Who is planning the REST API in the SPA application?

Question

Software design

Please tell me how to organize team work?
The team has 1 frontender and 1 backender. The task is to make a SPA application with a REST API on the back end.
Which of them should think about what endpoints and data structure should the REST API have?
1. The frontender makes the front and, as necessary, tells the backender what API endpoints it needs and with what data
2. The backender designs the API on its own, and the frontender adapts to its structure
3. Or are there other options?

Answer 1

The type that the business model knows is described to developers, then the back builds the api, and the front builds the front, everyone should already know approximately what he needs and the front can successfully build its object interfaces for mocks and then it can already map fields with api if you want to try to negotiate so that less mapping, that is, response description standards, for example https://jsonapi.org/

Answer 2

The "type" that describes the model is called the analyst.
Make a mind map, describe the structure, create sprints, describe the structure in sprints, hang small tasks as smart tasks.

Answer 3

let them sit down together and discuss politics. Ideally, a more experienced one would design, but does anyone bother them to communicate?
The main thing is that the recorded things are recorded somewhere. Like one said "this is needed", the second looked, made sure that it was feasible and looks normal, confirmed it.
After that, you can start working independently, you can do two stages for the backend - when the backend makes an endpoint with a stub, and when it makes a full-fledged endpoint.
You can use UML to write