feat(ota): persist ota_channel selector in NodePrefs

(cherry picked from commit db1db5b57ecce408c7441cb6aa70f29608b09603)

src/helpers/CommonCLI.h

@@ -70,6 +70,7 @@ public:
   uint8_t path_hash_mode = 0;   // which path mode to use when sending
   uint8_t loop_detect = 0;
   uint8_t cad_enabled = 0;      // hardware Channel Activity Detection before TX (boolean)
+  uint8_t ota_channel = 0;      // OTA release channel selector: 0=native, 1=stable, 2=dev
   uint8_t extra_sf[4];
 
   // NOTE: observer settings (MQTT/WiFi/timezone/SNMP/alert) are not in NodePrefs.
@@ -182,6 +183,7 @@ protected:
     def("lat", node_lat);
     def("lon", node_lon);
     def("disc_mod", discovery_mod_timestamp);  // gates 'since'-filtered DISCOVER replies
+    def("ota_ch", ota_channel);   // OTA release channel: 0=native, 1=stable, 2=dev
     def("radio", radio);
     def("bridge", bridge);
     def("gps", gps);

test/test_config_serializer/test_config_serializer.cpp

@@ -214,6 +214,35 @@ TEST(NodePrefs, FemGainSettingsRoundTrip) {
     EXPECT_EQ(1, loaded.radio_fem_txgain);
 }
 
+TEST(NodePrefs, OtaChannelDefaultsToNative) {
+    NodePrefs prefs;
+    EXPECT_EQ(0, prefs.ota_channel);  // 0 == native
+}
+
+TEST(NodePrefs, OtaChannelRoundTrip) {
+    NodePrefs saved;
+    saved.ota_channel = 2;  // dev
+
+    MockPrintStream output;
+    ASSERT_TRUE(saved.saveSerial(output));
+    std::string serialised(reinterpret_cast<const char*>(output.getBytes()), output.getLength());
+    EXPECT_NE(std::string::npos, serialised.find("ota_ch:2"));
+
+    MockInputStream input(serialised.c_str());
+    NodePrefs loaded;
+    loaded.ota_channel = 1;  // start different
+    ASSERT_TRUE(loaded.loadSerial(input)) << serialised;
+    EXPECT_EQ(2, loaded.ota_channel);
+}
+
+TEST(NodePrefs, OtaChannelMissingKeyKeepsDefault) {
+    // A /prefs.json written before this field existed has no ota_ch key.
+    MockInputStream input("{name:\"n\"}");
+    NodePrefs loaded;               // ota_channel default 0 (native)
+    ASSERT_TRUE(loaded.loadSerial(input));
+    EXPECT_EQ(0, loaded.ota_channel);
+}
+
 
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