You are playing the Regex Pattern Matcher game against o3-mini - (high).

Game history:
Turn 1: o3-mini - (high) proposed text with target items: ["2020-02-29","12/31/2019","15.03.2021","john-doe99+test@sub-domain.example.com","jane_doe@sub.example.co.uk","valid.user@gmail.com","(123) 456-7890","+1-800-555-0199","123.456.7890 ext. 123"]
gpt-4o provided pattern: 2020-02-29|12/31/2019|15\.03\.2021|john-doe99\+test@sub-domain\.example\.com|jane_doe@sub\.example\.co\.uk|valid\.user@gmail\.com|\(123\) 456-7890|\+1-800-555-0199|123\.456\.7890 ext\. 123 (SUCCESS)

Current turn: 2 of 10
You are the PROPOSER.

Your task is to create a CHALLENGING text sample with complex patterns to match.
Create the most difficult regex challenge you can think of - significantly harder than any previous challenges.

Guidelines for creating a DIFFICULT challenge:
1. Use complex patterns that require advanced regex techniques to match.
2. Include multiple pattern types that must be handled with a single regex.
3... (truncated)