role-java-engineer

role-java-engineer is a skill for Claude Code, Codex from saemihemma/lead-producer-oss. It costs 46 tokens per session (637 once invoked), scanned A, original, MIT.

A code-review guide for modern Java, including records, sealed classes, immutable data, JUnit 5, AssertJ, and Spring Boot conventions. It checks both implementation style and test quality.

In plain words
What is it for?
Use it when writing or reviewing Java 14+ code, especially code using Spring Boot, records, sealed classes, Optional, JUnit 5, AssertJ, Mockito, or Testcontainers.
Why use it?
It catches common Java design, error-handling, immutability, formatting, and testing problems before they spread through a codebase.

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/saemihemma/lead-producer-oss/role-java-engineer
Any agent
npx skills add saemihemma/lead-producer-oss --skill role-java-engineer
Clone the repo
git clone --depth 1 https://github.com/saemihemma/lead-producer-oss

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 role-java-engineer

README.md
[![agentmods](https://agentmods.dev/badge/skills/saemihemma/lead-producer-oss/role-java-engineer.svg)](https://agentmods.dev/skills/saemihemma/lead-producer-oss/role-java-engineer)
Your own site
<a href="https://agentmods.dev/skills/saemihemma/lead-producer-oss/role-java-engineer"><img src="https://agentmods.dev/badge/skills/saemihemma/lead-producer-oss/role-java-engineer.svg" alt="Measured on agentmods" height="20"></a>
Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 637 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 $0.00046 $0.00637
Opus 5 $0.00023 $0.00318
Sonnet 5 $0.00009 $0.00127
Haiku 4.5 $0.00005 $0.00064

Measured 4d ago against content hash a2c55c70c041, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

role-java-engineer 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 4d ago.

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.

.claude/skills/role-java-engineer/SKILL.md · 64 lines

How it starts

The opening of the file, as written. The whole thing — 64 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Java Engineer

Use When

  • Reviewing or writing Java code
  • Assessing modern Java feature usage, test quality, or Spring patterns
  • Evaluating immutability, Optional handling, or error strategy

Do NOT Use When

  • Problem is architecture-level, not language-level
  • Code is Kotlin (different idioms on same platform)

What You Own

  • Modern Java enforcement (14+: records, sealed classes, pattern matching, text blocks)
  • Immutability discipline (final fields, defensive copies, records for value types)
  • Optional handling (return-only, functional methods)
  • JUnit 5 + AssertJ test quality
  • Spring Boot conventions when applicable

Working Method

  1. Check formatting (google-java-format or Checkstyle) compliance.
  2. Verify modern Java usage: records for value types, sealed classes for closed hierarchies, switch expressions.
  3. Inspect immutability: final fields default, List.copyOf() for defensive copies.
  4. Check Optional discipline: return-only (never as field/parameter), functional methods.
  5. Verify test quality: JUnit 5 + AssertJ, Mockito for mocking, Testcontainers for integration.
  6. Produce verdict with highest-risk issues first.

Key Idioms

  • record for value types (Java 16+)
  • sealed classes for closed hierarchies (Java 17+)
  • Pattern matching with instanceof (Java 16+)
  • Switch expressions (Java 14+)
  • Optional.map(), flatMap(), orElseThrow() — never Optional.get() without isPresent()
  • Stream pipelines: max 3-4 operations for readability
  • Prefer unchecked exceptions with context-rich messages
  • One public top-level type per file

Testing Standards

  • Framework: JUnit 5 + AssertJ for fluent assertions
  • Mocking: Mockito with @ExtendWith(MockitoExtension.class)
  • Parameterized: @ParameterizedTest with @CsvSource
  • Integration: Testcontainers for real database testing
  • Naming: methodName_scenario_expectedBehavior() with @DisplayName
  • Coverage: 80%+ via JaCoCo, prioritize domain/service logic
  • Structure: mirror src/main/java in src/test/java

Read the full file on GitHub · 64 lines

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. 4d ago First seen · 64 lines · 46 tokens per session scan A a2c55c70c041

Subscribe to this mod's changes

role-java-engineer is a skill published in the GitHub repository saemihemma/lead-producer-oss (2 stars, last pushed today), licensed MIT. It adds 46 tokens to every session and 637 once invoked, about $0.0002 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.

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