elixir

Q: How to install elixir?

Create the skills directory: mkdir -p .claude/skills. Then run: mkdir -p .claude/skills && curl -o .claude/skills/elixir.md https://raw.githubusercontent.com/georgeguimaraes/claude-code-elixir/main/SKILL.md. Finally, /elixir in Claude Code.

Q: What is elixir best for?

elixir is categorized under Development. It covers: elixir, phoenix, ecto, otp, oban, liveview, genserver.

New

158Community RegistryDevelopmentby George Guimaraes

Thinking skills for Elixir, Phoenix, Ecto, OTP, and Oban patterns

First seen 5/22/2026

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Summary

This skill enhances Claude Code with deep expertise in Elixir, Phoenix, Ecto, OTP, and Oban patterns.

It provides language server support, auto-formatting, compilation checks, and code quality analysis to streamline Elixir development workflows.

Overview

Claude Code plugins for Elixir development.

Installation

bash

claude plugin marketplace add georgeguimaraes/claude-code-elixir

Install all plugins:

bash

claude plugin install elixir-lsp@claude-code-elixir && \
claude plugin install mix-format@claude-code-elixir && \
claude plugin install mix-compile@claude-code-elixir && \
claude plugin install mix-credo@claude-code-elixir && \
claude plugin install elixir@claude-code-elixir

Prerequisites

Install the expert binary and make sure it's on your PATH. See installation instructions.

Note: mix-format, mix-compile, and mix-credo require bash (Git Bash or WSL on Windows).

Plugins

Overview

Plugin	Type	Description
elixir-lsp	LSP	Language Server with completions, go-to-definition, diagnostics
mix-format	Hook	Auto-format `.ex`/`.exs` files on save
mix-compile	Hook	Compile with `--warnings-as-errors` on save
mix-credo	Hook	Run Credo code quality checks on save
elixir	Skills	BEAM architecture, Phoenix, Ecto, OTP patterns

Tools

Elixir Language Server integration powered by Expert.

Feature	Description
Navigation	Go to definition, find references
Completions	With signature help and docs
Diagnostics	Compiler warnings and errors
File types	`.ex`, `.exs`, `.heex`, `.leex`

Auto-runs mix format after editing .ex and .exs files.

Auto-runs mix compile --warnings-as-errors after editing .ex files.

•Only .ex files (not .exs scripts/tests)
•Finds mix.exs by walking up directories
•Fails on warnings or errors

Auto-runs mix credo after editing .ex and .exs files to check code quality.

•Runs on both .ex and .exs files
•Uses project's default Credo configuration
•Gracefully skips if Credo is not installed
•Fails on code quality issues

Skills

Paradigm-shifting skills for Elixir, Phoenix, and OTP development. Includes a SessionStart hook that auto-suggests skills when working on Elixir code.

Included skills:

Skill	Use When
`elixir-thinking`	Designing modules, processes, data structures
`phoenix-thinking`	Working with Phoenix, LiveView, PubSub
`ecto-thinking`	Working with Ecto, contexts, schemas
`otp-thinking`	Implementing GenServers, supervisors, Tasks

Mental models for writing Elixir — how it differs from OOP.

Concept	Insight
Iron Law	NO PROCESS WITHOUT A RUNTIME REASON
Three dimensions	Behavior, state, mutability are decoupled
Processes	For runtime (state/concurrency/faults), not code organization
"Let it crash"	Means "let it heal" — supervisors restart
Polymorphism	Behaviors → Protocols → Message passing (least to most dynamic)

<details> <summary>Sources</summary>

</details>

Architectural patterns for Phoenix and LiveView.

Concept	Insight
Where to load data	mount/3 by default; handle_params/3 for live navigation (push_patch)
Initial double-load	mount and handle_params both run twice; use connected?/1, assign_async/3, or assign_new/3
Scopes (1.8+)	Security-first authorization threading
PubSub	Scoped topics, `broadcast_from` to avoid self-broadcast
Channel fastlane	Socket state can be stale — re-fetch or include in broadcast

<details> <summary>Sources</summary>

</details>

Architectural patterns for Ecto and contexts.

Concept	Insight
Contexts	Bounded domains with their own "dialect"
Cross-context refs	Use IDs, not `belongs_to` associations
Schemas	Multiple changesets per schema, `embedded_schema` for forms
Preloads	Separate vs join — pick based on data shape
pool_count vs pool_size	pool_count = DBConnection pools, pool_size = connections per pool

<details> <summary>Sources</summary>

•Phoenix Contexts Guide
•German Velasco - DDD for Phoenix Contexts (ElixirConf 2024)
•Ecto Multi-Tenancy Guide

</details>

OTP design patterns and when to use each abstraction.

Concept	Insight
Iron Law	GENSERVER IS A BOTTLENECK BY DESIGN
ETS	Bypasses bottleneck — concurrent reads with `:read_concurrency`
Task.Supervisor	THE pattern for async work (not raw `Task.async`)
Registry + DynamicSupervisor	Named dynamic processes without atom leaks
Broadway vs Oban	External queues vs background jobs — different problems

<details> <summary>Sources</summary>

</details>

Known Issues

elixir-lsp: `client/registerCapability` workaround. Claude Code's LSP client doesn't respond to client/registerCapability requests that Expert sends during initialization (anthropics/claude-code#32595). The plugin includes a Python wrapper (expert-wrapper) that intercepts these requests and auto-responds so Expert can initialize properly. The wrapper will be removed once the upstream fix lands. Requires Python 3 on PATH.

Troubleshooting

expert not found: Ensure the expert binary is on your PATH. See installation instructions.

License

Licensed under the Apache License, Version 2.0. See LICENSE for details.

Install & Usage

Create the skills directory

mkdir -p .claude/skills

Download the skill file

mkdir -p .claude/skills && curl -o .claude/skills/elixir.md https://raw.githubusercontent.com/georgeguimaraes/claude-code-elixir/main/SKILL.md

Invoke in Claude Code

/elixir

Use Cases

Navigate Elixir codebases with go-to-definition and find references using the LSP plugin.

Automatically format .ex and .exs files on save with mix-format to maintain consistent style.

Compile Elixir projects with warnings-as-errors to catch issues early during development.

Run Credo code quality checks on save to enforce best practices and detect code smells.

Design fault-tolerant systems using OTP patterns like GenServer, Supervisor, and Task.

Build real-time features with Phoenix LiveView and manage database interactions with Ecto.

Usage Examples

/elixir Explain how to implement a GenServer for managing a pool of workers.

/elixir Show me how to set up a Phoenix LiveView with a form that updates in real-time.

/elixir Write an Ecto query that joins posts and comments, filtering by recent date.

View source on GitHub

elixirphoenixectootpobanliveviewgenserver

Security Audits

LicenseUnknownSourceWarnRepositoryPass

Frequently Asked Questions

What is elixir?

This skill enhances Claude Code with deep expertise in Elixir, Phoenix, Ecto, OTP, and Oban patterns. It provides language server support, auto-formatting, compilation checks, and code quality analysis to streamline Elixir development workflows.

How to install elixir?

To install elixir: create the skills directory (mkdir -p .claude/skills), then run: mkdir -p .claude/skills && curl -o .claude/skills/elixir.md https://raw.githubusercontent.com/georgeguimaraes/claude-code-elixir/main/SKILL.md. Finally, /elixir in Claude Code.

What is elixir best for?

elixir is a skill categorized under Development. It is designed for: elixir, phoenix, ecto, otp, oban, liveview, genserver. Created by George Guimaraes.

What can I use elixir for?

elixir is useful for: Navigate Elixir codebases with go-to-definition and find references using the LSP plugin.; Automatically format .ex and .exs files on save with mix-format to maintain consistent style.; Compile Elixir projects with warnings-as-errors to catch issues early during development.; Run Credo code quality checks on save to enforce best practices and detect code smells.; Design fault-tolerant systems using OTP patterns like GenServer, Supervisor, and Task.; Build real-time features with Phoenix LiveView and manage database interactions with Ecto..