# 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.

- Skill: `v1truv1us-ai-eng-system/principle-subtract-before-you-add` (Agent Skill)
- Install (CLI): `npx skillmds add v1truv1us-ai-eng-system/principle-subtract-before-you-add`
- Raw SKILL.md: https://api.skillmd.com/api/skills/v1truv1us-ai-eng-system/principle-subtract-before-you-add/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: v1truv1us (https://skillmd.com/u/v1truv1us-ai-eng-system)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/v1truv1us-ai-eng-system/principle-subtract-before-you-add

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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