Function explore 

pub fn explore<F: Fs>(
    db: &GraphDb<F>,
    repo: Option<&Path>,
    target: &str,
    depth: Depth,
    full: bool,
) -> ExploreReport

Everything depth asks for about target.

repo and full are context_with’s: the working tree the body is quoted from, and whether to quote one at all. Every other answer is the graph’s alone.

A target that resolves to nothing — an unknown name, or an ambiguous bare one — has no file behind it, so no depth adds anything: the answer is the context report, which is the one that says why there is nothing else.