Built the loyalty and reputation system — 67 functions over a 31‑table ledger, with leagues, badges and a redemption shop — taking a row lock on the balance to close the double‑spend window.

Situation. Professional networking has a cold start problem: the platform is worth using once other people are already using it, and until then there is little reason to come back. The usual lever is a rewards system — points for contributing, standing that reflects reputation — which is easy to describe and treacherous to build, because the moment points can be spent they are money, and every mistake money makes is available to be made here.

Task. Contribution had to be measurable and rewardable, with a balance that could not be spent twice.

Action. The loyalty schema runs to 31 tables and 67 functions, with standing in a further 5 tables and 32 functions, and discovery and personalization schemas alongside them to decide what a given member sees. On top of the ledger sit leagues, badges and a redemption shop where a balance turns into something real. The part that took the care is the oldest bug in the book: check the balance, then spend it, and two requests arriving together both pass the check. Every mutation takes a row lock on the wallet before reading it, so the second request waits for the first to finish rather than racing it. That the wallet is in the same database as everything else is what makes it possible at all — the balance and the thing it bought commit together or not at all.

Result. Contribution is measured and rewarded, and a balance is arithmetic rather than an approximation. Row locking is the slower answer and was chosen anyway: contention on a wallet is a queue, and the alternative is a member spending the same points twice and someone reconciling it by hand afterwards.