N1 check

Skill oliver-kriska/claude-elixir-phoenix/plugins/elixir-phoenix/skills/n1-check

Claude Code plugin for Elixir/Phoenix/LiveView — 20 specialist agents, Iron Laws enforcement, and Tidewave MCP integration. Plan features with parallel research agents, execute with automatic verification, review with 4-agent parallel audits, and capture learnings as reusable knowledge.

Install

npx -y skills add oliver-kriska/claude-elixir-phoenix --skill n1-check

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

What its author says it does

Copied from the file, not written here

Detect N+1 query anti-patterns specifically — Repo calls inside Enum/for loops, missing preloads on associations. Use when N+1 is explicitly suspected, NOT for unrelated Ecto questions or wider database performance.

SKILL.md

2.2 KB, as published. Nobody here has run it

N+1 Query Detection

Identify and fix N+1 query anti-patterns in Ecto/Phoenix applications.

Iron Laws - Never Violate These

Never access associations without preload - Always preload before Enum.map
No Repo calls inside loops - Restructure to batch queries
Preload at context boundary - Load associations in context, not controllers/views
Use joins for filtering - Use join + preload when filtering by association

Detection Patterns

Pattern 1: Enum.map with Repo

# BAD: N+1 queries
users
|> Enum.map(fn user -> Repo.get(Order, user.order_id) end)

# GOOD: Single query with preload
users
|> Repo.preload(:orders)

Pattern 2: Association Access Without Preload

# BAD: Lazy loading triggers N queries
for user <- users do
  user.posts  # Triggers query for each user!
end

# GOOD: Eager load first
users = Repo.all(User) |> Repo.preload(:posts)
for user <- users do
  user.posts  # Already loaded
end

Pattern 3: Nested Association Access

# BAD: N+1 for nested associations
user.posts |> Enum.map(fn post -> post.comments end)

# GOOD: Nested preload
Repo.preload(user, posts: :comments)

Quick Detection Commands

Use Grep with context lines (-B 5 -A 5) to find Enum.map near Repo. calls in lib/**/*.ex. Use Grep to find association access patterns (.posts, .comments, .orders) in lib/**/*.ex. Use Grep with context (-B 3) to find Repo.get or Repo.one near loop patterns (for, Enum) in lib/**/*.ex.

Analysis Command

For a context module, run:

Use Grep to find all Repo. calls in the context module, then verify each has appropriate preloads.

Then verify each query has appropriate preloads.

References

For detailed patterns, see:

${CLAUDE_SKILL_DIR}/references/preload-patterns.md - Efficient preloading strategies
${CLAUDE_SKILL_DIR}/references/query-optimization.md - Query batching techniques