diff --git a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/include/iot_mqtt_srv.h b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/include/iot_mqtt_srv.h
index 27fc883..62aa77e 100644
--- a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/include/iot_mqtt_srv.h
+++ b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/include/iot_mqtt_srv.h
@@ -52,6 +52,7 @@ void  iot_mqtt_poll(void);             // 主循环轮询 (状态机 + 心跳 +
 void  iot_mqtt_handle_sock_int(uint8_t socketid, uint8_t intstat);  // Socket 中断处理
 void  iot_mqtt_publish_sensor(void);   // 推送传感器数据到 MQTT
 void  iot_evt_handle_ack(uint32_t msg_id, int code);  // event_report 平台应答入口 (V1.04)
+void  iot_watchdog_init(void);           // 初始化硬件 IWDG (无条件, 主循环卡死兜底)
 void  iot_watchdog_kick(void);         // 喂硬件 IWDG (主循环调用)
 
 #endif /* __IOT_MQTT_SRV_H__ */
diff --git a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/iot_mqtt_srv.c b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/iot_mqtt_srv.c
index 1ca60d5..061646e 100644
--- a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/iot_mqtt_srv.c
+++ b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/iot_mqtt_srv.c
@@ -177,10 +177,12 @@ static void iot_sensor_ingest(const LUP_SensorReport *sr) {
 /* lup 传感回调: uart_srv 消费路径的帧从这里喂入 (lup_process_frame 已过校验) */
 static void iot_evt_sensor_cb(const uint8_t *pkg, uint16_t len) {
     LUP_SensorReport sr;
+    FAULT_MARKER(MK_EVT_CB_IN);
     memset(&sr, 0, sizeof(sr));
     if (lup_parse_sensor_report(pkg, len, &sr) == 0) {
         iot_sensor_ingest(&sr);
     }
+    FAULT_MARKER(MK_EVT_CB_OUT);
 }
 
 /* 序列化并发布队列头 n 条事件 (首发与重发共用: 同 id/ts 同内容) */
diff --git a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/peripheral_main.c b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/peripheral_main.c
index 2d78f9e..25bcd2a 100644
--- a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/peripheral_main.c
+++ b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/peripheral_main.c
@@ -302,6 +302,7 @@ void Main_Circulation(void)
     while(1)
     {
         FAULT_MARKER(MK_LOOP_TOP);
+        iot_watchdog_kick();   /* 无条件喂狗 (2026-08-13): 原只在 iot_mqtt_poll, tcp_json 分支不喂 */
         TMOS_SystemProcess();
 
         if(g_net_state.flag < 2)
@@ -380,6 +381,8 @@ int main(void)
        每次上电必打, 区分看门狗死锁 vs 掉电 vs 外部复位 */
     PRINT("RST_REASON: 0x%08lx\n", (unsigned long)OFFLOG_RCC_RSTSCKR);
     fault_diag_init();   /* 打印上次复位现场 (HardFault mcause/mepc + 执行轨迹 marker) */
+    iot_watchdog_init(); /* 无条件 IWDG (2026-08-13): iot_enable=0 时 iot_mqtt_init 不调,
+                            卡死无兜底 → 永久冻结。IWDG 4s 超时 + 主循环喂狗 */
     PRINT("%s\n", VER_LIB);
     PRINT("SystemCoreClock:%d\n", SystemCoreClock);
     /* ===== 实验: 禁用全部 Flash/SPI 操作 (2026-08-12) =====
diff --git a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/tcp_json_srv.c b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/tcp_json_srv.c
index 1774eaa..ee17cdb 100644
--- a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/tcp_json_srv.c
+++ b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/tcp_json_srv.c
@@ -19,6 +19,7 @@
 #include "simple_json.h"
 #include "storage.h"
 #include "offlog.h"
+#include "fault_diag.h"
 #include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -872,6 +873,7 @@ static int format_loop_param_json(char *buf, uint16_t buf_size, const LUP_ParamG
 
 static void json_sensor_callback(const uint8_t *pkg, uint16_t len)
 {
+    FAULT_MARKER(MK_EVT_CB_IN);
     PRINT("JSON: sensor_cb enter socket=%d auth=%d report=%d\n",
           g_json_socket_listen, g_json_auth_state, g_report_cfg.enable);