How I Built a Masking Tool Without Showing AI Any Real Data: Column-wise Shuffling as the Scaffold

TL;DR I never write code or send real data to LLMs — but I built a complete data-masking tool through AI collaboration. The technique: column-wise independent shuffling (Japan PPC's official anonymization method) plus Faker replacement. Four phases: send column names → run shuffling batch → manually craft sample CSV → send sample for Faker batch + structural review. Key discipline: survey naive ideas in industry terminology before having AI implement — that alone compresses code 10x. The output