System Design Classroom

The Most Dangerous Agent Memory Was Once Correct

How outdated facts, changing policies, and stale indexes create confident but incorrect decisions.

Sep 12 • Raul Junco

12

1

August 2026

Your AI Agent Won’t Crash. It Will Happily Pay an Invoice Without Approval

A practical guide to observing AI decisions with OpenTelemetry

Aug 22 • Raul Junco

16

1

2

July 2026

Safe Database Rollback Starts Before Deployment

How to deploy schema changes without painting yourself into a corner.

Jul 25 • Raul Junco

61

4

How to Survive the Recommendation Engine Question

Most engineers focus on the matching algorithm. The real test is separating generation from serving.

Jul 11 • Raul Junco

37

3

June 2026

A Good System Design Tackles Down the Hot Path First

Before you add cache, replicas, queues, or microservices, understand where the system actually feels pressure.

Jun 13 • Raul Junco

67

7

9

May 2026

Most System Design Mistakes Hide Between the Boxes

Five gaps your architecture diagrams don't show

May 30 • Raul Junco

57

6

Bad Retries Can Break Good Systems

A practical guide to using backoff, jitter, retry budgets, idempotency, and circuit breakers in backend systems.

May 9 • Raul Junco

54

2

5

April 2026

Event-Driven Systems Are Easy to Build but Hard to Keep Correct

4 ways event-driven systems fail without looking broken

Apr 25 • Raul Junco

53

9

Consistency is negotiable. But the bill always lands somewhere.

Linearizable, causal, eventual, and quorum: how to pick the right consistency guarantee for each workflow in your system.

Apr 18 • Raul Junco

35

5

Good System Design Starts With Constraints, Not Diagrams, Not Tools

Most Engineers Learn System Design Backwards

Apr 4 • Raul Junco

101

5

18

March 2026

Async systems scale your system… and your problems.

Many developers only realize it after consistency breaks.

Mar 28 • Raul Junco

56

1

Refactoring Databases Is a Different Animal

A practical pattern for evolving database schemas without breaking production

Mar 14 • Raul Junco

55

9