Cards

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Why 80% Full Is Already Too Full — system design card, day 8, reliability

ReliabilityDay 8Aug 8, 2026

Why 80% Full Is Already Too Full

performance reliability system-design

Your RAG Isn't Hallucinating — system design card, day 7, ai systems

AI SystemsDay 7Aug 7, 2026

Your RAG Isn't Hallucinating

ai ai-systems rag

The Bug That Passes Every Test — system design card, day 6, databases

DatabasesDay 6Aug 6, 2026

The Bug That Passes Every Test

databases postgresql system-design

Netflix Doesn't Stream From The Cloud — system design card, day 5, case study

Case StudyDay 5Aug 5, 2026

Netflix Doesn't Stream From The Cloud

case-study netflix system-design

Ship It Before They Ask — system design card, day 5, caching

CachingDay 5Aug 5, 2026

Ship It Before They Ask

cache-warming caching system-design

Order Is A Choice, Not A Gift — system design card, day 4, kafka

KafkaDay 4Aug 4, 2026

Order Is A Choice, Not A Gift

kafka partitions system-design

The Only Numbers You Must Memorise — system design card, day 3, foundations

FoundationsDay 3Aug 3, 2026

The Only Numbers You Must Memorise

foundations latency system-design

Amazon's Honest Answer — system design card, day 2, case study

Case StudyDay 2Aug 2, 2026

Amazon's Honest Answer

availability case-study system-design

Clocks That Count, Not Tick — system design card, day 2, distributed systems

Distributed SystemsDay 2Aug 2, 2026

Clocks That Count, Not Tick

distributed-systems system-design vector-clocks

The Cart That Refuses To Say No — system design card, day 1, case study

Case StudyDay 1Aug 1, 2026

The Cart That Refuses To Say No

availability case-study system-design

There Is No Best Design — system design card, day 1, foundations

FoundationsDay 1Aug 1, 2026

There Is No Best Design

foundations system-design tradeoffs

A flow of five numbered WHY boxes descending from MACHINE STOPS to ROOT CAUSE

Problem-SolvingJul 31, 2026

The Five Whys

problem-solving toyota root-cause

A gold line drawing of the Ise Grand Shrine between two pines, on a black card

ArchitectureJul 30, 2026

The Japanese Rebuild A 1,300-Year-Old Shrine Every 20 Years — On Purpose

architecture craft japan

Green line icons of a dollar, a clock and a person on a black card, above a boxed takeaway

EconomicsJul 29, 2026

Opportunity Cost

economics decisions time

A glowing blue brain with a pencil icon, beside the line about remembering the last time you remembered

NeuroscienceJul 28, 2026

Memory Is A Rewrite, Not A Replay

neuroscience memory psychology

A cream panel on a starfield, with the closing line set in a dark inset box

AstronomyJul 27, 2026

The Light You See From The Stars Is A Message From The Dead

astronomy time light

A line-drawn allen key and flat-pack panel on a cream card

PsychologyJul 26, 2026

The IKEA Effect — Why You Overvalue What You Build

psychology bias product

A circuit-traced brain labelled AI, beside two identical-looking citations, one true and one fabricated

The "Hallucination" Problem Isn't A Bug — It's The Point

ai llm epistemics

Gold line drawings of a steaming cup, a sandcastle and a pile of sand, in sequence

PhysicsJul 24, 2026

Entropy Doesn't Care About Your Plans

physics entropy habits

Gold line-drawn scales with a tick on one pan and a cross on the other, on a black card

StoicismJul 23, 2026

The Dichotomy Of Control

stoicism philosophy epictetus

A shuttered Blockbuster store beside a Netflix screen, split by a VS divider

Business StrategyJul 22, 2026

Why Netflix Killed Its Most Profitable Business On Purpose

business-strategy disruption netflix

A dark outline map of South America with a dotted line running east from Brazil's bulge toward Africa

GeographyJul 21, 2026

Brazil Is So Wide That Its Easternmost City Is Closer To Africa Than To Its Own Western Border

geography brazil scale

Two panels — a hand on a lever diverting a trolley, and a figure pushing a man from a bridge

EthicsJul 20, 2026

A Trolley Is About To Kill Five People. You Have Two Choices.

ethics philosophy morality

Six domains each with the same threshold curve — flat for a long time, then a sudden vertical break

Systems ThinkingJul 19, 2026

One Law, Six Disguises: Things Resist Change Until A Threshold — Then Flip All At Once

systems-thinking thresholds compounding