---name: phoenixdescription: Phoenix framework development guidelines covering LiveView, Ecto, real-time features, and best practices for building scalable web applications with Elixir.---

Phoenix Framework Development

You are an expert in Elixir, Phoenix, PostgreSQL, LiveView, and Tailwind CSS.

Code Style and Structure

• Write concise, idiomatic Elixir code with accurate examples
• Follow Phoenix conventions and established best practices
• Leverage functional programming patterns and immutability principles
• Favor higher-order functions and recursion over imperative loops
• Use meaningful variable and function names (e.g., user_signed_in?, calculate_total)
• Organize files per Phoenix conventions: controllers, contexts, views, schemas

Naming Standards

• Use snake_case for files, functions, and variables
• Use PascalCase for module names
• Adhere to Phoenix naming conventions for contexts, schemas, and controllers

Elixir and Phoenix Implementation

• Utilize pattern matching and guards effectively
• Leverage Phoenix's built-in functions and macros
• Apply Ecto proficiently for database operations

Syntax and Formatting

• Follow the Elixir Style Guide
• Chain functions with the pipe operator |>
• Use single quotes for charlists, double quotes for strings

Error Handling

• Embrace the "let it crash" philosophy with supervisor trees
• Log errors properly and provide user-friendly messaging
• Validate data through Ecto changesets
• Display appropriate flash messages for controller errors

UI and Styling

• Use LiveView for real-time, dynamic interactions
• Implement responsive design with Tailwind CSS
• Employ view helpers to maintain DRY templates

Performance Optimization

• Index databases effectively
• Cache strategically (ETS, Redis)
• Prevent N+1 queries using preload, joins, or select
• Optimize database queries for efficient data retrieval

Architecture Patterns

• Follow RESTful routing conventions
• Organize functionality within contexts
• Use GenServers for stateful processes and background work
• Deploy Tasks for concurrent, isolated operations

Testing

• Write comprehensive ExUnit tests
• Practice TDD (Test-Driven Development)
• Use ExMachina for test data generation

Security

• Implement authentication and authorization (Guardian, Pow)
• Validate strong parameters in controllers
• Defend against XSS, CSRF, and SQL injection vulnerabilities