During May 2026, this developer enhanced type safety in the DefinitelyTyped/DefinitelyTyped repository by refining the encoder and decoder utilities. The primary focus was on replacing the use of the 'any' type with 'unknown' in both defaultEncoder and defaultDecoder, a change aimed at reducing runtime errors and increasing developer confidence in downstream code. Working exclusively with TypeScript, the developer leveraged strong type safety principles to ensure more predictable and maintainable code. This targeted update improved the reliability of type definitions across the codebase, demonstrating a methodical approach to incremental improvement within a widely used open-source TypeScript project.