Settlement

Base is the central settlement layer for Shildo. It anchors proofs, state roots, and delivery authorization for every supported route.

Why Base

Base provides the economic and technical properties Shildo needs as a settlement hub:

Low fees suitable for proof verification batches and frequent root updates
Fast blocks (~2s) with sub second user perceived finality after proof inclusion
EVM compatibility for verifier contracts, bridge adapters, and existing tooling
Coinbase ecosystem liquidity for relayer funding and operational runway

Settlement flow (step by step)

Prover submits Groth16 proof and public inputs to the Base verifier contract
Contract validates proof against the pinned verification key
Nullifier set is checked and updated atomically
Settlement root is replaced with the new root from public inputs
DeliveryAuthorized event is emitted with route id and nonce
Relayers on destination chains execute release after confirmation depth

Finality model

Shildo distinguishes three block heights in the demo explorer:

Metric	Meaning	Demo source
Latest block	Current chain tip	`chain_state.latest_block`
Last safe block	Tip minus reorg buffer	Computed in UI
Last finalized block	Irreversible under Base assumptions	Computed in UI

Production integrations should wait for finalized depth before treating delivery as irreversible.

Gas and batching

Verifier contracts use precompiled pairing operations on BN254. Integrators can batch multiple proofs in one transaction to reduce amortized gas. The SDK exposes submitProofBatch(intents[]) for high throughput merchants.

Liquidity model

Outer chains use local token pools. Base does not hold user deposits for every route. Instead relayers stake collateral on Base and maintain inventory on destination chains. Misbehavior is slashable through fraud proofs tied to the settlement root.

Chain stats (demo explorer)

The wallet network panel tracks:

Registered wallets count
Latest block number
Total transaction count
Shielded transaction count
Med gas price (0 SHILDO in demo)
Last finalized block and last safe block

These metrics are derived from Supabase tables and simulated chain state, not live Base mainnet data.

Contract interfaces (production)

interface IShildoVerifier {
  function verifyProof(
    uint256[2] calldata a,
    uint256[2][2] calldata b,
    uint256[2] calldata c,
    uint256[] calldata publicInputs
  ) external returns (bytes32 newRoot);

  function settlementRoot() external view returns (bytes32);
}