exec-jvm

exec-jvm is a skill for Claude Code from anhnguyen0905/codex-mcp. It costs 39 tokens per session (368 once invoked), scanned A, original, MIT.

A set of Java and Kotlin coding guidelines for projects running on the Java Virtual Machine, or JVM. It tells the coding agent how to handle nulls, immutable data, errors, frameworks, databases, coroutines, and tests.

In plain words
What is it for?
Use it when asking a coding agent to change a Java, Kotlin, Android, Spring Boot, Quarkus, Ktor, or similar JVM project. It embeds relevant implementation and testing guidance in the prompt.
Why use it?
It helps generated code fit common Java or Kotlin practices and the conventions already used by the project's framework.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions Codex.

Part of the codex-flow plugin — 61 skills, 1 command, 1 MCP server shipped together

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/anhnguyen0905/codex-mcp/exec-jvm
Any agent
npx skills add anhnguyen0905/codex-mcp --skill exec-jvm
Clone the repo
git clone --depth 1 https://github.com/anhnguyen0905/codex-mcp

Made for: Claude Code.

Or install codex-flow, the plugin that ships this one along with the rest of its 61 skills, 1 command, 1 MCP server.

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 exec-jvm

README.md
[![agentmods](https://agentmods.dev/badge/skills/anhnguyen0905/codex-mcp/exec-jvm.svg)](https://agentmods.dev/skills/anhnguyen0905/codex-mcp/exec-jvm)
Your own site
<a href="https://agentmods.dev/skills/anhnguyen0905/codex-mcp/exec-jvm"><img src="https://agentmods.dev/badge/skills/anhnguyen0905/codex-mcp/exec-jvm.svg" alt="Measured on agentmods" height="20"></a>
Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 368 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 5.1 $0.00039 $0.00368
Opus 5 $0.00019 $0.00184
Sonnet 5 $0.00008 $0.00074
Haiku 4.5 $0.00004 $0.00037

Measured 6d ago against content hash 12211c102632, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

exec-jvm 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 6d 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.

skills/exec-jvm/SKILL.md · 28 lines

What it actually says

Java / Kotlin Idioms (embed when project is JVM)

JVM standards:
- Null safety: Kotlin — no !! in production code, use ?./?:/require; Java — Optional for
  possibly-absent returns, @Nullable/@NonNull annotations if the project uses them, Objects.requireNonNull
  at boundaries.
- Immutability: Kotlin — val + data class + immutable collections by default; Java — records
  (or final fields + builders), List.copyOf/unmodifiable views for exposed collections.
- Errors: specific exceptions with messages that carry context; try-with-resources / use{} for
  resources; never catch Exception/Throwable broadly except at top-level handlers that log.
- Follow the framework the repo uses (Spring Boot/Quarkus/Ktor/Android): its layering
  (controller/service/repository), DI style (constructor injection, no field injection), config
  binding, and transaction boundaries — do not hand-roll what the framework provides.
- Persistence: no N+1 queries (fetch joins/entity graphs); DTOs at API boundaries, entities stay
  internal.
- Coroutines (Kotlin): structured concurrency — no GlobalScope; propagate cancellation; switch
  dispatchers at the boundary, not deep inside logic.
- Style: match existing formatter (ktlint/spotless/google-java-format) and package structure.
- Tests: JUnit 5 + the repo's assertion/mocking libs (AssertJ/Kotest/MockK/Mockito); given-when-then
  naming consistent with existing tests.
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. 6d ago First seen · 28 lines · 39 tokens per session scan A 12211c102632

Subscribe to this mod's changes

exec-jvm is a skill published in the GitHub repository anhnguyen0905/codex-mcp (3 stars, last pushed 3d ago), licensed MIT. It adds 39 tokens to every session and 368 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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