sub output : Chained('buildChain') PathPart Args(1) {
    my ($self, $c, $outputName) = @_;
    my $build = $c->stash->{build};

    error($c, "This build is not finished yet.") unless $build->finished;
    my $output = $build->buildoutputs->find({name => $outputName});
    notFound($c, "This build has no output named ‘$outputName’") unless defined $output;
    error($c, "Output is not available.") unless isValidPath $output->path;
    $c->response->header('Content-Disposition', "attachment; filename=\"build-${\$build->id}-${\$outputName}.nar.bz2\"");
    $c->stash->{current_view} = 'NixNAR';
    $c->stash->{storePath} = $output->path;
}