I switched machine the other day and waited for Dropbox to sync a bunch of files, then I started working. But I forgot that rules.dropboxignore was not synced. I had read the doc a while ago, created it with meaningful rules, it was fire-and-forget. I noticed that some files started getting synced like .obsidian/workspace.json every time I close a tab in Obsidian, or the heavy npm_modules of a web project causing vite.js Error: EBUSY: resource busy or locked while Dropbox app running (https://stackoverflow.com/questions/74133060/vite-js-error-ebusy-resource-busy-or-locked-while-dropbox-app-running , so for non-clickable URL, I get error "Site's 'stackoverflow.com' robots.txt did not allow access to the url." when auto-generating hyperlink because it tries to create an image preview, and preventing me from Posting (and even saving draft) altogether — I think it should be allowed to simply disable the preview in this case, but I had to remove the whole hyperlink).
When I went to Dropbox root, I saw that rules.dropboxignore was missing, I had to create another one in Preferences > Sync > Create rules and only then I noticed that it was not synced.
It's very convenient to sync an ignore file in VCS like git .gitignore so that myself on other machines, or team members avoid committing unwanted files.
In this case rules.dropboxignore is only in Dropbox root so the "team" case doesn't happen, but if you implement rule files in sub-folders later (another feature request I'd like, but would need to open another ticket) then it will make sense for teams working on shared folders as well (otherwise, my teammates who forgot to setup a local ignore file will still sync their npm_modules… and that will be particularly odd as I will receive them although my own ignore file says I shouldn't! I wonder how it actually currently works with shared folders if people having conflicting rules on their root ignore file)
To preserve retrocompatibility, you may create a new rule file with a new name (not very elegant since you'd have to add a 2nd button in Sync Preferences UI just for that, but safer). Maybe synced_rules.dropboxignore or something (I would have rather called the other one local_rules.dropboxignore to be extra explicit).
Only that new file would be synced, and always in priority by Dropbox since it will control how other files are synced. In case of conflicts, it will create the usual "(conflict by … on …)" safety files and warn the user (important since it's a critical file).
For now, as odd as it may seem, I have to create a copy of rules.dropboxignore on the same Dropbox, but with a different name (to avoid the hardcoded check preventing sync), and on a new machine, duplicate that file and rename it to recreate the same config – or manually copy-paste the backup content of the file – not very elegant.
