Bug Fix Knowledge Base

Comprehensive knowledge for diagnosing and fixing bugs in PHP applications following DDD, CQRS, and Clean Architecture patterns.

Bug Categories and Symptoms

1. Logic Errors

Symptoms:

• Incorrect output for valid input
• Wrong branch taken in conditionals
• Inverted boolean logic
• Off-by-one errors in loops
• Missing edge case handling

Common Causes:

• > instead of >=, && instead of ||
• Negation errors (!$condition vs $condition)
• Loop boundary mistakes (< count vs <= count)
• Missing break in switch statements