Close the Session Controller's remaining per-file coverage debt: a named
fork adopting the child its earlier attempt stored, refusing a name another
Session holds or one seeded at a different cut, and the named-child
observation failures; prompt admission sharing one in-flight requestId and
refusing a duplicate from another caller; the retry read from a drained
splice; the access-withdrawn and aborted-admission delivery paths; cancel
after the caller's grant is gone; and the Assistant settlement that appends
past the last entry. Test-only: no production behavior changed.
mektpoy
bbccdd5141