The LI.FI Contract is built using the EIP-2535 (Multi-facet Proxy) standard. The contract logic lives behind a single contract that in turn uses DELEGATECALL to call facet contracts that contain the business logic.
All business logic is built using facet contracts that live in
A basic example would be a user bridging from one chain to another using Hop Protocol. The user would interact with the LI.FIDiamond contract which would pass the Hop-specific call to the HopFacet which then passes required calls + parameters to Hop Protocol's contracts.
The basic flow is illustrated below.
The LiFiDiamond contract is deployed along with some helper contracts that facilitate things like upgrading facet contracts, look-ups for methods on facet contracts, ownership checking and withdrawals of funds. For specific details please check out EIP-2535.