Hunt ReDoS (CWE-1333, Catastrophic Backtracking) — identify regexes with nested quantifiers or overlapping alternation that cause super-linear matching time, trace tainted input paths to regex sinks, demonstrate timing PoC, and validate with response-time delta. Covers PCRE/RE2/V8/Python re engine differences. Triggers on: 'ReDoS', 'regex denial', 'catastrophic backtracking', 'redos', 'regex complexity', 'nested quantifiers', 'regex amplification', 'CWE-1333'.