From 493826bef5bfca71114c79081c5cc005f30e92f8 Mon Sep 17 00:00:00 2001
From: Scott Penrose <scooter.me@gmail.com>
Date: Wed, 10 Jun 2026 11:26:13 +1000
Subject: [PATCH] fully drain sync messages

---
 src/MeshCoreCompanion.cpp | 14 ++++++++++++--
 src/MeshCoreCompanion.h   |  5 +++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/MeshCoreCompanion.cpp b/src/MeshCoreCompanion.cpp
index cf97faa..f4d6aa5 100644
--- a/src/MeshCoreCompanion.cpp
+++ b/src/MeshCoreCompanion.cpp
@@ -32,6 +32,7 @@ void MeshCoreCompanion::loop() {
     while (mc_rx_poll(&_rx, _scratch, sizeof(_scratch), &olen)) {
         mc_event_t ev;
         if (mc_parse(_scratch, olen, &ev)) dispatch(ev);
+        else if (_onUnparsed) _onUnparsed(_scratch, olen);   /* frame we couldn't decode */
     }
 }
 
@@ -121,7 +122,11 @@ void MeshCoreCompanion::syncNextMessage() {
 }
 
 void MeshCoreCompanion::drainMessages() {
-    if (!_draining) { _draining = true; syncNextMessage(); }
+    // Always (re)issue a sync — recovers a wedged drain (a lost reply leaving
+    // _draining stuck true), not only when idle.  Safe to call periodically:
+    // the radio answers each sync with the next queued message or NoMoreMessages.
+    _draining = true;
+    syncNextMessage();
 }
 
 void MeshCoreCompanion::getStats(uint8_t statsType) {
@@ -217,7 +222,12 @@ void MeshCoreCompanion::dispatch(const mc_event_t &ev) {
         if (_onBinaryResp) _onBinaryResp(ev.u.binary_resp);
         break;
     case MC_PUSH_MSG_WAITING:
-        if (_autoSync && !_draining) { _draining = true; syncNextMessage(); }
+        // Always (re)start the drain on a MsgWaiting push.  If a prior sync
+        // reply was lost (e.g. the host stalled and its UART RX overflowed),
+        // _draining can be left stuck true; gating on !_draining would then
+        // ignore every later push and silently stop pulling messages.
+        // Re-kicking unconditionally self-heals that.
+        if (_autoSync) { _draining = true; syncNextMessage(); }
         break;
     case MC_RESP_CHANNEL_MSG_RECV:
     case MC_RESP_CHANNEL_MSG_RECV_V3:
diff --git a/src/MeshCoreCompanion.h b/src/MeshCoreCompanion.h
index 73b3b36..c4ee87f 100644
--- a/src/MeshCoreCompanion.h
+++ b/src/MeshCoreCompanion.h
@@ -105,6 +105,10 @@ public:
     void onContactsDone(ContactsDoneCb cb){ _onContactsDone = cb; }
     void onBinaryResponse(BinaryRespCb cb){ _onBinaryResp = cb; }
     void onEvent(EventCb cb)              { _onEvent = cb; }   /* every parsed frame */
+    /* Raw frames the parser did NOT recognise (payload incl. code byte).  For
+     * diagnosing firmware/protocol mismatches — normally unused. */
+    using RawCb = std::function<void(const uint8_t* payload, size_t len)>;
+    void onUnparsedFrame(RawCb cb)        { _onUnparsed = cb; }
 
 private:
     void sendPayload(const uint8_t *payload, size_t len);
@@ -134,6 +138,7 @@ private:
     ContactsDoneCb _onContactsDone;
     BinaryRespCb  _onBinaryResp;
     EventCb       _onEvent;
+    RawCb         _onUnparsed;
 };
 
 #endif /* MESHCORE_COMPANION_HPP */