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I have following layers in my app: `UI` , `Presentation` , `Business` and `Data` . I’m launching a coroutines from the `Presentation` layer where I have setup `backgroundScope` with an exception handler. I want to share a `Flow` in the data layer using `shareIn` operator. Which scope should I pass to it? If I pass different scope than the `backgroundScope` used in the presentation layer, the exceptions won’t be propagated up to the exception handler in that `backgroundScope` . Also I want to share that `Flow` globally, not in the scope of that `ViewModel` in the presentation layer. So the question is how to share a `Flow` on the data layer from some repository class which is a singleton and still propagate the exceptions to the exception handler that’s setup in the presentation layer?

Do you *really* need the Data layer `Flow` to be a singleton? This becomes trivial if you just share within the Presentation layer.

If you want `backgroundScope` to handle the exception, you have to throw it in the Presentation layer. If the Data layer encounters an error, it can encode that as an error event in the `Flow` (part of a sealed class or `Result`). The Presentation layer can re-throw the exception when it encounters the error event. This pattern of encoding errors into the data is what the `SharedFlow` docs mean when they say "All errors and completion signals should be explicitly materialized if needed"

Don't forget about situations if an error may happen when there is no Presentation layer (do you need to save it?), or if many collectors may encounter the same Data layer exception (will you spam the user or crash reporting?).