dry

A guideline for managing repeated code, based on the idea that an abstraction is usually worth extracting after the same pattern appears three times.

In plain words
What is it for?
Deciding when to extract shared code and when to leave similar code separate.
Why use it?
It reduces premature abstractions, which can couple unrelated code and become costly to undo. Some duplication is acceptable when parts may change independently.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/5uck1ess/devkit/dry
Any agent
npx skills add 5uck1ess/devkit --skill dry
Clone the repo
git clone --depth 1 https://github.com/5uck1ess/devkit

Made for: Claude Code, Codex.

Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 454 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00020 $0.00454
Opus 5 $0.00010 $0.00227
Sonnet 5 $0.00004 $0.00091
Haiku 4.5 $0.00002 $0.00045

Measured yesterday against content hash 61bb2b321fb5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dry scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/dry/SKILL.md · 42 lines

What it actually says

DRY (Don't Repeat Yourself)

The Rule of Three

Don't abstract on the first duplication. Wait for three instances.

  1. First time — Just write it.
  2. Second time — Notice the duplication, wince, keep going.
  3. Third time — Now extract. You have enough examples to see the real pattern.

Premature abstraction is worse than duplication. Wrong abstractions are expensive to undo.

When Duplication Is Fine

Not all duplication is bad. Duplication is acceptable when:

  • The duplicated code serves different concerns. Test setup that looks similar to production code isn't "duplication" — they change for different reasons.
  • The cost of coupling exceeds the cost of duplication. If extracting a shared function means two unrelated modules now depend on each other, keep them separate.
  • The "duplication" is coincidental. Two things look the same today but will evolve independently. Forcing them to share code creates a false coupling.

The test: if one copy changes, must the other change too? If yes, extract. If maybe not, leave it.

Extracting the Right Abstraction

When you do extract, get the abstraction right:

  • Name it for what it does, not where it came from. formatCurrency not extractedFromOrderPage.
  • Parameterize the differences. The parts that vary between call sites become parameters.
  • Don't over-parameterize. If the shared function needs 8 config options to handle all cases, the cases are probably too different to share.
  • Keep it simple. If the abstraction is harder to understand than the duplication, the duplication was better.

The Real DRY Principle

DRY is about knowledge, not code. The principle says every piece of knowledge should have a single authoritative source. Two functions with identical code but representing different business rules are not a DRY violation.

"Every piece of knowledge must have a single, unambiguous, authoritative representation within a system." — Andy Hunt & Dave Thomas

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 42 lines · 20 tokens per session scan A 61bb2b321fb5

Subscribe to this mod's changes

dry is a skill published in the GitHub repository 5uck1ess/devkit (5 stars, last pushed 13d ago), licensed MIT. It adds 20 tokens to every session and 454 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

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