Design Large-Document Uploads and Multi-Device Synchronization

Design a document-sharing service that supports uploading documents, including large files, and synchronizing changes across multiple devices. ### Clarifying Questions Clarify whether documents are opaque files or collaboratively edited content, how sharing permissions work, and how concurrent offline edits should be resolved. No file-size limit or traffic target is supplied. For a baseline, treat documents as versioned files with explicit conflict copies rather than real-time character-level collaboration. ### What a Strong Answer Covers Resumable uploads, metadata and object storage, version publication, change discovery, device cursors, permissions, deletions, and concurrent-update handling. ### Follow-up Questions - How do you avoid exposing a partially uploaded file as the latest version? - What happens when two offline devices edit the same base version?