Hello and welcome! This question is so good it deserves it’s own permanent example!
Your instinct is good—it’s an anti-pattern to modify your code to suit a tool like Guild. Guild should support your project, not the other way around!
The example shows how output scalars are captured using patterns from output. The configuration is one of the more advanced forms supported by Guild, but it shows the flexibility.
For more examples on how to configure output scalars, see Guild File Reference.