Developed a scalable bulk thread-subscription workflow for the matrix-org/matrix-rust-sdk repository, focusing on backend efficiency and data integrity. Leveraging Rust and asynchronous programming, implemented a bulk upsert API for thread subscriptions within the StateStore interface, supporting in-memory, SQLite, and IndexedDB backends. Introduced bump-stamp logic to ensure updates were applied only when appropriate, maintaining consistency during bulk operations. Enabled bulk processing of thread subscription updates from both sync responses and a companion endpoint, which improved throughput and reduced per-update overhead. Added comprehensive tests and validation to verify cross-backend consistency, resulting in faster, more reliable subscription processing for users.