Manual file locking

I am new to OC and have been evaluating the system and it all looks great, except for one item, the ability to lock a file so that only one person can use/edit the file at one time. I have read about OC allowing multiple uses to edit one file at the same time and that sound interesting. But I just need to be able to lock the file so that other uses can then see the file is locked and if they try to use it will just say it is in use.

Have done a couple of searches but can only find multi-use edit and that OC uses locking to stop multiple uses from save the file at the same time.

Is there some way to do simple file locking IE Lock the file, do some work on the file (Edit), unlock the file. When locked other users can only access the file as read only. Is there an add-on that does this?

No, this is a feature request for the future. Please check in github for the proper issue and add your input. How would you deal with the issue that people forget locks - what happens then? What about editing off-line? etc. Do you know a system which provides this feature and works perfectly - how does it work, etc.

File locking can be complex but when the file is locked the system would need to note the PC and user that locked the file.

If they leave the lock set on the file then a timed warning (admin timeout setting) popup/nag screen from OC client.
Plus option for the administrator to clear the lock.

For offline editing - provide a category/tag for files/folders that can only be accessed online. If user edits OC client file on local drive then OC client locks the file locally and on the server - no file lock no edit - just read only.