17 May 2026 · 3 min read
The case of the disappearing discount
A customer pinged us because their checkout said "Promo (LAUNCH15) -$0.45 → $2.82" but the USDT QR generated for the full $3.32. A 13% leak hiding behind a column that stored the gross amount instead of the net. Here's how we tracked it down and the regression test that locks it.