Bundles and Orders

How bundles coordinate cross-chain actions through hostFills. Covers structure and standards ensuring atomic execution of transactions across Ethereum and Signet.

Bundles coordinate cross-chain actions

We extend Flashbots bundles with a single field: hostFills. This connects Signet transactions with Ethereum actions:

{
  "txs": ["0xabc...", "0xdef..."],
  "blockNumber": "0x123",
  "hostFills": {
    "outputs": [...],
    "permit": {
    }
  }
}

This straightforward extension enables atomic cross-chain execution: the Signet transactions and the necessary host chain actions either all succeed together or the entire bundle fails.

Bundle Structure

A Signet bundle includes:

• An array of transactions (txs)

• Block targeting information (blockNumber, minTimestamp, maxTimestamp)

• Optional revertingTxHashes identifying Signet transactions allowed to revert without failing the whole bundle

• Optional replacementUuid for identifying updated bundles

• The hostFills field containing required host chain actions (if any)

Bundles come in two forms:

• With host fills:

  • Contain signed orders requiring separate validation

  • The bundle builder tracks and validates these orders

  • Host fills ingest with bundles and pass to submission

• Without host fills:

  • Standard bundles with typical transactions

  • Processed like regular transaction lists

Bundle Standards

When building systems that handle real value, reliability isn't optional. That's why we've adopted flashbots-style bundle standards:

1. Ordering: Transactions execute exactly as specified

2. Atomicity: All operations succeed or none happen

3. Revertibility: Transactions only revert when explicitly marked as revertible

Related Pages

• Market Participants
• Cross-chain transfers on Signet
• Order Processing