This document is meant to record the intended effect of future changes and the tasks that have to be performed to bring them to fruition.
If a given note is changed on two devices while they are offline then when they go online one of them might discover that it has changes that are newer than the supposedly new version the server.
We can reconcile many such changes automatically if we maintain a copy of the file as it existed before both sets of changes. We can then do a three way merge on the using the ancestor file the most recent file uploaded to the server and the local file. The result replaces the local file. The most recent server file replaces the ancestor and the new local file replaces the server file.
To make this happen we need the following:
- Save the ancestor file,
- Add a library that can do a three way textual merge.
In addition we should implement some way of locking the files so that two devices attempting to synchronize simultaneously will not interfere with each other. This can probably be left to a later time on the grounds that such collisions will be rare.
To connect ancestor files and current files we will need either to maintain the uid of the ancestor in the database record or abandon the use of uid and give the files names that can be discovered from the subject lines. That way we can store the same message in two folders on the server, one for the ancestors and one for current files.