#18 verified there is no spurious load-narrow on a chained global-ptr field read into an i64 sink -- the only MOVSXD is the legitimate :i32 return cast, byte-identical in both stages. Lock it: a chain_i64_sink row reads q:i64 = 0x1_0000_0001 and asserts the high word == 1. A truncating load-narrow would drop the high word to 0, so the row pins the spine-narrow family (runtime + byte-id, both stages).