+    assert throttle.debounce_seconds(now=base + 5) == CONFIG_PUSH_DEBOUNCE_BURST_SEC
+
+
+def test_burst_window_expires() -> None:
+    throttle = ConfigPushThrottle()
+    base = 1_700_000_000.0
+    for i in range(CONFIG_PUSH_BURST_MIN_CONNECTS):
+        throttle.note_peer_connected(now=base + i)
+    assert throttle.debounce_seconds(now=base + 20) == CONFIG_PUSH_DEBOUNCE_NORMAL_SEC