phx:techdebt

Technical Debt Detection

Find and eliminate duplicate code patterns, anti-patterns, and refactoring opportunities in Elixir/Phoenix projects.

Iron Laws - Never Violate These

1. Search before refactoring - Understand full scope of duplication before extracting
2. Three strikes rule - Extract shared code only after 3+ duplications
3. Prefer composition - Use behaviours and protocols over inheritance-style abstractions
4. Test coverage first - Ensure tests exist before refactoring duplicated code

Analysis Checklist

1. Run Credo for Automated Detection

Run mix credo --strict.

Focus on:

• Design issues (duplication, complexity)
• Consistency issues (naming, patterns)
• Refactoring opportunities

2. Find Duplicate Ecto Query Patterns

Use Grep to search for repeated Repo calls (Repo.get!, Repo.get, Repo.one) in lib/**/*.ex. Use Grep to find duplicate query patterns (from.*in.*where) in lib/**/*.ex.

3. Find Duplicate Validation Logic

Use Grep with output_mode: "count" to count def changeset occurrences in lib/**/*.ex. Use Grep to find repeated validations (validate_required, validate_format) in lib/**/*.ex.

4. Find Copy-Pasted Controller Actions

Use Grep to find similar action patterns (def create, def update, def delete) in lib/*_web/**/*.ex.

Common Duplication Patterns

Pattern	Symptom	Solution
Repeated queries	Same Repo.get in multiple contexts	Create shared query module
Duplicate validations	Same validate_* calls	Extract to shared changeset
Similar controllers	Copy-pasted CRUD actions	Use Phoenix generators consistently
Repeated transforms	Same Enum.map patterns	Extract to domain module

Reporting Format

For each duplication found, report:

1. Location: File paths and line numbers
2. Pattern: What code is duplicated
3. Extraction: Suggested shared function/module
4. Effort: Low/Medium/High to fix

Usage

Run /phx:techdebt to analyze the codebase and generate a prioritized report of technical debt with specific remediation steps.