Worked on the espressif/esp-usb repository to deliver a compatibility-focused update for USB Mass Storage FAT registration, targeting support for ESP-IDF 5.3 and newer. Refactored the driver codebase in C to utilize esp_vfs_fat_register_cfg with conditional compilation, replacing the legacy esp_vfs_fat_register function. This approach improved the robustness and maintainability of both host and device implementations, ensuring smoother upgrades for users transitioning to newer ESP-IDF versions. The update addressed cross-version compatibility challenges in embedded systems and driver development, reducing integration risks and build-time errors while aligning the USB MSC stack with evolving ESP-IDF filesystem APIs for forward compatibility.