Feat/math validation agent (#6012)

Co-authored-by: James Brunton <[email protected]>
Co-authored-by: EthanHealy01 <[email protected]>

engine/src/stirling/logging.py

@@ -0,0 +1,22 @@
+"""Shared logging utilities for the Stirling AI engine."""
+
+from __future__ import annotations
+
+import json
+
+
+class Pretty:
+    """Lazy JSON formatter — only serialises when ``str()`` is called.
+
+    Designed for use with ``logging``'s ``%s`` formatting so that the
+    JSON serialisation is skipped entirely when the log message is
+    never emitted.
+    """
+
+    __slots__ = ("_obj",)
+
+    def __init__(self, obj: object) -> None:
+        self._obj = obj
+
+    def __str__(self) -> str:
+        return json.dumps(self._obj, indent=2, default=str, ensure_ascii=True)