Okay I'm a jerk for not telling you this before but, despite the "don't send in an action" rule, there is a send action, which gets around the rule because it's one of those special pure actions that the interpreter knows what to do with. I'm noticing that we're sending REFRESH_TIMELINE every time we go into build.idle. Putting sends inside of services makes it less obvious that they're happening (like, they don't show up on the diagram) and doesn't capture that pattern.

So I'm wondering if we can add an entry action to build.idle to send (this is imported from xstate, like assign) REFRESH_TIMELINE. I'm also wondering if we really do want to refresh the timeline whether the service succeeds or fails. If we don't want to do it in case of failure, I'm not sure we can make actions conditional the way we can make transitions conditional with guards. So in that case I might just add the send action to the end of the action lists for each onDone. At least that way we can see in the diagram that they exist.

I don't see a reason to nest idle inside loadedBuilds. It's just one state. Also, I'm concerned that we have a state called idle that has no outgoing arrows. I'm not sure what the best resolution is (do we want to be able to retry? was it intended to lead to the other idle?).

Sure, I can take idle out of loadedBuilds.

Regarding the second idle (the one we transition to after error): I think perhaps it would be best to get rid of that and, in the case of an error, transition right back to loadedBuilds. This will give the user to ability to retry loading timeline. In the future, if we want to build a more concrete UI around the error case, we can.

The machine will be simplified like:

If we don't want to do it in case of failure, I'm not sure we can make actions conditional the way we can make transitions conditional with guards. So in that case I might just add the send action to the end of the action lists for each onDone. At least that way we can see in the diagram that they exist.

I'm a fan of this approach but I'm having a hard time using that send action pattern within an onDone:

Types of property ‘onDone’ are incompatible.
  Type ‘{ actions: string; target: SendAction<unknown, EventObject, EventObject>; }[]’ is not assignable to type ‘string | SingleOrArray<TransitionConfig<WorkspaceContext, DoneInvokeEvent<any>>> | undefined’.

There are two refreshingTemplate states, one at the top level, and one inside the build submachine. The inner one has no incoming arrows, so I don't think it will ever happen. Not sure if it should happen or just needs to be cleaned up.

I can clean this up. I got rid of the stale one, and renamed the other one to getTemplate since we aren't refreshing.