I'm trying to figure out where the app content is served from in a distributed deployment. For example, is the entirety of each app stored on every server in the deployment, or is it served from a single location?
What sort of distributed environment? In a simple search head/indexer set-up, make those changes on the SH then restart the SH. In a search head cluster, make the changes on the SHC deployer and apply the bundle.
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For your second question answer is yes. Actually it’s better to use some other tools like code editors with suitable add-ones. You should do this on your own dev environment and then distribute app as package(s) to the target servers.