5-node Raft cluster

Not a game.

This is the Raft consensus algorithm running locally in your browser — same algorithm that runs etcd, CockroachDB, and Consul. The 5 dots are nodes. The lines between them are RPC channels. The traveling dots are messages in flight (cyan = AppendEntries, magenta = RequestVote).

Nothing is faked. Every leader you see won an actual majority vote. Every commit went through actual log replication and a quorum check.

Try this in order:

1. 1Wait 3–5 seconds. One node turns cyan — that's the leader.
2. 2Click that leader to crash it. A new election fires; a new leader takes over with a higher term.
3. 3Hit the {n1,n2} | {n3,n4,n5} partition. The minority side cannot elect a leader, ever — that's the safety property.
4. 4Click No partition. The cluster reconciles to a single leader at the highest term.
5. 5Type a value into PROPOSE and hit →. Watch the entry replicate to followers, commit on the majority, then apply to each state machine.

Invariants this proves:

• ✓ At most one leader per term — no split-brain
• ✓ No committed entry is ever lost on a partition heal
• ✓ A node only votes for one candidate per term
• ✓ A leader only commits entries from its current term (§5.4.2)

10 of these invariants are checked in CI via tests/scripts/verify-raft-sim.mjs.