OP Stack Compatibility

OP Stack's standard execution client (op-geth) strictly order transactions by priority fee (gas price). However, SBB requires preconfirmation of inclusion order before the transaction contents are decrypted, meaning transactions must follow a first-come, first-served (FCFS) order based on the encrypted arrival time. This deterministic ordering logic is fundamentally incompatible with the OP Stack’s default tx_list block production mechanism.

To maintain compliance and alignment with the Superchain, and avoid modifying core OP Stack logic, we integrate SBB using a specialized sidecar architecture (Rollup Boost + a modified rBuilder).

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SBB Integration: Rollup-Boost + rBuilder Sidecar

Our integration solution leverages Flashbots' Rollup-Boost technology alongside a custom rBuilder implementation.

• Rollup-Boost: This functions as a bridge between OP Stack's op-node and op-geth, preserving canonical interfaces.

• rBuilder: This is the external, modular block builder that incorporates SBB's logic. It is modified to incorporate SBB's cryptographic ordering constraints (FCFS pre-confirmation logic) when constructing the transaction payload.

This sidecar integration ensures we can fully support SBB while maintaining full alignment with Superchain governance and upgrade paths.