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.
npx skills add kousen/claude-code-training --skill modernize-javagit clone --depth 1 https://github.com/kousen/claude-code-trainingWrote 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.
[](https://agentmods.dev/skills/kousen/claude-code-training/modernize-java)<a href="https://agentmods.dev/skills/kousen/claude-code-training/modernize-java"><img src="https://agentmods.dev/badge/skills/kousen/claude-code-training/modernize-java/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.
<a href="https://agentmods.dev/skills/kousen/claude-code-training/modernize-java"><img src="https://agentmods.dev/badge/skills/kousen/claude-code-training/modernize-java.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00042 | $0.00324 |
| Opus 5.5 | $0.00017 | $0.00130 |
| Sonnet 5.5 | $0.00008 | $0.00065 |
| Haiku 4.5 | $0.00004 | $0.00032 |
Grade A, and why
modernize-java 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.
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.
What it actually says
Modernize Java Code
Update the target code to use modern Java features:
- Records instead of mutable POJOs where the type is a value carrier
- Switch expressions with arrow syntax and exhaustiveness checking
- Pattern matching for
instanceofandswitch - Local variable type inference (
var) where it helps readability - Virtual threads (Java 21+) for I/O-bound operations —
Executors.newVirtualThreadPerTaskExecutor() - Sealed classes when the type hierarchy is closed
- Text blocks for multiline strings
- Sequenced collections (Java 21+) where ordered access matters
- Collection factory methods (
List.of,Map.of,Map.entry)
Constraints
- Don't change behavior — preserve the public API and observable semantics.
- Don't apply
varwhere the inferred type would harm readability (e.g., factory results that could be any of several types). - If the project's target Java version is below 21, skip the 21+ features and note it in your summary.
- Run the test suite after non-trivial changes; if tests don't exist, surface that as a follow-up rather than as a blocker.
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.
- 1mo ago First seen · 30 lines · 42 tokens per session scan A 0f57690bbcff
modernize-java is a skill published in the GitHub repository kousen/claude-code-training (339 stars, last pushed 7d ago), licensed MIT. It adds 42 tokens to every session and 324 once invoked, about $0.0002 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 2026-08-30.
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