builder

The builder crate group produces blocks and flashblocks. It assembles flashblocks at 200ms intervals and publishes them to streaming clients.

Sub-crates

Crate	Package Name	Purpose
core	base-builder-core	Core block building logic and flashblock production
metering	base-builder-metering	Resource metering for block building
publish	base-builder-publish	Block/flashblock publishing and distribution

Role in the Architecture

The builder sits between the execution layer and the consensus layer. It:

1. Receives transactions from the transaction pool
2. Builds execution payloads using the EVM
3. Produces flashblocks at ~200ms intervals during the 2-second block time
4. Publishes flashblocks via WebSocket for real-time streaming
5. Finalizes the canonical block at the end of each slot

The base-builder-core crate contains the main building logic, base-builder-metering handles gas and resource accounting, and base-builder-publish handles distribution of produced blocks.

Source

crates/builder/