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Stage 5 of 7 · Break it

Dropbox-Style File Sync Service: Two offline edits are both real work

The files can be arbitrary binaries: text documents, photos, archives or video. The server does not know whether merging bytes would preserve the user's intent.

System so far· 2 parts
1CLIENTDesktop andmobile clientsSERVICEChange notifier

Select a component to see what it is responsible for and which state it owns.

  1. 1Change notifier → Desktop and mobile clients: Wake, then page from cursor

What you need to know

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  1. A last-write-wins update silently discards one valid edit. Compare the client's base revision to the current revision at commit. If they differ, preserve both versions or create an explicit conflict copy. A product-specific merge is appropriate only when the format has a safe, well-defined merge algorithm.

  2. Check

    Both versions changed since revision 12. What is the default for arbitrary files?