Java Design Patterns Reference
decebals/claude-code-java
A practical Java reference for Builder, Factory, Singleton, Strategy, Observer and other patterns, with a table matching problems to patterns.
A skill your agent uses when Java design, refactoring, or implementation tradeoffs should be evaluated with Kent Beck's simple design rules, including passes the tests, reveals intention, has no…
Install 053 Design Simple Rules
$ npx skills add jabrena/plinth --skill 053-design-simple-rules -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install jabrena/plinth 053-design-simple-rules --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/jabrena/plinth.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/053-design-simple-rules .claude/skills/053-design-simple-rules && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "053-design-simple-rules" agent skill from https://github.com/jabrena/plinth/tree/main/skills/053-design-simple-rules into .claude/skills/053-design-simple-rules/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "053-design-simple-rules", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/jabrena/plinth/tree/main/skills/053-design-simple-rulesType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add jabrena/plinth --skill 053-design-simple-rules -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install jabrena/plinth 053-design-simple-rules --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/jabrena/plinth.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/053-design-simple-rules .agents/skills/053-design-simple-rules && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "053-design-simple-rules" agent skill from https://github.com/jabrena/plinth/tree/main/skills/053-design-simple-rules into .agents/skills/053-design-simple-rules/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "053-design-simple-rules", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add jabrena/plinth --skill 053-design-simple-rules -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install jabrena/plinth 053-design-simple-rules --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/jabrena/plinth.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/053-design-simple-rules .cursor/skills/053-design-simple-rules && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "053-design-simple-rules" agent skill from https://github.com/jabrena/plinth/tree/main/skills/053-design-simple-rules into .cursor/skills/053-design-simple-rules/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "053-design-simple-rules", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/jabrena/plinth.git --path skills/053-design-simple-rules--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add jabrena/plinth --skill 053-design-simple-rules -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install jabrena/plinth 053-design-simple-rules --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/jabrena/plinth.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/053-design-simple-rules .gemini/skills/053-design-simple-rules && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "053-design-simple-rules" agent skill from https://github.com/jabrena/plinth/tree/main/skills/053-design-simple-rules into .gemini/skills/053-design-simple-rules/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "053-design-simple-rules", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install jabrena/plinth 053-design-simple-rulesInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add jabrena/plinth --skill 053-design-simple-rules -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/jabrena/plinth.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/053-design-simple-rules .github/skills/053-design-simple-rules && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "053-design-simple-rules" agent skill from https://github.com/jabrena/plinth/tree/main/skills/053-design-simple-rules into .github/skills/053-design-simple-rules/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "053-design-simple-rules", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add jabrena/plinth --skill 053-design-simple-rules -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install jabrena/plinth 053-design-simple-rules --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/jabrena/plinth.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/053-design-simple-rules .opencode/skills/053-design-simple-rules && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "053-design-simple-rules" agent skill from https://github.com/jabrena/plinth/tree/main/skills/053-design-simple-rules into .opencode/skills/053-design-simple-rules/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "053-design-simple-rules", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
053-design-simple-rules- GitHub stars
- 447
- Token cost
- ~847 tokens
- SKILL.md length
- 363 words
- Files
- 2 (incl. references)
- Skills in repo
- 124
- Repo updated
- First seen
- Licence
- Apache-2.0
At a glance
A skill your agent uses when Java design, refactoring, or implementation tradeoffs should be evaluated with Kent Beck's simple design rules, including passes the tests, reveals intention, has no…
- Implementation tradeoffs should be evaluated with Kent Becks simple design rules
- SKILL.md covers Constraints, When to use this skill, Workflow and Reference
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
- Including passes the tests
What it does
053 Design Simple Rules is an agent skill from jabrena/plinth. Use when Java design, refactoring, or implementation tradeoffs should be evaluated with Kent Beck's simple design rules, including passes the tests, reveals intention, has no duplication, and has the fewest elements. This should trigger for requests such as Apply simple design rules; Review this design with Beck's rules; Choose between these refactoring options; Keep this Java design simple. Part of Plinth Toolkit
Its SKILL.md is about 850 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/053-design-simple-rules.md`).
It sits in Development, covering Refactoring. It works with Java. The repository describes itself as: Plinth is an AI-native engineering toolkit for modern Java enterprise SDLC, built around reusable Commands, Agents, Skills, and MCP Servers. The licence is Apache-2.0.
When your agent uses it
- Implementation tradeoffs should be evaluated with Kent Becks simple design rules
- Including passes the tests
- Reveals intention
- Has no duplication
Example prompts
- “/053-design-simple-rules”
What it can do on your machine
Read from SKILL.md and the folder at commit dca88dc. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
053 Design Simple Rules loads about 847 tokens when it runs, and up to ~2.9k if it reads all its reference files. Until then it costs about 110 tokens; SKILL.md has 363 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from jabrena/plinth at commit dca88dc, republished under its Apache-2.0 licence (© jabrena). 363 words, ~847 tokens.
Download SKILL.mdSave it as
.claude/skills/053-design-simple-rules/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.- name
- 053-design-simple-rules
- description
- Use when Java design, refactoring, or implementation tradeoffs should be evaluated with Kent Beck's simple design rules, including passes the tests, reveals intention, has no duplication, and has the fewest elements. This should trigger for requests such as Apply simple design rules; Review this design with Beck's rules; Choose between these refactoring options; Keep this Java design simple. Part of Plinth Toolkit
- license
- Apache-2.0
- metadata.author
- Juan Antonio Breña Moral
- metadata.version
- 0.19.0
Simple Design Rules
Guide Java developers through Kent Beck's simple design rules when evaluating design and refactoring choices. This is an interactive SKILL.
What is covered in this Skill?
- Using tests as the first correctness boundary before design cleanup
- Revealing intention and maximizing clarity before abstraction pressure
- Reducing duplication without hiding domain meaning or worsening readability
- Treating fewer elements as the final simplification pressure after correctness, clarity, and duplication
- Comparing Java design and refactoring options with the ordered rules
- Reporting the chosen option, tradeoffs, validation signal, and remaining risk
Constraints
Apply simple design rules in priority order, and do not optimize later rules by weakening earlier rules.
- MUST read
references/053-design-simple-rules.mdbefore applying the rules - MUST evaluate the rules in this order: passes the tests, reveals intention, has no duplication, has the fewest elements
- MUST treat passing tests as the correctness boundary before design cleanup
- MUST prefer clear intention over abstraction for its own sake
- MUST reduce duplication only when the result preserves or improves clarity
- MUST consider fewer elements only after correctness, clarity, and duplication have been addressed
When to use this skill
- Apply simple design rules
- Use Beck's simple design rules
- Review this design with simple design rules
- Choose between these refactoring options
- Keep this Java design simple
- Does this design pass the simple design rules?
Show full SKILL.md (146 more words)Show less
Workflow
- Anchor Correctness
Read references/053-design-simple-rules.md, then identify the behavior under discussion and the tests, characterization checks, build checks, or manual evidence that define whether the code works.
- Reveal Intention
Evaluate whether names, types, responsibilities, control flow, API shape, and test descriptions make the domain decision clear to a future maintainer.
- Reduce Duplication Carefully
Find repeated knowledge, policy, mappings, validation, queries, or workflow decisions. Remove duplication only when the abstraction keeps the intent easier to understand.
- Minimize Elements Last
After correctness, clarity, and duplication are handled, remove unnecessary classes, methods, parameters, branches, layers, configuration, or indirection that no longer pay for themselves.
- Compare Options and Report
Compare available design or refactoring options against the ordered rules. Recommend the option that satisfies the earlier rules best, describe rejected tradeoffs, and name the verification signal.
Reference
For detailed guidance, examples, and constraints, see references/053-design-simple-rules.md.
© jabrena, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
SKILL.md and 1 other file (references) in skills/053-design-simple-rules of jabrena/plinth.
- SKILL.md
- references/053-design-simple-rules.md
Open the folder on GitHubat commit dca88dc
Compare with similar skills
053 Design Simple Rules next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| 053 Design Simple Rules this skilljabrena/plinth | 447 | — | ~847 | Automated safety check: Pass | Apache-2.0 | |
| Java Design Patterns Referencedecebals/claude-code-java | 751 | 1 repos | ~4.4k | Automated safety check: Pass | MIT | |
| Bootui Java Developmentjdubois/boot-ui | 314 | — | ~1.3k | Automated safety check: Pass | Apache-2.0 | |
| Goinference-gateway/inference-gateway | 214 | — | ~2.4k | Automated safety check: Pass | Apache-2.0 | |
| Java 21 Developer Guide for Grailsapache/grails-core | 2.9k | — | ~1.9k | Automated safety check: Pass | Apache-2.0 | |
| Spring Data Developmentarangodb/spring-data | 116 | — | ~620 | Automated safety check: Pass | Apache-2.0 |
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Questions about 053 Design Simple Rules
What does 053 Design Simple Rules do?
A skill your agent uses when Java design, refactoring, or implementation tradeoffs should be evaluated with Kent Beck's simple design rules, including passes the tests, reveals intention, has no…. 053 Design Simple Rules is an agent skill from jabrena/plinth. Use when Java design, refactoring, or implementation tradeoffs should be evaluated with Kent Beck's simple design rules, including passes the tests, reveals intention, has no duplication, and has the fewest elements.
When should I use 053 Design Simple Rules?
053 Design Simple Rules fits situations like: implementation tradeoffs should be evaluated with Kent Becks simple design rules; including passes the tests; reveals intention; has no duplication.
How do I install 053 Design Simple Rules in Claude Code?
Run `npx skills add jabrena/plinth --skill 053-design-simple-rules -a claude-code`. Or copy the skill folder (skills/053-design-simple-rules in jabrena/plinth) into .claude/skills/053-design-simple-rules in your project. Claude Code loads it when a task matches its description.
How do I install 053 Design Simple Rules in Codex?
Run `npx skills add jabrena/plinth --skill 053-design-simple-rules -a codex`. Or copy the skill folder (skills/053-design-simple-rules in jabrena/plinth) into .agents/skills/053-design-simple-rules in your project. Codex loads it when a task matches its description.
Can I use 053 Design Simple Rules in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add jabrena/plinth --skill 053-design-simple-rules -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/053-design-simple-rules, .gemini/skills/053-design-simple-rules, .github/skills/053-design-simple-rules and .opencode/skills/053-design-simple-rules in your project.
What does 053 Design Simple Rules need to run?
SKILL.md names no scripts, command-line tools or credentials: 053 Design Simple Rules is instructions for the agent only.
Does 053 Design Simple Rules access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is 053 Design Simple Rules safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does 053 Design Simple Rules use?
053 Design Simple Rules is published under the Apache-2.0 licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does 053 Design Simple Rules use?
About 847 tokens (SKILL.md is roughly 3.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 2.1k tokens, read only when the agent opens those files.
What are the alternatives to 053 Design Simple Rules?
Skills that share tags, products or a category with 053 Design Simple Rules: Java Design Patterns Reference (decebals/claude-code-java, 751 stars), Bootui Java Development (jdubois/boot-ui, 314 stars), Go (inference-gateway/inference-gateway, 214 stars) and Java 21 Developer Guide for Grails (apache/grails-core, 2.9k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains 053 Design Simple Rules?
jabrena (a GitHub user) maintains it in jabrena/plinth, which has 447 GitHub stars. The repository holds 124 skills in this directory. The repository was last updated on October 7, 2026.
Source: jabrena/plinth on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.