some fixes again

python_app/gui/app_window.py

@@ -140,8 +140,17 @@ class AppWindow(
         try:
             value = int(raw)
         except ValueError:
-            return 50
-        return value if value >= 1 else 50
+            value = 0
+        if value >= 1:
+            return value
+        # A non-empty but invalid value is an operator mistake — say so instead of
+        # silently swallowing it (stderr is captured by journald in headless mode).
+        print(
+            f"[radar] Ignoring invalid RADAR_SYSTEM_METRICS_REPORT_EVERY={raw!r}; using default 50.",
+            file=sys.stderr,
+            flush=True,
+        )
+        return 50
 
     def _init_config_profile_state(self) -> None:
         """Resolve startup profile path, load active profile, and queue fallback notices."""