Tell me about a time when you faced a challenging situation at work and how you handled it.

Situation: During a major product launch, a critical data pipeline failed. Downstream dashboards showed incorrect KPIs; execs were escalating; the root cause was unclear. Task: Restore data integrity and stakeholder confidence while preventing recurrence. Action: I triaged using a runbook: checked Spark/Airflow logs, source schema, and recent deployments. I identified a breaking schema change in the upstream API that wasn't in our contract. I shipped a hotfix with schema validation and backfilled affected partitions. I sent a structured status update (impact, ETA, root cause) to stakeholders every 2 hours. Post-incident, I led a blameless retrospective: we added schema evolution checks in CI, improved contract tests, and extended monitoring. I documented the incident in our knowledge base. Result: Data corrected within 4 hours. We implemented automated schema drift detection; similar incidents dropped to zero over 6 months.