feat: Multi-Worker Support — PR 1: Configuration

[grantkee]

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. They can even support multiple execution environments.

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:

Location	Current	Fix
manager.rs spawn_worker_node_components()	let worker_id = 0;	Loop over 0..num_workers
manager.rs GasAccumulator::new(1)	Hardcoded 1 worker	Use num_workers
manager.rs catchup_accumulator()	gas_accumulator.base_fee(0)	Restore per-worker base fees
manager.rs EpochManager struct	Singular worker_network_handle	Vec<WorkerNetworkHandle>
manager.rs create_consensus()	Returns (PrimaryNode, WorkerNode)	Returns (PrimaryNode, Vec<WorkerNode>)
config/genesis.rs NodeP2pInfo	Single worker: NetworkInfo	workers: Vec<NetworkInfo>
config/node.rs Parameters	No num_workers field	Add num_workers: u16 (default 1)
config/network.rs	Global topics tn-worker, tn-txn	Per-worker tn-worker-{id}, tn-txn-{id}
config/consensus.rs	Single LocalNetwork	Vec<LocalNetwork>

---

This PR: Configuration (foundation — must land first)

This PR lays the configuration foundation that all subsequent multi-worker PRs build on. It changes data structures and configuration to support multiple workers while defaulting to 1 (preserving current behavior).

Scope

crates/config/src/genesis.rs — NodeP2pInfo:

• Change NodeP2pInfo.worker from NetworkInfo to workers: Vec<NetworkInfo> (one entry per worker)
• Update NodeInfo::worker_network_address() to take a WorkerId parameter
• Update NodeInfo::worker_network_key() to take a WorkerId parameter
• Add NodeInfo::num_workers() -> usize that returns self.p2p_info.workers.len()
• Update Default impl to create a single-element vec (backward compatible)
• Update NetworkGenesis::validate() to ensure all validators have the same number of workers

crates/config/src/node.rs — Parameters:

• Add num_workers: u16 field with #[serde(default = "default_num_workers")] where default_num_workers() -> u16 { 1 }
• All nodes must agree on this value; changing it requires a coordinated upgrade

crates/config/src/node.rs — Config:

• Add convenience method Config::num_workers() -> u16 delegating to self.parameters.num_workers

crates/config/src/network.rs — LibP2pConfig topics:

• Change worker_batch_topic() to worker_batch_topic(worker_id: WorkerId) -> String returning format!("tn-worker-{worker_id}")
• Change worker_txn_topic() to worker_txn_topic(worker_id: WorkerId) -> String returning format!("tn-txn-{worker_id}")

Genesis / test fixtures:

• Update YAML genesis and committee files to use the new vec format for workers
• Update crates/test-utils-committee/src/builder.rs to generate per-worker network info