Detects vulnerabilities in upgradeable proxy smart contracts including storage layout collisions, uninitialized implementations, function selector clashing, delegatecall context issues, and upgrade path safety. Covers Transparent Proxy, UUPS (EIP-1822), Beacon, Diamond (EIP-2535), and Minimal Proxy (EIP-1167) patterns. Use when auditing upgradeable contracts, reviewing implementation upgrades, analyzing delegatecall architectures, or verifying proxy pattern compliance.