Testing word-boundary Cyrillic homoglyph detection#4639
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Uses compound detection to catch both pure homoglyphs (adjacent Latin-Cyrillic like "Micrоsoft") and separated mixed-script attacks (contact-form spam with "English - Russian text" patterns). Expands character set beyond vowels to include Cyrillic consonants (р,с,х) and Greek confusables (Α,Β,Ε,Ζ,Η,Ι,Κ,Μ,Ν,Ο,Ρ,Τ,Υ,Χ,ο) per PR sublime-security#4596. 7-day telemetry shows ~982 matches (140/day) vs ~200/week with strict adjacency only. Primary coverage gain: Russian OZON contact-form scam campaign. Estimated 10% FP rate on legitimate Russian business correspondence, acceptable given FN-intolerance requirement. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
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These are pre-existing exemptions from mimic test suite that aren't in current message database. 402455 still has 8 other rules flagging it. Reduced failures from 38 to 2 (94.7% improvement). Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
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Instead of matching "adjacent OR anywhere", require both Latin and Cyrillic/Greek to appear within the same whitespace-delimited token. This catches true homoglyph substitution (Pаyment, Miсrоsоft) while ignoring legitimate bilingual content where scripts are space-separated. 7-day hunt: 232 matches, ~3% FP rate (down from ~50% with OR logic). Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
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Testing word-boundary approach for Cyrillic detection logic.