The 13 active rows keep compile + cs==ws byte-id and the hidden-RDI
"(BP), DI" presence/absence polarity (present iff sret-class; the two
exactly-32B boundary rows must stay register). The per-row driver
build+run legs move to the r926 run fixture corpus per the residual
audit port split; the seven buildfail rows were already dead here,
owned by the r926_sret_reject_* fixtures.