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.
npx agentmods add skills/dallay/agents-skills/elixir-developmentnpx skills add dallay/agents-skills --skill elixir-developmentgit clone --depth 1 https://github.com/dallay/agents-skillsWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00054 | $0.03073 |
| Opus 5 | $0.00027 | $0.01537 |
| Sonnet 5 | $0.00011 | $0.00615 |
| Haiku 4.5 | $0.00005 | $0.00307 |
Grade A, and why
elixir-development 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 2d 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.
How it starts
The opening of the file, as written. The whole thing — 428 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Elixir Development
Production patterns for Elixir/OTP programming, covering Mix projects, GenServer, Supervisors, pattern matching, testing with ExUnit, and Phoenix basics.
When to Use This Skill
- Starting or structuring an Elixir project
- Building concurrent systems with OTP
- Implementing GenServers and Supervisors
- Writing pattern-matching-driven code
- Testing with ExUnit
- Working with Phoenix web framework
- Querying databases with Ecto
Core Concepts
1. Project Layout (Mix)
myapp/
├── lib/
│ ├── myapp/
│ │ ├── application.ex # OTP Application (supervisor tree root)
│ │ ├── accounts/
│ │ │ ├── user.ex # Ecto schema
│ │ │ └── accounts.ex # Context module (business logic)
│ │ ├── workers/
│ │ │ └── email_worker.ex
│ │ └── repo.ex # Ecto Repo
│ └── myapp.ex # Public API
├── test/
│ ├── myapp/
│ │ └── accounts_test.exs
│ ├── support/
│ │ └── fixtures.ex
│ └── test_helper.exs
├── config/
│ ├── config.exs
│ ├── dev.exs
│ ├── test.exs
│ └── runtime.exs
├── mix.exs
├── mix.lock
└── README.md
2. Key Principles
| Principle | Elixir Idiom |
|---|---|
| Immutability | All data is immutable; transform, don't mutate |
| Pattern matching | Destructure and branch in function heads |
| Pipe operator | Chain transformations with ` |
| Let it crash | Supervisors restart failed processes automatically |
| Processes | Lightweight, isolated; communicate via messages |
Quick Start
# Create a new project
mix new myapp --sup # --sup includes Application supervisor
# Create a Phoenix project
mix phx.new myapp
# Get dependencies
mix deps.get
# Run tests
mix test
mix test --cover
# Interactive shell
iex -S mix
# Format code
mix format
Patterns
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.
- 2d ago First seen · 428 lines · 54 tokens per session scan A 04582b987e6c
elixir-development is a skill published in the GitHub repository dallay/agents-skills (2 stars, last pushed 9d ago), licensed MIT. It adds 54 tokens to every session and 3,073 once invoked, about $0.0003 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 2026-08-31.
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