While not an inventory system or anything bound to your account, You can actually backup objects but keep them locally on your hard-drive / or use an pre-existing object json on a url, and you can import it via Unlocking the Advanced Menus
Scripts, unfortunately have to be either static defined and aren’t so quick to be edited, unless its running only locally.
If you just want to use it for your self or when developing, you can always just use a file url, like
to the script and it will automatically update as you edit the file: Just note that this will not work for anyone else but you. and any update that breaks the script engine, you may have to relog.
For other cases you’ll have to pull the script out, modify it, and then place it in the ATP which generates the URL, However do note, while partially harder to copy, ATP stuff is only available on your own sandbox domain, and if you want to use them outside your domain, you must use a web service to host your files, such as the amazon etc.
If you want to do it your self, there are myriad of “how setup an html server” tutorials out in the web and so forth, but I suggest looking up an existing web service, which allows for files, that does it for you instead if you dont have the time or patience to learn web security.
So the shorten, You can develop your stuff locally, then once its ready upload it to your web service, and you should be set to go. When updating the asset, you use the new url generated, or if just a simple web host, just add a parameter to cache bust.
A Little known feature however is that you can also, instead of pasting script URLs, you can paste the actual code directly into the Entity ScriptURL path. This however is limited for very, very small scripts however ( I estimate, 512 characters, havent tested it fully yet), and not something that should be done often.