The frontier becomes finite: a proved stop rule
An unbounded search was turned into a finite checklist. A proved stop rule says checking the primes up to a computable bound settles the away-generation question; the away algebra is boxed between exact dimensions 75 and 81, and every prime tested so far collapses into the known algebra.
Exact statement
The scalar deck-filtration stop rule at Sturm bound 2592 is proved by compactified finite-etale torsor and fpqc descent. Sandwich 75 <= dim H_away <= 81 by exact computation with independent replay; T3, T13, T17, T19, T23 each add exactly zero directions; certified prime ledger {2,3,5,11,13,17,19,23,29,43,53,59,79}.