Function single_trunk_guard 

pub fn single_trunk_guard(
    ctx: &Ctx,
    run: &mut Runner<'_>,
) -> Result<StepState, RkError>

The destructive step’s own guard: whether deleting a candidate branch can lose work.

Satisfied means every candidate is already gone or is an ancestor of the trunk; Unsatisfied means the deletion must refuse.

Errors

Propagates executor failures.