Why modules first
Your service starts as a module. A module is the unit Go uses to track your packages, dependencies, and Go version.
For this track, your final repo must be easy for a recruiter to clone and run. A clean go.mod file is the first proof that your project is a real Go project, not loose files.
Remember this
Start every Go service inside a module, before writing handlers or adding packages. The go.mod file is the project’s dependency record.