Block Production

Streaming Execution with Checkpoints

Kaizen uses streaming execution where transactions execute immediately upon arrival, with periodic checkpoints every 100ms for oracle updates.

Why Streaming?

Transactions no longer wait in a mempool. They execute immediately and are committed at the next checkpoint.

Checkpoint Operation

Every 100ms:

Important: Block N contains the oracle snapshot that was applied at the START of Block N, not the new one pulled for Block N+1.

Note: Settlement is handled by the Settler service via SystemSettle transactions, not during begin_block(). This keeps block production fast and decoupled from settlement logic.

Oracle Price Pulling

The Executor pulls prices from the Oracle Service, rather than receiving them as transactions:

Benefits:

• No nonce management for oracle data
• Deterministic sequencing - prices at block level, not tx level
• Lower latency - direct HTTP vs mempool processing

If oracle is unreachable, fallback to last known prices (up to 3s staleness).

Write → Read Synchronization

Read nodes receive blocks from Write node and execute the same STF to reconstruct state.

Normal Sync

• Receive new blocks via TCP streaming
• Apply oracle snapshot (from block) via begin_block()
• Execute all TXs with full verification
• Verify computed state_root matches block header (determinism check)
• Propagate events to WebSocket subscribers

Critical: The oracle snapshot in each block is the one that was applied BEFORE TX execution on the Write node, ensuring Read nodes produce identical state.

Catch-up (restart/recovery)

• Read node sends its last block height to Write node
• Write node sends subsequent blocks
• Read node re-executes STF for each block
• Switches to live stream after catching up

Snapshot Bootstrap

• Completely new Read node replaying from block 0 takes too long
• Load periodically saved State Snapshot and replay only subsequent blocks

Configuration

[block]
interval_ms = 100        # Checkpoint interval
max_txs_per_block = 1000 # Max txs per checkpoint
 
[oracle]
service_url = "http://oracle:8550"  # Oracle service URL
timeout_ms = 10                      # Oracle pull timeout
max_stale_ms = 3000                  # Max oracle staleness
 
[settler]
enabled = true
address = "0x..."  # Authorized settler address

Running Nodes

Write Node (Sequencer)

./target/release/kaizen-node --config config.toml

Read Node

./target/release/kaizen-node --mode read --write-node ws://localhost:9000

Settler

# All pairs
./target/release/settler --write-node 127.0.0.1:9000
 
# Per-pair deployment
./target/release/settler --pairs BTC/USDT
./target/release/settler --pairs ETH/USDT