Decode an EVM smart contract. Pass chain (ethereum, base, polygon, arbitrum, optimism, bsc, avalanche) + address; returns whether the contract is source-verified (Sourcify), its name/compiler/language, whether it is a proxy and its implementation address, and human-readable function and event signatures from the ABI. Optionally pass selector (a 0x 4-byte function selector) to decode what it calls — resolved from the contract's own ABI when verified, otherwise from the public 4byte directory. Pairs with crypto.tx (which gives a `to` address + calldata): turn an opaque contract + selector into "what is this and what does it do." Free, keyless.