Payload paginates by page, so floor(offset/limit)+1 alone returned the wrong window whenever offset % limit != 0 (B9). Fetch the straddled pages and slice the intra-page remainder. The test stub now honours page like real Payload (it silently ignored it before), and the contract pins aligned + non-aligned windows on mock and stub alike. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>