boundaries

boundaries is a skill for Claude Code from oliver-kriska/claude-elixir-phoenix. It costs 33 tokens per session (1,156 once invoked), scanned A, original, MIT.

A Phoenix architecture review that examines dependencies between contexts, which are groups of modules responsible for separate business areas. It uses mix xref to identify coupling, cycles, and boundary violations.

In plain words
What is it for?
It is for checking context boundaries, reviewing architecture before splitting modules, finding circular dependencies, and assessing the health of a Phoenix project.
Why use it?
It helps reveal when separate parts of an application depend on each other too much or expose more functions than intended.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Part of the phx plugin — 50 skills, 26 agents, 10 hooks shipped together

Good fit It is for checking context boundaries, reviewing architecture before splitting modules, finding circular dependencies, and assessing the health of a Phoenix project.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/oliver-kriska/claude-elixir-phoenix/boundaries
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 oliver-kriska/claude-elixir-phoenix --skill boundaries
Clone the repo
git clone --depth 1 https://github.com/oliver-kriska/claude-elixir-phoenix

Made for: Claude Code.

Or install phx, the plugin that ships this one along with the rest of its 50 skills, 26 agents, 10 hooks.

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 boundaries

README.md
[![agentmods](https://agentmods.dev/badge/skills/oliver-kriska/claude-elixir-phoenix/boundaries/github.svg)](https://agentmods.dev/skills/oliver-kriska/claude-elixir-phoenix/boundaries)
Your own site
<a href="https://agentmods.dev/skills/oliver-kriska/claude-elixir-phoenix/boundaries"><img src="https://agentmods.dev/badge/skills/oliver-kriska/claude-elixir-phoenix/boundaries/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 boundaries

Your own site · 80×15
<a href="https://agentmods.dev/skills/oliver-kriska/claude-elixir-phoenix/boundaries"><img src="https://agentmods.dev/badge/skills/oliver-kriska/claude-elixir-phoenix/boundaries.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,156 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00033 $0.01156
Opus 5 $0.00016 $0.00578
Sonnet 5 $0.00007 $0.00231
Haiku 4.5 $0.00003 $0.00116

Measured 9d ago against content hash 119492dbf094, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

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 9d 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

Copies of this mod

2 near-identical copies found in the catalogue:

plugins/elixir-phoenix/skills/boundaries/SKILL.md · 139 lines

How it starts

The opening of the file, as written. The whole thing — 139 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

/phx:boundaries              # Check for violations
/phx:boundaries --assess     # Score context health (0-100)
/phx: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 Glob to count .ex files per context directory under lib/my_app/*/. Use Grep 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 · 139 lines

Files

What ships with it

2 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. 9d ago First seen · 139 lines · 33 tokens per session scan A 119492dbf094

Subscribe to this mod's changes

boundaries is a skill published in the GitHub repository oliver-kriska/claude-elixir-phoenix (541 stars, last pushed 3d ago), licensed MIT. It adds 33 tokens to every session and 1,156 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 2026-08-30.

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