feat: report main-loop health in memStatus

memStatus now carries loopRate (loop() passes per second) and loopMaxUs
(the longest pass, in microseconds) over the window since the last
broadcast. Only a broadcast closes the window, so a client connecting
does not wipe a slow pass before Home Assistant has seen it.

/discovery is formatted on the web server's task, so its memory block
reports the last closed window through atomics instead of reading the
counters the loop task is still filling.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ESPNetwork.cpp

@@ -28,6 +28,7 @@ extern MqttConnection mqtt;
 extern rebootDelay_t rebootDelay;
 extern ESPNetwork net;
 extern SomfyShadeController somfy;
+extern LoopStats loopStats;
 
 static unsigned long _lastHeapEmit = 0;
 
@@ -680,8 +681,15 @@ void ESPNetwork::emitHeap(uint8_t num) {
   json->addElem("min", minHeap);
   json->addElem("total", ESP.getHeapSize());
   json->addElem("uptime", (uint64_t)millis());
+  // The window in progress.  Only a broadcast closes it, so a client
+  // connecting doesn't wipe a slow pass before Home Assistant has seen it.
+  json->addElem("loopRate", loopStats.rate(millis()));
+  json->addElem("loopMaxUs", loopStats.maxUs());
   json->endObject();
   if(target == heap_emit_t::room) sockEmit.endEmitRoom(0);
   else sockEmit.endEmit(num);
-  if(target == heap_emit_t::broadcast) _lastHeapEmit = millis();
+  if(target == heap_emit_t::broadcast) {
+    _lastHeapEmit = millis();
+    loopStats.publish(_lastHeapEmit);
+  }
 }

src/SomfyController.ino

@@ -41,6 +41,7 @@ SomfyShadeOps shadeOps;
 ShadeRequests shadeRequests(shadeOps);
 LoopQueue loopQueue;
 SnapshotSlots snapshotSlots;
+LoopStats loopStats;
 
 uint32_t oldheap = 0;
 
@@ -141,6 +142,9 @@ void setup() {
 void loop() {
   // put your main code here, to run repeatedly:
   //uint32_t heap = ESP.getFreeHeap();
+  // Times the whole pass for memStatus, including any time the loop task was
+  // pre-empted, since that delays the loop too.
+  ElapsedTimer pass;
   if(rebootDelay.reboot && millis() > rebootDelay.rebootTime) {
     ESP_LOGI(TAG, "Rebooting after %lums", rebootDelay.rebootTime);
     net.end();
@@ -180,4 +184,5 @@ void loop() {
     ESP.restart();
   }
   esp_task_wdt_reset();
+  loopStats.record(pass.us());
 }

src/Utils.cpp

@@ -152,3 +152,20 @@ heap_emit_t heapEmitTarget(uint8_t num, uint32_t sinceLastMs, uint32_t intervalM
   if(sinceLastMs >= intervalMs) return heap_emit_t::broadcast;
   return roomHasClients ? heap_emit_t::room : heap_emit_t::none;
 }
+void LoopStats::record(uint32_t passUs) {
+  _passes++;
+  if(passUs > _maxUs) _maxUs = passUs;
+}
+uint32_t LoopStats::rate(uint32_t nowMs) const {
+  // The unsigned subtraction keeps the window right across a millis() wrap.
+  const uint32_t elapsedMs = nowMs - _startMs;
+  if(elapsedMs == 0) return 0;
+  return (uint32_t)((uint64_t)_passes * 1000 / elapsedMs);
+}
+void LoopStats::publish(uint32_t nowMs) {
+  _publishedRate.store(this->rate(nowMs), std::memory_order_relaxed);
+  _publishedMaxUs.store(_maxUs, std::memory_order_relaxed);
+  _passes = 0;
+  _maxUs = 0;
+  _startMs = nowMs;
+}

src/Utils.h

@@ -1,6 +1,7 @@
 #ifndef utils_h
 #define utils_h
 #include <Arduino.h>
+#include <atomic>
 
 
 #define DEBUG_SOMFY Serial
@@ -78,6 +79,26 @@ enum class heap_emit_t : uint8_t { none, client, broadcast, room };
 // num is the socket client asked for, 255 for everyone.  A broadcast goes out
 // every intervalMs; in between only the clients in room 0 get one.
 heap_emit_t heapEmitTarget(uint8_t num, uint32_t sinceLastMs, uint32_t intervalMs, bool roomHasClients);
+// How well loop() keeps up: the passes it made per second and its longest
+// pass, over the window since the last memStatus broadcast.  Only the loop
+// task calls record(), rate(), maxUs() and publish().  publish() closes the
+// window and keeps its figures where another task (the /discovery response)
+// can read them without seeing a half reset window.
+class LoopStats {
+  uint32_t _passes = 0;
+  uint32_t _maxUs = 0;
+  uint32_t _startMs = 0;
+  std::atomic<uint32_t> _publishedRate{0};
+  std::atomic<uint32_t> _publishedMaxUs{0};
+  public:
+    void record(uint32_t passUs);
+    // Passes per second since the window started, 0 for an empty window.
+    uint32_t rate(uint32_t nowMs) const;
+    uint32_t maxUs() const { return _maxUs; }
+    void publish(uint32_t nowMs);
+    uint32_t publishedRate() const { return _publishedRate.load(std::memory_order_relaxed); }
+    uint32_t publishedMaxUs() const { return _publishedMaxUs.load(std::memory_order_relaxed); }
+};
 
 class Timestamp {
   char _timeBuffer[128];

src/entryPoints/Web.cpp

@@ -28,6 +28,7 @@
 extern ConfigSettings settings;
 extern SSDPClass SSDP;
 extern rebootDelay_t rebootDelay;
+extern LoopStats loopStats;
 extern SomfyShadeController somfy;
 extern Web webServer;
 extern MqttConnection mqtt;
@@ -276,6 +277,10 @@ static void discoveryHeader(JsonFormatter &json, const model_snapshot_t &snap) {
   json.addElem("min", ESP.getMinFreeHeap());
   json.addElem("total", ESP.getHeapSize());
   json.addElem("uptime", (uint64_t)millis());
+  // This runs on the web server's task, so it reports the last window the
+  // loop task closed rather than reading the one it is still filling.
+  json.addElem("loopRate", loopStats.publishedRate());
+  json.addElem("loopMaxUs", loopStats.publishedMaxUs());
   json.endObject();
 }