In a redefined service, generation creates base DPC/MPC classes and _EXT extension classes. Which one do you put custom CRUD logic in — and what happens if you code in the wrong one?

When you add a property to an entity type in a redefined SEGW service, you fill in Name, Label, EDM Core Type, Max Length, and the ABAP Field Name binding. If the binding and the EDM type/length disagree, which one governs — and why does that matter?

An extension touches the ABAP back end, the Gateway (ABAP front end), and the UI layer. A teammate opens SEGW to add a DDIC append field. What did they get wrong, and which tool belongs to each layer?

SAP ships the full SAPUI5 project of every transactional app. Does that mean you can insert custom content anywhere in any view — and how do you know where you actually can?

A colleague claims the nine-step Fiori extension flow survives standard-app upgrades 'because everything is in its own transport.' Why is that the wrong reason, and what is the real one?

You deployed a custom app and set up LPD_CUST, the FLP catalog/tile, and a PFCG role — but the tile still 404s. Which easily-skipped step did you likely miss?

Your extended view shows the binding key {i18n>EXT_STATE} literally instead of the word 'State'. Where must the text live, and why not in the app's existing properties file?