phoenix

phoenix is a skill for Claude Code, Codex from FortiumPartners/ensemble. It costs 22 tokens per session (6,215 once invoked), scanned A, original, MIT.

A quick reference for building web applications with Phoenix, a framework for the Elixir programming language. It covers APIs, real-time pages, databases, background jobs, deployment, testing, security, and performance.

In plain words
What is it for?
Use it when developing or reviewing Phoenix applications, including REST APIs, LiveView interfaces, database operations with Ecto, real-time channels, background jobs with Oban, deployment, and ExUnit tests.
Why use it?
It gives an agent commonly used Phoenix and Elixir patterns in one place, reducing the need to search through broad documentation while working on a project.

Skill for Claude CodeCodex

Written for Claude Code and Codex: user-invocable in frontmatter, but also installed under .codex/.

Part of the ensemble-codex plugin — 40 skills shipped together

Good fit Use it when developing or reviewing Phoenix applications, including REST APIs, LiveView interfaces, database operations with Ecto, real-time channels, background jobs with Oban, deployment, and ExUnit tests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/fortiumpartners/ensemble/phoenix
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.

Any agent
npx skills add FortiumPartners/ensemble --skill phoenix
Clone the repo
git clone --depth 1 https://github.com/FortiumPartners/ensemble

Made for: Claude Code, Codex.

Or install ensemble-codex, the plugin that ships this one along with the rest of its 40 skills.

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 phoenix

README.md
[![agentmods](https://agentmods.dev/badge/skills/fortiumpartners/ensemble/phoenix/github.svg)](https://agentmods.dev/skills/fortiumpartners/ensemble/phoenix)
Your own site
<a href="https://agentmods.dev/skills/fortiumpartners/ensemble/phoenix"><img src="https://agentmods.dev/badge/skills/fortiumpartners/ensemble/phoenix/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.

agentmods 80×15 button for phoenix

Your own site · 80×15
<a href="https://agentmods.dev/skills/fortiumpartners/ensemble/phoenix"><img src="https://agentmods.dev/badge/skills/fortiumpartners/ensemble/phoenix.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,215 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00022 $0.06215
Opus 5.5 $0.00009 $0.02486
Sonnet 5.5 $0.00004 $0.01243
Haiku 4.5 $0.00002 $0.00622

Measured 1mo ago against content hash 79f854f6598d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

phoenix 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.

packages/codex/.codex/skills/phoenix/SKILL.md · 1,011 lines

How it starts

The opening of the file, as written. The whole thing — 1,011 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Phoenix Framework Skill - Quick Reference

Version: 1.0.0 | Last Updated: 2025-10-22 | Agent: backend-developer

Quick reference for Phoenix and Elixir development patterns. For comprehensive documentation, see REFERENCE.md.


Table of Contents

  1. Phoenix API Development
  2. OTP Patterns
  3. Phoenix LiveView
  4. Ecto Database Operations
  5. Phoenix Channels
  6. Background Jobs (Oban)
  7. Production Deployment
  8. Testing with ExUnit
  9. Security Best Practices
  10. Performance Optimization

Phoenix API Development

RESTful Controller Pattern

defmodule MyAppWeb.PostController do
  use MyAppWeb, :controller
  alias MyApp.Blog
  alias MyApp.Blog.Post

  # List all posts
  def index(conn, _params) do
    posts = Blog.list_posts()
    render(conn, "index.json", posts: posts)
  end

  # Show single post
  def show(conn, %{"id" => id}) do
    post = Blog.get_post!(id)
    render(conn, "show.json", post: post)
  end

  # Create post
  def create(conn, %{"post" => post_params}) do
    case Blog.create_post(post_params) do
      {:ok, post} ->
        conn
        |> put_status(:created)
        |> render("show.json", post: post)
      {:error, changeset} ->
        conn
        |> put_status(:unprocessable_entity)
        |> render("error.json", changeset: changeset)
    end
  end

  # Update post
  def update(conn, %{"id" => id, "post" => post_params}) do
    post = Blog.get_post!(id)
    case Blog.update_post(post, post_params) do
      {:ok, updated_post} ->
        render(conn, "show.json", post: updated_post)
      {:error, changeset} ->
        conn
        |> put_status(:unprocessable_entity)
        |> render("error.json", changeset: changeset)
    end
  end

  # Delete post
  def delete(conn, %{"id" => id}) do
    post = Blog.get_post!(id)
    {:ok, _post} = Blog.delete_post(post)
    send_resp(conn, :no_content, "")
  end
end

Read the full file on GitHub · 1,011 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. 1mo ago First seen · 1,011 lines · 22 tokens per session scan A 79f854f6598d

Subscribe to this mod's changes

phoenix is a skill published in the GitHub repository FortiumPartners/ensemble (12 stars, last pushed 7d ago), licensed MIT. It adds 22 tokens to every session and 6,215 once invoked, about $0.0001 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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