Constant UNCLAIMABLE 

const UNCLAIMABLE: [(&str, &str); 1];

Pages in the facade’s tree that no map key can claim, and why.

Written as a list of (prefix, reason) rather than left to a comment, because the reverse check is only worth having if every exception to it is stated. A page matching a prefix here is skipped and the reason is printed in the summary, so the exceptions stay visible rather than becoming invisible once they are written down.