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

Game history:
Turn 1: o3-mini - (low) proposed text with target items: ["first.last+category@sub.domain.com","user_name123@co-op.io","+44 207 946 0128","+1-800-555-0199","2021-12-31","AB12-XY_9"]
claude 3.7 sonnet provided pattern: first\.last\+category@sub\.domain\.com|user_name123@co-op\.io|\+44 207 946 0128|\+1-800-555-0199|2021-12-31|AB12-XY_9 (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. Create patterns where naive approaches would either miss matches or match too many items.
4. ADVANCED PATTERNS to consider:
   -... (truncated)