Regex builder

Goal

Produce a correct, testable regex with rationale and runnable verification.

Inputs to confirm (ask if missing)

• Target regex flavor/engine (PCRE, Python, JavaScript, .NET, RE2, etc.).
• Example matches and non-matches (at least 3 each when possible).
• Scope: single-line vs multi-line; file types/paths.
• Output needs: capture groups, named groups, replacement template.