Reentrancy Watchtower: Live Block-Level Cross-Function Reentrancy Alerts

A live defense tripwire for DeFi security operations and incident-response teams: it evaluates every new Ethereum block's transaction traces against cross-function reentrancy rules and pages the team the moment that pattern executes against a contract they defend, while the attack is still running. The value is the response window — seconds-to-minutes of head start to fire an emergency pause or circuit breaker, plus a clean incident timeline afterward. It is not an audit or a history replay; it answers 'are we being exploited right now?' rather than 'is this code vulnerable?'