Developed a readonly persistent cache feature for the web-infra-dev/rspack repository, targeting improved performance in continuous integration environments. The solution introduced a disk-backed cache that supports read operations without writes, reducing I/O and enhancing build determinism during CI runs. Leveraging JavaScript and Rust for backend development and testing, the implementation included robust handling of storage resets to ensure data integrity and prevent partial writes. Additional guard rails were added to stabilize readonly mode, while expanded test coverage and updated documentation facilitated adoption. This work delivered measurable improvements to CI throughput and reliability, with a focus on maintainability and minimal operational risk.