Delivered a robust file download suite for UKGovernmentBEIS/inspect_ai, enhancing data integrity and reliability by introducing SHA-256 checksum verification, caching, and transient-error retry. Implemented download() and gdrive_download() wrappers to fetch external files efficiently and safely. Ported the existing, battle-tested helpers from inspect_evals.utils.download to align with broader Inspect practices and enable cross-repo reuse. Features include atomic writes via a .partial tempfile, checksum-mismatch cleanup, and skip logic when destination exists with a valid checksum. Integrated gdrive_download() using optional [gdown] dependency for Google Drive sources. Reused httpx_should_retry policy to improve resilience against transient network errors. Overall, these changes reduce failed downloads, lower bandwidth usage, and standardize external file retrieval across the Inspect ecosystem.