feat: abstract MQTT network transport

test/README.md

@@ -29,6 +29,7 @@ does not reflect the GoogleTest count — run the built binary directly
 | `test_topic_template` | `src/helpers/MQTTTopicTemplate.h` | `{iata}/{device}/{token}/{type}` expansion, overflow/NUL-termination, and a buffer-size fuzz |
 | `test_mqtt_topic_router` | `src/helpers/MQTTTopicRouter.h` | complete preset/custom topic-routing contract; MeshRank all types except raw; required identifiers; invalid inputs/slots; exact buffer boundaries |
 | `test_mqtt_connection_policy` | `src/helpers/MQTTConnectionPolicy.h` | reconnect guard/backoff/stagger and breaker transitions; stable reset; JWT lifetime/renewal policy; exact timing boundaries and 32-bit `millis()` rollover; WiFi current-outage start sticky across STA reconnect attempts |
+| `test_network_policy` | `src/helpers/NetworkPolicy.h` | transport-neutral MQTT link-transition actions and `start ota` selected-LAN versus forced/fallback SoftAP choice |
 | `test_alert_fault_policy` | `src/helpers/AlertFaultPolicy.h` | WiFi/MQTT fault edge detector; `OutageSnapshot` (down / started_ms / initiating reason) fed to tick and `formatWifiAlert`; reason-8 reconnects change neither duration nor initiating reason; flap between status polls; down at `millis()==0`; packed 64-bit cross-task word; rate-limit floor and first-fire; 5 s poll cadence and `millis()` rollover |
 | `test_display_viewport` | `src/helpers/ui/DisplayViewport.h`, `src/helpers/ui/DisplayFrameSignature.h` | logical-to-physical portrait mapping; fractional span coverage; fitted-width conversion; preferred/fallback text scaling; stable visible-frame change detection |
 | `test_mqtt_packet_queue_policy` | `src/helpers/MQTTPacketQueuePolicy.h` | queue-full eviction; stale-disconnect flush; adaptive drain limits; bounded QoS0 retries; exact timing boundaries and 32-bit `millis()` rollover |

test/test_alert_fault_policy/test_alert_fault_policy.cpp

@@ -350,6 +350,17 @@ TEST(AlertFaultPolicy, FormatWifiAlertUsesSnapshotReason) {
   EXPECT_STREQ("WiFi down 47m", text);
 }
 
+TEST(AlertFaultPolicy, FormatNetworkAlertUsesSelectedMediumLabel) {
+  Alert::Fault f = OkFault();
+  const Alert::OutageSnapshot snap = Down(1000, 0);
+  const Alert::TickResult r = Alert::tick(
+      f, 1000 + kWifiThresh, snap, kWifiThresh, kMinInterval);
+  char text[80];
+  ASSERT_TRUE(Alert::formatNetworkAlert(
+      text, sizeof(text), "Ethernet", r, snap));
+  EXPECT_STREQ("Ethernet down 30m", text);
+}
+
 TEST(AlertFaultPolicy, FormatMqttSlotMessages) {
   char text[100];
   Alert::formatMqttDown(text, sizeof(text), 1, "analyzer-us", 30U * 60000U);

test/test_network_policy/test_network_policy.cpp

@@ -0,0 +1,36 @@
+#include <gtest/gtest.h>
+
+#include "helpers/NetworkPolicy.h"
+
+TEST(NetworkPolicy, MqttDownDisconnectsSlotsWithoutRequestingImmediateRetry) {
+  const auto actions = NetworkPolicy::mqttActions(NetworkTransition::Down);
+  EXPECT_TRUE(actions.disconnect_slots);
+  EXPECT_FALSE(actions.retry_disconnected_slots_now);
+}
+
+TEST(NetworkPolicy, MqttUpRequestsImmediateRetryWithoutDisconnectingSlots) {
+  const auto actions = NetworkPolicy::mqttActions(NetworkTransition::Up);
+  EXPECT_FALSE(actions.disconnect_slots);
+  EXPECT_TRUE(actions.retry_disconnected_slots_now);
+}
+
+TEST(NetworkPolicy, NoTransitionHasNoMqttSideEffects) {
+  const auto actions = NetworkPolicy::mqttActions(NetworkTransition::None);
+  EXPECT_FALSE(actions.disconnect_slots);
+  EXPECT_FALSE(actions.retry_disconnected_slots_now);
+}
+
+TEST(NetworkPolicy, StartOtaUsesReachableSelectedNetworkByDefault) {
+  EXPECT_TRUE(NetworkPolicy::startOtaUsesSelectedNetwork(false, true));
+  EXPECT_FALSE(NetworkPolicy::startOtaUsesSelectedNetwork(false, false));
+}
+
+TEST(NetworkPolicy, StartOtaForceApOverridesAReachableSelectedNetwork) {
+  EXPECT_FALSE(NetworkPolicy::startOtaUsesSelectedNetwork(true, true));
+  EXPECT_FALSE(NetworkPolicy::startOtaUsesSelectedNetwork(true, false));
+}
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}