Illia Kotvitskyi

A client disputed a data discrepancy and was escalating toward cancellation. I reconstructed the transaction timeline from audit logs and found an async integration callback that had retried, failed, and given up without a compensating transaction — leaving records half-applied. That made it a system fault, not a misconfiguration on their side, and I had 48 hours to prove it. The lasting fix was architectural: I documented the missing compensating transaction, which became an infrastructure ticket.

The service buckled at peak load. I reproduced it under representative traffic, profiled down to the root cause, tuned the configuration, and validated the fix before promoting it to production. The change itself was small; finding it was the whole job.

On-call triage was slow because the signal was spread across dashboards and logs. Nobody was assigned to fix that, so I proposed a small CLI, built it, and drove its adoption across the team. It pulls the scattered signal into one structured summary.

Services needed to react to each other’s state changes without brittle coupling. I designed event-driven messaging with an auto-retry dead-letter path, so a transient failure retries itself instead of paging someone at 2am. Other teams on the platform later reused the pattern.