Backend/Domain foundation

Today I continued my TypeScript learning project after a short break.

Instead of jumping into React right away, I decided to keep working on the backend/domain side of the Candidate Tracker project.

The main lesson today:

• TypeScript is not just useful for components and props.


• It also helps clarify ownership, data flow, and service boundaries.

Some examples from today:

• using Omit and Partial to define create/update inputs


• deciding which fields the caller can change and which fields the service owns


• using generics for reusable helpers like findById and filterByProperty


• typing async repository functions with Promise<AsyncResult<T>>
  


• using Promise.all for independent data loading


• splitting async loading into stages when later data depends on earlier results

One useful distinction:

• Services express behavior.


• Repositories decide where data comes from.

That separation should make the next steps cleaner: adding tests first, then replacing seed data with a real database later.

I’m intentionally delaying the frontend a bit.

Not because React is less important, but because I want the domain and data flow to be understandable before putting UI on top.

Next step: tests.