# Challenge

Challenge mode reviews - rigorous questioning before approving changes.

- Repository: https://github.com/oliver-kriska/claude-elixir-phoenix (572 stars)
- Category: Design
- License: MIT
- Last updated: 2026-10-30
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add oliver-kriska/claude-elixir-phoenix --skill challenge -g -a claude-code -y`
Codex: `npx skills add oliver-kriska/claude-elixir-phoenix --skill challenge -g -a codex -y`
Cursor: `npx skills add oliver-kriska/claude-elixir-phoenix --skill challenge -g -a cursor -y`
Gemini CLI: `npx skills add oliver-kriska/claude-elixir-phoenix --skill challenge -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add oliver-kriska/claude-elixir-phoenix`

## Description

Challenge mode reviews - rigorous questioning before approving changes. Use when you want thorough scrutiny of Ecto changes, LiveView events, OTP designs, or PR readiness.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Challenge Mode Reviews

Rigorous, critical review patterns inspired by Boris Cherny's "Grill me" approach. Push beyond first solutions to ensure quality.

## Iron Laws - Never Violate These

1. **No approval without verification** - Don't approve until all concerns addressed
2. **Assume bugs exist** - Look for edge cases, race conditions, missing handlers
3. **Question everything** - Even "obvious" code can hide issues
4. **Demand proof** - Ask for tests, show state transitions, verify behavior

## Adversarial Lenses (Apply to ALL Modes)

1. **"What Would Break This?"**, Production failure modes under load, during deploys, with unexpected data
2. **"Assumption Stress Test"**, List every assumption; which are most fragile?
3. **"Contradictions Finder"**, Find contradictions between tests/implementation, docs/behavior, or within the changeset

## Challenge Modes

### Ecto Challenge (`/phx:challenge ecto`)

Grill the developer on database changes:

**Migration Safety**

- Will this migration lock the table in production?
- What happens to existing records without the new field?
- Is the migration reversible?
- Are there any unsafe operations (column removal, type change)?

**Query Performance**

- Have you introduced any N+1 queries?
- Are there missing indexes for new WHERE clauses?
- Will this query scale with data growth?

**Schema Integrity**

- Are all constraints enforced at database level?
- What happens during rolling deployment (old code, new schema)?
- Are foreign key cascades correct?

**Backward Compatibility**

- Will old code work during deployment?
- Are there any breaking changes to the context API?

### LiveView Challenge (`/phx:challenge liveview`)

Prove the LiveView handles all cases:

**Event Coverage**

- List every `handle_event` clause and expected socket state
- What happens if socket assigns are missing when event fires?
- Are there race conditions between user events and server pushes?

**PubSub Handling**

The rest: https://github.com/oliver-kriska/claude-elixir-phoenix/blob/HEAD/plugins/elixir-phoenix/skills/challenge/SKILL.md