Justine Peterson Mahinyila — Writing https://justinecodez.com/blog Engineering notes from production systems in Tanzania. en Debugging a UTC vs EAT epoch boundary bug in a telecom campaign engine https://justinecodez.com/blog/utc-vs-eat-epoch-boundary-bug https://justinecodez.com/blog/utc-vs-eat-epoch-boundary-bug Wed, 10 Jun 2026 00:00:00 GMT A campaign engine misbehaved for exactly three hours a day. The root cause: midnight-boundary date bucketing disagreeing between UTC and UTC+3.