diff --git a/zephcore/adapters/gps/ZephyrGPSManager.cpp b/zephcore/adapters/gps/ZephyrGPSManager.cpp
index e436191..8b22c01 100644
--- a/zephcore/adapters/gps/ZephyrGPSManager.cpp
+++ b/zephcore/adapters/gps/ZephyrGPSManager.cpp
@@ -104,6 +104,8 @@ static uint32_t gps_wake_interval_ms   = CONFIG_ZEPHCORE_GPS_POLL_INTERVAL_SEC *
 #define GPS_REPEATER_SYNC_TIMEOUT_MS   (5 * 60 * 1000)           /* 5 minutes */
 
 static bool gps_repeater_mode = false;  /* True = repeater (time sync only), False = companion */
+static bool gnss_activity_seen_this_cycle = false;  /* Runtime-only: set by GNSS callback while acquiring */
+static bool gps_runtime_no_gnss_activity = false;   /* Runtime-only: repeater disables periodic GPS until reboot */
 
 /* Forward declarations for work handlers and state functions */
 static void gps_wake_work_fn(struct k_work *work);
@@ -213,6 +215,11 @@ static void gnss_data_cb(const struct device *dev, const struct gnss_data *data)
 		return;
 	}
 
+	if (gps_current_state == GPS_STATE_ACQUIRING) {
+		/* Any callback means GNSS hardware/UART path is alive, even without a fix. */
+		gnss_activity_seen_this_cycle = true;
+	}
+
 	LOG_DBG("GNSS callback: fix=%d sats=%d state=%d",
 		data->info.fix_status, data->info.satellites_cnt, gps_current_state);
 
@@ -878,6 +885,21 @@ static void gps_software_wake(void)
  * FORCE_ON pin LOW for L76K hardware standby. */
 static void gps_go_to_standby(void)
 {
+	if (gps_repeater_mode && gps_runtime_no_gnss_activity) {
+		LOG_WRN("GPS: No GNSS activity detected; disabling repeater GPS cycles until reboot");
+		gps_current_state = GPS_STATE_OFF;
+		consecutive_good_fixes = 0;
+		standby_start_ms = 0;
+		standby_interval_ms = 0;
+
+#if HAS_GPS_POWER_CONTROL
+		gps_power_control(false, true);
+#elif HAS_GPS_UART
+		gps_software_sleep();
+#endif
+		return;
+	}
+
 	uint64_t wake_interval = gps_repeater_mode ?
 		GPS_REPEATER_SYNC_INTERVAL_MS : gps_wake_interval_ms;
 
@@ -921,9 +943,15 @@ static void gps_go_to_standby(void)
  * queue which may be processing stale UART data. */
 static void gps_start_acquiring(void)
 {
+	if (gps_repeater_mode && gps_runtime_no_gnss_activity) {
+		LOG_INF("GPS: Repeater cycles are runtime-disabled (no GNSS activity detected)");
+		return;
+	}
+
 	LOG_INF("GPS: Waking for %s", gps_repeater_mode ? "time sync" : "position fix");
 	gps_current_state = GPS_STATE_ACQUIRING;
 	consecutive_good_fixes = 0;
+	gnss_activity_seen_this_cycle = false;
 
 #if HAS_GPS_POWER_CONTROL
 	gps_power_control(true);
@@ -976,6 +1004,11 @@ static void gps_timeout_work_fn(struct k_work *work)
 	LOG_WRN("GPS: Timeout after %d/%d fixes, deferring standby to main thread",
 		consecutive_good_fixes, GPS_GOOD_FIX_COUNT);
 
+	if (gps_repeater_mode && !gnss_activity_seen_this_cycle) {
+		LOG_WRN("GPS: Repeater acquire window had no GNSS callbacks; disabling periodic GPS until reboot");
+		gps_runtime_no_gnss_activity = true;
+	}
+
 	atomic_or(&pending_gps_actions, GPS_ACTION_TIMEOUT);
 	if (gps_event_cb) {
 		gps_event_cb();
@@ -1257,6 +1290,7 @@ void gps_set_repeater_mode(bool repeater)
 		LOG_INF("GPS: Repeater mode - starting initial time sync, then every 48h");
 
 		gps_enabled = true;  /* Logically enabled */
+		gps_runtime_no_gnss_activity = false;
 
 		/* Start acquiring immediately for initial time sync at boot.
 		 * GPS hardware is already powered from bootloader, so we just