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Single Responsibility Principle
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One thing, done well. From Unix — do one thing and do it right.
The Idea
A Unix tool does one job. Programs compose by piping. The same idea applies to products: one clear purpose is more durable and composable than a sprawling suite.
Why It Matters
- Single-purpose tools are easier to learn, test, and trust.
- Composition beats integration — small tools stitch together cleanly.
- Bloated products develop internal contradictions over time.
How to Apply
- Name the one thing your product is responsible for. Write it down.
- New feature? Check whether it belongs or whether it's a different product.
- Prefer integration via APIs over swallowing adjacent tools.
The Trap
Treating this as "one feature only." Single responsibility is about one purpose — which can span many features as long as they serve that purpose.
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