This is the set of Protobuf definitions of types used by various parts of CometBFT:

• The Application Blockchain Interface (ABCI), especially in the context of remote applications.
• The P2P layer, in how CometBFT nodes interact with each other over the network.
• In interaction with remote signers ("privval").
• The RPC, in that the native JSON serialization of certain Protobuf types is used when accepting and responding to RPC requests.
• The storage layer, in how data is serialized to and deserialized from on-disk storage.

The canonical Protobuf definitions live in the proto folder of the relevant release branch of CometBFT. These definitions are published to the Buf registry for integrators' convenience.

This is as a result of CometBFT being a fork of Tendermint Core and wanting to provide integrators with as painless a way as possible of transitioning from Tendermint Core to CometBFT.

As of CometBFT v1, however, the project will transition to using and providing a cometbft package of Protobuf definitions (see #1330).

At present, the canonical source of Protobuf definitions for all CometBFT v0.x releases is on each respective release branch. Each respective release's Protobuf definitions are also, for convenience, published to a corresponding branch in the tendermint/tendermint Buf repository.