I'm trying to understand how the project state machine works - I've read through here: https://github.com/LLK/scratch-gui

So when you click on the “Save now” button, it sets the state to MANUAL_UPDATING (I think), but nothing actually happens. So I can see that the state is changing, but at what point is a call made to the projectHost to save it? And do those calls exist already, or do they need to be added to the scratch-gui?

Thanks!

When the state is MANUAL_UPDATING, getIsUpdating returns true. (https://github.com/LLK/scratch-gui/blob/develop/src/reducers/project-state.js#L87 ) getIsUpdating change are received by Project Saver HOC(High Order Components) - https://github.com/LLK/scratch-gui/blob/develop/src/lib/project-saver-hoc.jsx , because they have isUpdating props set to its value (L413). If it changes, componentDidUpdate will be fired, and since isUpdating changed, updateProjectToStorage is called there (L81). updateProjectToStorage(L155) calls storeProject as well as handle errors. storeProject(L219) saves all assets and call onUpdateProjectData(L247), which by default, is saveProjectToServer(L398).

TL;DR: 1) When state changes to MANUAL_UPDATING and HOC receives the state change. 2) Yes, it exists. (see above)