Is it correct that a .feature file always maps to a step file?

Not necessarily. A .feature file in Cucumber or SpecFlow describes a feature or user story in the application under test. The steps in the .feature file are implemented in step definition files, which contain the code that will be executed for each step in the scenario.

So, in general, a .feature file maps to one or more step definition files. However, you can also have multiple .feature files that map to the same step definition file, especially when the steps are reused across multiple scenarios.

In summary, there is a one-to-many relationship between .feature files and step definition files, with each .feature file potentially mapping to multiple step definition files.