Function expand_paths 

pub fn expand_paths(
    paths: &[PathBuf],
    predicate: fn(&Path) -> bool,
) -> Vec<PathBuf>

Expand a list of explicit paths (files and/or directories) into a sorted, deduplicated set of files matching predicate.

Dedup because drep check a.rs . would otherwise pay a whole LLM round-trip twice. An explicit file is filtered by the same predicate as directory walks, so naming notes.txt cannot smuggle in a type drep does not read; conversely, gitignore is not consulted for explicit files — the user naming a path is a stronger signal than the repo’s ignore file. Paths that do not exist are skipped silently.