tests: Multi-Worker Support — PR 6: Tests

[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.

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: Tests

Update existing tests that hardcode worker_id = 0 and add new multi-worker integration tests that verify N workers operate independently.

Scope

Update existing test fixtures:

File	What to update
crates/node/tests/it/main.rs (lines 142, 309, 438)	Batch construction with worker_id: 0 — parameterize or test multiple worker_ids
crates/consensus/primary/src/tests/proposer_tests.rs (lines 65, 112)	Proposer tests with worker_id: 0 in header payloads — ensure proposer handles digests from multiple workers
crates/consensus/worker/tests/it/network_tests.rs (line 41)	Worker network tests — test per-worker topic subscriptions and message isolation
crates/execution/faucet/tests/it/faucet.rs (lines 296, 646)	Faucet tests with hardcoded worker_id — verify faucet only attaches to worker 0
crates/batch-validator/src/validator.rs (lines 279, 302)	Batch validator tests — add test for cross-worker batch rejection (worker 1 batch sent to worker 0 validator)

Update test-utils-committee builder:

• crates/test-utils-committee/src/builder.rs — generate per-worker network info (multiple addresses + keys per validator)

New multi-worker integration test:

• Spawn a test environment with 2+ workers per validator
• Verify batches from different workers are independently validated
• Verify execution correctly attributes blocks to the right worker (check difficulty field)
• Verify per-worker gas accumulation
• Verify per-worker base fee isolation
• Verify cross-worker batch rejection (worker 1 batch rejected by worker 0's validator)

blocked by #554 #555 #556 #557 #558

• Can be developed in parallel with PRs 2-5 against the configuration changes from PR 1