As described in the RFC post, Aztec's sequencer selection design leaves block building entirely up to the sequencing nodes. This allows for the outsourcing of block production, potentially creating a market structure similar to the status quo between MEV-Boost and Ethereum validators. We propose a method of integrating Astria's decentralized shared sequencer into Aztec's sequencer nodes to provide this off-chain block building infrastructure. Leveraging Astria's decentralized MEV marketplace and much quicker finality, Aztec sequencer nodes can provide MEV searching infrastructure and fast preconfirmations for bundle inclusion without sacrificing security or introducing centralized points of failure. Background: Astria image Write Path: Transaction Submission

Flame is an Astria-based EVM rollup that serves as TIA’s DeFi hub. The top of the block (ToB) in a DeFi-enabled rollup is particularly valuable because it provides an execution guarantee. As the amount of liquidity on Flame increases, the volume of MEV opportunities will grow, thereby increasing the value of Flame’s blockspace. With an increased demand for ToB execution, an auction is the efficient mechanism for allocating this privilege to a bidder, accumulating revenue for the Flame ecosystem. rolluptobsequencingrule Flame leverages Astria's lazy sequencer and sequencing rules to construct an auction for only the top-of-block bundle slot. As lazy sequencing separates inclusion from execution, Flame’s trusted Auctioneer simply needs to allocate, sign and include the auction-winning bundle in the sequencing-layer block. Flame’s execution enforces a sequencing rule that places the Auctioneer’s signed Allocation deterministically at the top of the block it was successfully included in. This provides bidders with a dedicated submission path that offers two key benefits: Bidders submit their bundles directly to the trusted Auctioneer's node, keeping their traffic separate from regular (i.e. MetaMask) users who submit transactions via the rollup’s mempool. This contains congestions and prevents the adverse effects on regular users during periods of high market activity, such as spikes in gas costs. The auctioneer runs a sealed-bid first-price auction that allocates the top-of-block slot to the highest bidder. This ensures that only the winning bidder's bundle is posted and only they pay for their transactions.Unlike priority fees, which charge all bidders regardless of winning, this system only charges the winning bidder. Bids are sent by bidders directly to the Auctioneer’s node, and do not go through a public mempool. Bidders cannot see other submitted bids nor the corresponding payloads.

By: Elizabeth Intro Astria has developed a native bridging protocol for rollups built on the Astria sequencing layer to transfer funds to and from the Astria sequencing layer and between rollups built on top of it. Rollups can opt-in to using this protocol by enshrining it into their consensus. To enshrine the protocol as part of a rollups consensus, and therefore implement deposits of tokens from the Astria sequencer, all the rollup has to do is create a sequencer bridge account and assign a specific sequencer address as the bridge operator. Incoming transfers to this bridge account are locked in the sequencer and minted on the rollup. This is similar to how existing L1-to-rollup bridges work, where some lock event happening on the L1 results in a deposit transaction being derived automatically on the rollup. Note that since deposits are a lock-mint, withdrawals are a burn-unlock. bridgeflow Withdrawals from a rollup back to the sequencing layer happen in two steps: (1) tokens are burned on the rollup and (2) the corresponding tokens are unlocked on the sequencing layer to the destination address. The rollup-side tokens serve as a receipt for assets locked on the sequencing layer, and burning them absolves their holder of the receipt to the unlocked tokens. Bridge operators are trusted to settle withdrawals on the sequencing layer, and the protocol is currently secured by a threshold signing protocol between operators. Future upgrades to the sequencing layer will provide trust minimized guarantees using validity proofs.

By: Elizabeth Astria is developing a decentralized shared sequencer network. We have designed the network to provide rollups with fast finality, censorship resistance, composability guarantees, and decentralization at inception. This post explores the current state of rollups, explains parts of Astria's architecture, and how Astria's sequencer tackles the limitations of centralized rollup operations through shared sequencing. 1. How Rollups Work A rollup is a blockchain that consists of a state transition function executed over some subset of data contained in another blockchain, the L1. Bridging to/from the L1 (by enshrining the rollup’s state transition in the L1) is implemented by non-sovereign rollups. 1.1 Rollup full node architecture