app-component.json

By default, an app-component.json file is added to each project. This file opens a flow to test your new component before the release.

This file already embraces all the project files - component.html, component.js, and config.json. When you are done with some editions in these files, open app-component.json, Apply Changes (to apply changes in the project files), build a flow, hit Deploy (to apply changes in the flow), and test the component’s appearance and behavior.

You should remove and drag a component that you changed on the workspace again after hitting the Apply Changes button - otherwise, the component will remain obsolete.

Deploying will not save the flow for future work with the project. To save the flow in app-component.json click Apply Changes, even if you didn't change the project files and just played with the flow after the last saving.

See how to save the project properly in Compose an App.