Multiplayer with the engine

Owners, replication, rpc and claims, the host as a page, shared time, rooms of 30.

• An entity has an owner. world.spawn([...], { owner: me.id }) makes a player's page simulate it and write its components; { owner: 'host' } is for the host's rules (bots, pickups, a ball). A component with net: { owner: 'host' } is written by the host even on a player's entity (health, score): clients can't award themselves anything, not even its starting value (the host starts it from the schema; set it in net.onSpawn on the host when it depends on the entity).
• Replicate what others must see, nothing else. defineComponent(name, schema, { net: { replicate: true } }) sends only changed fields, quantized by each field's step, batched inside the room's budget, drawn about 100 ms behind between two updates. Use predict: true on the owner's movement for instant feel; the host corrects it smoothly. Don't replicate what is derived.
• Actions are calls. net.rpc('fire', { args: { angle: t.f32(...) }, to: 'host', rate: 10, validate, run }): arguments are checked on arrival, a bad call is refused and never run, a player can only call so fast, and during a match only its players can call (spectators: true lets watchers in). Contested things ("two players reach one chair", a pickup) are net.claims: the host settles them by the room's clock. Never trust a client's word about damage, score, position of someone else, or time.
• The host is a page. It can reload, drop or leave. Rules behind authority: 'host' follow the role at once; entities the host owns are kept in the room and come back with a new host. The engine tests exactly this (below): run check.
• Time and randomness. Rules use time.dt and world.rng('stream') (seeded from the match), shared deadlines use the match clock (world.time.match, paused with the match), never Date.now() or Math.random() in rules.
• 30 players. Per-entity update rates of 10 to 20 Hz, interest by distance (Net({ focus })), priority on what matters.