ABCI Interface

The Application Blockchain Interface (ABCI) is the thin protocol boundary between Tendermint Core and the application logic. It defines a set of request-response messages (e.g., CheckTx, DeliverTx, Commit) that the consensus engine calls while processing blocks.

Because ABCI is language-agnostic and transport-agnostic, developers can implement the state machine in Go (via Cosmos SDK), Rust, or even other languages, while still inheriting Tendermint’s consensus guarantees. This separation keeps consensus upgrades and application upgrades largely independent.

For Lylo, the ABCI layer is where custom modules—such as intent parsers or AI verification pallets—hook into block processing without touching the lower-level consensus code.