https://takanomedev.com My personel space where i write about things i learn en-us Mon, 10 Aug 2026 13:57:51 GMT https://takanomedev.com/writings/mistake-made-with-concurrent-requests A double-submit bug let users request more than their available balance. The fix was one database lock — and a rule I now follow everywhere. Sat, 25 Jul 2026 00:00:00 GMT https://takanomedev.com/writings/mistake-made-with-concurrent-requests