19. Sync Protocol
The Kortana synchronization subsystem provides robust, multi-tier state synchronization mechanisms, enabling newly joined, restarted, or partitioned nodes to quickly catch up with the canonical chain tip.
19.1 Block Sync
Block Sync is the canonical, full-verification synchronization mode in Kortana. In this mode, a syncing node connects to high-reputation peers and downloads the complete historical sequence of block headers and block bodies starting from its current local head height up to the latest finalized network tip.
For every downloaded block, the sync engine executes full cryptographic verification: it validates the attached BLS12-381 Quorum Certificate against the active validator set, re-executes all transactions through the dual-engine Execution Router (KEVM and KVM), verifies that the resulting state trie root matches the header's state_root, and writes state transitions atomically to RocksDB. While Block Sync is computationally intensive, it provides total trustlessness by ensuring that the node has independently verified every state mutation since Genesis.
19.2 Snapshot Sync
To allow production RPC nodes, validator candidates, and explorer backends to bootstrap within minutes rather than waiting hours for full historical re-execution, Kortana implements Snapshot Sync.
Snapshot Sync leverages cryptographically certified state trie snapshots generated at recurring epoch boundaries (every 2,400 slots). The syncing node queries peers for the latest finalized snapshot metadata, verifies that the snapshot root hash matches a block header certified by a valid HotStuff Quorum Certificate, and downloads the compressed state chunks in parallel. Once all trie nodes, account balances, and contract bytecodes are unpacked directly into the state_trie and code column families, the node switches to standard live block sync, executing only the few blocks produced since the snapshot.
19.3 Fast Sync
Fast Sync offers an intermediate synchronization strategy that balances speed and bandwidth efficiency by pipelining header verification and state downloading across concurrent worker thread pools.
During Fast Sync, the node downloads the entire chain of block headers first, verifying the continuous SHA-256 dPOH hash chain and BLS Quorum Certificates at multi-gigabit speeds. Once the header skeleton is verified to the tip, worker threads download the state trie corresponding to the target pivot block. Transactions and receipts for historical blocks are downloaded concurrently in the background without full EVM re-execution, allowing the node to serve RPC read queries almost immediately.