elixir-phoenix-document

A documentation guide for Elixir and Phoenix projects, used only when the user explicitly asks for documentation.

In plain words
What is it for?
Use it to add module and function documentation, update a user-facing README, and record important implementation decisions after a feature is tested.
Why use it?
It helps keep public modules and functions understandable while preserving existing documentation. It also records design reasons in architecture decision records and avoids documenting untested code.

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/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-document
Any agent
npx skills add ccarvalho-eng/codex-elixir-phoenix --skill elixir-phoenix-document
Clone the repo
git clone --depth 1 https://github.com/ccarvalho-eng/codex-elixir-phoenix

Made for: Claude Code, Codex.

Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 737 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 $0.00027 $0.00737
Opus 5 $0.00014 $0.00368
Sonnet 5 $0.00005 $0.00147
Haiku 4.5 $0.00003 $0.00074

Measured 3d ago against content hash 7d8288fefb95, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

elixir-phoenix-document 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 3d 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/elixir-phoenix-document/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Document

Generate documentation for newly implemented features.

Usage

`elixir-phoenix-document` .codex/plans/magic-link-auth/plan.md
`elixir-phoenix-document` magic link authentication
`elixir-phoenix-document`  # Auto-detect from recent plan

Iron Laws

  1. Never remove existing documentation — Existing docs may reflect design intent that isn't obvious from code alone; update rather than replace
  2. @moduledoc on every public module — Undocumented modules accumulate quickly and create onboarding friction for new team members
  3. ADRs capture the "why", not the "what" — Code shows what was built; ADRs explain why this approach was chosen over alternatives
  4. Match @doc to function's public API — Document parameters, return values, and edge cases; callers shouldn't need to read the implementation
  5. DO NOT add @doc to untested code — documentation implies a stable contract; document only after tests confirm the function behaves as described

What Gets Documented

Output Description
@moduledoc For new modules missing documentation
@doc For public functions without docs
README section For user-facing features
ADR For significant architectural decisions

Workflow

Step 0: Pre-check (avoid no-op runs)

Run git diff --name-only HEAD~5 | grep '\.ex$' | head -20 to check for new .ex files.

If NO new .ex files were added (only modifications), skip the full audit and report: "No new modules — documentation coverage unchanged." This prevents 35-message analysis sessions that conclude "PASS" with zero output (confirmed: session bb0a0454 wasted ~2K tokens on no-op).

  1. Identify new modules from recent commits or plan file
  2. Check documentation coverage (@moduledoc, @doc)
  3. Generate missing docs using templates
  4. Add README section if user-facing feature
  5. Create ADR if architectural decision was made
  6. Write report to .codex/plans/{slug}/reviews/{feature}-docs.md

Read the full file on GitHub · 80 lines

Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 3d ago First seen · 80 lines · 27 tokens per session scan A 7d8288fefb95

Subscribe to this mod's changes

elixir-phoenix-document is a skill published in the GitHub repository ccarvalho-eng/codex-elixir-phoenix (11 stars, last pushed 4mo ago), licensed MIT. It adds 27 tokens to every session and 737 once invoked, about $0.0001 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 2026-08-30.