fix(storage): harden sql persistence compatibility

backend/packages/storage/store/repositories/contracts/__init__.py

@@ -15,6 +15,7 @@ from store.repositories.contracts.run_event import (
     RunEventRepositoryProtocol,
 )
 from store.repositories.contracts.thread_meta import (
+    InvalidMetadataFilterError,
     ThreadMeta,
     ThreadMetaCreate,
     ThreadMetaRepositoryProtocol,
@@ -37,6 +38,7 @@ __all__ = [
     "RunEventCreate",
     "RunEventRepositoryProtocol",
     "RunRepositoryProtocol",
+    "InvalidMetadataFilterError",
     "ThreadMeta",
     "ThreadMetaCreate",
     "ThreadMetaRepositoryProtocol",

backend/packages/storage/store/repositories/contracts/thread_meta.py

@@ -6,6 +6,10 @@ from typing import Any, Protocol
 from pydantic import BaseModel, ConfigDict, Field
 
 
+class InvalidMetadataFilterError(ValueError):
+    """Raised when all client-supplied metadata filters are rejected."""
+
+
 class ThreadMetaCreate(BaseModel):
     model_config = ConfigDict(extra="forbid")