Consensus & Finality

Xian uses CometBFT for Byzantine Fault Tolerant consensus.

What CometBFT Does

• gossips transactions and blocks between peers
• orders transactions into blocks
• coordinates validator voting
• gives instant finality once a block is committed

What Xian Adds on Top

Xian does not replace consensus. It provides the deterministic application behind it:

• contract execution
• state storage
• app-hash generation
• contract/query APIs

Finality Model

Once a block is committed by the validator set, it is final. Xian does not use probabilistic reorg-style finality.

Block Time

Contract time comes from the finalized block timestamp agreed by consensus. That means:

• now in contracts is chain time, not local validator clock time
• every transaction in the same block sees the same now
• different block-production policies only change whether time advances during idle periods

Version Discipline

Consensus depends on validators producing the same application state. In Xian, that means validators must stay aligned on:

• network configuration
• xian-abci and xian-contracting versions
• CPython minor version