The review's follow-ups on the open-seal fix: (1) the settlement note's seal
section now records the HOST-side open hold seal (openParts -> openSealed,
mirroring the child _LogStream and stray-capture seals), paired. (2) the
first-fragment guard comment notes the empty-first-frame case (bills cost + 1 =
3, establishes no hold, bounded over-charge in the safe direction). (3) a
regression case commits a SEALED open hold before the truncation marker —
verified to fail if truncateLogs drops openSealed.