Leonard R. developed an extensible assertion metadata feature for the contentauth/c2pa-rs repository, enabling support for arbitrary key/value fields beyond the standard schema. He designed and implemented a robust set and get API in Rust, allowing clients to define custom metadata attributes while preserving provenance integrity. Comprehensive unit tests were written to ensure correctness and prevent regressions, with particular attention to schema compatibility and metadata manipulation. This work improved the flexibility and interoperability of C2PA assertions, reducing integration effort for downstream systems. Leonard’s contributions demonstrated depth in API development, Rust programming, and software engineering best practices within a focused project scope.