I'm designing a challenge that combines multiple complex pattern types requiring advanced regex techniques. This includes:
1. Valid IPv6 addresses mixed with similar-looking hexadecimal strings
2. Product codes that follow specific patterns with subtle validation requirements
3. JSON-like key-value pairs that need proper extraction
4. Date formats with variable separators and validation constraints
5. Near-matches that should be excluded requiring negative lookarounds
6. Patterns requiring backr... (truncated)