Butler is itch.io's build-upload tool. Push a test build to a nonpublic channel, install it with the itch app, then push a small update and confirm that the right files and version reach that channel. Test the same steps from CI if automation is the goal.
Keep channel names and credentials explicit. A fast incremental upload is valuable, but a mistaken channel can expose the wrong build. Record how to inspect a release, promote it, and recover if an upload contains a bad artifact.
Akousa