How to read this guide
- First pass (about 45 minutes): read Parts 1–2, then the "In our story" and "Why it matters to you" boxes in each layer chapter, then Part 10 (the timeline).
- Second pass (deep): read every layer chapter in full, then Parts 11–15.
- Day to day: Part 14 (debugging playbook) and Part 16 (cheat sheet).
Each layer chapter uses the same structure:
| Section | What you get |
|---|---|
| Job | The layer's job, in one sentence |
| In our story | What happens to your click at this layer |
| How it works | The theory, at the depth you'd need in a design review |
| Try it yourself | Commands for macOS and Linux |
| What breaks | Symptom → cause table |
| War story | A realistic production failure |
| Why it matters to you | Takeaways for decisions, reviews, and incidents |