From 4bd4a77989daccb51279c0244cf47858cdc0b177 Mon Sep 17 00:00:00 2001
From: mikecarper <mikecarper@gmail.com>
Date: Tue, 8 Sep 2026 12:35:37 -0700
Subject: [PATCH] Reset RX recovery deadline after successful transmissions

---
 src/Dispatcher.cpp                            |   9 +-
 .../test_radio_liveness.cpp                   | 103 ++++++++++++++++++
 2 files changed, 110 insertions(+), 2 deletions(-)

diff --git a/src/Dispatcher.cpp b/src/Dispatcher.cpp
index 8b849536e..36156bc31 100644
--- a/src/Dispatcher.cpp
+++ b/src/Dispatcher.cpp
@@ -429,10 +429,15 @@ void Dispatcher::loop() {
       }
 
       _radio->onSendFinished();
+      // RX can occur entirely between two loop observations during a TX
+      // burst. Start a fresh RX recovery allowance after each successful TX;
+      // otherwise a later CAD pause can trip the eight-second watchdog using
+      // the start time of the whole healthy burst.
+      radio_nonrx_start = _ms->getMillis();
 #ifdef RADIO_LIVENESS_SOFT_ONLY
-      last_radio_activity_ms = _ms->getMillis();  // TX success -> radio is alive
+      last_radio_activity_ms = radio_nonrx_start;  // TX success -> radio is alive
 #else
-      radio_liveness.noteActivity(_ms->getMillis());  // TX success -> radio is alive
+      radio_liveness.noteActivity(radio_nonrx_start);  // TX success -> radio is alive
 #endif
       restoreOutboundTxOverrides();
       logTx(outbound, 2 + outbound->getPathByteLen() + outbound->payload_len);
diff --git a/test/test_radio_liveness/test_radio_liveness.cpp b/test/test_radio_liveness/test_radio_liveness.cpp
index 9140b9bad..44621e416 100644
--- a/test/test_radio_liveness/test_radio_liveness.cpp
+++ b/test/test_radio_liveness/test_radio_liveness.cpp
@@ -3,6 +3,8 @@
 #include <helpers/RadioLivenessTracker.h>
 #include <helpers/radiolib/LR2021Band.h>
 #include <helpers/radiolib/RxBoostedGainDefaults.h>
+#include <Dispatcher.h>
+#include <helpers/StaticPoolPacketManager.h>
 
 using mesh::RadioLivenessTracker;
 using mesh::RadioRecoveryAction;
@@ -63,6 +65,107 @@ TEST(LR2021Band, SelectsTheCorrectFrontEnd) {
   EXPECT_TRUE(mesh::lr2021::isHighBand(2400.0f));
 }
 
+namespace {
+class AdvancingClock : public mesh::MillisecondClock {
+public:
+  unsigned long now = 1;
+  unsigned long getMillis() override { return now++; }
+};
+
+class BurstRadio : public mesh::Radio {
+public:
+  bool receiving = true;
+  bool cad_busy = false;
+  bool broken_rx = false;
+  int completed = 0;
+  int recoveries = 0;
+  int recvRaw(uint8_t*, int) override {
+    if (!broken_rx) receiving = true;
+    return 0;
+  }
+  uint32_t getEstAirtimeFor(int) override { return 1000; }
+  float packetScore(float, int) override { return 1; }
+  bool startSendRaw(const uint8_t*, int) override {
+    receiving = false;
+    return true;
+  }
+  bool isSendComplete() override { ++completed; return true; }
+  void onSendFinished() override { receiving = false; }
+  bool isInRecvMode() const override { return receiving; }
+  bool isReceiving() override {
+    // Active CAD may leave the radio outside RX until the next recvRaw().
+    if (cad_busy) receiving = false;
+    return cad_busy;
+  }
+  bool recoverRadio(bool) override {
+    ++recoveries;
+    receiving = !broken_rx;
+    return !broken_rx;
+  }
+};
+
+class WatchdogDispatcher : public mesh::Dispatcher {
+public:
+  WatchdogDispatcher(BurstRadio& radio, AdvancingClock& clock,
+                     StaticPoolPacketManager& packets)
+      : Dispatcher(radio, clock, packets) {}
+  mesh::DispatcherAction onRecvPacket(mesh::Packet*) override { return ACTION_RELEASE; }
+  uint16_t errors() const { return _err_flags; }
+};
+}
+
+TEST(DispatcherRadioWatchdog, SuccessfulTxBurstDoesNotTriggerStuckRxRecovery) {
+  AdvancingClock clock;
+  BurstRadio radio;
+  StaticPoolPacketManager packets(16);
+  WatchdogDispatcher dispatcher(radio, clock, packets);
+  dispatcher.begin();
+  for (int i = 0; i < 12; ++i) {
+    auto* packet = packets.allocNew();
+    ASSERT_NE(packet, nullptr);
+    packet->header = ROUTE_TYPE_DIRECT | (PAYLOAD_TYPE_TXT_MSG << 2);
+    packet->path_len = 0;
+    packet->payload_len = 1;
+    packet->payload[0] = 0;
+    ASSERT_TRUE(dispatcher.sendPacket(packet, 0));
+  }
+  dispatcher.loop();
+  // RX happens inside each loop between completed TX and the next TX. The
+  // watchdog at the top of the loop sees only TX, for longer than 8 seconds.
+  for (int i = 0; i < 10; ++i) {
+    clock.now += 1000;
+    if (i == 9) radio.cad_busy = true;
+    dispatcher.loop();
+  }
+  ASSERT_EQ(radio.completed, 10);
+  clock.now += 100;
+  dispatcher.loop();
+  EXPECT_EQ(radio.recoveries, 0);
+  EXPECT_EQ(dispatcher.errors() & ERR_EVENT_STARTRX_TIMEOUT, 0);
+
+  // A subsequent genuine RX failure still gets its own recovery deadline.
+  radio.broken_rx = true;
+  clock.now += 8100;
+  dispatcher.loop();
+  EXPECT_EQ(radio.recoveries, 1);
+  EXPECT_NE(dispatcher.errors() & ERR_EVENT_STARTRX_TIMEOUT, 0);
+}
+
+TEST(DispatcherRadioWatchdog, StuckReceiverStillRecoversWithoutTransmitActivity) {
+  AdvancingClock clock;
+  BurstRadio radio;
+  StaticPoolPacketManager packets(2);
+  WatchdogDispatcher dispatcher(radio, clock, packets);
+  dispatcher.begin();
+  radio.broken_rx = true;
+  radio.receiving = false;
+  dispatcher.loop();
+  clock.now += 8100;
+  dispatcher.loop();
+  EXPECT_EQ(radio.recoveries, 1);
+  EXPECT_NE(dispatcher.errors() & ERR_EVENT_STARTRX_TIMEOUT, 0);
+}
+
 int main(int argc, char** argv) {
   ::testing::InitGoogleTest(&argc, argv);
   return RUN_ALL_TESTS();