Function doas_persist_snippet 

pub fn doas_persist_snippet(choice: DoasPersistChoice, username: &str) -> String

What: Build a recommended doas.conf persist snippet for the selected profile.

Inputs:

• choice: Selected snippet profile.

Output:

• A single-line permit persist recommendation.

Details:

• Generated text is guidance only. The app never writes /etc/doas.conf automatically.