Moved audit forward somewhat

audit_core/__init__.py

@@ -1,6 +1,24 @@
-"""Audit Core public interface."""
+"""Audit Core public interface.
 
-from audit_core.interface import AuditBackend, AuditEvent
+Contract reference: ``docs/audit-backend-contract.md``.
+"""
+
+from audit_core.interface import (
+    AuditBackend,
+    AuditEvent,
+    EventValidationError,
+    RetentionPolicy,
+    SCHEMA_VERSION_V1ALPHA1,
+    validate_event,
+)
 from audit_core.mock_file_backend import MockFileAuditBackend
 
-__all__ = ["AuditBackend", "AuditEvent", "MockFileAuditBackend"]
+__all__ = [
+    "AuditBackend",
+    "AuditEvent",
+    "EventValidationError",
+    "MockFileAuditBackend",
+    "RetentionPolicy",
+    "SCHEMA_VERSION_V1ALPHA1",
+    "validate_event",
+]