Initial commit: add .gitignore and README

fusionagi/verification/validators.py

@@ -0,0 +1,51 @@
+"""Formal validators: JSON schema, policy constraints, lint/type check on outputs."""
+
+import json
+from typing import Any
+
+from fusionagi._logger import logger
+
+
+class FormalValidators:
+    """
+    Validates outputs against JSON schema, policy constraints.
+    Extend with lint/type check for code outputs.
+    """
+
+    def __init__(self) -> None:
+        self._schemas: dict[str, dict[str, Any]] = {}  # name -> JSON schema
+
+    def register_schema(self, name: str, schema: dict[str, Any]) -> None:
+        """Register a JSON schema for output validation."""
+        self._schemas[name] = schema
+
+    def validate_json(self, data: str | dict[str, Any], schema_name: str | None = None) -> tuple[bool, str]:
+        """
+        Validate JSON structure. If schema_name given, validate against that schema
+        (requires jsonschema lib for full validation; else structure-only).
+        Returns (valid, error_message).
+        """
+        if isinstance(data, dict):
+            obj = data
+        else:
+            try:
+                obj = json.loads(data)
+            except json.JSONDecodeError as e:
+                return False, str(e)
+        if schema_name and schema_name in self._schemas:
+            try:
+                import jsonschema
+                jsonschema.validate(instance=obj, schema=self._schemas[schema_name])
+            except ImportError:
+                logger.warning("jsonschema not installed; skipping schema validation")
+            except Exception as e:
+                return False, str(e)
+        return True, ""
+
+    def validate_policy(self, action: str, context: dict[str, Any]) -> tuple[bool, str]:
+        """
+        Check action against policy (context has tool_name, domain, etc.).
+        Returns (allowed, reason).
+        """
+        # Placeholder: no policy rules by default
+        return True, ""