The `SneakyVault` contract is deployed via `CREATE2` by the `SneakyAuction` contract. It holds collateral from bidders before deployment. Upon deployment, it checks if it holds the winning bid's collateral. If so, it transfers the bid amount to the seller using `SafeTransferLib`. Finally, it self-destructs, returning any excess ETH to the bidder.

The `SneakyAuction` contract implements an on-chain, exact-collateralization, sealed-bid, second-price auction for ERC721 tokens. It allows users to create auctions, place and reveal bids, and ensures bids are collateralized. The highest bidder wins the auction, paying the second-highest bid price. The contract handles bid reveals, collateral verification, and asset transfers, ensuring secure and fair auction processes.

The `OverCollateralizedAuction` contract facilitates on-chain, over-collateralized, sealed-bid, second-price auctions for ERC721 tokens. Sellers create auctions specifying start times, bid periods, reveal periods, and reserve prices. Bidders commit bids with collateral, reveal them later, and the highest bidder wins, paying the second-highest bid. The contract handles bid commitments, reveals, and collateral management.

This smart contract library, `LibBalanceProof`, validates Merkle proofs of the Ethereum state trie to trustlessly retrieve the balance of an account at a past block. It decodes and verifies RLP-encoded block headers and trie nodes, traverses the state trie using the provided Merkle proof, and extracts the account balance. The library includes error handling for various invalid states and optimizations for gas efficiency.

The `AztecConnectAuction` contract facilitates auctions for ERC721 tokens using a sealed-bid, second-price auction mechanism. Bidders commit to bids by locking collateral, which is revealed later. The highest bidder wins the auction but pays the second-highest bid. The contract supports bid commitments and withdrawals via the Aztec rollup processor, ensuring secure and private bidding.