Principle Subtract Before You Add

Apply when sequencing an addition, refactor, or rewrite. Remove dead weight, redundant validators, and stub references first, then build on the simpler base.

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Subtract Before You Add

When evolving a system, remove complexity first, then build. Deletion gives you a simpler base, which makes the next addition smaller and less brittle.

Why: Adding to a complex system compounds complexity. Removing first cuts the surface area, reveals the essential structure, and usually makes the next design obvious. Default to subtraction.

The pattern:

  • Sequence removal before construction
  • Cut before you polish (get to the minimum before investing in quality)
  • Design for observed usage, not speculative edge cases
  • No speculative validators, parsers, or guards beyond what the spec demands
  • Out-of-spec features drag validators behind them. Persistence, retry-on-startup, and schema migration each need guards to defend their inputs.
  • Simplify prompts (remove redundant instructions, excessive templates)
  • When a reference has no novel content, delete it rather than leaving a stub

v1truv1us/ai-eng-system/tree/main/.gemini/skills/pstack/principle-subtract-before-you-add commit fca2ef81de

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npx skillmds add v1truv1us-ai-eng-system/principle-subtract-before-you-add