Where it usually breaks
And how to keep it from happening.
- Allocation exceeds receipt. Compare all component amounts with confirmed received money before accepting the result.
- Different entry point bypasses the guard. Exercise both page-triggered and repeated runs against the same schedule. The existing unreversed allocation must still block another allocation.
- History overwritten. Preserve the original application and schedule context when correcting executed work. An unexplained balance edit cannot substitute for reviewed change evidence.