some fixes

python_app/orchestration/config_writer.py

@@ -43,7 +43,10 @@ class ConfigWriter:
     def write(self, config: RunConfigModel, output_path: Path) -> Path:
         """Write run configuration JSON file."""
         output_path.parent.mkdir(parents=True, exist_ok=True)
-        output_path.write_text(json.dumps(config.to_dict(), indent=2), encoding="utf-8")
+        # allow_nan=False: a stray NaN/Infinity must fail loudly here in Python
+        # rather than serialize to a non-standard token that aborts every C++
+        # consumer at startup with an opaque JSON parse error.
+        output_path.write_text(json.dumps(config.to_dict(), indent=2, allow_nan=False), encoding="utf-8")
         return output_path