Handle edge cases in caching

**Description**
Currently validation lacks proper serialization support.

**Proposed solution**
Add configurable serialization with sensible defaults.

**Priority**: Low/Medium

Start by tracing the existing caching and validation flow to identify where serialization is currently assumed or missing. Clarify the supported configuration and default behavior with the maintainers, then add coverage for validation and relevant caching edge cases; done means serialized values behave consistently under the chosen defaults and configuration.

Written by the indexing model from the issue text.