# System Design
All System Design notes →Chapter 1 — Architectural Decision Records
Why an ADR outlives the meeting that produced it, and the Context/Decision/Consequences structure that makes one actually useful later.
Chapter 2 — Evolutionary Architecture
Designing for incremental change rather than a big-bang rewrite, and the fitness functions that keep an architecture from drifting.
Chapter 3 — Build vs. Buy
The decision framework for build-vs-buy that goes beyond cost — differentiation, lock-in, and long-term maintenance burden.
Chapter 4 — Organization Scaling
How team topology and Conway's Law force architecture decisions as an org grows past the size where everyone fits in one room.
Chapter 5 — Platform Strategy
Positioning a platform as an internal product with a roadmap, not a shared-services team that reacts to tickets.
Chapter 6 — Engineering Economics
Framing technical decisions in terms of cost, risk, and opportunity cost so they're defensible to a non-engineering stakeholder.
Chapter 7 — Technical Debt Management
Distinguishing deliberate from accidental technical debt, and the prioritization model for paying it down against feature work.
Chapter 8 — Leading Cross-Functional Architecture
Driving an architecture decision across teams that don't report to you, using influence rather than authority.
Chapter 9 — Executive Communication
Translating an architecture decision into the risk/cost/timeline framing an executive audience actually needs to approve it.
Chapter 10 — Principal Engineer Interview Preparation
How the L6/L7 loop differs from senior-level loops — the narrative, leadership, and technical-vision signals interviewers are calibrated to look for.