The page transition diagram helps you easily understand the positional relationship between pages by visually representing transitions as a diagram. In the case of an SPA (a single page app), requests (HTTP(S) communication) are considered to be in JSON format, and there are no page transitions in general.
For that reason, a page transition diagram is not suitable for this type of application in the first place.
However, you may create a page transition diagram and use mechanical scan settings (bulk settings) by manually adjusting the positional relationship of each request. However, if there are values to be handed over within the JSON format parameters, use Handler since bulk settings cannot be used.