diff --git a/firmware/src/main.cpp b/firmware/src/main.cpp
index 54e6cda..8fdf7f6 100644
--- a/firmware/src/main.cpp
+++ b/firmware/src/main.cpp
@@ -18,8 +18,9 @@
 #define CAM_INTERVAL_MS   (1000 / CAM_FPS)
 #define REPORT_INTERVAL_S 3600
 
-static DeviceConfig g_cfg;
-static CVState      g_cv;
+static DeviceConfig     g_cfg;
+static CVState          g_cv;
+static SemaphoreHandle_t s_cv_mutex = nullptr;
 
 // LED: simple on/off — blink patterns can be added later
 static void led_set(bool on) { digitalWrite(LED_PIN, on ? HIGH : LOW); }
@@ -38,10 +39,13 @@ static void check_factory_reset() {
 
 // Camera + CV task — runs on core 1 at 5 fps
 static void task_camera(void*) {
-    uint8_t frame[CV_PIXELS];
+    static uint8_t frame[CV_PIXELS];  // static: avoids 9KB on task stack
     while (true) {
         if (camera_capture_96(frame)) {
-            cv_process(g_cv, frame, g_cfg.line_offset);
+            if (xSemaphoreTake(s_cv_mutex, pdMS_TO_TICKS(100)) == pdTRUE) {
+                cv_process(g_cv, frame, g_cfg.line_offset);
+                xSemaphoreGive(s_cv_mutex);
+            }
         }
         vTaskDelay(pdMS_TO_TICKS(CAM_INTERVAL_MS));
     }
@@ -49,13 +53,18 @@ static void task_camera(void*) {
 
 // Hourly reporter task — runs on core 0
 static void task_reporter(void*) {
-    uint32_t last_report_ts = (uint32_t)(time(nullptr));
+    uint32_t last_report_ts = 0; // 0 = not initialized yet
+
     while (true) {
         vTaskDelay(pdMS_TO_TICKS(10000)); // check every 10s
 
         uint32_t now = (uint32_t)(time(nullptr));
-        // Skip if NTP not synced or hour not elapsed
-        if (now < 1700000000UL || (now - last_report_ts) < REPORT_INTERVAL_S) continue;
+        if (now < 1700000000UL) continue; // NTP not synced
+
+        // First valid timestamp — initialize without reporting
+        if (last_report_ts == 0) { last_report_ts = now; continue; }
+
+        if ((now - last_report_ts) < REPORT_INTERVAL_S) continue;
 
         uint32_t period_start = last_report_ts;
         uint32_t period_end   = now;
@@ -65,9 +74,17 @@ static void task_reporter(void*) {
         ble_scanner_pause();
         led_set(true); // yellow indicator (single LED: on = uploading)
 
-        CameraHourlyRecord cam_rec = {period_start, period_end,
-                                      g_cv.entries, g_cv.exits};
-        cv_reset_counts(g_cv);
+        CameraHourlyRecord cam_rec;
+        if (xSemaphoreTake(s_cv_mutex, pdMS_TO_TICKS(500)) == pdTRUE) {
+            cam_rec = {period_start, period_end, g_cv.entries, g_cv.exits};
+            cv_reset_counts(g_cv);
+            xSemaphoreGive(s_cv_mutex);
+        } else {
+            // Failed to acquire — skip this cycle, will report next hour
+            ble_scanner_resume();
+            led_set(false);
+            continue;
+        }
 
         BLEHourlyRecord ble_rec = ble_scanner_collect(period_start, period_end);
 
@@ -124,6 +141,8 @@ void setup() {
 
     ble_scanner_start();
 
+    s_cv_mutex = xSemaphoreCreateMutex();
+
     xTaskCreatePinnedToCore(task_camera,   "cam",  4096, nullptr, 2, nullptr, 1);
     xTaskCreatePinnedToCore(task_reporter, "rep",  8192, nullptr, 1, nullptr, 0);
 }