code-quality

Code Quality Automation

Automated detection of code quality issues in Elixir projects. These checks run automatically via hooks when files are written, and can be run on-demand for full project analysis.

RULES — Follow these with no exceptions

1. Duplicated functions must be extracted — when 2+ modules share >70% identical function implementations, create a shared module
2. Functions must stay below ABC complexity 30 — break complex functions into smaller helpers with single responsibilities
3. Unused private functions must be removed — dead code increases maintenance burden and confusion
4. Duplicated templates must become components — when 2+ HEEx files share >40% identical markup, extract to a function component
5. Run full analysis before major refactors — use run_analysis.sh to establish a baseline before and after
6. Address duplication before complexity — extracting shared code often reduces complexity as a side effect
7. Prefer composition over inheritance — extract shared functions into modules imported/used where needed, not into base modules

---

What Gets Detected

Code Duplication

Detects when the same function appears in multiple modules with >70% body similarity.

How it works: AST-based analysis parses function bodies and compares them using trigram similarity. Functions with the same name, arity, and similar bodies are flagged.

Example output:

  Duplication Detected
   Function `format_time/1` (85% similar)
     lib/app_web/live/cycle_time.ex:45
     lib/app_web/live/lead_time.ex:52
   Suggestion: Extract to a shared module

How to fix:

# Create: lib/app_web/live/helpers.ex
defmodule AppWeb.Live.Helpers do
  def format_time(%Decimal{} = seconds) do
    seconds |> Decimal.to_float() |> format_time()
  end

  def format_time(seconds) when is_number(seconds) do
    # shared formatting logic
  end
end

# In each LiveView:
import AppWeb.Live.Helpers, only: [format_time: 1]