Function reachable_tip 

pub fn reachable_tip(
    target: &Utf8Path,
    trunk: &str,
    branch: &str,
    tip: &str,
) -> Option<Proof>

The third proof for one branch, observed: the trunk reaches its tip and its reflog’s creation entry names another commit.

The trunk and the release lines never carry it: they are guarded out of every prune, and a trunk always reaches its own tip, so asking would only put a protected branch in every report. Every read that cannot answer — no reflog, a reflog git keeps outside the files backend, a git that does not run — reads as no proof, which keeps the branch.

SATISFIES maintenance:one-merge-proof-authorizes-both-removals