语言说明 / Language Note: This post is bilingual. Each section appears in English first, followed by a 中文摘要 (Chinese summary). Jump to any section that works for you.

Some projects accumulate debt quietly. Leverage OJ was not one of them — it accumulated it loudly, in the form of a ranking system that froze mid-competition, an auth system that broke under PM2 clustering, a leaderboard that scanned the entire submissions table on every request, and a password hashing scheme that was one config leak away from a full credential dump.

Every codebase has a story. Leverage — the Online Judge platform I've been maintaining — has one too, and it's not pretty. After years of incremental feature additions, quick fixes pushed at midnight, and the occasional "works on my machine" hack making it to production, the codebase had accumulated enough debt to fund a small startup.