Owner prime_gap_density. Write only routes/prime-gap-multistrip. Read-only inputs: routes/prime-gap and lab branch research/prime-powers 1aff81ebbdb5b749c638a6450016e167f9b3f61e, lab base f4ef0715bbe2f4890b3dcea034757ef0c823053a. Goal: multi-strip density refinement for all-n seventh-power prime intervals under QRH(7/8), keeping prior eighth-power result unchanged. Each run serial below20sec; no paid compute, Git edits or external writes.