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App-Specific Sequencing

App-specific sequencing is a paradigm where an application—rather than Ethereum’s proposers or block builders—controls transaction ordering for its own state. To achieve this, applications generally enforce three key properties:

  1. Restricted Sequencing Rights
    Only a designated sequencer or staked validator set can execute the application’s on-chain logic, preventing external entities from bypassing the app’s sequencing rules.

  2. App-Specific Mempools
    Users send signed messages (intents) to a private or semi-private mempool controlled by the app’s sequencers, rather than sending full formed transaction via the public mempool.

  3. Order-Agnostic Outcomes
    All user actions are consolidated into a single batch transaction for on-chain submission, so proposers or block builder cannot reorder the actions inside it. Which ensures that the desired outcome is agnostic to the block’s ordering.

By coordinating these properties, app-specific sequencing enables applications to prioritize user welfare—mitigating harmful MEV, and ensuring more predictable execution.

How Angstrom Implements App-Specific Sequencing​

Angstrom fundamentally rewires decentralized trading by enforcing its own sequencing rules—rather than relying on Ethereum’s block proposers or builders to do so. This is achieved through two core components:

1. Protected Liquidity Pools​

  • Hook Enforcement: Angstrom’s Uniswap V4 pools leverages a beforeSwap hook that restricts the swap function, only staked Angstrom validators can call it.
  • Lock & Unlock:
    • Lock: The pool’s swap functions remain locked until Angstrom’s validators execute the Angstrom batch.
    • Unlock: Once the batch is settled, the pool unlocks for the rest of the block, preserving atomic composability with other Ethereum contracts.

2. The Angstrom Network (Validators)​

  • App-Specific Mempool: Users send signed orders to Angstrom nodes instead of the public mempool. Validators collect, verify, and gossip these orders.
  • Consensus on The Batch: A randomly selected leader aggregates all user swaps and winning arbitrage bids into one optimized batch transaction.
  • Atomic On-Chain Execution: The leader then submits this batch transaction to Ethereum, preventing proposers or builders from rearranging the actions inside it.

Putting It All Together​

Angstrom runs its arbitrage auction and batch auction off-chain each block. The results of which get executed in a single transaction.