The problem
Marketplaces like this are easy to game: both sides can settle off-platform and dodge the commission, and chats can be opened on somebody else's request.
What we built
We closed each path in turn: a participation check on every chat, cash confirmation bound to ownership, and rejection of empty coordinates that were silently killing orders.
The result
An extended audit against the requirements document surfaced 53 confirmed defects, 5 of them critical — all closed, with the platform covered by 118 automated tests.
