Customizing a builder on Signet

Getting transactions and bundles

Mon, 01 Jan 0001 00:00:00 +0000

Getting Transactions and Bundles

The transaction cache offers endpoints for getting simple transactions and Flashbots-style transaction bundles.

Fetching bundles requires authentication. This is because Builders are only allowed to build blocks for their assigned slots. See Authentication for details.

Transaction cache basics:

API Endpoint: transactions.api.signet.sh
Cache Duration: 10 minutes
Authentication: Authentication is required to retrieve bundles, but not to retrieve transactions.

API Endpoints

Get Transactions

http

GET /transactions

Returns a list of transactions available for inclusion in a block.

Bundle guarantees

Mon, 01 Jan 0001 00:00:00 +0000

Bundle Guarantees

Signet bundles are Flashbots-style bundles of transactions wrapped with a host_fills field.

When building blocks containing Signet orders, the atomicity constraints apply to host_fills as well, meaning that if a host_fill is included and no corresponding rollup transaction is included, it would be considered invalid.

Bundle Guarantees

Block Builders should respect the following guarantees around bundles when building blocks.

Ordering: The transaction ordering in a bundle must be preserved.
Atomicity: Bundles won’t be split up and will be applied as a contiguous block of transactions or won’t be applied at all.
Revertibility: Transactions in a bundle won’t revert unless explicitly marked as revertible.

Getting a sequencer signature

Mon, 01 Jan 0001 00:00:00 +0000

Getting a Sequencer Signature

Blocks must be cosigned by the Sequencer. The Sequencer blindly signs any number of candidate blocks for the current Builder via a simple API.

The Sequencer API accepts a SignRequest via a POST call to the /signBlock endpoint, and returns a SignResponse. For details on calculating the contents hash, see the rust builder example.

The sequencer is allowed to modify the returned copy of the SignRequest. This is to allow the sequencer to set a specific gas_limit. It currently does not modify the request before returning it, but may do so in the future.

Slot Timing

Quincey follows a round-robin sequencing approach, allowing builders to request block signatures according to their spot in the rotation.

Submitting a block to Ethereum

Mon, 01 Jan 0001 00:00:00 +0000

Submitting a Block to Ethereum

Rollup blocks are submitted to the host chain by calling the Zenith submitBlock function, attaching transaction data in a 4844 blob.

Code Flows

These examples assume one has already chosen a set of transactions and bundles, and gotten a co-signature from the Sequencer API.