Architecture

Summary

DA Builder combines offchain transaction aggregation with onchain EIP-7702 proposer execution so multiple participants can share Ethereum execution overhead.

System Architecture

Component Responsibilities

User EOA With EIP-7702 Proposer Code

The user EOA contains delegated EIP-7702 account code. The proposer code can be Spire’s TrustedProposer or a TrustlessProposer implementation. TrustedProposer is best for dedicated EOAs where trusting Spire’s DA Builder service is acceptable. TrustlessProposer is best for applications that require account-owner authorization for each delegated call.

DA Builder Service

The DA Builder service accepts transaction submissions, validates account setup and GasTank funding, groups compatible transactions, returns transaction hashes, and manages status tracking. DA Builder is not a full Ethereum RPC provider. Use a standard RPC provider for reads, archive queries, event logs, and direct fallback.

ProposerMulticall Contract

ProposerMulticall executes aggregated onchain transactions. It calls each participant’s proposer account code in sequence so multiple user operations can share duplicated execution overhead.

GasTank Contract

GasTank stores user deposits and provides the accounting source for DA Builder transaction costs. dab_accountInfo returns GasTank balance and outstanding_charge for an account.

Data Flow

The user deposits ETH into GasTank.
The user delegates a dedicated EOA to TrustedProposer or TrustlessProposer.
The application sends a signed transaction to the DA Builder RPC endpoint.
DA Builder validates the account, funding, and transaction.
DA Builder aggregates compatible transactions.
ProposerMulticall executes proposer calls onchain.
DA Builder calculates costs and updates GasTank charges.
The application polls eth_getTransactionReceipt or dab_transactionStatus.

Trust Boundaries

Boundary	TrustedProposer	TrustlessProposer
Delegated execution	Spire’s DA Builder service can execute through the delegated EOA	Proposer code verifies account-owner authorization before execution using ecrecover
Application signing changes	Not required after delegation	Required for EIP-712 proposer payloads
Best account type	Dedicated hot-wallet EOA with limited permissions	EOA that needs explicit authorization for delegated calls
Main risk	Overbroad delegated authority	Incorrect signing, nonce, deadline, or storage-layout implementation

Failure Modes

Failure mode	Effect	Handling
GasTank not funded	Submission will be unable to aggregate	Deposit ETH and poll `dab_accountInfo`
DA Builder unavailable	DA Builder submission path fails	Submit directly through standard RPC
Unsupported RPC method	Request fails or is not appropriate for DA Builder	Use a standard Ethereum RPC provider
Bad TrustlessProposer payload	Delegated call reverts	Validate EIP-712 signing, nonce, deadline, and gas limit

Unsupported Uses

Do not use DA Builder as an archive node, indexer, read-heavy RPC provider, general-purpose wallet backend, or blob compression system. DA Builder’s architecture is for transaction aggregation and GasTank-based cost accounting.

Internal Links

Full Integration Guide - Choose proposer path.
Monitor Account - Monitor GasTank and status.
Quick Reference - Endpoints and methods.
Compare Alternatives - Decide whether DA Builder fits.

​Summary

​System Architecture

​Component Responsibilities

​User EOA With EIP-7702 Proposer Code

​DA Builder Service

​ProposerMulticall Contract

​GasTank Contract

​Data Flow

​Trust Boundaries

​Failure Modes

​Unsupported Uses

​Internal Links