Question: best approach for a Sharepoint embedded app #302

Hi all,
before going deep in trying it, I'm thinking on the best approach to create a sharepoint embedded app and would like some suggestion here. Prompts exist for such apps (i.e. contoso legal starter) but would like to use spec driven approach.
While the specify step is clear to me, I'm wondering what is the best place to put api list, external references and so on.
Should I put in the constitution.md all the links to the docs and in the plan phase the APIs I want to be created? Other ideas?
Thanks