BeaconChain2

/// Owns the subsystems required to produce beacon blocks.
/// Constructed once by the builder; methods use &Arc<Self>.
pub struct BlockProducer<T: BeaconChainTypes> {
    spec: Arc<ChainSpec>,
    store: BeaconStore<T>,
    config: Arc<ChainConfig>,
    op_pool: Arc<OperationPool<T::EthSpec>>,
    canonical_head: Arc<CanonicalHead<T>>,
    execution_manager: Arc<ExecutionManager<T>>,
    attestation_manager: Arc<AttestationManager<T::EthSpec>>,
    // ... (20 fields total — key domain deps shown)
}

impl<T: BeaconChainTypes> BlockProducer<T> {
    pub async fn produce_block_on_state(
        self: &Arc<Self>,
        state: BeaconState<T::EthSpec>,
        produce_at_slot: Slot,
        randao_reveal: Signature,
        // ...
    ) -> Result<BeaconBlockResponseWrapper<T::EthSpec>> {
        // All deps accessed via self.* -- no god object needed
        let attestations = self.op_pool.get_attestations(&state, &self.spec)?;
        let health = is_healthy(&self.canonical_head, /* ... */)?;
        // ...
    }
}