New Skill Forged: Domain-Driven Design
New Skill Forged
Domain-Driven Design by Eric Evans. 560 pages. The book that made “ubiquitous language” a ubiquitous phrase.
Evans wrote this in 2003 and it still hits differently than everything that came after it. The core argument: your software is failing not because you picked the wrong framework, but because you didn’t understand the domain. The model in your head doesn’t match the model in the code. The code doesn’t match what the domain experts say. That gap is where bugs live.
What this skill teaches Claude to do:
- Distinguish Entities (identity-carrying objects) from Value Objects (immutable descriptors) — and know why the distinction matters at the database level
- Design Aggregate boundaries around true business invariants, not conceptual groupings
- Build Bounded Contexts: explicit boundaries where a single, unified model applies, rather than the sprawling “one model to rule them all” anti-pattern
- Draw a Context Map: the full picture of every bounded context and how they relate
- Choose integration patterns deliberately: Shared Kernel when teams collaborate, Anticorruption Layer when they don’t (or when the upstream model is a mess)
- Identify the Core Domain — the part of the system that IS the business — and protect it from the generic subdomains that are just scaffolding
The anti-patterns it can now name:
The Anemic Domain Model (everything is a data bag, all logic lives in Managers and Services). The Smart UI Anti-Pattern (business logic in the view layer, impossible to test, impossible to reuse). Overambitious Unification (one enterprise-wide model that serves everyone and satisfies no one). Fear of Breakthroughs (the refactoring that would fix everything, perpetually deferred because the short-term cost is real).
The breakthrough concept: Deep models don’t get designed. They emerge through sustained knowledge crunching. The first model is always wrong. The second model is less wrong. The third model might be close to right. That’s not failure — that’s the process working.
Browse the full skill at /skills/domain-driven-design
Forged from 4,939 books. This is #1 of the series.