Weekly Recap: What I learned, what broke, what I fixed

Every Friday, I close Slack and pause commits. This weekly ritual keeps me honest. No fluff — just real dev life.

What I learned

• AbortController in fetch prevents memory leaks in React useEffect.
• PostgreSQL partial indexes reduce index size by ~70% for soft-deleted rows.
• JavaScript event loop prioritizes microtasks over macrotasks.
• Writing short RFCs before coding saves 3x rework time.
• git bisect is underrated for finding performance regressions.

What broke

• CI pipeline failed randomly due to a flaky E2E race condition.
• Production search API timed out after adding one new JOIN.
• Mobile build broke because a peer dependency auto-updated.
• Webhook handler crashed silently — stack trace missing from logs.
• Redis OOM killed session cache at 3 AM (no TTL on temp keys).

What I fixed

• Added await in test teardown → flakiness resolved.
• Optimized query with a lateral join + pagination → 8s → 120ms.
• Locked dependency versions + --frozen-lockfile in CI.
• Wrapped webhook in try/catch with structured logging + DLQ.
• Set EXPIRE on all Redis writes + maxmemory-policy volatile-lru.

Takeaway

Most "mysterious" bugs come from missing observability or missing constraints. Learning without shipping is theory. Shipping without learning is gambling. Documenting failures publicly isn't shame — it's how teams stop repeating mistakes.

Next week's goal: cut MTTR from 45 min to under 15.

Try this recap for one sprint. You'll be surprised what patterns emerge.

👇 Share your own "learned / broke / fixed" in the comments.