write-extension-remote

write-extension-remote is a skill for Claude Code, Codex from aayushmau5/eva. It costs 49 tokens per session (1,917 once invoked), scanned A, original, MIT.

Instructions for writing an Eva extension that runs on another machine. Eva is the extension system described by the source, and a Mix project is an Elixir project managed by Mix.

In plain words
What is it for?
Creating, changing, or debugging remote Eva extensions, including ports, served resources, shared secrets, and remote sessions.
Why use it?
It explains the extra configuration needed when the extension is remote, including connecting machines and exposing the project node.

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/aayushmau5/eva/write-extension-remote
Any agent
npx skills add aayushmau5/eva --skill write-extension-remote
Clone the repo
git clone --depth 1 https://github.com/aayushmau5/eva

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 write-extension-remote

README.md
[![agentmods](https://agentmods.dev/badge/skills/aayushmau5/eva/write-extension-remote.svg)](https://agentmods.dev/skills/aayushmau5/eva/write-extension-remote)
Your own site
<a href="https://agentmods.dev/skills/aayushmau5/eva/write-extension-remote"><img src="https://agentmods.dev/badge/skills/aayushmau5/eva/write-extension-remote.svg" alt="Measured on agentmods" height="20"></a>
Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,917 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 $0.00049 $0.01917
Opus 5 $0.00024 $0.00958
Sonnet 5 $0.00010 $0.00383
Haiku 4.5 $0.00005 $0.00192

Measured 5d ago against content hash ce68b084c042, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

write-extension-remote 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 5d 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.

.eva/skills/write-extension-remote/SKILL.md · 160 lines

How it starts

The opening of the file, as written. The whole thing — 160 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Writing a remote Eva extension

A remote extension is a project extension that runs on another machine. The contract is identical to a local one — same setup/1, same %Spec{}, same callbacks, same API, same module namespace. Read the write-extension-local skill for all of that. This skill covers what is different about running one elsewhere:

  1. how the node offers itself to other machines (:port, :serve)
  2. how the two machines agree on a secret (the cluster cookie)
  3. how the session's Eva is pointed at it (mix eva.ext.remote)
  4. what changes in the code you write (paths, and tool/command names)

When it is remote

Only projects, and only if you ask for it. A script (.exs) always compiles into the session's own VM and can never run on another machine. A project node is loopback-only until you pass :port, so "remote" is one option, not a different kind of extension.

The scaffolding is the same as any project — a mix.exs depending on eva_core, and an application that starts Eva.Core.Extension.Node (see write-extension-local). Only the node's options change:

children = [
  {Eva.Core.Extension.Node,
   name: "gpu",
   module: Eva.Extension.Gpu,
   port: 9001,                                   # offer this node to your tailnet
   serve: [:"[email protected]"]}   # ...to these Evas only
]

:port is the whole of "another machine may dial me". It picks the interface, the port, and the node's name together — the node names itself for this machine's address and listens on exactly that port. Without it, the node listens on loopback and only its own machine can see it.

:serve is your veto over who gets answered. Being dialable means anything reaching the cookie can ask this node to instantiate an extension; :serve names the Evas that get an answer. It defaults to :any, which is right for a loopback-only node — everything able to reach it is already you, on your own machine. Being listed in someone else's config cannot open a socket here. Eva names itself eva_<pid>@<host>, which is what an entry here matches.

Read the full file on GitHub · 160 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. 5d ago First seen · 160 lines · 49 tokens per session scan A ce68b084c042

Subscribe to this mod's changes

write-extension-remote is a skill published in the GitHub repository aayushmau5/eva (5 stars, last pushed 4d ago), licensed MIT. It adds 49 tokens to every session and 1,917 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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