feat: publish/respond version string

components/mqtt_publisher/include/mqtt_publisher.h

@@ -46,10 +46,12 @@ void mqtt_publisher_send_ota_status(const char *status, const char *version);
  * sensor_id   — stable anchor ID string (e.g. "anchor_a1b2c3")
  * broker_uri  — e.g. "mqtt://192.168.1.100:1883"
  * evt_group   — FreeRTOS event group; publisher sets bits above on events
+ * version     — firmware version string included in announce payload and version query responses
  */
 esp_err_t mqtt_publisher_init(const char *sensor_id,
                                const char *broker_uri,
-                               EventGroupHandle_t evt_group);
+                               EventGroupHandle_t evt_group,
+                               const char *version);
 
 /** Publish an RSSI reading. Non-blocking (QoS 1). */
 void mqtt_publisher_send_rssi(const char *tag_id, int8_t rssi);

components/mqtt_publisher/src/mqtt_publisher.c

@@ -11,6 +11,7 @@
 
 static esp_mqtt_client_handle_t  s_client          = NULL;
 static char                      s_sensor_id[32];
+static char                      s_firmware_version[32];
 static EventGroupHandle_t        s_evt             = NULL;
 static mqtt_reconfigure_data_t   s_reconfigure_data;
 static mqtt_ota_data_t           s_ota_data;
@@ -60,6 +61,7 @@ static void handle_cmd(const char *data, int data_len)
         else if (strcmp(a, "selected")        == 0) xEventGroupSetBits(s_evt, MQTT_SELECTED_BIT);
         else if (strcmp(a, "deselected")      == 0) xEventGroupSetBits(s_evt, MQTT_DESELECTED_BIT);
         else if (strcmp(a, "factory_reset")   == 0) xEventGroupSetBits(s_evt, MQTT_FACTORY_RESET_BIT);
+        else if (strcmp(a, "version")         == 0) mqtt_publisher_announce();
         else if (strcmp(a, "ota") == 0) {
             memset(&s_ota_data, 0, sizeof(s_ota_data));
             cJSON *url_j = cJSON_GetObjectItemCaseSensitive(root, "url");
@@ -122,9 +124,11 @@ static void mqtt_event_handler(void *arg, esp_event_base_t base,
 
 esp_err_t mqtt_publisher_init(const char *sensor_id,
                                const char *broker_uri,
-                               EventGroupHandle_t evt_group)
+                               EventGroupHandle_t evt_group,
+                               const char *version)
 {
     strncpy(s_sensor_id, sensor_id, sizeof(s_sensor_id) - 1);
+    strncpy(s_firmware_version, version ? version : "", sizeof(s_firmware_version) - 1);
     s_evt = evt_group;
     build_topics();
 
@@ -147,8 +151,10 @@ esp_err_t mqtt_publisher_init(const char *sensor_id,
 void mqtt_publisher_announce(void)
 {
     if (!s_client) return;
-    esp_mqtt_client_publish(s_client, s_topic_announce, "", 0, 1, 0);
+    char payload[48];
-    ESP_LOGI(TAG, "Announced on %s", s_topic_announce);
+    int len = snprintf(payload, sizeof(payload), "{\"version\":\"%s\"}", s_firmware_version);
+    esp_mqtt_client_publish(s_client, s_topic_announce, payload, len, 1, 0);
+    ESP_LOGI(TAG, "Announced on %s (version: %s)", s_topic_announce, s_firmware_version);
 }
 
 void mqtt_publisher_send_rssi(const char *tag_id, int8_t rssi)

main/main.c

@@ -221,12 +221,15 @@ void app_main(void)
     snprintf(broker_uri, sizeof(broker_uri), "mqtt://%s:%u", broker_host, broker_port);
 
     // init MQTT
-    ESP_ERROR_CHECK(mqtt_publisher_init(sensor_id, broker_uri, s_evt));
+    const esp_partition_t *running = esp_ota_get_running_partition();
+    esp_app_desc_t app_desc;
+    const char *fw_version = (esp_ota_get_partition_description(running, &app_desc) == ESP_OK)
+                             ? app_desc.version : "unknown";
+    ESP_ERROR_CHECK(mqtt_publisher_init(sensor_id, broker_uri, s_evt, fw_version));
     xEventGroupWaitBits(s_evt, MQTT_CONNECTED_BIT, pdFALSE, pdTRUE, portMAX_DELAY);
 
     /* Confirm this firmware is healthy so the bootloader won't roll back */
     esp_ota_img_states_t ota_state;
-    const esp_partition_t *running = esp_ota_get_running_partition();
     if (esp_ota_get_state_partition(running, &ota_state) == ESP_OK &&
         ota_state == ESP_OTA_IMG_PENDING_VERIFY) {
         esp_ota_mark_app_valid_cancel_rollback();