How do I install the Elixir Boundaries skill?

Run npx skillmds@latest add andrewdryga/elixir-boundaries in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Elixir Boundaries safe to use?

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Which AI agents work with Elixir Boundaries?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Elixir Boundaries free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Elixir Boundaries?

AndrewDryga (@andrewdryga) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Elixir Boundaries by andrewdryga — Agent Skill

Name: Elixir Boundaries
Rating: 4.2 (5 reviews)
Author: AndrewDryga

Elixir Boundaries

Audit context boundaries and coupling in portal/apps/emisar via mix xref + greps — find the web/MCP layer reaching past contexts, one context reaching into another's Query/Schema/Changeset, and dependency cycles. Use before splitting a context, after adding cross-context calls, or to check architecture health.

AndrewDryga Updated Sep 22, 2026

File contents

Context boundary audit

The architecture has one rule that everything else hangs off: the context module is the only public surface. This skill checks that the rule holds.

What's allowed to call what

Layer	May call	May NOT call
LiveView / controller / channel / MCP	context public functions, `CoreComponents`, PubSub	`Repo`, a schema's `Query`/`Changeset`/`Schema` directly
Context (`lib/emisar/<ctx>.ex`)	its own schemas/Query/Changeset, `Repo`, other contexts' public API	another context's `Query`/`Changeset`/`Schema` internals; web-layer modules
Query / Changeset / Schema	(pure building blocks)	`Repo` (Query/Changeset), each other

Checks

1. Web/MCP bypassing contexts (the most common drift):

cd portal
rg -n '\bRepo\.' apps/emisar_web/lib            # should be ~none — go through a context
rg -n 'Emisar\.\w+\.(Query|Changeset)\b' apps/emisar_web/lib   # web reaching into internals

2. One context reaching into another's internals:

# in lib/emisar/<ctx>.ex, references to ANOTHER context's Query/Changeset/Schema
rg -n 'Emisar\.\w+\.(Query|Changeset)\b' apps/emisar/lib/emisar/*.ex

A context should call OtherContext.fetch_thing(id, subject), not OtherContext.Thing.Query.by_id/1.

3. Coupling + cycles (mix xref — confirm the flags with mix help xref):

cd portal
mix xref graph --format stats                       # fan-in / fan-out per module
mix xref graph --format cycles --label compile      # compile-time cycles (should be none)
mix xref callers Emisar.<Ctx>.<fun>                 # who depends on a function before you change it

Output

Report each violation as file:line → which boundary → the fix (almost always: "add a public function to context X and call that"). List the coupling hotspots (a context with high fan-out may be doing too much) and any cycle. Don't move modules around without running xref first — refactoring boundaries blind creates new violations. Fixes that add a context function: hand to /elixir-context-fn.

---name: elixir-boundariesdescription: Audit context boundaries and coupling in portal/apps/emisar via mix xref + greps — find the web/MCP layer reaching past contexts, one context reaching into another's Query/Schema/Changeset, and dependency cycles. Use before splitting a context, after adding cross-context calls, or to check architecture health.---# Context boundary auditThe architecture has one rule that everything else hangs off: **the context moduleis the only public surface.** This skill checks that the rule holds.## What's allowed to call what| Layer | May call | May NOT call ||-------|----------|--------------|| LiveView / controller / channel / MCP | context public functions, `CoreComponents`, PubSub | `Repo`, a schema's `Query`/`Changeset`/`Schema` directly || Context (`lib/emisar/<ctx>.ex`) | its own schemas/Query/Changeset, `Repo`, **other contexts' public API** | another context's `Query`/`Changeset`/`Schema` internals; web-layer modules || Query / Changeset / Schema | (pure building blocks) | `Repo` (Query/Changeset), each other |## Checks**1. Web/MCP bypassing contexts** (the most common drift):```shcd portalrg -n '\bRepo\.' apps/emisar_web/lib # should be ~none — go through a contextrg -n 'Emisar\.\w+\.(Query|Changeset)\b' apps/emisar_web/lib # web reaching into internals```**2. One context reaching into another's internals:**```sh# in lib/emisar/<ctx>.ex, references to ANOTHER context's Query/Changeset/Schemarg -n 'Emisar\.\w+\.(Query|Changeset)\b' apps/emisar/lib/emisar/*.ex```A context should call `OtherContext.fetch_thing(id, subject)`, not`OtherContext.Thing.Query.by_id/1`.**3. Coupling + cycles** (mix xref — confirm the flags with `mix help xref`):```shcd portalmix xref graph --format stats # fan-in / fan-out per modulemix xref graph --format cycles --label compile # compile-time cycles (should be none)mix xref callers Emisar.<Ctx>.<fun> # who depends on a function before you change it```## OutputReport each violation as `file:line → which boundary → the fix` (almost always:"add a public function to context X and call that"). List the coupling hotspots(a context with high fan-out may be doing too much) and any cycle. Don't movemodules around without running xref first — refactoring boundaries blind creates newviolations. Fixes that add a context function: hand to `/elixir-context-fn`.

Frequently asked questions