A field guide for Solution, Domain & Enterprise Architects
Mental models for people who design systems.
129 big ideas from physics, economics, biology, and software, rewritten for the decisions architects actually face: where to draw boundaries, what to bet on, and how things fail.
New here? What a mental model is, and how to use this siteInertia (Legacy Gravity)
Established systems keep doing what they're doing unless a force greater than their momentum acts on them.
Eleven disciplines
All 129 models- 14 models
Ways of Thinking
How to think before you design.
- 9 models
Systems & Structure
Where to draw the lines.
- 9 models
Distributed Systems & Data
Physics of the network.
- 9 models
Trade-offs & Economics
Every choice has a price.
- 9 models
Risk & Resilience
Designing for the bad day.
- 10 models
Change & Evolution
Systems are never finished.
- 18 models
People, Org & Influence
Architecture is social.
- 14 models
Strategy & Enterprise
Where to place your bets.
- 6 models
Product Thinking
Build the right thing.
- 13 models
AI Systems
Designing with models that learn.
- 18 models
From the Masters
Lessons from the people who shaped the craft.
What are you seeing?
Start from the problem, and find the models that explain it.
- “Delivery keeps slowing down as the system grows”Design Stamina Hypothesis · Technical Debt as Interest
- “One failure takes everything down”Blast Radius · Single Point of Failure
- “Every decision gets reopened”Disagree and Commit · Architecture Decision Records
- “Several teams built the same thing”Capability Mapping · Conway's Law
- “We can't leave a vendor we're unhappy with”Exit Strategy (Lock-in as a Design Input) · Optionality
- “Our AI feature works in demos but not in production”The Jagged Frontier · Workflows Before Agents
I'm about to…
Playbooks that sequence the right models for a common moment.
- Starting a new system6
- Reviewing a solution design9
- Deciding whether to split into services7
- Integrating systems or designing an API6
- Building a feature with AI7
- Choosing a data store6
- Designing for failure8
- Solving a performance or scaling problem7
- Handling an outage7
- Migrating a legacy system6
- Making the case to pay down technical debt6
- Evaluating a vendor or platform7
- Designing team boundaries5
- Setting an architecture strategy7
- Presenting to executives7
- Getting a decision agreed8
- Rationalising the application portfolio7
- Integrating after a merger7
- Setting principles and running governance7
- Responding to new regulation7
- Defining a target state and roadmap7
- Your first 90 days as an architect8
- AI transformation 1: Before you start8
- AI transformation 2: Making the enterprise AI-ready8
- AI transformation 3: From assistants to agents7
- AI transformation 4: Organising for AI8
- Deciding what to build7
- Making a hard decision8