## EIP-7732 builder payment config
EIP-7732 introduces a fundamental change to how proposers interact with block builders, Unlike the current mev-Boost system where proposers blind-sign blocks, EIP-7732 requires builders(prefix:0x3) to sign bid and payload, which enable trustless payments. However, trustless option is one option, it's not mandated. Proposers retain the flexibility to accept off-protocol (trusted) payments from whitelisted builders when they choose to do so. The configuration file proposed below provides the mechanism for node operators to specify their payment preferences: which builders they trust for off-protocol payments, how to weight trusted versus trustless bids during selection, and what thresholds must be met before accepting any builder bid over a or p2p bids locally-constructed bid.

### Usages
This config can be loaded on either the beacon node or the validator client. When loaded on the beacon node, all validator clients connected to that beacon node will user the same policy, when loaded on the validator client, the configuration must be passed to the beacon node via api and the api spec is outside the scope of this document.

### Desideratum

- Endpoint-based builder identification: trusted builders are identified by their endpoints rather than individual pubkeys in beacon state, allowing flexibility, key rotation, and middleware relays while still ensuring accountability through validator index allowlists
- Validator index proof of ownership: Each endpoint must provide signatures proving control of authorized validator indices, which prevents impersonation
- Flexible payment preferences: Per-endpoint settings can define whether to accept trusted bids, trustless bids, or both, with the highest bid chosen when multiple options are allowed
- Bid boosting for special arrangements: multipliers can be applied to bids from specific endpoints to account for off-protocol payment agreements or established trust relationships

### Pre-reqs
- For trusted payment, builder's`getBid` rpc end point adds an optional `offchain_value` field
- The `signature` contains a bls signature over the hash of ``(endpoint URL, validator_index, genesis_validators_root)`` signed with the validator's private key and verified against the validator's pubkey from the beacon state, proving the builder controls that specific validator index

### Config

# Builder payment configuration for EIP-7732
builder_payment_config:
  
  # List of builder endpoints and their authorized signing keys
  builders:
    - endpoint: "https://relay.alce.eth"
      indices:
        - validator_index: 12345
          signature: "0xabc..."  # Proof builder controls this validator
        - validator_index: 67890
          signature: "0xdef..."
      trusted: true
      bid_boost: 1000000000
      min_bid: "0.1"
      min_advantage: "0.05"
    
    - endpoint: "https://relay.bob.xyz"
      indices:
        - validator_index: 11111
          signature: "0x123..."
      trusted: true
      bid_boost: 500000000
      min_bid: "0.2"
      min_advantage: "0.1"
    
    - endpoint: "https://builder.charlie.ca"
      indices:
        - validator_index: 22222 # Optional if trustless
          signature: "0x456..." # Optional if trustless
      trusted: false 
      bid_boost: 1
      min_bid: "0.0"
      min_advantage: "0.0"