Worked on the rolldown/rolldown repository to stabilize asset deduplication under concurrent conditions, restoring full parity with Rollup and ensuring deterministic, reproducible builds. Addressed a race condition that previously caused metadata loss during concurrent asset emission by introducing locking mechanisms to preserve asset references and original file names. Implemented deterministic naming for deduplicated assets by consistently selecting the shortest name, with lexicographic tie-breaking, to align outputs with Rollup and reduce build variance. Comprehensive tests were added to validate asset deduplication behavior under concurrency. The work leveraged Rust, backend development, and concurrency expertise to improve build reliability and cross-tool compatibility.