Problem

The node currently hardcodes a single worker per validator (worker_id = 0). The EpochManager, network layer, and several initialization paths assume exactly one worker. This blocks the ability to run independent fee markets, specialized transaction pools, or any form of worker-level parallelism.

Goal

Refactor the node to support N independent workers per validator. Each worker operates as a standalone unit with its own:

• libp2p swarm (dedicated gossip topics, listen address, network key)
• RPC server (unique port)
• Transaction pool
• Batch builder + batch validator
• LocalNetwork instance for primary communication

Workers share only the Primary (consensus) and the execution engine (block production). The num_workers count is a consensus-level parameter — all validators must agree on it.

Why

The immediate motivation is multiple fee markets. Once multi-worker is in place, a follow-up (Phase 2) spawns 2 workers by default:

• Worker 0 (General): accepts all transactions, standard EIP-1559 fee market
• Worker 1 (Whitelisted Transfers): accepts only whitelisted ERC-20 transfer/transferFrom calls, operates with a reduced base fee

This architecture also enables future process separation — workers can be extracted into standalone processes communicating with the primary over RPC.

Design Constraints

1. Workers are fully independent — no cross-worker shared state. Each worker has its own network identity, pool, and gossip topics.
2. Per-worker gossip topics — tn-worker-{id} and tn-txn-{id} replace the current global tn-worker and tn-txn topics. This provides network-level isolation.
3. Per-worker LocalNetwork — each worker gets its own LocalNetwork instance for primary communication. The primary registers as the handler on every worker's LocalNetwork. This is the seam for future process separation.
4. num_workers is a consensus parameter — changing it requires a coordinated upgrade across all validators. Defaults to 1 for backward compatibility.
5. Execution engine is shared — batches from all workers are processed sequentially by the same engine. Worker ID is already encoded in the block difficulty field.
6. Faucet on worker 0 only — the testnet faucet attaches to the general-purpose worker.

Current State

Much of the infrastructure already supports N workers but is only called with worker_id = 0:

• ExecutionNodeInner.workers: Vec<WorkerComponents> — vec exists, only 1 element
• GasAccumulator — supports N workers internally, but initialized with new(1)
• BatchValidator — already stores worker_id and rejects mismatched batches
• adjust_base_fees() — loops over num_workers() but is a no-op
• Block difficulty field — already encodes batch_index << 16 | worker_id

Hardcoded locations that block multi-worker:

This PR: Per-Worker Network Swarms

Each worker gets its own libp2p swarm with dedicated gossip topics, listen address, and network key. With num_workers = 1, behavior is identical to today.

Scope

crates/node/src/manager.rs — EpochManager struct:

• Change worker_network_handle: Option<WorkerNetworkHandle> to worker_network_handles: Vec<WorkerNetworkHandle> (indexed by WorkerId)
• Change worker_event_stream: QueChannel<...> to worker_event_streams: Vec<QueChannel<...>> (one per worker)

crates/node/src/manager.rs — spawn_node_networks():

• Loop for worker_id in 0..num_workers:
  • Create a QueChannel for this worker's events
  • Call ConsensusNetwork::new_for_worker() with:
    • The worker-specific NetworkInfo from NodeInfo.p2p_info.workers[worker_id]
    • Worker-specific topics: worker_batch_topic(worker_id), worker_txn_topic(worker_id)
  • Spawn the swarm as a critical task: "Worker Network {worker_id}"
  • Push the handle and event stream into the respective vecs

crates/network-libp2p/ — ConsensusNetwork::new_for_worker():

• Accept worker_id: WorkerId parameter
• Subscribe to per-worker topics using worker_batch_topic(worker_id) and worker_txn_topic(worker_id)
• Each swarm listens on a distinct address (from NodeInfo.p2p_info.workers[worker_id])
• Each swarm uses its own network keypair

All callsites that access self.worker_network_handle:

• Update to index into self.worker_network_handles[worker_id]
• Primarily spawn_worker_node_components() and spawn_worker_network_for_epoch()

blocked by #554