I've been trying to find a good solution to this problem for *years* but I'm still hitting problems with it. The current problem is that syncthing doesn't deal well with directories and files which have different owners on different systems.
The essential problem is that web files which are manipulated by apache need to be owned by www-data but I want to be able to edit these files as well. In particular I have a wiki where I sometimes edit the files using the wiki (ownership ends up as www-data) and sometimes I edit them directly with an editor (ownership ends up as chris).
Currently I use access control lists (setfacl) to make things so that both chris and www-data can both manipulate files in the wiki directory regardless of whether they are owned by chris or www-data but this isn't a perfect solution as the correct settings don't always get put on new files.
What I really need is:-
All the wiki files are owned by 'chris' (the wiki is rooted in my home directory and is synchronised across a couple of machines by syncthing).
www-data can read/write/create files in the ~/chris/wiki directory but they will always be owned by 'chris'.
Can anyone see a way of implementing this? ... or any other reasonable solution?