How to make new file permission inherit from the parent directory?

Problem

I have a directory called . Then I am running a script under the user id 'robot'. robot writes to the directory and update files inside. The idea is is open for both me and robot to update. So I setup the permission and owner group like this where both me and robot belongs to the 'robot-grp'. I change the permission and the owner group recursively like the parent directory. I regularly upload new files into the directory using . Unfortunately, new files uploaded does not inherit the parent directory's permission as I hope. Instead it looks like this When robot tries to update , it fails due to lack of file permission. I'm not sure if setting umask helps. In anycase the new files does not really follow it. I'm often confounded by Unix file permission. Do I even have a right plan? I'm using Debian lenny.