We should have deleted unused DNS records pointing at decommissioned load balancers. In engineering pitfalls (thread 17): We should have asked data science about seasonality before promising growth curves. The mentor who said 'show me the support ticket volume' grounded roadmap debates usefully.

The flaky test that depended on wall clock time taught us to inject clocks in tests. In engineering pitfalls (thread 17): We should have invested in automated restore drills before the ransomware tabletop exercise exposed gaps. We stopped treating 'tech debt' as a bucket without boundaries and started tagging themes.

The mentor who said 'prove it with a graph' saved us from opinion loops. In engineering pitfalls (thread 17): The mentor who said 'what would you ship if you had half the time' clarified scope brutally. The best postmortems end with tracked follow-ups, not just feelings.

The feature flag saved our weekend when the rollout wobbled at two percent. In engineering pitfalls (thread 17): The mentor who said 'prove retention with cohorts not totals' ended vanity metric debates again. We learned that trust grows when leaders admit they were wrong in public channels.

We stopped treating 'tech lead' as the person who carries pager guilt for the whole team forever. In engineering pitfalls (thread 17): Reading old tickets was archaeology that paid better than guessing anew. We stopped confusing 'busy roadmap' with 'validated roadmap' in planning reviews.

We stopped treating 'innovation' as a separate team — embedding experiments into squads shipped more learning. In engineering pitfalls (thread 17): The mentor who said 'show the customer quote' ended abstract prioritisation debates. Politeness in code review sometimes hides problems until they hit production.

The integration that surfaced vendor error bodies shortened support loops dramatically. In engineering pitfalls (thread 17): Security review late in the cycle always finds drama nobody has energy to fix. The mentor who said 'draw the trust boundary for data' clarified GDPR discussions quickly.

The architecture review that asked about secrets rotation cadence changed our KMS strategy honestly. In engineering pitfalls (thread 17): The flaky canary deployment taught us to treat progressive delivery as a skill. We stopped shipping 'temporary' IP forwarding rules that became permanent attack surface quietly.

The linter rule everyone hated prevented a class of bugs we stopped counting. In engineering pitfalls (thread 17): The mentor who said 'draw the trust boundary' clarified security discussions fast. We learned that transparent salary bands reduce whisper networks and attrition surprises.

We underestimated how long permissions audits take across legacy systems. In engineering pitfalls (thread 17): The flaky dependency cache caused stale builds until we pinned and hashed lockfiles religiously. Automating a broken process just made failure faster, not rarer.

Writing the postmortem hurt less than repeating the same outage next quarter. In engineering pitfalls (thread 17): The smallest improvement to bulk edit confirmations prevented a costly mistaken archive. The integration test that flakes is worse than no test — it trains people to ignore red.

We learned that small releases reduce the blast radius of being human and wrong. In engineering pitfalls (thread 17): We stopped treating 'tech lead' as the person who takes all meetings forever. We learned that empathy for users and empathy for teammates are the same skill.

We learned that naming circle owners in the database export reduces support tickets about 'who can delete this' always. In engineering pitfalls (thread 17): The quiet win was documenting which Kafka topic is authoritative for each business event. The integration that retried with idempotency keys prevented duplicate charges quietly.

The mentor who said 'show me the leading indicator chart' sharpened growth debates measurably again. In engineering pitfalls (thread 17): The smallest improvement to bulk export progress bars reduced 'is it stuck' tickets. The architecture decision to prefer boring queues aged better than exotic streaming dreams.

Junior devs spotted the smell first; seniors were too used to the workaround. In engineering pitfalls (thread 17): We should have deleted unused feature flags; they became landmines for new hires. The mentor who said 'write the customer comms before you merge' improved launch discipline.