When extending a Fiori app, which tool serves each layer — ABAP back end, UI layer, and ABAP front end?

How do you prove the extended service really carries the new field, rather than trusting generation?

What are the six UI-layer extension steps?

After successfully generating a custom OData service in the back end, it is still inaccessible from the client. Which registration step is missing?

In an SAP Fiori extension scenario, which skills does each layer demand?

Once a custom app is deployed, which steps publish it to the launchpad?

What does SAP ship that makes UI-layer extension of transactional apps possible?