Challenge
Both of the hard kinds of work met here at once.
The first is a live platform on a closed third-party engine: one hundred and forty-three modules, one hundred and thirteen tables, part of the core unreadable by design. Behaviour is established by experiment, and the system moves real money every day.
The second is a new generation written from scratch, which has to be safer than its predecessor in the places where the predecessor relied on luck.
Solution
We did not rewrite the legacy platform for the sake of rewriting it. We took it apart, documented what experiment could establish, and maintain it in targeted pieces, starting with payment integrations.
The new generation was built around the two things that decide everything here: balance correctness and key protection. Operations are idempotent, a repeated callback does not credit twice, and concurrent debits cannot push a balance below zero. Keys are stored encrypted, with the encryption key outside the repository.
Architecture and implementation
What was done:
· mapping and documenting the legacy core, closed modules included
· maintaining payment integrations on both platforms
· an incoming operations flow with automatic crediting
· withdrawals behind a multi-step check, and user-to-user deals that lock funds
· identity checks and anti-money-laundering controls
Stack: Laravel and PHP, PostgreSQL, Redis, plus the inherited environment of the older platform.
Result
Both platforms are running. The value here is not in the subject area but in two skills that rarely appear together: holding load and money in a new system, while maintaining somebody else's, where there is neither documentation nor access to part of the source. The second usually costs more than the first.
