What an offline verification of a custody or genealogy bundle leaves to the
reader. Every header in the bundle carries proof of work and nothing more, so
the result holds against whatever chain the reader takes as real. A hop
header's hash is a value any caller can check against any chain view at no
marginal cost, which is why saying so is a complete remedy here and why the
unprovable heights the verifier refuses outright are a different case: those
appear in no header, so no amount of chain view settles them.
What an offline verification of a custody or genealogy bundle leaves to the reader. Every header in the bundle carries proof of work and nothing more, so the result holds against whatever chain the reader takes as real. A hop header's hash is a value any caller can check against any chain view at no marginal cost, which is why saying so is a complete remedy here and why the unprovable heights the verifier refuses outright are a different case: those appear in no header, so no amount of chain view settles them.