The Session

ctx.session is a GameSession — the live handle to one connection. It is the root of the game model: entities, world, items, and the raw packet connection all hang off it.

return (ctx) => {
  const session = ctx.session;
  ctx.on("tick", () => {
    const player = session.entityState.localPlayer;
    // ...
  });
};

GameSession

Member	Type	Description
connection	Connection	The MITM connection — inject and flow-control packets.
events	EventEmitter<GameSessionEvents>	The high-level game events (ctx.on wraps this).
entityState	EntityStateTracker	Entities, the player list, and the local player.
itemState	ItemStateTracker	Inventories, containers, forms, and the item registry.
levelState	LevelStateTracker	The world: blocks, chunks, raytrace, collision.
sendChatMessage(message)	void	Print a client-side chat line (not sent to the server).

Tip — session.sendChatMessage vs. the player's. session.sendChatMessage(msg) prints a local, client-only line. To actually send chat to the server as the player, use localPlayer.sendChatMessage(msg).

session.events

ctx.on(event, cb) is the normal way to subscribe — it binds to the module's enabled state and tears down automatically. The underlying emitter is exposed as session.events for the cases ctx.on doesn't cover, e.g. a one-shot listener:

session.events.once("post_tick", () => {
  // runs on the next post_tick only
});

The event names and payloads are the GameSessionEvents map.

The three trackers

GameSession exposes the game state as three trackers. Each has its own reference page:

• entityState — EntityStateTracker: the entity map, the player list, and localPlayer.
• levelState — LevelStateTracker: blocks, chunks, subchunks, ray-tracing, collision, and the block-state registry.
• itemState — ItemStateTracker: the local inventories, open containers, forms, item movement, and the item registry.

And the raw network layer:

• connection — Connection: inject packets in either direction and gate/flush the packet queue.

Reaching types

The classes reachable through the session graph (Connection, ItemStack, the inventory classes, the trackers, Scheduler, …) are fully typed — your editor resolves session.entityState.localPlayer.inventory.hand?.definition.name end to end. You rarely need to import those type names; you reach them by property access.

A handful of types are exported by name because you name them directly:

• Value exports (importable, usable with instanceof / extends): GameSession, AbstractEntity, EntityPlayer, EntityNetworkPlayer, EntityCreature, EntityItem, EntityLocalPlayer, BlockState, Chunk, SubChunk, AbstractBlockLocationTracker, Option, ModuleCategory, ModuleMode, ModuleTriggerMode, plus defineModule, moduleManager, utils, nbt.
• Type-only exports: GameSessionEvents, FullPacketEvents, ModuleContext, ModuleOptions, ModuleMeta, ModuleBuild, Color, NumberOptionProps, BlockEntry, Session (a deprecated alias of GameSession).

Math/vector types and many internal types are also available under the utils namespace.