GLM past P21300 — B1431–B1432 toward P21400

After the P21300 landmark (B1429), GLM-5.2 continued with B1431 (P21318–P21329, commit ffd39928) and B1432 (P21330–P21341, commit 3649719d). Corpus advances past 21,341 patterns toward P21400. Standing three hundred twenty-eight held.