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design-patterns

design-patterns is a skill for Claude Code, Codex from cookieMonsterDev/agents-skills. It costs 104 tokens per session (1,597 once invoked), scanned A, original, MIT.

A guide to the 23 Gang of Four design patterns: commonly named ways to structure software objects and their relationships. It includes explanations and runnable examples in several programming languages.

In plain words
What is it for?
Use it to learn, compare, choose, or apply patterns such as factory, builder, observer, strategy, decorator, and adapter, including refactoring existing code.
Why use it?
It helps match a recurring code-design problem with a known approach, while covering when that approach is unsuitable. This avoids improvised or overly generic pattern explanations.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

not rated 6repo today A scan 104 tokens original MIT

Good fit Use it to learn, compare, choose, or apply patterns such as factory, builder, observer, strategy, decorator, and adapter, including refactoring existing code.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/cookiemonsterdev/agents-skills/design-patterns
View source ↗ cookieMonsterDev/agents-skills
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.

Any agent
npx skills add cookieMonsterDev/agents-skills --skill design-patterns
Clone the repo
git clone --depth 1 https://github.com/cookieMonsterDev/agents-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for design-patterns

README.md
[![agentmods](https://agentmods.dev/badge/skills/cookiemonsterdev/agents-skills/design-patterns/github.svg)](https://agentmods.dev/skills/cookiemonsterdev/agents-skills/design-patterns)
Your own site
<a href="https://agentmods.dev/skills/cookiemonsterdev/agents-skills/design-patterns"><img src="https://agentmods.dev/badge/skills/cookiemonsterdev/agents-skills/design-patterns/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for design-patterns

Your own site · 80×15
<a href="https://agentmods.dev/skills/cookiemonsterdev/agents-skills/design-patterns"><img src="https://agentmods.dev/badge/skills/cookiemonsterdev/agents-skills/design-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 104 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,597 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00104 $0.01597
Opus 5.5 $0.00042 $0.00639
Sonnet 5.5 $0.00021 $0.00319
Haiku 4.5 $0.00010 $0.00160

Measured 1mo ago against content hash 02f274d52427, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

design-patterns 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 1mo ago.

The scan reads SKILL.md. This mod also ships 12 executable files (examples/abstract-factory/abstract-factory.js, examples/abstract-factory/abstract-factory.py, examples/adapter/adapter.js, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

architecture-skills/design-patterns/SKILL.md · 99 lines

How it starts

The opening of the file, as written. The whole thing — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Design Patterns

Ground design-pattern answers in the reference files bundled with this skill instead of improvising definitions. Each pattern has a reference file explaining it and a folder of runnable examples in popular languages.

When to Use

  • The user names a pattern directly ("show me the builder pattern in Rust")
  • The user describes a design problem that maps to a pattern ("I need to create objects without specifying their concrete class")
  • The user asks to compare patterns ("strategy vs state?")
  • The user wants existing code refactored toward a pattern

Workflow

  1. Identify the pattern(s) from the user's question using the catalog below.
  2. Read the reference file at references/<pattern>.md for the explanation, applicability, trade-offs, and related patterns.
  3. Read the language example at examples/<pattern>/<pattern>.<ext> when the user works in (or asks for) a specific language. Adapt it to their domain rather than pasting the generic example verbatim.
  4. Answer with: what the pattern does, when to use it (and when not to), and code adapted to the user's context.

If the user's problem does not match any pattern cleanly, say so — do not force a pattern where a plain function or data structure is simpler.

Pattern Catalog

Creational

Patterns that abstract the instantiation process.

Pattern Intent Reference
Abstract Factory Create families of related objects without specifying concrete classes references/abstract-factory.md
Builder Construct complex objects step by step, separating construction from representation references/builder.md
Factory Method Let subclasses decide which class to instantiate references/factory-method.md
Prototype Create objects by cloning an existing instance references/prototype.md
Singleton Ensure a class has one instance with a global access point references/singleton.md

Read the full file on GitHub · 99 lines

Files

What ships with it

60 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 1mo ago First seen · 99 lines · 104 tokens per session scan A 02f274d52427

Subscribe to this mod's changes

design-patterns is a skill published in the GitHub repository cookieMonsterDev/agents-skills (6 stars, last pushed today), licensed MIT. It adds 104 tokens to every session and 1,597 once invoked, about $0.0004 per session on Opus 5.5. 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.

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