iw4L/docs/ENTITIES.md

World entities and the funnel

There is one funnel

human  ─┐
bot     ├─→ TickInput ─→ sim::step ─→ Snapshot ─→ client / theater / demo
replay ─┘

pub fn step(world: &mut SimWorld, tick: Tick, input: &TickInput, msec: i32) -> Snapshot;

Headless, prediction, replay and the determinism test call exactly this one. msec is the length of the step; time enters only as an argument. Details in crates/sim/src/lib.rs. step ≈ G_RunFrame; the single funnel is ours. The comparison is GROUNDED.md.

What can be an entity at all — a retail fact (entity_iw4)

The wiring is ours, the taxonomy is not. The crate neither serializes nor orders fields "for the network" (E2); every value carries the address it was read from (E3).

EntityState	replicated snapshot slot, stride 0x100
Centity	client-side slot, stride 0x204 (pose plus snapshot anchors)
ClientState	per-client slot, stride 0x7c (command, name[16])
CorpseInfo	server-side corpse slot, stride 0x53c, 8 of them
ET_PLAYER / ET_PLAYER_CORPSE / ET_ITEM / ET_MISSILE
Trajectory	BG_EvaluateTrajectory: gravity 400, delta 800
events	the CG_EntityEvent ring, an 11-bit wrapper
ENTITYNUM_NONE	0x7FF

The player and the input are playerstate_iw4 (playerState_t, usercmd_s): the two ends of the funnel.

Where everything else lives

• sim/ — gentity.rs, spawn.rs, world.rs, snapshot.rs, damage.rs, bullet*.rs, missile.rs, item.rs, corpse.rs, match_state.rs, score.rs, rules.rs, world_objects.rs, identities.rs (ScriptModelId is the one identity of a script model; a raw u32 does not get to be a second);
• frame — frame and session markers: AppScreen, HasWorld, RuntimeRole, LaunchIdentity. No plugins, no systems;
• session — standing the match up and tearing it down (MatchInstalled / MatchTornDown); net — the wire, deltas, prediction; bots — they see exactly their own Snapshot.

The snapshot publishes the semantics of DObj composition, not runtime trees and not posed vertices — see ANIM.md.