Step 5 (health): temperatures in status.temps

- aes67_health: status.temps = [{name, c, min_c, max_c, warn_c}]
  (0.1 °C), sampled every 2 s by a health task. On-die "SoC" sensor via
  driver/temperature_sensor.h, range 20..100 °C, warn at 85 °C.
  health_temp_register(name, read_cb, warn_c) for board sensors.
  Warning logged when crossing warn_c, cleared below warn_c - 5 °C.
- Verified: SoC 26-28 °C at idle with min/max since boot; with a
  temporary 27 °C threshold the warning was logged and arrived via
  syslog as <132>, status carried warn_c 27.

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

components/aes67_health/aes67_health.c

@@ -1,9 +1,98 @@
 #include "aes67_health.h"
 
+#include <string.h>
+
 #include "aes67_web.h"
+#include "driver/temperature_sensor.h"
 #include "esp_app_desc.h"
 #include "esp_heap_caps.h"
+#include "esp_log.h"
 #include "esp_timer.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/semphr.h"
+#include "freertos/task.h"
+
+#define MAX_SENSORS     8
+#define SAMPLE_MS       2000
+#define HYSTERESIS_C    5.0f
+#define SOC_WARN_C      85.0f
+
+static const char *TAG = "health";
+
+typedef struct {
+    char name[16];
+    health_temp_read_cb_t read;
+    float warn_c;
+    bool valid, hot;
+    float c, min_c, max_c;
+} sensor_t;
+
+static sensor_t s_sensors[MAX_SENSORS];
+static int s_n;
+static SemaphoreHandle_t s_lock;
+static temperature_sensor_handle_t s_tsens;
+
+esp_err_t health_temp_register(const char *name, health_temp_read_cb_t read, float warn_c)
+{
+    if (!s_lock || s_n >= MAX_SENSORS) {
+        return ESP_ERR_INVALID_STATE;
+    }
+    xSemaphoreTake(s_lock, portMAX_DELAY);
+    sensor_t *t = &s_sensors[s_n++];
+    strlcpy(t->name, name, sizeof(t->name));
+    t->read = read;
+    t->warn_c = warn_c;
+    xSemaphoreGive(s_lock);
+    return ESP_OK;
+}
+
+// On-die sensor: measures the die, not ambient; expect well above room temperature.
+static esp_err_t soc_read(float *c)
+{
+    return temperature_sensor_get_celsius(s_tsens, c);
+}
+
+static void health_task(void *arg)
+{
+    while (1) {
+        for (int i = 0; i < s_n; i++) {
+            float c;
+            if (s_sensors[i].read(&c) != ESP_OK) {
+                continue;
+            }
+            xSemaphoreTake(s_lock, portMAX_DELAY);
+            sensor_t *t = &s_sensors[i];
+            t->c = c;
+            t->min_c = t->valid && t->min_c < c ? t->min_c : c;
+            t->max_c = t->valid && t->max_c > c ? t->max_c : c;
+            t->valid = true;
+            bool was_hot = t->hot;
+            if (t->warn_c > 0) {
+                if (!t->hot && c >= t->warn_c) {
+                    t->hot = true;
+                } else if (t->hot && c < t->warn_c - HYSTERESIS_C) {
+                    t->hot = false;
+                }
+            }
+            xSemaphoreGive(s_lock);
+            // Logged outside the lock; goes to syslog like any warning.
+            if (t->hot != was_hot) {
+                if (t->hot) {
+                    ESP_LOGW(TAG, "temperature %s %.1f °C: at or above %.0f °C", t->name, c, t->warn_c);
+                } else {
+                    ESP_LOGI(TAG, "temperature %s %.1f °C: back below %.0f °C", t->name, c,
+                             t->warn_c - HYSTERESIS_C);
+                }
+            }
+        }
+        vTaskDelay(pdMS_TO_TICKS(SAMPLE_MS));
+    }
+}
+
+static double round1(float v)
+{
+    return (double)(int)(v * 10.0f + (v < 0 ? -0.5f : 0.5f)) / 10.0;
+}
 
 static void health_status(cJSON *st)
 {
@@ -11,9 +100,46 @@ static void health_status(cJSON *st)
     cJSON_AddNumberToObject(st, "uptime_s", (double)(esp_timer_get_time() / 1000000));
     cJSON_AddNumberToObject(st, "heap_free", heap_caps_get_free_size(MALLOC_CAP_INTERNAL));
     cJSON_AddNumberToObject(st, "psram_free", heap_caps_get_free_size(MALLOC_CAP_SPIRAM));
+
+    cJSON *temps = cJSON_AddArrayToObject(st, "temps");
+    xSemaphoreTake(s_lock, portMAX_DELAY);
+    for (int i = 0; i < s_n; i++) {
+        const sensor_t *t = &s_sensors[i];
+        if (!t->valid) {
+            continue;
+        }
+        cJSON *o = cJSON_CreateObject();
+        cJSON_AddStringToObject(o, "name", t->name);
+        cJSON_AddNumberToObject(o, "c", round1(t->c));
+        cJSON_AddNumberToObject(o, "min_c", round1(t->min_c));
+        cJSON_AddNumberToObject(o, "max_c", round1(t->max_c));
+        if (t->warn_c > 0) {
+            cJSON_AddNumberToObject(o, "warn_c", t->warn_c);
+        }
+        cJSON_AddItemToArray(temps, o);
+    }
+    xSemaphoreGive(s_lock);
 }
 
 esp_err_t aes67_health_init(void)
 {
+    s_lock = xSemaphoreCreateMutex();
+    if (!s_lock) {
+        return ESP_ERR_NO_MEM;
+    }
+    // 20..100 °C (+-2 °C): the die runs well above ambient and the warning level must be in range.
+    temperature_sensor_config_t cfg = TEMPERATURE_SENSOR_CONFIG_DEFAULT(20, 100);
+    esp_err_t err = temperature_sensor_install(&cfg, &s_tsens);
+    if (err == ESP_OK) {
+        err = temperature_sensor_enable(s_tsens);
+    }
+    if (err == ESP_OK) {
+        health_temp_register("SoC", soc_read, SOC_WARN_C);
+    } else {
+        ESP_LOGE(TAG, "on-die temperature sensor: %s", esp_err_to_name(err));
+    }
+    if (xTaskCreate(health_task, "health", 3072, NULL, 2, NULL) != pdPASS) {
+        return ESP_ERR_NO_MEM;
+    }
     return status_register(health_status);
 }