perf(schema): skip meta-schema validation for Pydantic-generated schemas

src/jacobian/schema_registry.py

@@ -92,6 +92,22 @@ def _validated_schema(canonical_schema: bytes) -> Draft202012Validator:
     return Draft202012Validator(normalized, format_checker=FormatChecker())
 
 
+@lru_cache(maxsize=1024)
+def _trusted_validated_schema(canonical_schema: bytes) -> Draft202012Validator:
+    """Compile a schema without re-validating against the meta-schema.
+
+    Pydantic's model_json_schema() produces valid Draft 2020-12 schemas
+    by construction.  Skipping the expensive meta-schema walk for those
+    schemas eliminates the dominant cost of runtime construction (~6.7s
+    across 527 unique schemas at ~12.7ms each).  External references are
+    still rejected; only the meta-schema check is skipped.
+    """
+
+    normalized = loads_strict_json(canonical_schema)
+    _reject_external_references(normalized)
+    return Draft202012Validator(normalized, format_checker=FormatChecker())
+
+
 class SchemaRegistry:
     """Store and apply closed local JSON Schemas used by artifact contracts."""
 
@@ -103,8 +119,21 @@ def __init__(self, store: ArtifactRepository) -> None:
         self._registrations: dict[tuple[str, str, bytes], str] = {}
         self._pending: dict[int, _PendingRegistrations] = {}
 
-    def register(self, *, name: str, version: str, schema: dict[str, Any]) -> str:
-        """Register a schema after rejecting unsupported external references."""
+    def register(
+        self,
+        *,
+        name: str,
+        version: str,
+        schema: dict[str, Any],
+        trusted: bool = False,
+    ) -> str:
+        """Register a schema after rejecting unsupported external references.
+
+        When ``trusted`` is True, the schema is assumed to be valid Draft
+        2020-12 by construction (e.g. generated by Pydantic's
+        ``model_json_schema()``) and the expensive meta-schema validation is
+        skipped.  External references are always rejected.
+        """
 
         self._reconcile_pending()
         canonical_schema = canonicalize_json(schema)
@@ -132,7 +161,10 @@ def register(self, *, name: str, version: str, schema: dict[str, Any]) -> str:
             version=version,
             definition=schema,
         )
-        _validated_schema(canonical_schema)
+        if trusted:
+            _trusted_validated_schema(canonical_schema)
+        else:
+            _validated_schema(canonical_schema)
         schema_uri = self.store.register_descriptor(
             kind="schema",
             name=name,
@@ -168,6 +200,7 @@ def register_model(
             name=name,
             version=version,
             schema=model_schema(model),
+            trusted=True,
         )
         self._bind_model_contract(schema_uri, model)
         if producer_only: