elixir-phoenix-boundaries

elixir-phoenix-boundaries is a skill for Claude Code, Codex from ccarvalho-eng/codex-elixir-phoenix. It costs 20 tokens per session (1,138 once invoked), scanned A, a copy of boundaries, MIT.

A Phoenix code-review skill that checks whether modules are grouped into clean, separate business areas called contexts, using Mix dependency reports.

In plain words
What is it for?
Use it to check context boundaries, review dependency health, calculate a context-health score, and get suggested fixes for detected violations.
Why use it?
It helps reveal tangled dependencies, oversized contexts, circular references, and code that crosses context boundaries in ways that make changes harder.

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

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 elixir-phoenix-boundaries

README.md
[![agentmods](https://agentmods.dev/badge/skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-boundaries.svg)](https://agentmods.dev/skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-boundaries)
Your own site
<a href="https://agentmods.dev/skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-boundaries"><img src="https://agentmods.dev/badge/skills/ccarvalho-eng/codex-elixir-phoenix/elixir-phoenix-boundaries.svg" alt="Measured on agentmods" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,138 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 88% copy Near-identical to another mod 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 $0.00020 $0.01138
Opus 5 $0.00010 $0.00569
Sonnet 5 $0.00004 $0.00228
Haiku 4.5 $0.00002 $0.00114

Measured 5d ago against content hash 54c308c18f7f, 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-boundaries 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.

Origin

This is a copy

88% identical to boundaries — 29 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/elixir-phoenix-boundaries/SKILL.md · 138 lines

How it starts

The opening of the file, as written. The whole thing — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Phoenix Context Boundary Validation

Analyze module dependencies to ensure clean context separation and proper architectural boundaries.

Usage

`elixir-phoenix-boundaries`              # Check for violations
`elixir-phoenix-boundaries` --assess     # Score context health (0-100)
`elixir-phoenix-boundaries` --fix        # Suggest fixes for violations

--assess Mode: Context Health Score

Evaluate overall boundary health with a quantified score.

Metrics Calculated

Metric Healthy Range Red Flag Weight
Modules per context 3-15 >20 or <2 20%
Public API surface 5-30 funcs >40 funcs 15%
Fan-out (contexts called) 1-4 >6 20%
Fan-in (called by contexts) 1-6 >10 15%
Circular dependencies 0 >0 15%
Boundary violations 0 >0 15%

Commands for Assessment

Use rg --files to count .ex files per context directory under lib/my_app/*/. Use rg to count public function definitions per context file under lib/my_app/*.ex. Run mix xref graph --format stats for dependency analysis. Run mix xref graph --format cycles --label compile for compile-time circular dependencies.

Output Format

## Context Health Assessment

### Overall Score: 82/100 (Good)

| Context | Modules | API | Fan-Out | Fan-In | Score |
|---------|---------|-----|---------|--------|-------|
| Accounts | 5 | 12 | 2 | 4 | 95 |
| Orders | 18 | 45 | 8 | 3 | 62 |
| Shared | 2 | 8 | 0 | 12 | 78 |

### Issues Found

1. **Orders** - Too large (18 modules, 45 funcs)
   - Consider: Extract Fulfillment, Invoicing sub-contexts

2. **Orders** - High fan-out (8 contexts)
   - Consider: Review if all dependencies necessary

### Recommendations

- Split Orders into Orders + Fulfillment
- Review Accounts ← Billing dependency

Iron Laws - Never Violate These

  1. Controllers call only contexts - No direct Repo access from web layer
  2. Schemas are pure data - No side effects, no Repo calls in schema modules
  3. Contexts own their schemas - Don't import schemas from other contexts
  4. Explicit dependencies only - Cross-context calls must be intentional
  5. DO NOT refactor context boundaries without running mix xref first — Refactoring without dependency data creates new violations; always map the dependency graph before moving modules

Read the full file on GitHub · 138 lines

Files

What ships with it

3 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. 5d ago First seen · 138 lines · 20 tokens per session scan A 54c308c18f7f

Subscribe to this mod's changes

elixir-phoenix-boundaries is a skill published in the GitHub repository ccarvalho-eng/codex-elixir-phoenix (11 stars, last pushed 4mo ago), licensed MIT. It adds 20 tokens to every session and 1,138 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 88% identical to boundaries, differing in 29 lines, and is treated as a copy.

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