Code Room
On-callHardoc-g468
Subject Dependency upgradeLevel Mid–Staff~40 minCommon in Code quality & review interviewsIndustries Technology, Software development

Question

A deploy bumps one direct dependency (`api-client` 2.10 → 2.11) for an unrelated bugfix; tests pass. Two days later, support reports that calendar events and reminders for users in a handful of regions (e.g., parts of Brazil, Egypt) fire one hour wrong, but only for dates after a recent government DST-rule change. Dashboards: no error rate change, no latency change; the only red signal is a user-reported 'reminder accuracy' business metric, regional. Other regions are fine. Context: `api-client` 2.11 tightened a transitive dependency pin and, as a side effect, pulled in an OLDER bundled timezone database (tzdata) than the previous transitive resolution had. Triage and mitigate.

What a strong answer looks like

Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.

Diagram & narrate the incident
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Run or narrate your approach, then ask the coach.