This is a submission for DEV's Summer Bug Smash: Clear the Lineup powered by Sentry.
Project Overview
Polymarket ships a unified Python SDK, py-sdk, for building on their prediction market: constructing, pricing, signing, and submitting orders. It's currently in beta and moving fast, which is exactly where money path bugs like to hide. I've been running the SDK against live markets, so I pointed an audit pass at its order validation and signing code and found a real one.
Bug Fix or Performance Improvement
Before an order is signed, the SDK validates the price against the market's tick size (the smallest allowed price increment). Two functions do this, _resolve_price for limit orders and _resolve_protected_market_price for market orders, and both check the wrong thing. They validate the price's decimal place count, not whether the price is an actual multiple of the tick:
