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# Scene (asset type) A scene is a saved, loadable snapshot of an entity scenegraph inside a world: the entity hierarchy, transforms, components, lighting, and a declared `player` intent, plus an auto-discovered startup script. A scene is the unit of "level" or "screen" — a title screen, a lobby, a gameplay area, and an end-of-game summary each get their own scene. Scenes load as **layers**. One root scene is active at a time; additional scenes can load additively as overlays on top of it. Each scene owns its own multiplayer relay room. Switching scenes is a local call: the client that makes it leaves the old scene's room and joins the new scene's room. ## When to use one - You want a savable, re-loadable snapshot of an entity scenegraph plus its lighting and player setup. - You want a runnable starting state for a level or screen. - You want a scenes-as-data flow: `layers.load("lobby")`, edit live, then `layers.active:save()` to publish the edits back to the scene. For a reusable entity assembly (a prop, a vehicle, a UI panel) that many scenes spawn into themselves, use a `.bundle`. A scene is a whole-world snapshot; a bundle is one prefab that lives inside scenes. ## Folder shape A scene asset is a folder ending in `.scene`. Its identity is the folder name with the suffix stripped (`Lobby.scene` → `Lobby`). - `scene.json` — the scenegraph: `entities[]`, lighting, and the top-level `player` intent. **Required.** Written by the engine — a build, a save, a human dragging something in. Not hand-edited. - `build.luau` — what the scene is made of, written as code. Runs while you author; saving bakes its result into `scene.json` (see Building a scene). - `entrypoint.luau` — the startup script. Auto-discovered as a sibling of `scene.json`; define lifecycle callbacks here (see The entrypoint). - `<name>.<type>/` — an asset the build makes, authored here by `build.asset` (see The assets a build makes), alongside `.build.assets`, which records which `build.luau` produced each of them. - `prefabs/` — optional subfolder for scene-local bundles. - `scripts/` — optional subfolder for scene-local Luau helpers, required from `entrypoint.luau`. - `README.md` — optional per-scene notes about THIS scene. Author one only when there is scene-specific detail worth recording; the general scene model lives here, in `guides { path: "types/scene" }`. `scene.json` is version 7. It carries `"format": "scene"`, `"version": 7`, an `entities[]` array, and a top-level `"player"` string intent. ## The `player` intent Every scene declares how it handles players with a top-level `player` field in `scene.json`: - `"spawns"` — the scene carries an authored player setup, and the engine spawns a player for each connecting user from it. This is the default for a freshly created scene. - `"none"` — the scene spawns no player and authors no camera. Author your own Camera entity for the view (menus, UI-only screens, cinematics). ### How `"spawns"` works A `"spawns"` scene authors two things in `scene.json`: 1. A **PlayerPrototype** — an entity carrying the `PlayerPrototype` component, whose `body` field names a child entity (the body). The body carries an avatar (an `Asset` pointing at an avatar, e.g. `@builtin::avatars.humanoid`). A `CameraRig` child carries a `Camera` with a camera behavior (e.g. `orbital_follow`). The prototype root is authored `PrototypeOnly` so it exists as a clonable template. 2. A **PlayerSpawn** — an entity carrying the `PlayerSpawn` component, whose `prototype` field names the PlayerPrototype to instantiate and whose transform is where players appear. The scaffolded scene groups these under two organizing entities, `PlayerSetups` (holding the prototype) and `Spawns` (holding the spawn), so the authoring tree stays legible. On each user join — entering play, and each subsequent connect — the engine runs the spawn for that user: - It clones the PlayerPrototype subtree. - The clone root becomes the user's **internal identity** — a registry-only entity named `user` carrying the `UserIdentity` component. The identity is the anchor for who the player is; it has no world presence. - The body named by `PlayerPrototype.body` is adopted as the user's **avatar** — their visible presence in the world — and placed at the PlayerSpawn's world transform. Move the PlayerSpawn (or drag it in the editor) to set where players appear. - The `CameraRig`'s Camera follows the bound avatar. The player prototype is live in edit mode so you can see and adjust it. In play mode it is deactivated and marked internal — it stays a clonable source while each user gets their own clone. ### Reaching the live player The player surface lives on the root scene's registry, `layers.active.players`: - `players.localPlayer` — this client's player, a curated handle. - `players.localReady` — `true` once the local player's avatar is bound (or the scene opted its avatar out). - `players:list()` / `players:count()` — the players connected in this scene's room. - `players:get(userId)` — a connected player by account id. - `players:ownerOf(avatar)` — the player whose body is a given avatar. A player handle is a data record about who the player is, plus a link to their body: - `player.avatar` — the body's entity ref. Act on the body through it (`player.avatar.position`, raycasts, rig access). - `player.isLocal` — whether this client owns the player. - `player.ready` — whether a live avatar is bound. - `player.userId` / `player.identity` / `player.displayName` — the player's account identity. - `player.avatar = ref` — bind a live body entity as the player's body (assign nil to clear). To use a `.bundle` / `.avatar` asset, spawn it into the world first, then bind the resulting entity. The player's identity entity is the internal anchor; the handle exposes the body (`player.avatar`) and the player's data, and reaching for `.entity` / `.id` / `.component` raises with a redirect to `player.avatar`. ## Building a scene `build.luau` declares what the scene holds. It is ordinary engine code — `entity.spawn`, `component.add`, transform writes, `for` loops, a `require` of a module that computes a layout — and what it creates is what ends up in the scene. ```lua function content() for i = 0, 4 do local crate = entity.spawn("crate") crate.localPosition = { i * 2, 0.5, 0 } crate.component.add("Model", { model = asset.resolve("cube", "mesh") }) end end ``` The build runs while you author, in **edit** mode, and what it created lands in the live scene. Saving the scene bakes it into `scene.json`, which is what makes the entities durable content: a human can select and inspect them, they replicate, and they are there when the world opens without `build.luau` running at all. Play mode never runs it — in play the entities load from `scene.json` like anything else the scene holds. **Editing the file rebuilds the scene in place.** Writing `build.luau` is the signal; there is nothing to reload, and the rebuild saves. An entity keeps the id it had, so a reference to it — a spawn naming a prototype, another entity's component naming this one — survives every rebuild. Add a crate to the loop and the other four do not move. The write returns as soon as the file is on disk and the rebuild finishes behind it, so what it landed comes back as a notice: ``` [info] a write to build.luau rebuilt the scene { content="6", scene="scenes.main", editorOnly="1" } ``` An edit saved while a rebuild is still running is an edit to code that rebuild has already read, so it gets a rebuild of its own once that one finishes, and says which it was: ``` [info] a write to build.luau arrived during a rebuild and was rebuilt after it { content="7", scene="scenes.main", editorOnly="1" } ``` Several edits saved during the same rebuild get the one run after it, which reads the file as it stands then. A scene that declares a build also runs it when it **loads** in edit, so the scene shows what the code says now, including an edit made while the world was closed. A load whose `.build.state` records the current script reads `scene.json` as the build and runs nothing. When the load does run it, a world's own scene saves the result, unless the scene holds unsaved edits: those stay the author's to keep or discard, and the file write waits for their save. A library scene (one under `/libs/`, the `@builtin` library included) is read by its load: the build lands in the live scene and its files stay as the library states them. Play reads `scene.json`, so it comes up without that build until `:build()` saves it. ### The two surfaces - `content()` — the scene's own entities. Present in play. - `editorOnly()` — entities present while authoring and absent in play. They carry the `EditorOnly` participation the runtime deactivates and hides when play begins, and they are baked too, so a collaborator opening the world sees the same ones. Anything an author needs to see and a player does not goes here — an alignment guide, a spacing marker, a debug volume. Both are optional. A scene with neither has no build. ### What a rebuild touches Only the entities the build itself placed. Anything a human dragged in, or a tool placed directly, is invisible to a rebuild and never moved or removed. Within what it owns, the build is authoritative: an entity the code stopped emitting is despawned, a component it stopped adding is removed. The build writes its own name and each entity's place in the hierarchy onto the entity, and `scene.json` records that pair beside the entity's name and transform — which is why a rebuild after a reload, in a later session, lands on exactly the entities it placed the first time without anything having been remembered. ### When the file did not change `:build()` runs the build against what it resolves right now — for the case where something the builder *reads* changed and the file did not: a module it requires, an asset it resolves. After a write it is unnecessary; the write has already run it. ```lua layers.active.asset:build() -- rebuild and save layers.active.asset:build({ save = false }) ``` It answers with how many entities each surface placed — `{ content = 6, editorOnly = 1 }` — and with nil for a scene that has no `build.luau`. Called while a build for that scene is already running, it returns at once with `{ inFlight = true, scene, trigger, startedBy, message }` naming that build instead of starting a second one; `inFlight` is what tells the two answers apart. An operation the bake cannot hold is **refused** rather than applied. A build accepts what its records carry: entity lifecycle, transforms, hierarchy, names, visibility, active state, participation mode, network scope, attributes, and components with their public data. Anything else raises while the build runs, naming the operation and the build it answered to, instead of leaving the scene depending on something no reload brings back. When that happens the previous build stays exactly as it was. A runtime resource a build needs — a mesh it generates, a texture it writes — is made as an asset instead, below. Everything else a refusal names goes outside the builder, or into a component the builder attaches, which runs at play. ### The assets a build makes `build.asset(type, name, produce)` makes an asset the build's content names — a mesh a lathe produces, a texture a pattern writes. `produce` takes nothing and returns the creation parameters `asset.create` takes for that type; the call returns the asset's `AssetRef`, which is what a component field holds. ```lua function content() local tower = build.asset("mesh", "tower", function() local positions, indices = lathe(profile, 16) return { positions = positions, indices = indices } end) entity.spawn("tower").component.add("Model", { model = tower }) end ``` The asset is authored inside the scene's own folder — `Lobby.scene/tower.mesh` — and the scene records which `build.luau` produced it in `.build.assets`. So `produce` runs when the build script changed and never otherwise: a reload re-runs the build and reuses the asset, while editing the profile re-authors `tower.mesh` **in place**, keeping its path and its guid. That is what holds the reference — `scene.json` names assets by guid. For a part of a scene that several scenes place — or that one scene places many times with different settings — see `guides { path: "types/sceneModule" }`, which is the same idea with declared `inputs` a placement sets. `guides { path: "core/scenes-as-code" }` covers both. ## The entrypoint `entrypoint.luau` is the scene's **runtime** — what happens while the game is being played. What the scene *is* comes from `build.luau` above; nothing here has to construct it. `entrypoint.luau` is auto-discovered as a sibling of `scene.json`. The loader runs it in a fresh environment and folds its top-level `function name(...)` declarations into the matching scene lifecycle event. Define the callbacks the scene needs — the recognised set: - `onLoad()` — the scene loaded in **play** mode. Gameplay-start hook, runs on every connected client. - `onHostLoad()` — the scene loaded in **play** mode, on the client that owns the scene's synced content (the relay room creator; offline and single-player count as host). Fires once. Entities spawned here — and anywhere downstream — become synced automatically, so this is where shared world content is spawned: it runs on exactly one peer, and every other peer receives the entities from the relay snapshot. - `onEditLoad()` — the scene loaded in **edit** mode. Custom per-scene authoring tools. Writing this file while the scene is loaded in edit mode reloads its layer, so the new `onEditLoad` runs after the previous load's `onUnload`. - `onUnload()` — before the scene's entities are torn down. Extra cleanup; engine-managed teardown (entity despawn, resource release) runs separately. - `update(dt)` — per frame in play mode, while the gameplay clock runs. - `editorUpdate(dt)` — per frame in edit mode, running or paused. Play-paused ticks neither hook. The scene loader partitions these strictly on mode; a component's hooks of the same name read `engine.paused` instead, so the two rules differ — `man components` has that table. - `localPlayerReady(player)` — once the local player's avatar is ready. Gameplay wiring for the local player: attach state, bind UI, swap the avatar. The avatar is already placed at the PlayerSpawn, so this is for behavior, not positioning. - `playerJoined(player)` — a remote player joined this scene's room. Use for per-player UI (nameplates, greetings). The local player arrives through `localPlayerReady`. - `playerLeft(eid)` — a remote player left this scene's room. Receives the departed entity's id (the entity is already despawned). Each scene's entrypoint runs in its own environment, so two scenes can declare the same top-level names without clashing. Keep each callback short; push per-scene logic into `scripts/` modules and `require` them. ## Layers Scenes load through the `layers` namespace. - `layers.load(ref, opts?)` — load a scene. `ref` is a scene AssetRef or identity string. Without `opts.additive`, this is a **root** load: it replaces the current root scene. `opts`: - `additive` — load as an overlay alongside the current root instead of replacing it. - `persistent` — keep an additive overlay mounted across mode flips and root swaps. - `origin` — a `{x, y, z}` world offset for the overlay's entities. - `deferred` — spread the entity spawn across frames (for thousand-entity scenes); the load signals complete only once the scene has settled. - `layers.active` — the current root scene proxy (nil before any load). - `layers.list()` — every loaded layer (root + additive overlays). - `layers.find(ref)` / `layers.is_loaded(ref)` — look up a loaded layer by ref. - `layers.onLoad(cb)` / `layers.onUnload(cb)` / `layers.onBeforeLoad(cb)` — subscribe to every scene load / unload (distinct from a scene proxy's own `:on_load` / `:on_unload`, which fire only for that scene). A root scene carries the `players`, `camera`, and `settings` surfaces; additive overlays inherit the root's players and lighting and do not carry their own. ### The scene proxy `layers.active` (and `layers.find` / `layers.list` entries) returns a scene proxy: - Fields: `.guid` (canonical identity), `.name`, `.path`, `.asset`, `.additive`, `.visible`, `.state` (`"loading"` → `"loaded"` → `"ready"` → `"unloading"`), `.ready`, `.players`, `.camera`, `.settings`, `.entrypoint`. - `.camera` — a proxy over the scene's primary camera entity; read and write the live Camera component through it, and `.camera.behaviors._list()` enumerates the available camera behaviors. - `:save(opts?)` — publish the live scenegraph to canonical `scene.json` (see Saving). A convenience that forwards to the scene ASSET's `save` (`self.asset:save(opts)`): the proxy is the runtime view and owns nothing on disk, so persistence lives on the asset. - `:reload()`: unload and reload the same scene (a runtime respawn). A scene with a `build.luau` runs its build again and saves the scene, so `scene.json` holds what the reload built and the next play loads it; a library scene's rebuild lands in the live scene alone. - `:clearDirty()` — discard unsaved edits and respawn from canonical. Forwards to the scene asset's `discard` (`self.asset:discard(opts)`). - `:sceneAsset()` — the durable `AssetRef<scene>` this live layer maps to. - `:promoteDirty()` / `:writeDirty()` / `:hasDirty()` — manage the dirty overlay directly. - `:unload()` — despawn the layer and free its slot. - `:onReady(cb)` — fire once the scene reaches `ready` (latched: a late subscriber fires immediately). ## Multiplayer & relay rooms Every scene has its own relay room, keyed by the world guid, the boot profile, the mode, and the scene guid. Switching scenes with `layers.load` runs a room transition — leave the old room, tear down, join the destination scene's room — all on the client that made the call. Teardown of the old scene never leaks to peers in the new one. In play mode connected to a relay, the scene's entities are host-authoritative: only the room creator instantiates them (marked synced), and every joiner receives them from the relay snapshot rather than spawning their own. This is why shared world content belongs in `onHostLoad` — spawning it in `onLoad` would run on every peer and duplicate it. Each player's own avatar spawns per-user from the PlayerSpawn on every client. Edit mode and offline boots spawn locally and never auto-sync. ## Loading and saving **Loading** — `layers.load(ref)` for a root scene: 1. Despawns the current root scene's non-persistent entities. 2. Instantiates the entities from `scene.json` (including the player prototype and spawn for a `"spawns"` scene). 3. Applies lighting and sky. 4. Runs `entrypoint.luau` and fires lifecycle callbacks as their events occur. **Saving** — persistence lives on the scene ASSET. `sceneRef:save()` writes the scene's current state back to canonical `scene.json`; when the scene is loaded it captures the live scenegraph, and when it is not loaded it promotes the pending dirty overlay. `layers.active:save()` is the convenience form — it forwards to the active layer's mapped asset (`layers.active.asset:save()`). Writing canonical is the only path that does so: edit ↔ play cycles never save, so hitting play to test never overwrites the scene. Between saves, live edits accumulate in a per-scene dirty overlay that the loader merges on top of canonical. `sceneRef:discard()` throws the overlay away and restores the saved state — deleting the overlay, and respawning the live layer when the scene is loaded. It works whether or not the scene is loaded, because the overlay belongs to the asset, not the runtime layer. `layers.active:clearDirty()` forwards here. Saves capture entity data, not the entrypoint script — edits to `entrypoint.luau` and `scripts/` are always preserved. `opts.to` on `save`/`discard` targets a different scene ("save as"), taking either a bare name (`"level_2"`) or a full VFS path. **What a record states.** A component's record in `scene.json` holds the fields that instance's configuration states: the keys of the table it was added with (a `build.luau` call's own init table, or the record it was loaded from) and every field written since, through code, a tool or the inspector. A field nothing set stays out of the record and takes the component's declared default each time the scene loads, so changing that default reaches every entity that left the field to it. To have an entity follow the default again, remove the field from its record. A field set on a live entity after its record was made is a change the scene review names (`sceneAuthoring.changes` lists it as `+ Type.field = value`), and accepting it writes the field into the record. A scene saved before records were stated this way holds every field; those values load and save as they are, since a stored value cannot be told apart from one an author chose, and a hot reload that changes a default one of them shadows names it. A stored field the component no longer declares is named by a `[component.add]` warning when the record loads and left out of the next save. ## Lighting Lights are ordinary entities: a directional light, an ambient light, and a sky are entities carrying `Light` / `ProceduralSky` components in `scene.json`. Author, move, and tune them like any other entity. If a scene is missing any of {directional light, ambient light, sky}, the loader adds a temporary default for the absent one so a scene never loads dark or skyless; the defaults are never saved into the scene. Scene-level lighting state that is not an entity — clear color and sky descriptor — lives under `layers.active.settings.lighting` (`clear_color`, `sky`); writing those fields updates the engine live. ## Modes Scenes load in both edit and play mode (see `man modes`). The mode governs behavior: - An entrypoint's `update(dt)` runs in play while the gameplay clock runs, and its `editorUpdate(dt)` runs in edit. A component's hooks of the same name follow the clock rather than the mode — `man components` has the four states that produces. - Player prototypes are live in edit and deactivated + internal in play, where each user instead gets a clone. `EditorOnly` entities follow the same edit-live / play-internal toggle. - `onLoad` / `onHostLoad` fire on a play-mode load; `onEditLoad` fires on an edit-mode load. ## How to create one ```luau asset.create("scene", "<Name>") -- Creates /zero/source/<Name>.scene/ with: -- build.luau where this scene's content is written. A new one starts -- with the sun / ambient / sky lighting and the "spawns" -- player setup, commented for editing — everything else the -- scene comes to hold is written here too. -- scene.json what that code produces, baked. -- entrypoint.luau commented lifecycle-callback stubs. ``` A freshly created scene has a player with a following camera on the first press of play. It carries no ground, so the first thing to author is what the player stands on — a `content()` line away in `build.luau`. ## Discovery - `asset.list("scene")` — every registered scene. - `asset.inspect("<name>")` — entity count, lighting summary, source path, and this type README. ## Authoring conventions - Keep static layout in `scene.json` — geometry, lights, props, the player prototype and spawn. - Keep dynamic setup in `entrypoint.luau` lifecycle callbacks — event listeners, gameplay state, services attached to spawned entities. - Spawn shared, synced world content from `onHostLoad`; spawn each player's own gameplay wiring from `localPlayerReady`. - Set the world's startup scene in `/.world_settings` — that is the scene the world boots into. - Y is up; +Z is forward. - Renaming the folder changes the scene's identity — update every `layers.load` callsite and the world's startup-scene field. ## Related types - `.bundle` — reusable entity hierarchies that scenes spawn into themselves. - `.service` — cross-scene background work that outlives a scene load. - `.world_settings` — picks the startup scene and world-level renderer / physics options. ## In the Inspector Selecting a scene opens its **Scene** section, read from `scene.json` without loading the scene: how many entities it holds, how many of them are roots (and their names), how players join and the file's format version when it states them, and whether the scene has edits not yet saved.

# debugViz_driver The ambient edit-mode debug-visualization driver. Requiring it registers the built-in providers (bounds, frustum, bones, colliders, icons, wireframe) with `@builtin::modules.debugViz`; the editor entrypoint requires it and calls `tick(dt)` every frame. ```lua local DebugVizDriver = require("@builtin::modules.debugViz_driver") -- In the editor entrypoint's per-frame hook: DebugVizDriver.tick(dt) ``` - `register()` — register the built-in providers. Idempotent: `registerProvider` replaces by name and a guard makes a re-require a no-op, so a category toggled off in the panel survives a module reload. Called on require and by `tick`. - `tick(dt)` — per-frame hook for both modes. Edit mode always rebuilds the overlay; play mode rebuilds only while a debug session is active (`debugViz.setPlaySession`) and otherwise clears the batch, so play mode carries no debug-draw cost by default. There is no per-entity opt-in — the overlay is editor tooling, driven here for the whole scene. Toggle categories through the Debug → Visualization panel or the `debug` toolbox.

# viewport_select Turns a viewport pointer gesture into an editor selection change, applying the standard modifier semantics, and drives the per-frame bridge that reads real pointer + modifier input. Selection is written into the shared `modules.api.editor.selection` service's `entity` scope, so the viewport, the selection outline, and the outliner stay in lockstep. A left press+release within a few pixels is a click-select; a larger left drag is a **marquee** (rubber-band) that selects every entity whose screen position falls inside the band. The band is drawn by `modules.api.editor.marquee_overlay`. ## Exports - `M.applyClick(Sel, scope, hitId, mods)` — pure decision: `hitId == nil` clears (unless a modifier is held); ctrl toggles the hit; shift adds it; neither replaces. Entity ids become `{ kind = "entity", id }` refs. - `M.applyMarquee(Sel, scope, ids, mods)` — pure decision for a completed marquee: an empty band with no modifier clears, an empty band with a modifier leaves the selection unchanged; ctrl toggles each id, shift adds the set, neither replaces with the set. - `M.worldToScreen(m, w, h, p)` — project a world point through a 16-float column-major view-projection matrix and viewport size to viewport pixels (`sx, sy`), or nil when the point is at/behind the camera. Mirrors the engine's own `world_to_screen_px`. - `M.pointInRect(rect, sx, sy)` — inclusive screen-rect hit test. - `M.nearestIcon(cands, cx, cy, thresholdPx)` — the nearest icon candidate `{ id, sx, sy }` to the cursor within a pixel threshold, or nil. - `M.entitiesInRect(rect)` — engine-driven: the selectable entity ids whose world position projects inside `rect` (viewport-pixel space) this frame. - `M.iconPick(cx, cy)` — engine-driven: the entity whose meshless icon is nearest the cursor within `ICON_PICK_PX`, or nil. - `M.tick(dt?)` — call once per editor frame; prunes dead selection refs, reads pointer press/drag/release + modifiers, and routes a click or a marquee through the pure decisions above. ## Notes - The decision functions are pure so they can be unit-tested against the real selection service. - **Icon-pick fallback.** A click that hits no mesh/collider (the engine pointer pick returns nil) falls back to selecting the nearest meshless-entity icon (light / camera / audio source / reflection probe) within `ICON_PICK_PX`, so lights and cameras — invisible to the raycast — are selectable by their billboard. The engine pointer pick wins whenever it hits. - **Gizmo precedence.** A marquee only starts on a frame where the pointer has moved past the click slop AND the transform gizmo is not dragging. `tick` runs before the gizmo's tick in the editor entrypoint, so by the time a drag passes the slop the gizmo has already had a frame to claim a grabbed handle.

# edui (module) The editor UI framework, built on the CSS-parity `ui.*` surface. `edui` is **editor-only** — gameplay and normal UI author raw `ui.*` widget trees (`{ type, style, props, children }`) and need no framework. `edui` provides the one thing a framework earns its keep for: editor chrome — a reactive app, a dock shell, and chrome primitives (panels, trees, toolbars, inspector rows, context menus, drag-and-drop). It replaces the deprecated `zui` for the editor. ## The reactive core (`edui.app`) `ui.*` dispatches interaction through **string callback ids** — a widget carries `props.onClick = "<id>"`, and the screen's registered env receives `onCallback(id, data)`. Closures can't cross the FFI boundary, so raw `ui.*` makes you manage those ids by hand. An `edui` **app** hides that. During a build it allocates an id per closure and records id→closure; its single `onCallback` looks the id up, calls the closure, and rebuilds: ```lua local edui = require("@builtin::modules.edui") local count = 0 local app = edui.createApp("counter", { layer = editorMask }) app:mount(function(a) return { type = "vertical", children = { { type = "label", props = { text = "count: " .. count } }, { type = "button", props = { text = "+1", onClick = a:cb(function() count += 1 end, "inc") } }, }, } end) ``` - `app:cb(closure, key?)` — allocate a callback id for `closure`. Pass a stable `key` so the id survives rebuilds (required for focus / drag / `ui.widgetState`). - `app:dispatch(id, data)` — what the broadcast calls; routes id→closure and rebuilds. Returns whether this app owned the id. - `app:markDirty()` — request a rebuild (coalesced during an in-progress build). - `app:rebuild()` / `app:mount(fn)` / `app:unmount()` — lifecycle. - `edui.current()` — the app whose builder is running (the primitives use it so you don't thread the app through every call). Builder and handler errors are logged, never thrown — one bad build never wedges the editor.

# dotbotRun Module A DotBot run driven from a boot rather than from the DotBot panel. ## Purpose `start_instance { world, prompt }` (the engine's `--agent dotbot --agent-prompt <text>`) hands the prompt to DotBot, the agent the engine ships in its DotBot panel, as the first message of a fresh conversation. `resume` (`--agent-resume`) sends a message into the conversation this world's run already holds. The editor starts the run as it comes up; a browser engine is handed it by the proxy once the engine answers. DotBot is a plugin inside the engine, so a run is the plugin's own surface used in order: 1. wait for the plugin to load; 2. find the DotBot agent the boot named (`dotbot` is DotBot on the Claude account connected to it, `dotbot-chatgpt` on the ChatGPT account) and check an account is connected to it; 3. open a new conversation (`/new`), set the model and thinking level the boot asked for. DotBot keeps what it is set to as the model and thinking level it runs that account on from then on, its panel included, and a boot that names no model runs the one it already holds; 4. send the prompt. ## What a run records - The conversation, in this machine's agent-session store under (world guid, dock slot 1), with `harness` naming the DotBot agent, once the first event of the prompt's turn names it. A resume reads it. - Every prompt and every turn event of that conversation (streamed text fragments aside: a turn's `done` carries the whole answer), one JSON line each, through `agentSessions.record`, at `<config dir>/agent-transcripts/<agent>_<conversation>.jsonl`. `agent_run_report` reads it: turns, tokens, tool calls with their timings, failures, the skills opened and the guides read. - Its state: the last entry recorded is the in-engine agent's state in `GET /engine/status` (`agent.run`), which `instance_health` prints. ## When a run cannot start It is refused, sends nothing, and records the reason as its state: - the engine is bound to no world (DotBot acts through the live agent endpoint a world-bound engine publishes); - the plugin did not load, or had not after five minutes; - no account is connected to the DotBot agent named. An account is connected once on a machine, in the DotBot panel, and every later run uses it; - DotBot refused the model or the thinking level the boot named; - a resume found no DotBot conversation recorded for the world and slot. ## Functions - `dotbotRun.start(opts)`: start a run in the background. `opts` is `{ agent, worldGuid, slot?, prompt?, resume?, model?, effort? }`. One run per engine. - `dotbotRun.startArmed()`: start the run this boot's settings arm, if any. - `dotbotRun.agentFor(name)`: the DotBot agent id an agent name runs. - `dotbotRun.new(deps)`: a run over a transport of the caller's, for tests.

# selection_highlight Mirrors the editor's entity selection onto the outline render feature as an edit-only hint (the rim drops automatically when the world leaves edit mode). Subscribes to the shared `modules.api.editor.selection` service's `entity` scope and reconciles the outline sink so exactly the selected entities are rimmed. ## Exports - `M.reconcile(sink, ids)` — pure: drives `sink` (`set(id)` / `clear(id)`) so exactly `ids` are outlined, clearing anything previously set that is no longer selected. Only touches ids it owns. - `M.attach()` — wire `reconcile` to the real selection scope (via `Selection.subscribe`) and the real outline sink (`outline.setEditorHint` / `outline.clear`). ## Notes - `reconcile` is pure so it can be unit-tested against a mock sink.

# gizmo Transform gizmo — draggable translate/rotate/scale handles at the selection pivot. Handles draw through a debugViz provider; hit-testing and dragging use `gizmo_math` against the cursor's `screenToRay`. Each drag edits every selected entity through the entity proxy transform setters and is wrapped in a multiplayer undo operation, so a whole drag reverts as a single Ctrl+Z. The mode (translate / rotate / scale), the local/world space toggle, and the active drag live in module state; the editor scene entrypoint calls `tick` every frame and switches mode from the tool hotkeys. Handles size themselves to stay a roughly constant on-screen length, and holding the snap modifier quantizes translation to a grid, rotation to angle steps, and scale to fixed steps.

# zinput zinput is the engine's Luau-side input framework and the **only** public Luau input API. It sits on top of the internal `__zero_input.*` FFI (snapshot, events, frameId, pointer-lock, simulate\*) and builds the control model above it in pure Luau: control assets grouped into maps, the live set of activated maps and its per-frame dispatch, per-device-class binding evaluation, the on-screen touch overlay, gesture recognisers, and the tick coordinator that advances all of it. The top-level module re-exports every submodule under a single table and owns the tick coordinator (`Zin.tick`) plus the unified handle namespace for `Zin.disconnect`. ## The control model A control is a `<name>.inputBinding/` folder inside a `<name>.inputMap/` folder. It carries a `label`, a `kind` (`button` / `axis1` / `axis2`), and a binding for each of the three device classes — `kbm`, `gamepad`, `touch`. A class set to `false` is a deliberate refusal. Nothing is live until something activates a map. A world activates the map it needs and subscribes to the controls it uses: ```luau public = { inputMap = Field.assetRef("inputMap", "@builtin::inputMaps.default", NoSync, "The controls this component reads."), speed = Field.number(5, NoSync, "World units per second at full deflection."), jumps = Field.number(0, NoSync, "How many times the jump control was pressed."), } local controls function awake() controls = public.inputMap:activate() controls.move:onInput(function(v, dt, active) if not active then return end local p = public.entity.position local step = public.speed * dt public.entity.position = { p.x + v.x * step, p.y, p.z - v.y * step } end) controls.jump:onPressed(function() public.jumps += 1 end) end function onDestroy() public.inputMap:deactivate(controls) end ``` What `activate` returned is this holder's claim on the map, and handing it back to `deactivate` disconnects the subscriptions made through it while the map stays live for whoever else holds it. Every activation reads the map's binding children again, so a control edited since it came up reaches the running set and the holders already standing on it. Several maps are live at once and compose: the player's surface is the union of them, so picking up a gun adds Fire beside the movement stick and dropping it takes away Fire alone. A map declares the `group` its controls belong to and the groups it `suppresses` while live, which is how a car stands walking down without owning the walk map. `Zin.scheme` holds the live set and runs the dispatch. `man topics/input` is the full walkthrough. ## Exports Subsystems (re-exported from the corresponding submodule): - `M.scheme` — the live set of activated maps and their per-frame dispatch. - `M.bindings` — binding constructors, evaluators, and the legend formatter. - `M.state` — per-frame snapshot reads plus held-time and synthetic repeat. - `M.events` — frame-event readers and `on`/`off` edge subscriptions. - `M.input` — `onBegan` / `onEnded` / `onChanged` / `onTextInput` listeners and `lastInputType()`. - `M.context` — the input context stack. - `M.chords` — sequence and simultaneous recognisers. - `M.gestures` — tap / double-tap / long-press / swipe / pinch / pan recognisers. - `M.touch` — per-finger contacts and `touch.*` listeners. - `M.surface` — touch-vs-kbm device-class classification. - `M.gamepad` — connected pads, family, and button legends. - `M.virtual` — the per-tick virtual-control store on-screen controls write. - `M.touchControls` — the on-screen touch overlay (stick, drag-look zone, buttons) and the API that adds a control while a world runs. - `M.emulation` — the map-driven key-emulation floor. - `M.pointer` — pointer-lock mutations. - `M.back`: Back, claims a world holds while Back means something to it, and `press` to issue one. The engine routes each press to the topmost dismissible overlay, else the most recent claim, else the platform's own default (an Android app moves to the background). - `M.test` — synchronous test-input helpers. - `M.controllers` — `free` / `orbit` / `fps` controller factories. - `M.profile` — binding profiles, saved as JSON and loadable from `@builtin::profiles.<name>`. - `M.rebind` — interactive binding-capture sessions. - `M.conflicts` — the binding-collision reverse index. - `M.autoTick` — the opt-in per-frame tick worker. - `M.utils` — pure helpers. - `M.actions` / `M.axes` / `M.map` — the name-registered action, axis and map registry. A control asset replaced them; each carries its own `--!deprecated` message naming the replacement. Tick coordinator: - `M.tick(dt: number?)` — advance every stateful subsystem. - `M.lastTickAt() -> number` / `M.lastTickFrameId() -> number` — test/debug accessors. - `M._resetTickGuard()` / `M._resetLiveArmed()` — test-only. Handles: - `M.disconnect(handle: number) -> boolean` — accepts any Zin handle (input listener OR action handler) and routes to the right `disconnect`. Constants: - `M.VERSION` — the library version string. - `M.SPEC` — the VFS path of the architecture spec. - `M.ROADMAP` — the VFS path of the roadmap document. ## Raw state `Zin.state` and `Zin.events` are the snapshot and event layer that bindings evaluate against — the layer the emulation floor, rebind capture, and dev tooling operate on directly. Gameplay code subscribes to controls; polling `Zin.state.keyDown` from a world makes that world keyboard-only and draws the `engine-raw-key-poll` diagnostic at author time. ## Notes - `Zin.tick(dt)` is the single hub that advances every stateful subsystem each frame. Stateless features (state / events / utils / bindings / context) work without ticking; the live binding dispatch, axes, chords, subscriptions, held-time, repeat, and rebind are dormant until something ticks. - The first real input read arms the input system on its own: it starts `Zin.autoTick`, so dispatch, the touch overlay and the emulation floor advance with no host component and no explicit tick call. A host script component can still call `Zin.tick(dt)` from its `update(dt)` hook, and `Zin.autoTick.start()` remains available directly; both stay idempotent alongside the self-arming path. `Zin.test` engagement suppresses the arming so suites keep explicit control over tick cadence. - Same-frame re-tick dedup: `__zero_input.events()` is non-draining, so running the observe-and-dispatch pipeline twice in one engine frame would double-fire subscribers. The frame-id guard in `M.tick` and the autoTick worker keeps this from happening. - The handle namespace is unified: every handle from `Zin.input.on*` and `Zin.actions.bind` is drawn from a single counter, and `Zin.disconnect` routes any of them to the correct `disconnect`. `Zin.input.disconnect` and `Zin.actions.disconnect` are also wired to the unified dispatcher. - Library users can either grab the whole table (`require("@builtin::modules.zinput")`) or pull one submodule (`require("@builtin::modules.zinput.state")`). - `__zero_input` is an internal namespace — reachable from Luau but hidden from `/docs/api/`; production game code goes through Zin.

# controller.editor The viewport camera you author from. It is the behavior on the editor scene's `EditorCamera` — a world's players never meet it, which is why it reads the editor's controls rather than a game's. Rotates the pivot child exposed by a sibling `Player` component if present, otherwise rotates self. Public fields: `moveSpeed`, `sensitivity`, `speedMin`, `speedMax`. Controls come from the map on `inputMap`, `@builtin::inputMaps.editor` by default: `move` to fly, `flyVertical` to rise and drop, `look` to aim while flying, `zoom` to adjust move speed. Rebind them by pointing `inputMap` at another map. ```luau entity(id).component.add("controller.editor", { moveSpeed = 10 }) ```

# Camera Manages viewport priority, render-to-texture, and capture. State is stored in the native `Camera` ECS component; the Rust camera system handles render scheduling and render targets. Public fields: `fov`, `near`, `far`, `priority`, `textureHandle` (the guid of the texture the camera renders into; empty = main viewport), `renderLayers` (which render layers this camera draws — a space-separated spec of names, e.g. `"all"`, `"all !ui"`, or `"default sky"`; `ui`/`sky`/`debug`/`EditorUI` are built-in layers), `postProcessing` (whether this camera runs the post-process chain), `debugChannel`, plus the behavior slot below. Methods: `:lookAt(target)` (entity id string OR `{x, y, z}` table), `:render()`, `:capture()`, `:setTargetTexture(tex?)` (a `renderer.texture.create` handle to render into, or nil for the viewport). ```luau entity(id).component.add("Camera", { fov = 90, priority = 10 }) entity(id).component.get("Camera"):capture() ``` The scene's play-mode camera is reached as `layers.active.camera`, a handle that reads and writes the fields above on whichever entity currently carries them. `layers.active.camera.entity` is the entity ref for that camera and `layers.active.camera.entityId` its id string, so a script that needs to attach something to the camera — an `AudioListener`, a child entity — goes through the ref: ```luau local cam = layers.active.camera cam.fov = 70 -- the camera's settings cam.entity.component.add("AudioListener") -- the entity carrying them ``` ## How the camera moves: `behavior` and `follow` A `Camera` does not move itself. `behavior` names a component that does, and setting it attaches that component to this entity. Clearing it detaches whatever was attached. ```luau local cam = entity(id).component.get("Camera") cam.behavior = asset.ref("@builtin::controller.orbital_follow", "component") cam.follow = playerBody ``` The attached behavior is an ordinary component on the camera's entity, so it is tuned the way any component is: read it with `component.get` and set its fields there. A `component.add` of the same type configures the instance the slot attached instead of adding a second one: the values it passes are written onto that instance and its proxy is returned. That add is the form a scene `build.luau` tunes the behavior with, because its values are saved with the scene and the loaded Camera's behavior takes them back. A key the component reads only as it is created (one of its `initKeys`, a private field) refuses the add and names the key. ```luau cam.behavior = asset.ref("@builtin::controller.third_person_follow", "component") local rig = entity(id).component.get("third_person_follow") rig.cameraDistance = 6 -- the same, as an add of the type the slot attached entity(id).component.add("third_person_follow", { cameraDistance = 6 }) ``` `follow` is the standard slot every shipped behavior reads. Set the follow target on the **Camera**, not on the behavior, so swapping behaviors keeps it. A behavior that finds its own `follow` field empty falls back to this one, which is what lets a rig keep tracking the player across a behavior swap. `followResolves` answers whether that slot names an entity that is live — `true` while it names a live one or names nothing at all, `false` once the target is despawned or the id names no entity. A rig whose target does not resolve holds its last pose, and this is the field that tells it from a rig posed correctly on a subject that has not moved. `camera.get` carries the same value beside `follow`, and a write naming an id with no entity behind it draws a warning where it lands. ```luau cam.followResolves -- false once the followed entity is gone tools.use("camera", "get", id).followResolves -- the same answer off the tool ``` The shipped behaviors live under `@builtin::controller.*`: `orbital_follow`, `third_person_follow`, `first_person`, `free`, `orbit`, `chase`, `isometric`, `rts`, `birds_eye`, `side_scroller`, `cinematic`, `menu`. ## Writing your own Any component can be a camera behavior. Write one that moves its own entity and attach it the same way: ```luau cam.behavior = asset.ref("MyChaseCam", "component") ``` `follow` lives on the Camera, so a behavior gets no property notification of its own when the target changes. Declare `onFollowChanged(newFollow, oldFollow)` to be told the moment it does — the Camera calls it on the component it attached, which is what lets a rig re-pose on the new subject at once. A behavior that reads `Camera.follow` on its own schedule declares nothing and is attached the same way. ```luau typed function public:onFollowChanged(newFollow: any, oldFollow: any) -- pose this entity against the new target end ``` To make it appear in the discovery catalog alongside the shipped ones, declare the `cameraBehavior` tag in the component's `.metadata`: ```json { "tags": ["cameraBehavior"] } ``` The tag governs **discovery**, not attachment. A tagged component is listed by `layers.active.camera.behaviors` and is what tooling offers when something asks "which camera behaviors exist"; an untagged component attaches just as well and simply stays out of that list. Tag the ones you want other people (and agents) to find. ```luau for name, ref in pairs(layers.active.camera.behaviors) do print(name, ref.identity) end ``` ## Texture colour space `textureColorSpace = "display"` applies the display transform when rendering into a texture. `"linear"` writes scene-linear values instead. `postProcessing` independently controls the effects chain in either mode. Floating-point targets retain values above one; normalized targets clamp to their representable range. The main viewport uses display encoding.

# scene runtime What a `.scene` folder does when it is loaded, saved, built, or swapped. A `<name>.scene/` carries `scene.json` (the entity arrangement), an optional `build.luau` (the code author's half), an optional `entrypoint.luau`, and a `scene_dirty/` overlay of unsaved edits. Reading, composing and writing all four is the scene type's own behaviour, so it lives in the type. ## Sub-modules | Module | Responsibility | |---|---| | `loader.module` | Reads scene.json v6 and v7, refuses versions it does not know, composes canonical + dirty overlay, spawns the entities, and runs the entrypoint. | | `saver.module` | Persists scene state as a delta overlay against the canonical file, promotes that overlay on save, and answers which edits are still pending. | | `build.module` | Runs a `build.luau` inside an entity capture scope and composes what it spawned into scene records. | | `observe.module` | The read side — the per-scene counts and costs `layers` and `loader` write. | | `swapOrchestrator.module` | Drives multiplayer room transitions and the scene-swap gate, so a local swap does not leak despawns to peers in the old room. | ## Reaching it ```luau local rt = require("@builtin::assetTypes.scene.shared") rt.saver.hasPendingSceneEdits(layers.active.name) ``` Fields resolve lazily. The prelude installs `swapOrchestrator` and starts `saver`'s dirty writer in a fixed order, which a table that required all five on load would take away from it.

# assetType (asset type) The `assetType` is the **type of types** — the meta-type that every `<typename>.assetType/` folder is an instance of, including itself. A `<typename>.assetType/` folder declares a new asset type called `<typename>`: its on-disk shape, its identity rule, and the structural contract instances of the type must satisfy. This type is self-hosting. `assetType.assetType/` conforms to its own schema — a `type.yaml` plus a `README.md` — so the type system is defined in terms of itself rather than a hidden engine special-case (the same way a C compiler is written in C). Every asset in the engine, including each `.assetType` definition, now resolves to a registered assetType: a `.material` resolves to `material.assetType`, and `material.assetType` resolves to `assetType.assetType`, which resolves to itself. ## Why it exists Assets used to be mapped to their type *implicitly*, by matching the folder suffix against a name-keyed registry. That match carried no stored link: nothing on a `Foo.material` recorded *which* `material.assetType` it was written against, so two worlds shipping a same-named type could silently disagree. Making `assetType` a real, resolvable asset closes that gap — the link from an asset to its type is now an explicit reference pinned in the asset's `.refs` sidecar (`via: "asset_type"`), exactly like every other dependency. ## Where it lives - Source: `/zero/source/.../<typename>.assetType/` - Identity: `<typename>` (the `.assetType` suffix strips from the identity; the folder retains the suffix on disk). - Folder shape: - `type.yaml` — the structural spec the validator reads. **Required.** - `README.md` — type-level documentation. **Required.** - `about.yaml` — three short plain-language texts saying what the type is for (see "Say what your type is for" below). Every built-in type ships one. - `behavior.luau` — optional behavior/scaffolding module. - `template/` — optional canonical placeholder body the templater copies into a new asset of the type. - `<name>.module/` — optional shared code the type ships to **every instance** of it, conventionally `shared.module/` (see below). ## Shared code its instances reach (`asset.containing` + `.modules`) A type ships code every instance of it uses by declaring the modules in its own `behavior.luau`, as a map of tracked `require`s: ```luau -- inside <typename>.assetType/behavior.luau M.modules = { shared = require(".shared") } -- the sibling shared.module/ ``` An instance reaches it with one location-independent line: ```luau -- inside any foo.<typename>/init.luau local api = asset.containing(__FILE__).modules.shared ``` `__FILE__` is the chunk's own VFS path; `asset.containing` resolves the calling asset, and `.modules.<name>` follows the instance's pinned `typeRef` (the type's **guid**, recorded in the instance's `.refs` as `via = "asset_type"`) to the module its type declares. Because resolution follows that link rather than a category name, the same line in an instance of a different type resolves to that type's module, and identically-named modules in two types never collide. `asset.typeRef(target)` reads that guid for any target; `asset.resolve(asset.typeRef(target))` gives the full `AssetRef<assetType>`. See `assetTypes/README.md` § "Shared code: type-owned modules" for the full mechanism. ## How to create one Authoring a new asset type is just creating a `<typename>.assetType/` folder under `/zero/source/`. The engine registers `<typename>` as a category **the moment the folder is written** — no engine restart, no Rust change, and it works for built-in (`@builtin/assetTypes/`) and user-defined types identically. Once `<typename>` is registered, `<name>.<typename>/` folders are recognised as assets of that type and resolve their `asset_type` link back to this definition. Creating a `<name>.<typename>/` folder *before* its `<typename>.assetType/` exists fails fast: the suffix has no registered type, so the folder can't be a valid asset. Author the type first. ## Say what your type is for (`about.yaml`) Every type carries a small `about.yaml` beside its `type.yaml`, and the README you write for the type documents how to author an asset of it. Both are required, and both are meant to be written as you make the type, while you know what it is for. `about.yaml` answers three questions in plain words, one key each: ```yaml intent: "Sets the typeface of the text in your game: UI, labels, signs and 3D lettering." function: "A font, from a TTF, OTF or WOFF file, made available to all of Zero's text, including 3D text." usage: "You choose it by name for your UI or your text, and the text appears in that typeface." ``` - **`intent`** is what the type is for in someone's game. Name the whole range of things it covers, in the words a game maker would use for them. - **`function`** is how it works today: what an asset of the type is made of and what the engine does with it. - **`usage`** is what a person or an agent does with one: how they pick it, place it, call it, or hand it to something else. A few habits keep it useful. Write about the type as a whole, so the text holds for every asset of it, and leave out any one asset's name. Say what the type does right now. Stay with words a game maker would say, and mention a file name or a call only where a game maker would know it. The limits are in bytes: `intent` 800, `function` 1500, `usage` 1200. Each is generous, and a few sentences usually say it. Why bother: agents working in a world read these three texts to learn what your type is for, so they reach for it when it fits and use it the way you meant. People searching find the type by what they want to make, and the three texts let them tell at a glance whether it is the one they need. `asset.create("assetType", name)` scaffolds the file with all three keys, and a README whose first paragraph is a `[[describe]]` note. Each value starts with `[[describe]]` followed by a note on what to write; replace the whole value with your own words. A value or a README line that still starts with `[[describe]]` counts as not written yet, which the push's check of each asset it carries against its type reports, naming the file. A type you leave as it was is not asked, so older types stand. Many types at once, or one you would rather not write by hand: `services describe` lists the types that lack these texts and what filling them costs, and `{ mode = "all" }` writes them into the same files, where you edit them like anything else you wrote. Where the texts show up: `asset.inspect("<typename>", "assetType")` returns them as `detail.about`, `assetTypeRef:getAbout()` returns them as a table with the keys `intent`, `function` and `usage`, the type's `types/<typename>` guide page ends with an "About this type" section holding them, and the Inspector's Type section lists them at the top. The guide page is this README plus that section, so a README that explains the type well and an `about.yaml` that says what it is for read well together. ## Ask your assets to say what they are A type can ask each of its assets to carry a description: a file, written by the author or generated, that says what that asset is and what it is for. The people and agents who find an asset read it to decide whether it fits, and the author knows what it is for at the moment of making it. **1. Declare the file with a `described` check.** This is the whole requirement: ```yaml files: required: - path: "README.md" # any file name works kind: "file" content: - { check: "described", message: "Say what this widget is for and where it goes." } ``` With that in place: - An asset whose file is missing, empty, or still has a line starting with `[[describe]]` does not meet the type's requirements. `asset.validate` names it, `zm status` and `world.publishBlockers()` list it, and a push that carries it is refused with `message`. - `services describe` finds it (`mode = "find"` lists it and the price) and can write the description for it (`mode = "all"`). It writes only this file. For a YAML file that holds several texts, name the keys and their limits in bytes, the way this type does for `about.yaml`: ```yaml content: - check: "described" keys: - { key: "intent", max_bytes: 800 } - { key: "usage", max_bytes: 1200 } message: "Write intent and usage." ``` `headings` names sections a Markdown file must have. `assetTypes/README.md` has the full check. **2. Optionally, steer what gets generated with a `describe:` block:** ```yaml describe: guidance: "Say what the widget shows, what input it reacts to, and where it fits in a UI." examples: - "<identity of an asset of this type whose description reads well>" ``` `guidance` says what a description of your type covers, and `examples` names assets whose descriptions show the shape you want. Without the block, generation still works from the general describing guide and the check's `message`. An example is an asset of your type in the library whose description is a true, written one, never a scaffold's placeholder, and never the asset being described. When the library has none, leave `examples` empty rather than name one that is not. A type whose assets the model cannot perceive (a sound it cannot hear, a motion it cannot see) says so in `guidance`: the description comes only from what the asset's own files state, such as its name and the `.metadata` where a generation service records the prompt that made it, and when they state nothing the model answers `cannot` with that reason. `services describe` then fails that one asset with the reason and leaves its file as it was. **3. Start the file unwritten in your template.** Put a heading and one line that starts with `[[describe]]` and a short note on what to write, in `template/<file>`, so a new asset starts unwritten rather than with text that only looks written. Do not put example content in it: every new asset carries the template verbatim, and the same text on many assets makes them impossible to tell apart in search. Types whose assets say what they are through their own content (a mesh, a texture, a sound) leave this out: declare nothing and nothing is asked. ## The `behavior.luau` contract `behavior.luau` is the type's code. It returns ONE table, and the keys below are the ones the framework reads off it for EVERY type — the surface you get by declaring them. Anything else on the table is your own: reachable by name through `require("@builtin::assetTypes.assetType.shared.ref").loadTypeModule("<typename>")` for a system that knows your type (`computeShader` publishes `dispatchKey` that way), and never called by the framework. ```luau local M = {} M.ref = { ... } -- methods on every AssetRef of this type M.modules = { ... } -- shared code the instances reach M.global = {} -- reserved key; ship the empty table function M.onCreate(name, opts) ... end return M ``` ### The tables | Key | Shape | What the engine does with it | |-----|-------|------------------------------| | `M.ref` | `{ [name] = function(self, ...) }` | Every function becomes a method on every `AssetRef` of this type: `ref:name(...)`, with `self` the ref. This is how a type gives its instances an API. Two names in here are contracted — see below. | | `M.modules` | `{ [name] = require(".sibling") }` | Shared code the type's instances reach through `asset.containing(__FILE__).modules.<name>`, resolved by the instance's pinned `typeRef` guid. See the section above. | | `M.refShapes` | `{ [method] = "TypeName" }` | Declares the result type of a `M.ref` method so the LSP can check what a call site does with it. See the `M.refShapes` section below. | | `M.events` | an events schema | The events an ASSET of this type fires, declared the way a component declares its own. Readers subscribe through `ref.events.<name>:connect(...)`; firing authority stays with the type. Keyed by the asset's guid, so every resolver of the same asset shares the signals and a re-resolved ref re-attaches to subscriptions already there. | | `M.namePattern` | a Lua pattern string | The name shape `asset.create` enforces for instances of this type, replacing the default `^[A-Za-z][A-Za-z0-9_]*$`. | | `M.global` | `{}` | Reserved. Ship the empty table. | ### The lifecycle hooks Each is optional; a type that omits one costs nothing. The engine calls them: | Hook | Signature | When it fires | |------|-----------|---------------| | `M.onCreate` | `(name, opts) -> { [filename] = contents }` | On `asset.create("<type>", name, opts)`. Returns the files that scaffold the new instance, as a map of relative path to contents; the framework writes them. The `opts` type annotation is the schema `asset.create` validates the caller's arguments against, so annotate it. | | `M.onReplace` | `(dest, files) -> { [filename] = contents }` | On an `asset.create` that writes over an asset already at `dest`, after `onCreate`. Receives the files `onCreate` produced and returns the files to write, so a type that re-derives its content (a rig re-imported from its source file) can carry what an author added to the asset it replaces. Optional. | | `M.onRegister` | `(self)` | Once per instance, the first time it registers: on `engine.onWorldLoaded` for instances already in the world, immediately on a live `asset.create`, and when an instance arrives after that sweep (installed, pulled, or synced from a peer). Guarded by the instance's path, so a double trigger never double-registers. An instance that leaves the runtime releases the guard, so one arriving at the same path again registers. This is what makes "write an asset into the world and it takes effect live" work for content that registers into a runtime registry. The `@builtin` library is excluded from the sweep. | | `M.onChange` | `(ref, change)` | On every VFS write to a file INSIDE one of this type's instances. `change` is `{ path, asset, type, kind, origin }`: `kind` is `"edited"` or `"seeded"`, `origin` is `"local"` or `"remote"` (an importer runs on the originator only). **Filter on `change.path`**: the hook fires for any file under the folder, so act on the one you care about. It runs as its own task and may wait on what it reads: a `vfs.read` of bytes only the blob store holds (a binary file on the web build) fetches them. The writes to one asset reach the hook in the order they were made, each once the hook before it has finished. A re-entrancy guard suppresses writes back into the same asset routed inline from the hook, and a write the hook makes is routed on a later frame like any other, so the hook must be convergent on its own: diff the meaningful state and short-circuit while your own regeneration is in flight. | | `M.onDelete` | `(ref)` | When an instance of this type leaves the runtime: it is deleted, or the engine swaps away from the world binding that held it. Its files are gone from `/zero/source` by then. A removal routed while the instance's `onChange` is waiting reaches `onDelete` once that hook, and every write queued behind it, has finished. On a swap the instance still exists in the world it belongs to, and a VFS write the hook makes reaches the world now bound. | | `M.validate` | `(assetRef) -> { { code, message, severity? } }` | On `asset.validate`, after the structural `type.yaml` check, for the type's own SEMANTIC validation. `severity` defaults to `"error"`; error-severity problems flip `ok` to false, warnings do not. A hook that raises or returns a non-table is itself reported as a `validate.hook_failed` error. `world.push` runs this per user asset, so declaring it enforces your type's rules at publish time with no further wiring. | ### The two contracted `M.ref` names Most `M.ref` methods are your type's own surface: name them what you like, return what you like. Two are read by the engine and mean the same thing for every type, so their shape is fixed: - **`instantiate(self, target?, opts?) -> (root, idMap)`** — makes an instance part of the scene. Defining it is the whole opt-in: `ref:canInstantiate()` is true exactly when it exists. Its **return is a contract** — see the next section. - **`inspect(self) -> detail`** — the type-specific half of `asset.inspect`. See its section below. ### Names a type cannot shadow Some keys resolve on every `AssetRef` before per-type dispatch, so an `M.ref` entry of the same name is never reached: `canInstantiate`, `getSource` / `getBytes` / `getText`, `exists`, `deps`, `meta`, `runtime`, `events`, `modules`, `typeRef`, and the residency flags `has_backing_asset`, `has_runtime_changes`, `cpu_resident`, `gpu_resident`. These are the behaviours every asset must expose identically, which is why they win. ### Reloading A `behavior.luau` edit ripples to existing refs with no restart: dispatch reads `mod.ref` fresh each time and `require`'s cache is re-run in place. A type whose folder appears at runtime is picked up on the next dispatch — negative results are not cached either. ## The names your type's assets hold (`references:`) An asset that names another asset by a string depends on it: the named asset travels with it into a pack or a pull, and a name nothing answers to is an unresolved dependency `worldValidation` reports and the push gate refuses. The engine reads `require(...)` and the asset lookups on its own; a name your type's format or API carries anywhere else is one you declare, in `type.yaml`: ```yaml references: # A top-level key of this type's own files that holds a name (or a table of them). keys: - { key: "shader", type: "shader" } # A call's argument, counting from 1, wherever the call is written. args: - { call: "g:node", position: 2, type: "procNode" } # A field of the options table a call takes. fields: - { call: "fx.beam", field: "material", type: "material" } ``` `type` is the category the name resolves in, one of `asset.categories()`. An argument declared once per category, at the same `call` and `position`, takes the name from whichever category answers. A key or a field holds one category: declared again with another `type`, it takes the later one. The block is declared as the type registers, when the library or the world holding it is laid into the VFS, so every reference table reads it whatever script has or has not run. `asset.declareReferenceKey`, `asset.declareReferenceArg` and `asset.declareReferenceField` declare the same things from a script, for a surface that is no type's. ## What search does with your type (`indexing:`) A type declares what search embeds for its instances. **This is not optional and there is no useful default**: ZeroMind runs your declaration and adds nothing of its own, so anything you do not point at is absent from the index — silently, and for every instance of the type forever. Twenty types once shipped with no `indexing:` block and every instance of them was unfindable. A type whose instances are never searchable (a run record, a log) says so with `indexing: none`; every other type declares a recipe. A type without an `about.yaml` beside its `type.yaml` refuses every push that carries it, whether or not the push edited the type. Texts in it that are not written yet follow the rule every `described` file follows: they refuse the push that edits, stages or commits the type. Two words carry the whole thing, and they are the same two the search tool exposes: - **`identity`** — what an instance IS. For anything you can look at, that is the picture (`content:` + `modality: image`, matched directly by a text query). For everything else it is the authored text that says what it is. - **`capability`** — what it DOES and how it is made. Code, settings, the model-written summary of them. A type with no behaviour has no `capability` entry. A type with nothing to look at has no image. Leaving a slot empty is a statement; filling it with whatever happens to be lying around is not. The one you have to decide when authoring a type is: *for an instance of this, what is the thing a person would recognise it by, and what is the thing it does?* A texture answers "the image" and "its compression settings". A module answers "its README" and "its code". Write those two answers into `indexing:` and the rest follows. Three specifics worth knowing before you write one: - **`derive` is instructed by this type's own `README.md`.** A model reads an instance's source and writes a description; what it embeds is the description, not the source. It follows your README to know what it is looking at, so a type whose README says what its instances are gets good derivations for free. There is no prompt to name. - **`derive` loses detail.** It keeps the main technique and drops secondary ones. If the source is code you want searchable by its own vocabulary, declare the same files a second time as `capability` with `extractor: verbatim`. Two entries, same role, different failure modes. - **Never `source: { field: name }`.** A filename is one or two words with no usable embedding, and a corpus indexed that way answers "language runtime" with `say_runtime_2.soundClip`. `facets:` is the second stage: a `file:` embedded whole (`.metadata`, so keys nobody declared still get indexed) plus computed keys that state a value for every instance including `false` — the raw file can imply "not rigged" and can never say it. The full schema, every extractor and the facet sources are in [`assetTypes/README.md`](../README.md); the scaffolded block with inline guidance is in [`template/type.yaml`](template/type.yaml). ## A container whose contents work together (`system: true`) A type that is a container can say its contents are one working whole by declaring `system: true` at the top level of its `type.yaml`. `package` declares it: the components, modules, scenes and tools a package ships are parts of one system. The declaration is plain data, read from the decoded `type.yaml` (`require("@builtin::assetTypes.assetType.shared.declaration").of("package").system`), and a type that leaves it out is an ordinary type. ## What your type looks like (`preview:`) A type declares how its instances are pictured, and the engine makes the picture when something needs it: staging an instance whose `preview.png` is missing or pictures content it no longer holds queues a render, a view that shows the instance asks for one, and `ref:preview()` renders one on demand. An edit renders nothing on its own. Each `preview.png` records the content it pictured, which is how a stale one is told from a current one. The preview studio owns the light, the backdrop, the framing and the camera, and nothing in the world reaches it, so an instance pictures the same in every world. Declare one of four recipes: | `kind` | The picture is | Your type provides | |---|---|---| | `instantiate` | the asset stood in the studio through its own `instantiate` | `ref.instantiate` | | `image` | a file the instance holds, fitted to the frame, nothing rendered | `source.files`, the candidate files in order | | `surface` | the asset painted on a builtin mesh | `mesh`, and `ref.previewMaterial(self) -> { material }` | | `custom` | whatever `ref.preview(self, opts)` returns | `ref.preview` | ```yaml preview: kind: surface mesh: sphere ``` A scene-instantiable type that declares nothing still answers `ref:preview()` through its `instantiate`, but persists no picture: the declaration is what makes the engine keep one. List `preview.png` among the type's files so an instance may hold it. The picture is findable only when `indexing.content` names it. The two are separate statements, and neither is derived from the other: ```yaml indexing: content: - role: identity modality: image source: { file: "preview.png" } ``` `@builtin::assetTypes.assetType.shared.previewRecipe` reads the declaration; the scaffolded block with inline guidance is in [`template/type.yaml`](template/type.yaml). ## Typing a result from the instance (`M.refShapes`) Every method on `M.ref` is checked against the type its `--!return` names, and every asset of the type gets the same one. That is right for most methods and wrong for the ones whose result is shaped by the ASSET: a method answering one entry per child folder, per row of a config, per binding an input map declares. The widest true annotation for those is `{ [string]: Thing }`, and an indexer accepts every key — so a caller's typo reads as valid and nothing reports. `M.refShapes` lets the type state the result per instance. Each entry is `function(self) -> (typeExpression, source?)`: a Luau type expression for THIS asset, and the module whose type vocabulary the expression uses. Read the asset; never run it — stating a type must not take effect. ```lua -- inputMap.assetType/behavior.luau — the shipped example. -- `activate()` hands back one handle per control the map declares. M.refShapes = { activate = function(self): (string, string) local names = {} for _, control in ipairs(M.ref.controls(self)) do table.insert(names, control.name .. ": Handle") end if #names == 0 then return "", "" end return "{ " .. table.concat(names, ", ") .. " }", "@builtin::modules.zinput.scheme" end, } ``` With it, `map.jump:onPressed(fn)` resolves and `map.noexisting` is reported with the map's real controls. Without it, both pass silently. ### What the call site has to say A per-instance type is matched by the asset's IDENTITY, so it applies only where the reference the method is called on says WHICH asset. Two spellings do: ```lua -- a component field, whose declared default names the asset public = { map = Field.assetRef("inputMap", "@builtin::inputMaps.default", Sync) } local controls = public.map:activate() -- typed for THAT map -- an annotation, naming category and identity local m: AssetRef<"inputMap", "@builtin::inputMaps.default"> ``` `asset.resolve("<identity>", "<category>")` carries the CATEGORY, so the methods the category defines are checked on the result — but not which asset it found, so a per-instance result keeps the category's declared return. A reference that names no asset (`asset.resolve(someVariable)`, a value passed in as a parameter) carries neither, and calls on it are unchecked. That is the same rule everywhere: the checker states what the code states, and a name computed at runtime states nothing. ### The result is a value, not a binding The type belongs to the expression, so it travels the way any inferred type travels. Indexing the call's result is checked; stashing it in a module local and indexing it from another function is not, because the local's declared type is what carries across — and `any` (or no annotation) carries nothing: ```lua -- checked: `d.greting` is reported function awake() local d = public.dialogue:lines() d.greeting:say() end -- NOT checked: `lines` is a module local typed `any` local lines: any = nil function awake() lines = public.dialogue:lines() end function start() lines.greting:say() end ``` Bind what you need at the call site and the names stay checked in both places — the asset-derived type at the boundary, ordinary scoping after it: ```lua local lineGreeting = nil function awake() local d = public.dialogue:lines() lineGreeting = d.greeting -- `d.greting` is reported here end function start() lineGreeting:say() end ``` ### When nothing is reported and you expected something From a call site, a type that is correct and a type that was never published look the same: no diagnostic either way. `require("@builtin::assetTypes.assetType.shared.refShapes").published()` answers which it is. It returns two maps — the category surfaces, and the per-asset results keyed by identity and then by method: ```lua local shapes = require("@builtin::assetTypes.assetType.shared.refShapes").published() shapes.categories.dialogue --> "{ lines: () -> any, lineNames: () -> { string } }" shapes.returns.Shopkeeper.lines --> "{ browsing: Line, farewell: Line, greeting: Line, wares: Line }" ``` An identity absent from `returns` was never published for, which is a different thing from published-and-correct — and the reason to look here rather than at the call site. The answers are recomputed when an instance is written, so a control added to a map reaches the checker with no restart. Only types that declare `refShapes` are read per instance, and at most 64 assets of one type are — past that the type keeps its declared return and the engine log names what was dropped. ## The instantiate hook (`M.ref.instantiate`) — a contracted return A type opts into becoming part of the scene by defining `instantiate` on its `ref` table. That is the whole opt-in: `ref:canInstantiate()` is true exactly when the hook exists, so consumers offer a scene path — an `Asset.source` field, a viewport drop, a tool argument — by CAPABILITY rather than by a list of type names. Unlike `inspect`, this hook's **return is a contract**. A caller writes one piece of code against every instantiable type, so what comes back cannot vary by type: ```lua -- behavior.luau local Instantiable = require("@builtin::assetTypes.assetType.shared.instantiable") local M = {} M.ref = { instantiate = function(self, target, opts) local root = Instantiable.root(self, target, opts) -- IN: the base opts -- ... compose whatever this type is, under `root`, NOW ... return Instantiable.result(self, root, idMap) -- OUT: the contract end, } return M ``` **IN.** `target` is an owning entity ref: the instance lands under (or, for a hierarchy type, onto) that owner. With no target the type spawns a fresh root. `position`, `rotation`, `scale`, `name` and `temporary` mean the same for every type — `Instantiable.root` applies them to a root you mint, `Instantiable.place` to one you adopt, so you never re-read the spec. Honour more opts of your own if your type needs them, and document them in the hook's `--!arg` docs. **OUT.** Return `(root, idMap)` through `Instantiable.result`: - **`root`** — the composed root, as an `EntityRef`. Composition is **synchronous**: everything your type builds is live when you return, so the caller can parent to it and read its components in the same statement. Do not defer the work to a component's `awake` and return an empty shell — a root that is not live is refused. - **`idMap`** — the `originalId -> runtimeId` map naming what you spawned, or nil for a type with no addressable children (`result` normalises it to `{}`). **A caller never receives nil.** A component that re-composes your asset on every load keeps this map and passes it back in, which is how a cross-entity reference into the composition survives a reload. `AssetRef` runs every `instantiate` through `result` on the way out whether or not your type called it, so returning something else fails at your own call rather than handing a caller a nil root. Calling it yourself is still how you say what you return, and running it twice changes nothing. `@builtin::assetTypes.assetType.shared.instantiable`'s README is the full reference for both halves. ## The inspect hook (`M.ref.inspect`) `asset.inspect(ref)` resolves `ref`, builds a common envelope shared by every asset (`identity`, `name`, `guid`, `source`, `typeName`, `typeDefinitionPath`, `scope`, `origin`, `description`, `tags`), then calls the resolved type's own inspect hook — `M.ref.inspect(self)` on `behavior.luau` — for the type-specific `detail`. The hook returns *only* `detail`; the framework fills in everything else: ```lua -- behavior.luau local M = {} M.ref = { inspect = function(self) -- self.path is the asset's own folder. Parse the asset's OWN -- files — source text, a native payload header, its `.metadata` -- — never runtime state (a live component instance, a GPU -- upload, a compiled schema): inspect must work on an asset that -- hasn't been compiled, uploaded, or registered yet. return { -- type-specific fields, whatever this type wants to surface } end, } return M ``` A type that omits `M.ref.inspect` yields the generic record: the envelope alone, `detail = nil`. That's a valid, working state — not an error — but it means agents calling `asset.inspect` / `tools.use("assets","describe", ...)` on an instance of the type see only identity and scope, none of what makes an instance of it meaningful. Declaring the hook is what makes a type's instances inspectable for what they actually are. A hook that raises leaves `detail = nil` and sets `record.warning` to the error text — `asset.inspect` itself never raises for a resolved ref. ## Discovery - `asset.list("assetType")` — every registered asset type. - `asset.inspect("<typename>")` — the type's identity, source path, and this README, plus its `about.yaml` texts as `detail.about`. - `asset.resolve("<typename>", "assetType")` — the `<typename>.assetType` asset itself (used by the validator to find the type's `type.yaml`). ## Related - `assetTypes/README.md` — the full `type.yaml` schema and validator rules. - `@builtin::assetTypes.assetType.shared.instantiable` — the instantiation contract's shared implementation, both halves. - Every other `*.assetType/` here — the concrete types built on this meta-type. ## The Inspector a type ships Every type names the file its Inspector sections come from with `inspector: { type: "inspector.luau" }` in its type.yaml. `asset.create("assetType", name)` scaffolds the block and an `inspector.luau` whose Contents section lists an asset's files, built from `ctx.parts`. `asset.validate` on a type that names none reports `assetType.inspector_required` (an error for a `@builtin` type the engine's library authors; a warning for a world's own, and for one the library carries by reference, which the world that published it answers for), and one whose file does not load `assetType.inspector_invalid`. ## In the Inspector Type: what the type.yaml declares (suffix, container, primary files, the settings and inspector blocks), whether the type ships a behavior, how many instances it has, and **Open** for its files. Schema: the settings every instance carries, as read-only typed controls at their defaults (a type whose schema is per instance says where it is declared). Instances: a link to each of the first 20 assets of the type, and how many there are when there are more.

# Module (asset type) A module is a reusable, stateless (or globally-stateful) Luau library that other code pulls in with `require()`. Modules are the unit of factored-out logic in a world: helpers, math libraries, format parsers, registries, shared algorithms. ## When to use one - You have logic you want to share across multiple components, services, scenes, or tools. - You have a registry, lookup table, or shared cache that callers all read from / write to. - You want a stable API surface (`M.fn`) other code can depend on. If the logic is bound to one entity, use a `.component`. If you want a named UI of fields rather than functions, use a `.preset`. ## Where it lives - Source: `/zero/source/.../<name>.module/` - Identity: the source path with `/` written as `.` and each segment's type suffix dropped — `/zero/source/demo/beats.module` is `demo.beats`, and `/zero/source/kit.package/beats.module` is `kit.beats`, the container's name kept and its `.package` suffix gone. `asset.create` returns this string, `asset.resolve(...).identity` reads it back, and the `require` forms below write it as `<identity>`. - Folder shape: - `init.luau` (or `init.lua`) — module body. **Required.** Returns a table (conventionally named `M`). - `README.md` — instance-level documentation. **Required.** - `.metadata` — agent-editable tags + free-form fields. **Required.** ## How to create one ```luau asset.create("module", "<name>") -- Creates: /zero/source/<name>.module/ -- init.luau (canonical `local M = {} … return M`) -- README.md (instance README template) -- `folder` places it in a subfolder of /source, and that subfolder -- leads the identity: `{ folder = "lib" }` produces `lib.<name>`. -- `into` authors it inside a resolved container (a package, a toolbox), -- whose own identity leads the same way: asset.create("module", "<name>", { folder = "lib" }) asset.create("module", "<name>", { into = asset.resolve("myPkg.package") }) ``` ## How it operates 1. **Registration.** Writing `init.luau` into a `.module/` folder indexes the asset and registers the module path with the resolver. 2. **Loading.** The first `require("<identity>")` runs the file's body and caches the returned table. Subsequent requires from anywhere return the **same table** — this is the shared-state lever for "module-local" registries. 3. **Hot reload.** Editing the file re-runs the module body and folds what it returns into the table already loaded, so that table keeps its identity: a caller that captured it with `require` reads the new source's functions and values through the reference it already holds, and a later `require` returns that same table. A key the new source drops goes away; a key something set at runtime stays. The body's own `local`s start again from their initial values, so state that must outlive an edit lives in `modules.state()` (`guides { path: "core/scripting-and-tasks" }`). 4. **Identity resolution.** A module is reached by its `<identity>`, and where the caller lives decides which spelling of it resolves. For a module in a **world**, from a caller in that same world — another module, a component, a scene entrypoint, or an `execute` chunk: - `require("<identity>")` — the identity on its own, resolved against the caller's own root. It carries every folder segment, so a module created with `{ folder = "demo" }` is `require("demo.beats")`. - `require("@root::<identity>")` — the same root-relative resolution, written out. - `require(".sibling")` — a module in the same folder, by its bare name; `..name` steps up one folder, `...name` two. Logs, stack traces and hot-reload notices name that same module `@local.source.<identity>` — its key under the world source root. The `<identity>` tail of that key is the form above, so a trace reading `@local.source.demo.beats` is `require("demo.beats")`. For a module in a **library** — content under `/zero/source/libs/@<lib>/` — `@<lib>::` addresses that library's root from anywhere: `require("@builtin::modules.transform")`. Mounting a world as a library moves its files under such a root and flips the caller root to `@<lib>::`, which is what keeps the root-relative forms above resolving across the move. ## Discovery - `asset.list("module")` — every registered module. - `asset.inspect("<name>")` — public functions, source path, this type README. - `ls /zero/source/<name>.module` lists the files the folder holds. ## Authoring conventions - Return a single `M` table from `init.luau`. Top-level statements with side effects run on first require — useful for one-time initialization, dangerous if they touch the engine before it's ready. - Write exported functions as `typed function`, not `function`: the argument types are enforced at the call and the checker knows the signature, so a caller's mistake is reported where they made it. - Annotate exported functions with `--!desc` / `--!arg` / `--!return` / `--!example` so the LSP, `tools.list`, and `asset.inspect` surface them. A function with no `--!desc` is reachable only by someone already reading this file. - Declare a VALUE with `Field.<kind>(default, mode, description)`, and a table whose members are reached through a metatable with `--!members <TypeName>` — the latter gives the surface its accepted member set, its type, and its documentation from one table. See `guides { path: "core/authoring" }` for all four rules and `modules/api/engine/entity.module/members.module` for a worked member table. - Keep module state in module-local upvalues or in `modules.state()`. Globals leak across reloads. Module-locals start again from their initial values with each hot reload; the table `modules.state()` returns is the same table on both sides of every reload. - Prefer focused modules over kitchen-sink modules. If two halves of a module have no shared state, split them. ## Common pitfalls - **Cyclic requires.** A `require` chain that loops will return the partial table (the half built before the cycle was detected). Design for one-way dependencies. - **Engine-time side effects.** Don't `entity.spawn` at module top-level — the engine may not be ready. Expose an `M.init` and call it from a scene entrypoint. - **Hot-reload + module-local cache.** A module that caches expensive computation in upvalues loses that cache on reload — fine for dev, but be aware in performance work. - **`init.lua` vs `init.luau`.** Either works, `.luau` is canonical. - **Writing one while play runs.** A `/source` write made while play is running lands on the play shadow, and a guarded play-exit discards it unless it is kept. One `.module` write shadows `init.luau`, the `README.md` and the `.metadata` together. `vfs.write(path, bytes, { durable = true })` skips the shadow, and `vfs.promotePlayShadow` keeps what is already on it — the `core/vfs` guide has the model and what each route costs. ## Related types - `.component` — for entity-bound state + lifecycle hooks. - `.service` — generates content you don't have yet (a mesh, sound, texture, …) via a metered provider. - `.tool` — for a single agent-callable function with a YAML schema. - `.package` — to group several modules + components + scenes into one shippable folder. ## In the Inspector Exports: what the module exports (name, kind, signature), parsed from its source without running it, with **Check** (the LSP's diagnostics for its entry file) and **Open**.

# edui The editor UI framework, on the CSS-parity `ui.*` surface. An editor-only toolkit: panels author closures instead of callback ids, a dock shell over `ui.*` native docking, and typed editor-chrome primitives. Gameplay and normal world UI author raw `ui.*` trees and need none of this. **`edui.guide` beside this file is how to use it** — creating a panel, the spec it returns, how a panel is drawn and redrawn, the whole widget vocabulary, and how a panel reaches the selection and the dock. ## What installs - **`framework`** — everything under one table. From outside the package, `require("@builtin::~edui.framework")`; inside it, `require("~.framework")`. It carries `app`, `widgets`, `shell`, `topbar`, `query`, `fileDialog`, `worldDialog`, `stats`, and the chrome primitives flat (`panel`, `tree`, `field`, `section`, `text`, `button`, `menu`, …). - **`app`** — maps a panel's closures to `ui.*` callback ids, dispatches to them, and coalesces redraws. - **`widgets`** — the primitives, plus the typed inspector layer (`widgets.tree`, `widgets.fields`, `widgets.controls`). - **`inspector`** — the Inspector as an ordered list of sections: the generic asset sections, the Settings section and its actions, and the merge with the sections a type's `inspector.luau` declares (`inspector.assetSections`, `inspector.settingsSection`), and the building blocks those sections compose (`inspector.parts`, reached as `ctx.parts`). - **`shell`** — the dock: one `ui.*` `dockArea` holding a `dockPanel` per registered panel, and the panel registry behind it. ## Referencing - Inside this package, modules reference siblings with `~.` — e.g. `require("~.app")`, `require("~.widgets.fields")`. - Editor content built on the framework references it by package identity — `require("~edui.framework")`, `require("~edui.shell")`.

# actions A name-registered action registry over `Zin.bindings` + `Zin.context`. A name maps to a list of binding descriptors and one declared context; polling queries (`held`, `pressed`, `released`, `value`, `heldTime`, `repeated`) evaluate those bindings against the live snapshot, and the handler surface (`bind` / `onPressed` / `onReleased` / `onChanged` / `onHeld`) fires the same state from inside `Zin.tick`, after axes and chords advance. A control asset replaced this. A `<name>.inputBinding/` folder inside an `.inputMap/` carries the label, the kind, and a binding for keyboard-and-mouse, gamepad and touch, and a world activates the map and subscribes to the controls it uses: ```luau public = { inputMap = Field.assetRef("inputMap", "@builtin::inputMaps.default", NoSync, "The controls this component reads."), speed = Field.number(5, NoSync, "World units per second at full deflection."), jumps = Field.number(0, NoSync, "How many times the jump control was pressed."), } local controls function awake() controls = public.inputMap:activate() controls.move:onInput(function(v, dt, active) if not active then return end local p = public.entity.position local step = public.speed * dt public.entity.position = { p.x + v.x * step, p.y, p.z - v.y * step } end) controls.jump:onPressed(function() public.jumps += 1 end) end function onDestroy() public.inputMap:deactivate(controls) end ``` `Zin.map.bake(name)` writes the currently active map out as an `.inputMap` asset. `man topics/input` covers the control model. ## Exports Registry: - `M.define(spec: ActionSpec)` — define / replace actions. - `M.remove(name: string)` — remove one action (also tears down handlers). - `M.clear()` — wipe every action + handler. - `M.has(name: string) -> boolean` - `M.names() -> { string }` - `M.get(name: string) -> ActionEntry?` — the registry record behind a name. - `M.active(name: string) -> boolean` — true iff the action's context matches the top of the stack. Polling queries (gated by context): - `M.held(name) / pressed(name) / released(name) -> boolean` - `M.value(name) -> number | Vec2 | 0/1` - `M.heldTime(name) -> number?` - `M.repeated(name, opts?) -> boolean` Event-driven handlers: - `M.bind(name, fn, opts?) -> ActionHandle?` — register a handler. - `M.disconnect(handle: ActionHandle) -> boolean` - `M.onPressed / onReleased / onChanged / onHeld(name, fn, opts?) -> ActionHandle?` - `M.handlerCount(name) -> number` Internal hooks (wired by `zinput/init.luau`): - `M._setAllocator(fn: () -> number)` — shared id allocator. - `M._setEnsureBindingsFn(fn)` / `M._setEnsureLiveFn(fn)` — the cold-read hooks. - `M._owns(handle: number) -> boolean` - `M._dispatchHandlers(firstTickThisFrame: boolean?)` — called by `Zin.tick`. - `M._clearHandlers()` — test isolation. Types: - `ActionEntry = { context: string, bindings: { any } }` - `ActionSpec = { [string]: any }` — define-spec entry shapes. - `ActionState = "Begin" | "Change" | "End" | "Held"` - `BindOpts = { priority: number?, fire: { ActionState }?, once: boolean? }` - `ActionHandle = number` ## Notes - Define-spec shorthand: - `binding` — single binding under the default context. - `{ binding1, binding2 }` — multiple bindings under the default context. - `{ context = "...", binding = ... }` / `{ context, bindings = {...} }` — explicit context. - Context gating is strict: the action's context string must equal `Zin.context.current()`. There is no inheritance up the stack. - Handlers run from `Zin.tick` after axes/chords advance. With no tick host (or `Zin.autoTick.start()`), handlers never fire. - Returning `"sink"` from a handler stops further (lower-priority) handlers on the same action this tick. Anything else continues. - A handler also ends with the context that bound it: one a component binds ends when that component instance goes (removed, hot-reloaded, or its entity despawned), one a module body binds at the module's next run. `scopes.list()` names each as a `luau` row under the context it follows. - `remove(name)` and `clear()` also wipe handlers bound to those actions — handler state never outlives its action. - The handler allocator is swapped at boot (`_setAllocator`) so handles drawn here share one namespace with `Zin.input.on*`.

# arming The predicate a look-style control hands to its `gate`, in the one place it is written. Backs `Zin.arming`. A mouse always has a delta, so an ungated mouse-look turns the camera whenever the cursor crosses the window. The gate answers "is the player steering?" — and every scheme answers it with the same list of gestures in a different combination. `Zin.arming.gate(opts)` takes the combination and returns the predicate. ```luau local Arming = require("@builtin::modules.zinput.arming") return { label = "Look", kind = "axis2", gate = Arming.gate({ dragZone = "right", stick = "right" }), kbm = B.mouseDelta(), gamepad = B.padStick("right", { as = "delta", unitsPerSecond = 1200 }), touch = B.touchDrag({ zone = "right" }), } ``` A locked pointer always arms: a cursor the scheme took is one the player gave to the camera. The rest is named in `opts` — `dragZone` for a finger inside a touch zone, `stick` for a deflected pad stick, `padButtons` for a trigger, `virtualButtons` for an on-screen button. ## The right mouse button `rightButton` is the field the schemes disagree about, because the button means two different things. | Value | Arms while | Used by | |-------|-----------|---------| | `"free"` (default) | the button is down and no other control that can answer on it declares it | the player scheme | | `"held"` | the button is down | the editor scheme, where holding it IS the fly gesture | | `"off"` | never | a control that reads the button through nothing but pointer lock | `"free"` is what lets a world bind the right button to a game action. The engine's default scheme arms mouse-look on that button, and a world that also binds it would otherwise get the camera turn and its own action from one gesture, with no way to decline the camera half short of standing down its whole control group. Under `"free"` the world's binding is the claim: declare the button in a live `.inputMap` control, or in the `Zin.actions` / `Zin.axes` registry, and the arming stands down for as long as that control can answer on it. A control whose map is standing down for a suppressor, or whose context is not the one on top, is one the player cannot reach — the same two terms the tick's own dispatch reads before it evaluates a control — so the button is free of it while that holds and the camera keeps the drag. `Zin.arming.rightButtonClaimants()` names who is holding it, which is the answer to "why did my right-drag stop turning the camera": ```luau Zin.arming.rightButtonClaimants() --> { "map:torch.torchToggle" } ``` The engine's own arming gesture — the `lookDrag` control on the standard scheme, and the `look_drag` action beside it in the registry — is what `"free"` arms FROM, so those two names are passed over by the search. A claim is decided on the frame the button goes down and holds until it comes up. A map activating mid-drag therefore cannot take a gesture away from the camera halfway through it, and the search runs once per press rather than once per gated control per frame.

# autoTick Opt-in per-frame tick loop for zinput. Spawns a `task.spawnSystem` worker that invokes a registered tick function (`Zin.tick`) once per frame, so code-mode snippets and tests without a host script component still drive the stateful subsystems — live binding dispatch, the touch overlay, the emulation floor, axes, chords, rebind, action handlers, event subscribers. `task.spawnSystem` (not `task.spawn`) makes the loop system-owned, so it keeps ticking while the editor pauses gameplay. The first real input read arms this worker on its own. A host script component can also call `Zin.tick(dt)` from its `update(dt)` hook, and `autoTick.start` can be called directly; all three are idempotent alongside each other. ## Exports - `M.start() -> boolean` — spawn the worker if not already running. Returns true when a new loop was started. - `M.stop()` — flag the loop to exit on its next yield. No-op if not running. - `M.isRunning() -> boolean` — current status. - `M._setTickFn(fn: (number?) -> ())` — internal hook. Called once by `zinput/init.luau` to register `Zin.tick`. - `M._setLastTickFrameIdFn(fn: () -> number)` — internal hook. Wires the frame-id accessor so the worker can dedup itself against explicit ticks within the same engine frame. ## Usage ```luau local Zin = require("@builtin::modules.zinput") -- One-shot test / code-mode setup: Zin.autoTick.start() -- ... later ... Zin.autoTick.stop() ``` ## Notes - Single-flight: calling `start()` twice is a no-op — there is at most one worker per VM. - Cross-coroutine dedup: when an explicit `Zin.tick` ran in the same engine frame, the worker skips that frame so `onHeld` handlers and event subscribers don't double-fire. - Module-local `_running` survives Luau require-cache reload, so a re-required `autoTick.module` still reports the loop is live. `restart_instance` resets the VM and clears everything. - `start()` raises if `_setTickFn` hasn't been wired yet — always `require("@builtin::modules.zinput")` first.

# axes A name-registered axis registry over `Zin.bindings`. Any axis or vector binding becomes a `Zin.axes` entry with optional deadzone, exponential smoothing, curve shaping, invert, context gating, and a per-frame gate function. Stateful — `Zin.tick` calls `advance(dt)` each frame to evolve the smoothed reading. A control asset replaced this. An `axis1` / `axis2` `<name>.inputBinding/` inside an `.inputMap/` carries a binding for keyboard-and-mouse, gamepad and touch, so one control reads a stick and a dragging thumb as well as a key, and the binding's own `as` / `unitsPerSecond` / `scale` bring every class into one unit. It declares the same `deadzone`, `smoothing`, `curve` and `invert`, applied by `Zin.scheme` through the same `Zin.utils` maths this reads: ```luau public = { inputMap = Field.assetRef("inputMap", "@builtin::inputMaps.default", NoSync, "The controls this component reads."), speed = Field.number(5, NoSync, "World units per second at full deflection."), jumps = Field.number(0, NoSync, "How many times the jump control was pressed."), } local controls function awake() controls = public.inputMap:activate() controls.move:onInput(function(v, dt, active) if not active then return end local p = public.entity.position local step = public.speed * dt public.entity.position = { p.x + v.x * step, p.y, p.z - v.y * step } end) controls.jump:onPressed(function() public.jumps += 1 end) end function onDestroy() public.inputMap:deactivate(controls) end ``` `Zin.map.bake(name)` writes the currently active map out as an `.inputMap` asset. `man topics/input` covers the control model. ## Exports Lifecycle: - `M.define(spec: AxisSpec)` — define / replace axes. - `M.remove(name: string)` / `M.clear()` — drop one / all axes. - `M.has(name) -> boolean` / `M.names() -> { string }` / `M.get(name) -> AxisDef?` Reads: - `M.value(name: string) -> any` — smoothed value (`number` for scalar, `{ x, y }` for vector). - `M.raw(name: string) -> any` — raw unsmoothed binding value. Tick hook: - `M.advance(dt: number)` — internal; called by `Zin.tick`. - `M._setEnsureBindingsFn(fn)` / `M._setEnsureLiveFn(fn)` — internal cold-read hooks. - `M._resetGateWarnings()` — test helper. Types: - `Curve = string | (number) -> number` — `"linear"` / `"quadratic"` / `"cubic"` / custom. - `AxisDef = { binding, deadzone, smoothing, curve, invert, context, gate, kind }` - `AxisSpec = { [string]: any }` — define-spec. ## Notes - `smoothing` is the exponential time constant in seconds. `0` means "snap to target instantly". Higher = laggier. - `deadzone` is radial for vector bindings — magnitude under the threshold zeros both axes — and scalar for scalar bindings. - Context gating is strict: the axis's declared context must equal `Zin.context.current()`. Mismatch snaps target to 0, and `advance` smooths current down toward 0. - A throwing `gate` falls through to "ungated" for that frame and logs one warning per axis per session (state cleared via `_resetGateWarnings()`). - Without a tick host (or `Zin.autoTick.start()`), `value()` returns the last computed snapshot; `raw()` always reads live.

# back Back, and the claims a world holds on it. Backs `Zin.back`. Back is the platform's own Back: Android's Back button and back gesture, and a keyboard's Back key (`BrowserBack`, which a browser names the same). A world binds any control of its own to it with `Zin.back.press`, which is how Escape or a pad's button becomes Back too. The engine routes every Back press to the first of these that stands: 1. the topmost overlay on screen that states how it is dismissed: an open `popup` carrying `onDismiss`, or an open, dismissible `modal` carrying `onClose`. Its dismissal runs, the way Escape runs it. 2. the claim held that takes it (`Zin.back.claim`: the highest priority, and the most recent among equals): its handler runs. 3. nothing: the platform's own default answers. On Android the app moves to the background; a desktop window and a browser page stay where they are. A claim says ahead of the press that the world takes Back, which is what Android's predictive back asks for: the system decides before a back gesture begins whether it previews going home. Hold a claim while Back means something to the world and release it when Back should leave. Every press is a `back` event in `input.events()`: `{ kind = "back", taker = "overlay" | "claim" | "none" }`. ## Exports - `M.claim(handler, { priority? }) -> Claim`: take Back. Of the claims held, the highest priority (0 when omitted) takes a press no overlay takes, and the most recent among equals. The editor's claim that leaves play is held at -1, under every claim a played world makes. `claim:release()` gives it up, `claim:held()` says whether it is held. A claim a component makes is released when its entity is destroyed. - `M.press()`: press Back, routed as above. - `M.claims() -> number`: how many claims are held. ## Usage ```luau local Zin = require("@builtin::modules.zinput") local claim local function closeMenu() menu.close() if claim then claim:release() claim = nil end end local function openMenu() menu.open() claim = Zin.back.claim(closeMenu) end -- Escape as Back too, through the world's own control. controls.pause:onPressed(Zin.back.press) ```

# bindings Binding primitives and evaluators. A binding names which physical input satisfies a control on one device class — the value a `.inputBinding` record's `kbm` / `gamepad` / `touch` field holds. A binding is a plain descriptor table (e.g. `{ kind = "key", code = "KeyW" }`); the evaluators (`evalHeld`, `evalPressed`, `evalReleased`, `evalAxis`, `evalVector`) dispatch on `kind` and read `Zin.state` / `Zin.virtual` to produce the live signal. `Zin.scheme` runs them once per tick for every live binding, and they are public so chords, axes and library authors can evaluate a binding without reimplementing the dispatch. ```luau -- boost.inputBinding/init.luau local B = require("@builtin::modules.zinput.bindings") return { label = "Boost", kind = "button", kbm = { B.key("ShiftLeft") }, gamepad = { B.padButton("left_shoulder") }, touch = { B.touchButton({ zone = "right-lower" }) }, } ``` ## Two frames, and which binding speaks which - **Stick bindings** (`vector`, `touchStick`, `padStick`) report the direction the player *means* — forward is `+y`. A `move` control carrying a keyboard class and a stick class drives both devices the same way. - **Delta bindings** (`mouseDelta`, `touchDrag`, `scroll`) report movement that happened — down is `+y`, because that is what the pointer did. They also differ in magnitude: a stick is a position bounded at 1.0, a delta is however far the device moved this frame. A control carrying both — look, zoom — declares `as = "delta"` on its held class with the `unitsPerSecond` a full deflection is worth, and `scale` on a delta class that counts in its own units (a pinch in pixels beside a wheel in notches). `Zin.scheme` applies both, so one sensitivity covers every device. ## Exports Keyboard and mouse constructors: - `M.key(code: string) -> Binding` - `M.mouse(button: string) -> Binding` — `"left"` / `"right"` / `"middle"`. - `M.modKey(spec: string) -> Binding` — `"Ctrl+S"`, `"Shift+Alt+P"`, `"Escape"`. - `M.axis(plus: Binding, minus: Binding, opts: StickOpts?) -> Binding` - `M.vector(right, left, up, down: Binding) -> Binding` - `M.wasd() -> Binding` - `M.arrowKeys() -> Binding` - `M.mouseDelta(axis: string?) -> Binding` — this frame's mouse delta. - `M.scroll(axis: string?) -> Binding` — scrollwheel delta. - `M.pointerLocked() -> Binding` — boolean, true while locked. Touch constructors (fed by `Zin.virtual`, which the on-screen controls write): - `M.touchStick(opts: { zone, axis? }) -> Binding` — vector. - `M.touchButton(opts: { zone?, label?, icon?, priority?, size?, group? }) -> Binding` — boolean. - `M.touchDrag(opts: { zone, axis? }) -> Binding` — per-frame delta vector. - `M.touchPinch(opts: StickOpts?) -> Binding` — scalar pinch delta. Gamepad constructors (addressed by canonical position; `slot` names one pad, omitting it means any connected pad): - `M.padButton(button: string, slot: number?) -> Binding` - `M.padAxis(axis: string, opts: StickOpts?) -> Binding` - `M.padStick(stick: string, opts: StickOpts?) -> Binding` - `M.padTrigger(trigger: string, slot: number?) -> Binding` Predicates: - `M.isBoolean(b) -> boolean` - `M.isAxis(b) -> boolean` - `M.isVector(b) -> boolean` Evaluators: - `M.evalHeld(b) -> boolean` - `M.evalPressed(b) -> boolean` - `M.evalReleased(b) -> boolean` - `M.evalAxis(b) -> number` - `M.evalVector(b) -> Vec2` Pretty-printers: - `M.format(b: any) -> string` — single binding ("Space", "Ctrl+S", "WASD"). - `M.formatAll(bindings: any?, sep: string?) -> string` — joined summary; non-table arg returns `"<no bindings>"`. Types: - `Binding = { [string]: any }` — descriptor table with `kind` plus type-specific fields. - `Vec2 = { x: number, y: number }` - `StickOpts = { slot: number?, as: string?, unitsPerSecond: number?, scale: number? }` ## Notes - Bindings are pure data tables — they serialize cleanly, compare with `Json.encode`, and have no metatables. - `modKey` normalises modifier order in `format()` so a key written as `Shift+Ctrl+KeyS` displays the same as `Ctrl+Shift+KeyS`. The internal `mods = { ctrl, shift, alt }` flags are the canonical representation. - Mouse-delta, scroll, drag and pinch values are raw physical deltas, not clamped to `[-1, 1]`. `as = "delta"` + `unitsPerSecond` on the stick class beside them is what puts every class in one unit. - `as = "delta"` needs `unitsPerSecond` and has no default: the number that makes a pad feel right is the point of declaring the conversion, and a default would be right for one control and quietly wrong for the next. - Reading a member this module does not have raises immediately, naming the nearest members and the full list — a wrong guess at a constructor surfaces at the call rather than as `attempt to call a nil value` later. - `format()` always returns a string, never throws — returns `"<invalid>"` for malformed input.

# chords Chord and sequence state machines. Two kinds: - `sequence` — ordered steps with a per-step window and an overall window (Konami-style codes). - `simultaneous` — N bindings pressed inside a tolerance window, order-insensitive (piano-chord / fighter-combo style). Chords are edge-triggered — `fired(name)` is `true` for exactly one frame when the full pattern completes. A continuous combo like "Ctrl+S held" is a `button` control whose `kbm` class is `B.modKey("Ctrl+S")`: a chord recognizes a pattern over time, which is a different question from whether a combination is down right now. ## Exports Lifecycle: - `M.define(spec: ChordSpec)` — define / replace chords. - `M.remove(name) / M.clear()` - `M.has(name) -> boolean` / `M.names() -> { string }` / `M.get(name) -> ChordDef?` Queries: - `M.fired(name) -> boolean` - `M.progress(name) -> number` (0..1) - `M.cancel(name)` — reset state. Subscriptions: - `M.onFire(name, callback, opts: OnFireOpts?) -> OnFireHandle` - `M.off(handle: OnFireHandle)` Tick hooks (called by `Zin.tick`): - `M._beginTick()` — clears per-frame fire flags. - `M._observeEvent(ev)` — advance state machines on an input event. - `M._advanceTime(dt)` — age out stale recognizers. - `M._dispatchFires()` — invoke onFire callbacks for chords that fired this tick. Types: - `ChordDef = { kind, context, steps?, stepWindowSec?, windowSec?, bindings?, toleranceSec? }` - `ChordSpec = { [string]: any }` - `OnFireOpts = { context: string?, once: boolean? }` - `OnFireHandle = { id: number, name: string, off: () -> () }` ## Usage ```luau local Zin = require("@builtin::modules.zinput") local B = Zin.bindings Zin.chords.define({ konami = { kind = "sequence", steps = { B.key("ArrowUp"), B.key("ArrowUp"), B.key("ArrowDown"), B.key("ArrowDown"), B.key("ArrowLeft"), B.key("ArrowRight"), B.key("ArrowLeft"), B.key("ArrowRight"), B.key("KeyB"), B.key("KeyA") }, stepWindowSec = 0.5, windowSec = 4.0, }, }) Zin.chords.onFire("konami", function() unlockBonus() end) ``` ## Notes - Without a tick host (or `Zin.autoTick.start()`) chords never fire — every state machine is dormant until `Zin.tick` drives it. - A wrong key in a sequence resets to step 0. If the wrong key happens to match step 1, the recogniser restarts from step 1 on the same event (so a long input run can self-recover). - For simultaneous chords, the tolerance window starts on the first matched press. If all bindings haven't matched before `toleranceSec` elapses the state resets — `firstPressAt` is reset too so the next press starts a fresh window. - Subscriber errors are caught and logged via `log.warn`.

# zinput / clock The wall-clock time source for zinput's time-window features — held-time and synthetic key repeat (`state`), chord step / total windows (`chords`), and the tick's fallback delta (`init`). `nowSeconds()` reads the engine's per-frame `getTime()` (seconds since engine start, published from the native clock), which advances with wall time on every platform. `os.clock` measures CPU time and barely moves across scheduler yields on wasm, so it is only the fallback for contexts with no engine time surface. ## API - `nowSeconds() -> number` — current wall-clock seconds for input timing. - `_setClock(fn: (() -> number)?)` — internal; override the clock with `fn` (returns seconds) or `nil` to restore the default. For deterministic timing: fixed-step replay and tests that need a controllable clock.

# conflicts Binding-conflict detection — reverse index over the `Zin.actions` / `Zin.axes` registries. Two bindings "conflict" when they map to the same canonical leaf key (e.g. both bind `Space`, or an action binds `Space` and an axis's `plus` side is `Space`). Backs `Zin.conflicts`. Rows carry a `kind = "real" | "intentional"` classification: two or more action owners in the *same context* are `real`; action + axis overlaps, cross-context actions, and explicitly marked pairs are `intentional`. `realOnly()` is the noise-filtered view the Input tab uses; `forActiveProfile()` is the full audit list. ## Exports Marking: - `M.markIntentional(actionA: string, actionB: string) -> (boolean, string?)` - `M.unmarkIntentional(actionA: string, actionB: string) -> boolean` - `M.isIntentional(actionA: string, actionB: string) -> boolean` - `M.listIntentional() -> { { string } }` Probing: - `M.bindingKey(b: any) -> string?` — `"key:Space"`, `"modKey:Ctrl+KeyS"`, `"mouse:left"`, or `nil`. - `M.find(binding: any) -> { Owner }` — owners that share any leaf key with the probe. - `M.forActiveProfile() -> { ConflictRow }` — every shared-key row. - `M.realOnly() -> { ConflictRow }` — subset where `kind == "real"`. Internal (wired by `zinput/init.luau`): - `M._setPersistFn(fn)` — registers the save-back closure. - `M._loadIntentionalPairs(pairs_)` — seed on profile activate. - `M._serializeIntentional() -> { { string } }` — for profile save. - `M._resetIntentional()` — test isolation. Types: - `Owner = { target: string, name: string, slot: any }` — `target` is `"action"` or `"axis"`. - `ConflictRow = { key: string, owners: { Owner }, kind: string }` — `kind` is `"real"` or `"intentional"`. ## Usage ```luau local Zin = require("@builtin::modules.zinput") -- Audit view (e.g. inside the Input tab): for _, row in ipairs(Zin.conflicts.forActiveProfile()) do print(row.key, row.kind, #row.owners) end -- Suppress an intentional same-context overlap: Zin.conflicts.markIntentional("crouch", "slide") ``` ## Notes - `modKey` leaf keys list modifiers alphabetically (`Alt+Ctrl+Shift`), so `Shift+Ctrl+KeyS` and `Ctrl+Shift+KeyS` compare equal. - Continuous-source bindings (`mouseDelta`, `scroll`, `pointerLocked`) never appear in conflict reports — two axes reading `mouseDelta` is by-design. - Persistence: `_setPersistFn` is wired by `zinput/init.luau` so marks flow into the active profile JSON without conflicts needing a hard dep on profile. - The classifier counts every same-context action pair. If even one pair is unmarked, the row is `"real"`; otherwise `"intentional"`.

# context The input context stack. Pushing a named context ("ui", "menu", "vehicle", ...) stands down everything whose declared context doesn't match the top of the stack; popping restores the previous mode. The bottom is permanently `"default"` so unbalanced pops never leave the stack empty. A control, an action, an axis or an event subscriber can declare one context. `Zin.scheme` honours it on every live binding, so a vehicle-context Brake neither fires nor draws its touch button while the default context is on top. A map standing another map's `group` down is the coarser instrument beside this one: `group` / `suppresses` on an `.inputMap` decides which whole schemes answer, while a context decides which entries within a live scheme do. ## Exports - `M.default() -> string` — the always-on context name (`"default"`). - `M.push(name: string)` — push a context. No-op when `name` is not a non-empty string. - `M.pop() -> string?` — pop the top context; returns `nil` when only `default` remains. - `M.current() -> string` — name at the top of the stack. - `M.contains(name: string) -> boolean` — true if `name` is anywhere in the stack. - `M.stack() -> { string }` — a copy of the live stack, bottom→top. - `M.reset()` — pop everything except `default`. - `M.with<T...>(name: string, fn: () -> T...) -> T...` — run `fn` with `name` pushed, pop guaranteed. ## Usage ```luau local Zin = require("@builtin::modules.zinput") -- menuClose.inputBinding/init.luau declares `context = "ui"`, so it reads -- only while "ui" is on top. Zin.context.push("ui") Zin.context.current() -- "ui" Zin.context.pop() Zin.context.with("ui", function() -- inside this block the "ui" controls are the ones that read end) ``` ## Notes - The stack lives in the module's upvalues, so it persists across Luau script runs that share the require cache. A `restart_instance` resets it (matches the standard caching contract). - Pushing the same context twice requires two pops to fully remove — matches typical UI nesting (a sub-menu pushes "ui" again). - A declared context is compared strictly equal to `current()`; there's no inheritance up the stack.

# controllers Reusable controller factories on top of the `Zin.actions` handler, `Zin.context` and `Zin.state` surfaces. Each factory returns a stateful controller object with the `:start / :stop / :update / :isActive` lifecycle and a small set of intent readers. `free`, `orbit` and `fps` read keyboard and mouse, and their `gamepadIndex` opt is accepted and ignored. `vehicle` reads an input map, so every control answers to keyboard, gamepad and touch. ## Exports Factories (module-level): - `M.free(opts: FreeOpts) -> FreeController` — free-fly designer/debug camera (WASD plane + Q/E vertical + Shift sprint + mouse-look). Writes the entity transform directly. - `M.orbit(opts: OrbitOpts) -> OrbitController` — orbit camera around a target (drag-rotate, scroll-zoom, optional pan). - `M.fps(opts: FpsOpts) -> FpsController` — first-person walker. Produces motion intent for the host (`getDesiredVelocity`, `consumeJumpRequest`, `isSprinting`, `isCrouching`); convenience `applyToTransform` writes directly. - `M.vehicle(opts: VehicleOpts?) -> VehicleController`: driving intent for a ground vehicle, read from `opts.inputMap` (an inputMap ref or its path; `@builtin::inputMaps.vehicle` by default): `getThrottle` (-1..1, positive forward), `getSteer` (-1..1, positive right), `getBrake` (0..1), `isHandbrakeHeld`, `isBoosting`, `consumeRecoverRequest` (true once per press), `consumeZoom` (wheel notches since the last read). `:start` activates the map, which stands the walking scheme down for as long as it is live; `:stop` releases it. The `VehicleController` component drives a car's `WheelCollider`s from this intent. Controller-object methods (returned by the factories; called with `:`): - `:start()` — define actions, push context, optionally request pointer-lock. - `:stop()` — drop actions, pop context, release pointer-lock if `:start` took it. - `:isActive() -> boolean` - `:update(dt: number)` — per-frame; no-op when context doesn't match. - `:actionNames() -> { string }` - `FreeController`: `:setMoveSpeed`, `:setLookSensitivity`, `:getCameraYaw`, `:getCameraPitch`, `:getVelocity`. - `OrbitController`: `:getDistance`, `:getYaw`, `:getPitch`, `:setDistance`, `:setTarget`. - `FpsController`: `:setMoveSpeed`, `:setLookSensitivity`, `:getCameraYaw`, `:getCameraPitch`, `:getDesiredVelocity`, `:isSprinting`, `:isCrouching`, `:consumeJumpRequest`, `:applyToTransform`. Types: - `FreeOpts`, `OrbitOpts`, `FpsOpts` — opts tables; `entity` is the only required field. - `VehicleOpts`: `{ inputMap?, label? }`; every field is optional. - `FreeController`, `OrbitController`, `FpsController` — opaque (typed as `any` so the metatable plumbing doesn't fight the LSP). ## Usage ```luau local Zin = require("@builtin::modules.zinput") local cam = Zin.controllers.free({ entity = cameraEntityId }) cam:start() -- per frame: Zin.tick(dt) cam:update(dt) ``` ## Notes - Each controller's actions are namespaced under `actionPrefix` (default `"free_fly."`, `"orbit."`, `"fps."`). Two co-existing controllers with overlapping prefixes will trample each other — override the prefix when stacking. - The context push/pop pair makes `Zin.context.push("ui")` cleanly suppress every controller without `:stop`. The controller's `:update` early-outs when `Zin.context.current()` doesn't match. - Rotation convention: yaw=0, pitch=0 → `(0, 0, -1)` (-Z forward). Mouse Δx adds to yaw; mouse Δy subtracts from pitch (invert with `invertY = true`). Pitch is clamped to `[-π/2 + ε, π/2 - ε]`. - `FpsController` produces *intent* — gravity, collision, and the jump impulse are the host's responsibility. The `consumeJumpRequest()` accessor returns `true` once per press, so the physics step can fire its impulse exactly once. - Free / FPS request pointer-lock at `:start` (opt out with `requestPointerLock = false`) and only release it on `:stop` when they were the ones who acquired it.

# emulation Map-driven input-emulation floor. Reads `Zin.virtual` (the store on-screen touch controls write) each tick and emulates the equivalent kbm keys / mouse delta, so raw-key-polling worlds (`Zin.state.keyDown`) move from touch input without themselves reading `Zin.virtual` or `Zin.bindings`. Backs `Zin.emulation`. ## What it derives, per tick, from the active effective map Only entries whose `context` matches the current input context (`Zin.context.current()`) participate — the same activity rule `Zin.actions` applies, so a vehicle-context Brake button emulates nothing while the default context is on top. - **touchButton actions** — the OR of every touchButton binding in an action's touch class drives its first kbm `key` binding's code, emulated on the held state's transitions. Actions with no kbm key binding are skipped. - **touchStick axes** whose kbm class is a `vector` of four `key` arms (the `B.wasd()` / `B.arrowKeys()` shape) — each stick component thresholded at `+-0.5` drives the matching direction key. The stick's y is screen-down positive (`Virtual.setStick`'s convention), so negative y (stick pushed up) drives the vector's `up` arm and positive y its `down` arm. - **touchDrag axes** whose kbm class is `mouseDelta` — the drag delta, scaled by `M.setSensitivity`, emulated via `input.emulateMouseDelta` whenever it's non-zero. A control that is already a live binding (`Zin.scheme.has(name)`) is skipped: its touch class drives it directly, and synthesising a key for it as well drives it twice, from opposite conventions. The judgement is per control, because a world can subscribe to some things and poll raw keys for others. Emitted keys are tracked locally and diffed each tick — a held key is emulated once, on the press transition, never re-emitted every tick a control stays held. Switching the active map (name change between ticks) or the input context (top-of-stack change) releases everything emitted under the previous map/context. ## Exports - `M.setSensitivity(n: number)` / `M.getSensitivity() -> number` — the touchDrag -> mouse-delta multiplier (default `1.0`). - `M._advance()` — internal: one tick of the floor, called by `Zin.tick`. - `M._reset()` — test-only: release everything emitted, clear state. ## Usage ```luau local Zin = require("@builtin::modules.zinput") Zin.map.ensureActive() Zin.emulation.setSensitivity(1.5) -- Zin.tick(dt) advances the floor; a virtual Jump press then reads as -- Zin.state.keyDown("Space") for any world that only polls kbm state. ```

# events Frame-event readers and edge-event subscriptions. Wraps the internal `__zero_input.events()` FFI with per-kind filters and a push-style `on/off` API that fires from `Zin.tick`. Backs `Zin.events`. `__zero_input.events()` returns the current frame's events in dispatch order; reading does not consume them. Subscription dispatch happens during `Zin.tick` (or `Zin.autoTick.start()`'s worker), so without a tick host `on()` callbacks never fire. ## Exports - `M.frame() -> { InputEvent }` — this frame's events in dispatch order. - `M.iter() -> iterator` — `ipairs` over `frame()`; reads better at call sites. - `M.keysDown / keysUp / mouseDowns / mouseUps / mouseMoves / mouseWheels / texts() -> { InputEvent }` — per-kind filters. - `M.on(filter: EventFilter, callback, opts: SubOpts?) -> SubHandle` — register an edge subscriber, returns handle. - `M.off(handle: SubHandle | number)` — cancel a subscriber. - `M.clearSubscribers()` — drop all subscribers (test isolation). - `M.subscriberCount() -> number` — current subscriber count. - `M._dispatch(events)` — internal; called by `Zin.tick`. Types: - `InputEvent = { [string]: any }` — one entry of the frame event log. - `EventFilter = string | { [string]: any } | (any) -> boolean` - `SubOpts = { context: string?, once: boolean?, priority: number? }` - `SubHandle = { id: number, off: () -> () }` ## Usage ```luau local Zin = require("@builtin::modules.zinput") for _, ev in ipairs(Zin.events.frame()) do if ev.kind == "key.down" and ev.code == "Space" then -- jump on the press edge, not on every frame the key is held end end local h = Zin.events.on({ kind = "key.down", code = "Escape" }, function(ev, gpe) if not gpe then closeMenu() end end, { context = "ui" }) -- later: h.off() ``` ## Notes - Reading `frame()` is non-destructive — multiple consumers can iterate the same frame's events. The log clears at end-of-frame and is rebuilt next frame. - Subscribers dispatch in priority-desc order; equal priorities preserve insertion order. Returning `"sink"` from a callback halts further dispatch for that single event (lower-priority subscribers skipped). - `once = true` subscribers auto-unsubscribe after their first matching dispatch. - A subscription ends with the context that made it as well as with `off`: one a component makes ends when that component instance goes (removed, hot-reloaded, or its entity despawned), one a module body makes at the module's next run. `scopes.list()` names each as a `luau` row under the context it follows. - Subscriber errors are caught and logged via `log.warn`; one bad handler doesn't break dispatch.

# gamepad The pad-facing surface: which controllers are connected, what family they belong to, and what a legend should call a canonical button on them. Backs `Zin.gamepad`. Bindings never come through here. A scheme binds `B.padButton("south")` and evaluates against whichever pad is connected; this module answers the questions a UI asks — how many players have controllers, and which letter to draw on a prompt. ## Position, not letter The canonical layout names a button by POSITION, because position is what every pad shares — `south` is the lower face button on all of them. The letter printed on it is not shared: `south` is `A` on an Xbox pad, `Cross` on a PlayStation one, and `B` on a Nintendo one. `label()` resolves that from the device name the platform reported, so a binding stays device-independent and only the drawn glyph changes. Anything unrecognised reads as `xbox`, because the standard mapping every backend normalises to is the Xbox layout. ## Exports - `M.list() -> { Pad }` — every connected pad, in slot order. - `M.count() -> number` — how many pads are connected. - `M.get(slot) -> Pad?` — the pad in one slot. - `M.family(slot?) -> string` — `"xbox"` | `"playstation"` | `"nintendo"`. - `M.label(button, slot?) -> string` — the legend for a canonical button. - `M.available() -> boolean` — whether the session has ever seen a pad. Latched by the first connection, so unplugging one does not flip a scheme's prompts back to keyboard glyphs on a cable knock. Types: - `Pad = { slot, name, buttons, buttons_pressed, buttons_released, axes, simulated }` — the button fields are arrays of canonical names, `axes` a map of canonical axis name to number, and `simulated` marks a pad that came from the `inputSim` toolbox rather than a device. ## Usage ```luau local Zin = require("@builtin::modules.zinput") if Zin.gamepad.count() >= 2 then startLocalCoop() end ui.text("Press " .. Zin.gamepad.label("south") .. " to jump") ```

# gestures Touch-gesture recognizers over the touch event stream + contact snapshot; backs `Zin.gestures`. Discrete gestures (tap, double-tap, long-press, swipe) fire subscriptions; continuous gestures (pinch, pan) expose per-tick deltas computed from the two-finger contact state. Advanced by the `Zin.tick` pipeline — dormant until ticked. ## Discrete vs continuous - **Discrete** (tap / double-tap / long-press / swipe) — recognized on a release or hold-duration edge, delivered via `on*` subscriptions on the tick they fire. - **Continuous** (pinch / pan) — recomputed every tick from the two-finger contact positions; read via `pinchDelta()` / `panDelta()`, reset to zero at the start of each tick. The pair is formed from the contacts no on-screen widget is working, the ones `Zin.touchControls` says its stick and buttons hold having been left out, so a thumb on a movement stick is no part of a pinch. ## Config `Zin.gestures.configure` overrides recognition thresholds (unspecified fields keep their current values): | Field | Default | Meaning | |---|---|---| | `tapMaxDuration` | `0.25` s | press→release within this = tap candidate | | `tapMaxMovement` | `16` px | total movement below this = tap candidate | | `doubleTapWindow` | `0.3` s | two taps within this = double-tap | | `longPressDuration` | `0.5` s | held past this (still) = long-press | | `swipeMinDistance` | `60` px | release travel at/above this = swipe candidate | | `swipeMinVelocity` | `800` px/s | release velocity at/above this = swipe | ## Exports - `M.configure(opts: { [string]: number })` — override recognition thresholds. - `M.getConfig() -> GestureConfig` — current thresholds (a copy). - `M.onTap(fn) -> number` — subscribe to taps; `fn(ev)` with `ev = { x, y, id, duration }`. - `M.onDoubleTap(fn) -> number` — subscribe to double-taps; `ev = { x, y, id }`. - `M.onLongPress(fn) -> number` — subscribe to long-presses (fires once per contact); `ev = { x, y, id }`. - `M.onSwipe(fn) -> number` — subscribe to swipes (fires on release); `ev = { direction, dx, dy, velocity, id }`. - `M.off(handle: number) -> boolean` — unsubscribe a handle from any `on*` function. - `M.pinchDelta() -> number` — this tick's two-finger pinch delta in px (positive = spreading). - `M.panDelta() -> (number, number)` — this tick's two-finger pan delta `(dx, dy)` in px. - `M._beginTick()` — internal: clear per-tick continuous deltas; wired by `Zin.tick`. - `M._observeEvent(ev: any)` — internal: builds contact tracks and classifies discrete gestures on release; wired by `Zin.tick`. - `M._advanceTime(dt: number)` — internal: time-based recognition (long-press) + continuous deltas; wired by `Zin.tick`. - `M._setWidgetContacts(ids: { [number]: boolean })` — internal: the contacts an on-screen widget is working; published each tick by `Zin.touchControls`. - `M._pairDown() -> boolean` — internal: whether two contacts no widget is working are down, which is the pair a two-finger gesture reads. - `M._dispatchFires()` — internal: deliver this tick's discrete gesture fires; wired by `Zin.tick`. - `M._reset()` — test-only: clear all tracks, fires, deltas, and subscriptions. Types: - `GestureConfig = { tapMaxDuration, tapMaxMovement, doubleTapWindow, longPressDuration, swipeMinDistance, swipeMinVelocity }` (all `number`) ## Usage ```luau local Gestures = require("@builtin::modules.zinput.gestures") Gestures.onTap(function(ev) print("tap at", ev.x, ev.y) end) Gestures.onSwipe(function(ev) if ev.direction == "left" then nextPage() end end) -- inside a per-frame update: local zoom = Gestures.pinchDelta() local dx, dy = Gestures.panDelta() ``` ## Notes - Pinch and pan deltas are zero unless exactly two contacts are down this tick that no on-screen widget is working. - Long-press fires once per contact — the contact must stay within `tapMaxMovement` for the full `longPressDuration` and is marked so it never also fires a tap on release. - Every qualifying release fires `tap`; the second tap of a double-tap fires `doubleTap` and `tap` on the same tick. - Handler errors during dispatch are caught and logged, not propagated.

# input Event-driven listeners for whole categories of raw input, on top of `Zin.events.on`. Sugar for the most-common filter shapes (`onBegan` / `onEnded` / `onChanged` / `onTextInput`) plus a `lastInputType()` accessor. Backs `Zin.input`. These sit beneath the control model: they answer "any key went down" rather than "the Jump control fired", which is what rebind capture, dev tooling and text-adjacent UI need. Gameplay subscribes to controls through an activated map — `man topics/input` covers that path. ## Exports - `M.lastInputType() -> string?` — userInputType of the most recent input event (`"Keyboard"` / `"Mouse"` / `"Touch"` / `nil`). - `M.onBegan(fn, opts?) -> Handle` — fires on `key.down` / `mouse.down`. - `M.onEnded(fn, opts?) -> Handle` — fires on `key.up` / `mouse.up`. - `M.onChanged(fn, opts?) -> Handle` — fires on `mouse.move` / `mouse.wheel`. - `M.onTextInput(fn, opts?) -> Handle` — fires on committed text input; handler signature is `(text, gpe)`. - `M.disconnect(handle: Handle) -> boolean` — tear down a subscription; idempotent. - `M.subscriberCount() -> number` — number of active composite subscriptions. - `M._reset()` — test-only: clear `lastInputType`. - `M._disconnectAll()` — test-only: tear down every subscription this session. - `M._observeEvent(ev: any)` — internal observer driven by `Zin.tick`. - `M._setAllocator(fn: () -> number)` — internal: wire the shared handle-id allocator. - `M._owns(handle: number) -> boolean` — internal: handle-ownership check for cross-API disconnect. Types: - `Filter = string | { [string]: any } | (any) -> boolean` - `SubOpts = { priority: number?, context: string?, once: boolean? }` - `Handle = number` — composite-handle id, drawn from a shared allocator with `Zin.actions`. ## Usage ```luau local Input = require("@builtin::modules.zinput.input") local h = Input.onBegan(function(io, gpe) if io.kind == "key.down" and io.code == "Space" then print("jumped") end end, { priority = 10 }) Input.disconnect(h) ``` ## Notes - Handler signatures: `fn(io, gpe)` for `onBegan` / `onEnded` / `onChanged`; `fn(text, gpe)` for `onTextInput`. `gpe` is the event's own `consumed_by_ui` marker, stamped as the event arrived against the focus the UI holds over that event's surface: pointer focus for a mouse or touch event, keyboard focus for a key or text event, and never for a pad. - Return `"sink"` from a handler to stop further (lower-priority) handlers receiving the same event. - A single `on*` call installs N underlying `Zin.events.on` subscribers but returns ONE composite handle — `disconnect` tears them all down together. - A composite handle also ends with the context that made it: one a component registers ends when that component instance goes (removed, hot-reloaded, or its entity despawned), one a module body registers at the module's next run. `scopes.list()` names each as a `luau` row under the context it follows. - Handle ids share a namespace with `Zin.actions` (`_setAllocator` wires this at boot), so `Zin.actions.disconnect` accepts handles returned here. - `lastInputType` is updated by the tick observer; text events do not bump it (the preceding key.* event already did).

# map A record-shaped map: `Zin.actions` / `Zin.axes` entries organized per device class (`kbm` | `gamepad` | `touch`) with single-parent `extends`, materialized into an EFFECTIVE map and applied as one binding set at a time. Backs `Zin.map`. An `.inputMap` asset with `.inputBinding` children is the map, and `Zin.scheme` is the live set: several maps are live at once and compose, each declaring the `group` its controls belong to and the groups it `suppresses` while live. `Zin.map.bake(name)` writes the map active here out as an `.inputMap` asset, with synthesis made explicit and editable. `man topics/input` covers the control model. Resolution order per action/axis and device class: 1. the map's own class bindings 2. the `extends` parent's (recursively) 3. synthesis from the `kbm` shape (touch class only) A vector `kbm` binding synthesizes a `touchStick`; a boolean `kbm` binding synthesizes a `touchButton`; a vector-shaped `mouseDelta` synthesizes a `touchDrag`; `scroll` synthesizes a `touchPinch`; an `axis`-kind `kbm` binding and a single-axis `mouseDelta` are left unsynthesized (ambiguous which touch shape to guess). A synthesized `touchButton` carries `priority = 100` — an authored `B.touchButton`'s default priority (50) always outranks synthesis on the touch-controls overlay, so a hand-tuned scheme's own layout hints win over whatever filled a gap automatically. A profile record (actions with `bindings`, axes with `binding`) is accepted anywhere a map record is — its bindings are treated as the `kbm` class. ## Activation and the `<axis>@<class>` convention `activate` flattens every class's bindings into each action/axis's single bindings list and applies it through `Zin.profile`, so any device fires the action. For axes — which evaluate exactly one binding — the primary slot is the first of `kbm` / `touch` / `gamepad` present; any OTHER class's binding registers as a class-suffixed sibling axis (`look` + `look@touch`). A consumer that wants both device values reads both names; a kbm-only world's primary axis (`Zin.axes.value("move")`) behaves identically whether or not a touch class exists. `Zin.profile.ensureActive("default")` delegates to `Zin.map.ensureActive()` when the resolved scheme is the builtin default, so it carries every device class rather than kbm alone. `Zin.map.ensureActive()` / `Zin.map.activate` win regardless of call order (`activate` re-registers the flattened profile under the same name and forces a reactivate). ## Exports - `M.materialize(record: any) -> effective map` — resolve `extends` + synthesize, without activating. - `M.activate(record: any) -> effective map` — materialize + apply as the live binding set (registers/activates a `Zin.profile`). - `M.effective() -> effective map?` — the active map's materialized form. - `M.activeName() -> string?` — the active map's name. - `M.bindingsFor(eff, name, class) -> bindings?` — one action/axis's bindings for one device class. - `M.ensureActive() -> effective map` — keep the current map, else activate `@builtin::inputMaps.default`. - `M.bake(name: string) -> AssetRef` — write the active effective map as a new `.inputMap` instance (`asset.create("inputMap", name, { record = ... })`). - `M.addTouchButton(actionName, buttonOpts, emitKey?) -> binding` — add a touchButton binding to an action's touch class on the live effective map (creating the action if absent) and re-activate. Used by `Zin.touchControls.button`. - `M.removeTouchButton(actionName, binding) -> boolean` — remove a binding added via `addTouchButton` and re-activate; drops the action entry once every class is empty. - `M._reset()` — test-only: clear active-map state. ## Usage ```luau local Zin = require("@builtin::modules.zinput") Zin.map.ensureActive() local eff = Zin.map.effective() print(eff.actions.jump.classes.touch ~= nil) -- synthesized or explicit -- Write the active scheme out as a control-asset map: Zin.map.bake("my_scheme") ```

# observe What became of a device event, and why a live control did not fire. Backs `Zin.observe`. A control can be live, its device can be producing input this frame, and the game can still receive nothing. The input layer works out why every frame — a gate said no, a live map stood the group down, the UI took the pointer, nothing subscribed — and until something reads that decision it is thrown away. This module keeps it. ## The one question ```luau local Zin = require("@builtin::modules.zinput") Zin.observe.whySilent("look") --> { -- name = "look", -- layer = "scheme", -- map = "default", -- reason = "gateRefused", -- means = "the control's own gate answered no. A look control gates on -- the player steering, so a cursor crossing the window reads -- nothing.", -- kind = "axis2", -- subscribers = 1, -- declaredClasses = { "kbm", "gamepad", "touch" }, -- carriedBy = { "scheme" }, -- } ``` One reason, from a closed set, with the particulars behind it. `Zin.observe.reasons()` lists the whole set with a sentence each, so what an answer means is readable from inside the engine rather than only from the source. ## The closed set, nearest cause first | Reason | What it says | |---|---| | `noMapActive` | No input map is activated at all, so there are no controls. | | `unknownControl` | No live map declares a control under that name. | | `groupSuppressed` | A live map stands this control's group down. | | `contextInactive` | The control declares a context that is not on top of the stack. | | `heldOnArrival` | A device the control binds was already held when the control went live. The control reads the hold as held; `pressed` and `released` wait for the next press. | | `gateErrored` | The control's own gate raised. | | `gateRefused` | The control's own gate answered no. | | `noBindingForDevice` | The control declares no binding for any device class this session has. | | `belowDeadzone` | The devices produced a reading and the control's own deadzone zeroed it. | | `noSubscriber` | The control is delivering and nothing subscribed to it. | | `atRest` | The control is live and its devices are not being driven. | | `delivering` | The control is delivering its value to its subscribers. | `atRest` and `unknownControl` are the two an outside reader could never tell apart: a value reader answers `0` for both. This is where they separate. ## Which layer answered Three naming layers coexist: the live maps' controls, and the `Zin.actions` and `Zin.axes` registries a control asset replaced. Their name sets are separate — `toolMove` is a live control and not an action, `move_forward` is an action and not a control — so a name that is live in one reads as silence in the others. Every answer carries `layer` (the one that answered) and `carriedBy` (every layer that has the name at all). ## One control, everything about it ```luau Zin.observe.control("move") --> { -- name = "move", live = true, carriedBy = { "scheme" }, -- entries = { { map = "default", kind = "axis2", subscribers = 1, -- gated = false, classes = { kbm = {...}, gamepad = {...} } } }, -- lastTick = { value = { x = 1, y = 0 }, active = true, delivered = true }, -- why = { reason = "delivering", ... }, -- } ``` ## The frame ```luau Zin.observe.frame() --> { frameId = 41207, window = "one tick of binding dispatch — the most -- recent one", context = "default", maps = {...}, controls = {...}, -- cost = { frameId = 41207, maps = 3, controls = 27, ms = 0.09 } } ``` The window is **one tick** — the most recent one — rather than a sum since anything last looked, and reading takes nothing away from the next reader. Two observers in the same frame both get the truth. `cost.ms` is that one tick's own milliseconds. The same number lands in `profiler.stats("*zin.scheme.advance*")` as `script.zin.scheme.advance`, where it carries the average and the peak across every tick as well. ## Reading it without running a script `/runtime/input` serves the same answers as a file, beside the engine's own account of the frame's device events: ``` /runtime/input the whole document /runtime/input/events the frame's device events, each with `consumed_by_ui` /runtime/input/device pointer lock, UI focus, the session's device classes /runtime/input/mapping this module's account of the tick /runtime/input/controls/<name> one control's entry from that account ``` `input.observe()` returns the same document to a script. Building this layer's half costs a frame of work, so it is built only while something is reading: a read of either surface arms it for a window of frames, and the document's `mappingStatus` says whether the half it carries is `current`, `stale`, `arming` (this read armed it — read again), or `unarmed`. `Zin.observe.armedFrames()` is how many frames that window has left; each frame that passes takes one off it, and the per-frame publish spends the window rather than renewing it, so it runs out once the last reader stops asking. A window that runs out — or that `Zin.observe.arm(false)` closes — drops the report the engine was carrying with it, so a frame nobody observes costs what it cost before anything ever read. `Zin.observe.arm(true)` holds it open for a tool that wants it continuously. ## Which frame an answer covers `Zin.observe.frame()` and `Zin.observe.control()` report the most recent tick of binding dispatch. `Zin.observe.whySilent()` resolves against the devices as they are at the moment of the call, so it answers for a control the tick has never reached and for a name that does not exist. The engine publishes its own half at the end of a frame, after the frame has been drawn and before the frame's events are cleared. A read taken from a script during frame N therefore answers for frame N-1.

# pointer Pointer-lock mutation API. Wraps the internal `__zero_input.requestPointerLock` / `releasePointerLock` primitives and backs `Zin.pointer`. The read side lives on `Zin.state.pointerLocked()`; this module owns the write side plus a convenience read alias. ## Exports - `M.lock()` — request pointer lock (cursor grab + hide). Native takes effect immediately; WASM queues for the next user gesture. - `M.unlock()` — release pointer lock (cursor ungrab + show). - `M.locked() -> boolean` — convenience read alias, identical to `Zin.state.pointerLocked()`. ## Usage ```luau local Pointer = require("@builtin::modules.zinput.pointer") Pointer.lock() if Pointer.locked() then -- pointer captured end Pointer.unlock() ``` ## Notes - Native: `lock()` takes effect immediately. WASM: queued for the next user gesture (browser policy). Both routes share the same underlying FFI mutation; the platform enforces the difference. - Write side and read side are intentionally split: `Zin.state.pointerLocked()` stays alongside the rest of the per-frame snapshot accessors; mutation lives here for discoverability. - All entry points are no-ops when the `__zero_input` FFI is absent (off-host script execution).

# profile Binding profile registry — bundles of named actions / axes / chords that can be loaded from `@builtin::profiles.<name>` Luau modules or saved as JSON under `/zero/profiles/<name>.json`. Activating a profile reconfigures `Zin.actions` / `Zin.axes` / `Zin.chords` in one shot. The active profile is per-client session state held in memory — each session resolves it fresh from the device-appropriate default (or an explicit `activate`), so it is never written to the world source tree. This is the persistence and activation layer for those three registries; `Zin.map.activate` applies a materialized map through it. A scheme is authored as an `.inputMap` of `.inputBinding` controls and goes live through `Zin.scheme` — `man topics/input` covers that path. ## Exports - `M.register(name: string, profile: any) -> (boolean, string?)` — validate + register a profile descriptor. - `M.load(name: string) -> (boolean, any?)` — load + register a profile from `@builtin::profiles.<name>` or `/zero/profiles/<name>.json`. - `M.activate(name: string, opts: ActivateOpts?) -> (boolean, string?)` — apply a profile's sections + set the active name for this session. - `M.current() -> string?` — active profile name for this session, or nil. - `M.get(name: string?) -> any?` — descriptor for the active profile or the named profile. - `M.ensureActive(fallback: string?) -> (boolean, string?)` — bootstrap helper for controllers. - `M.save(name: string, opts: SaveOpts?) -> (boolean, string?)` — capture current Zin.actions / Zin.axes / Zin.chords to JSON. - `M.delete(name: string) -> (boolean, string?)` — remove a user profile's JSON file (built-ins refused). - `M.export(name: string, vfsPath: string) -> (boolean, string?)` — write a serializable JSON snapshot to any VFS path. - `M.import(vfsPath: string, opts: ImportOpts?) -> (boolean, string)` — read + register a profile JSON from any VFS path. - `M.list() -> { string }` — sorted union of built-in + user profile names. - `M.onChange(cb: ChangeCallback) -> number` — subscribe to activation / re-register events; returns a handle. - `M.off(handle: number)` — drop a subscription. - `M._reset()` — test-only: clear in-memory state. Types: - `Profile = { name, description?, actions?, axes?, chords?, intentional_pairs? }` - `ActivateOpts = { reactivate: boolean? }` - `SaveOpts = { description: string?, overwrite: boolean? }` - `ImportOpts = { overrideName: string?, activate: boolean? }` - `ChangeCallback = (string, any) -> ()` ## Usage ```luau local Profile = require("@builtin::modules.zinput.profile") Profile.register("my-bindings", { name = "my-bindings", actions = { jump = { context = "default", bindings = { { kind = "key", code = "Space" } } } }, }) Profile.activate("my-bindings") local h = Profile.onChange(function(name) print("active:", name) end) Profile.off(h) ``` ## Notes - Built-in profiles ship as Luau modules at `@builtin::profiles.<name>` and can include functions (gate, curve). User profiles are pure JSON at `/source/profiles/<name>.json` — function fields are dropped on save. - Activation is no-op when the requested name is already active unless `opts.reactivate = true`. - `save` / `export` VFS writes use the bare `/source/...` mount — the `/zero/...` prefix is read-only and silently drops writes. - The conflicts module's `_setPersistFn` hook is wired here so mark/unmark of intentional pairs persists into the active user profile automatically.

# quiesce The dirty signal `Zin.tick`'s quiescence gate reads. A mutation of the mapping layer's structure outside the tick itself — a map activation, a context change, a virtual-control write, a forced surface class, a new axis over an already-held key — calls `mark()`, and the tick runs a full pass while a mark is pending. A tick with no pending mark and no live input events skips its pass. `mark()` raises the signal, `pending()` answers whether a full pass is owed, and the generation pair (`generation()` / `ack(g)`) keeps a mark raised DURING a full pass pending for the next one, so a mutation racing a tick is never lost. Internal to the zinput package: the mapping-layer modules mark it, the tick drains it.

# rebind Interactive binding-capture sessions. A session listens for the next keyboard or mouse event and produces a binding descriptor; the host can then `apply()` it back into a `Zin.actions` action or a `Zin.axes` axis. Backs `Zin.rebind`. Drives the editor's Input tab rebinding UI and is usable from any Luau code. Modifier-aware (captures `modKey` when Ctrl/Shift/Alt is held) and timeout-bounded (default 30 s). ## Exports - `M.begin(opts: BeginOpts?) -> Session` — start a capture session; subscribes to `Zin.events.on` and returns a session table. - `M.cancelAll()` — cancel every live session. - `M.liveCount() -> number` — number of capturing sessions still active. - `M._advanceTime(dt: number)` — internal: per-frame timeout sweep wired by `Zin.tick`. Types: - `Session = { target, name, slot, mode, status, timeoutSec, result, consume, apply, cancel, conflicts, ... }` - `Owner = { target: string, name: string, slot: any }` - `BeginOpts = { target?, name, slot?, mode?, timeoutSec?, filter?, applyOnCommit?, onCommit?, ... }` ## Usage ```luau local Rebind = require("@builtin::modules.zinput.rebind") local s = Rebind.begin({ target = "action", name = "jump", timeoutSec = 10, applyOnCommit = true, onCommit = function(session) print("captured:", session.result()) end, }) -- The session subscribes itself; just wait for the next tick. if s.status == "capturing" then -- ... end ``` ## Notes - Press Escape during a capture to cancel; a pure modifier press is ignored (the session waits for the base key). - A session that captures with Ctrl/Shift/Alt held returns a `modKey` binding rather than a plain `key` binding. - `session.conflicts()` is self-filtered — rebinding an action to a key it already owns reports no conflict. - Hot-reload safety: the live-sessions list survives require-cache reload; the `_advanceTime` wiring from `zinput/init.luau` keeps timeouts firing across re-requires. - `applyOnCommit = true` calls `apply()` automatically after commit; errors during apply are still visible via `result()` and `conflicts()`.

# scheme The live set of activated input maps, and the per-frame dispatch that turns their bindings into the events a controller subscribed to. Backs `Zin.scheme`. ## Nothing is live until something activates a map A controller holds an `inputMap` ref, activates it when it takes control, and releases it when it gives control up. The live binding set is exactly the union of what current holders asked for, so an empty world has an empty input surface and an empty screen — no scheme is active by default, and nothing appears on a phone that no component consumes. For a component that drives the thing it lives on, taking control and being awake are the same moment, so `awake` / `onDestroy` are the hooks. For anything a player enters and leaves — a car, a turret, a menu — they are not: the car is still there after the player gets out, so the map goes live on entry and stands down on exit. ```luau public = { inputMap = Field.assetRef("inputMap", "@builtin::inputMaps.default", NoSync, "The controls this component reads."), speed = Field.number(5, NoSync, "World units per second at full deflection."), jumps = Field.number(0, NoSync, "How many times the jump control was pressed."), } local controls function awake() controls = public.inputMap:activate() controls.move:onInput(function(v, dt, active) if not active then return end local p = public.entity.position local step = public.speed * dt public.entity.position = { p.x + v.x * step, p.y, p.z - v.y * step } end) controls.jump:onPressed(function() public.jumps += 1 end) end function onDestroy() public.inputMap:deactivate(controls) end ``` What `activate` returned is this holder's **claim** on the map. Keep it and hand it back: releasing the claim disconnects the subscriptions made through it, and the map stays live for whoever else holds it. A claim also ends with the context that opened it. A component's claim is released when that component instance goes, whether or not it writes an `onDestroy`: the component is removed from its entity, the entity despawns, or the component hot-reloads (its new life's `awake` activates again). A claim a module body opens ends at the module's next run. `scopes.list()` names each standing claim as a `luau` row under the context it follows, and `scopes.release(tag)` ends it with everything else that context holds. ## Several maps compose by all being live The player's surface is the union of every live map, which is what a game needs: picking up a gun activates a weapon map and Fire appears beside the movement stick; dropping it takes away Fire and nothing else. Two controllers that each activate a map with a movement stick produce two sticks — visible, attributable to the second controller, and the importer's to resolve. Two components activating the *same* map read one set of controls, each through its own claim. A claim's release disconnects what that holder subscribed and leaves the other holders' handlers attached; the map leaves the live set when its last claim goes. `Zin.scheme.live()` reports each live map's `holders` — how many claims are still standing on it — and `heldBy`, which says who each of them is: `kind` (`"component"` or `"execute"`), `entity`, `source` as the `chunk:line` the activation was opened at, and the `label` the caller passed to `activate("weapon-swap")`. ## An activation reads the map's children as they stand now Every `activate` re-reads the map's `<name>.inputBinding/` children, so a control added, edited or removed since the map came up reaches the running set on the next activation. The controls are edited in place, so it reaches the holders already standing on the map too: their handles keep working and every subscription they made carries on across the edit. ## A map can stand another one down Composition cannot say "not while this is happening". A map declares the `group` its controls belong to and the groups it `suppresses` while live: ```luau -- driving.inputMap/init.luau return { group = "vehicle", suppresses = { "player" } } ``` Every live map in a suppressed group reads nothing and draws nothing for as long as the suppressor is live. It is **not** released: it keeps its holders, its handles and every subscription, and resumes untouched when the suppressor goes. So a car stands down walking without ever finding, owning or releasing the walk map — and a menu stands down the whole game with one declaration. A map that declares no `group` belongs to one named after itself, so it collides with nothing and can still be named by something that wants to stand it down. Declaring neither field composes with everything. The drop frame runs on the tick a map stands down, so a stick held at that moment reports its neutral value once and whatever it drove stops rather than sticking. ## Dispatch `_advance(dt)` evaluates every live binding once per tick, across every device class it carries — a tablet with a keyboard attached and a desktop with a pad plugged in both answer to whichever the player actually used, rather than to a nominated primary. | Event | Fires | Cadence | |---|---|---| | `input` | Once while the binding is active with `(value, dt, true)`, and once more on the frame it goes inactive with the neutral value and `false` | Per engine frame | | `pressed` / `released` | A button's edges | Per engine frame | | `changed` | When the value differs from the previous tick | Per tick | `input` firing on the drop frame is what lets one handler both start and stop the motion it drives, without a second subscription to notice the release. A frame carries more than one tick whenever a host calls `Zin.tick` beside the tick the engine already runs, or fast-forwards several ticks to converge smoothing. Evaluation follows the tick, so the smoothing lands and `changed` reports each step of it. `input`, `pressed` and `released` are stamped with the engine frame they were reported for, so the frame carries one of each however many ticks ran in it. Both edge sources hold this frame's edge for as long as the frame lasts: the input snapshot's `pressed` flag, and `Zin.virtual`'s previous-frame button table. That is what a second reporting pass reads as another press. `Zin.scheme.fired`'s `count` is the number of engine frames a control was active since it last cleared, so a button held across two frames reads 2 for one press. The `pressed` / `released` subscriptions are what count edges. A binding that declares a `context` is live only while that context is on top, the same activity rule actions apply. An `axis1` / `axis2` control's own `deadzone`, `curve`, `invert` and `smoothing` are applied here, in that order, to the reading its classes produced — after `as` / `unitsPerSecond` / `scale` have brought every class into the control's unit, so one deadzone written in that unit covers the stick, the mouse and the finger together. A deadzone is per value on an `axis1` and **radial** on an `axis2`. The shaping maths is `Zin.utils`', shared with the axis registry. `smoothing` is the one piece of the four that is stateful: the value is held per control across frames and approaches whatever the devices report next over the declared time constant. A control that leaves its context, whose group stands down, or whose gate closes has a neutral target, so it drains rather than cutting — and reports its drop frame when it arrives. ## Validation happens before anything registers Activation reads every child binding, collects every fault across all of them, and raises once with the lot. A map with three broken bindings names all three rather than one per attempt, and a map that fails validation registers nothing — a half-live map is worse to debug than one that refused to come up. ## Exports - `M.activate(mapRef, label?) -> { [name]: Handle }` — activate a map, return its handles. `label` names this activation in `M.live()`. - `M.deactivate(mapRef) -> boolean` — release a claim on a map. - `M.live() -> { { guid, name, group, suppresses, suppressedBy, holders, heldBy, bindings } }` — every live map in activation order. What tells an author why two sticks are on screen, or why the controls they activated answer to nothing, or who is holding the map standing them down. - `M.bindings() -> { { map, group, name, label, kind, context, suppressedBy, subscribers, record } }` — every live binding in activation order. The touch overlay builds from this, so what is on screen is exactly what some awake component asked for and nothing is standing down. - `M.suppressed() -> { [group]: mapName }` — which groups are standing down and what put each one down. - `M.has(name) -> boolean` — whether a named control is live anywhere. - `M._advance(dt)` — one tick of dispatch; wired into `Zin.tick`. - `M._childBindings(mapRef) -> { ref }` — the map's `.inputBinding` children, in name order. - `M._reset()` — test-only: drop every live map without firing anything. Types: - `Handle = { onInput, onPressed, onReleased, onChanged, label, kind }` — a thin view over the binding asset's own event facade, so a subscription made through a handle is the same one `ref.events.input:connect` would make and ends the same way.

# state Synchronous per-frame input state. Thin wrapper over the internal `__zero_input.snapshot()` FFI; backs `Zin.state`. Pointer-lock mutations live on `Zin.pointer`; the read-side `pointerLocked()` query lives here with the rest of the snapshot accessors. Held-time and synthetic-repeat state is owned by this module and updated via `_observeEvent` from the `Zin.tick` coordinator. ## Exports - `M.get() -> Snapshot` — full per-frame snapshot table; empty when the FFI is unavailable. - `M.keyDown(key: string) -> boolean` — held this frame. - `M.keyPressed(key: string) -> boolean` — edge-pressed this frame. - `M.keyReleased(key: string) -> boolean` — edge-released this frame. - `M.mousePosition() -> (number, number)` — current mouse `(x, y)`. - `M.mouseDelta() -> (number, number)` — `(dx, dy)` since last frame. - `M.scrollDelta() -> number` — wheel delta this frame. - `M.mouseButtonDown(idx: number?) -> boolean` — held; default idx = 0. - `M.mouseButtonPressed(idx: number?) -> boolean` — edge-pressed. - `M.mouseButtonReleased(idx: number?) -> boolean` — edge-released. - `M.pointerLocked() -> boolean` — pointer-lock query (writes are on `Zin.pointer`). - `M.uiWantsPointer() -> boolean` — `true` when the UI layer claims pointer focus. - `M.uiTookPress() -> boolean?`: `true` while a UI widget sensing a click or a drag holds the pointer press in progress; `false` with no press held and for a press on empty space; `nil` from the moment a press arrives until a UI pass has decided it. - `M.setRepeatDefaults(opts: RepeatOpts?)` — set default delay / period for synthetic repeat. - `M.getRepeatDefaults() -> RepeatDefaults` — read the active synthetic-repeat defaults. - `M.keyHeldTime(code: string) -> number?` — seconds since the key was pressed (or nil). - `M.mouseButtonHeldTime(idx: number?) -> number?` — seconds since a mouse button was pressed. - `M.keyRepeatFired(code: string, opts: RepeatOpts?) -> boolean` — should a synthetic key-repeat fire this frame? - `M._observeEvent(ev: any)` — internal: per-event observer, wired from the tick coordinator. - `M._reset()` — test-only: clear held-time and synthetic-repeat state. Types: - `Snapshot = { [string]: any }` - `RepeatOpts = { delay: number?, period: number? }` - `RepeatDefaults = { delay: number, period: number }` ## Usage ```luau local State = require("@builtin::modules.zinput.state") -- Rebind-capture-style probe: how long has a key been held, and is a -- synthetic repeat due this frame? local heldFor = State.keyHeldTime("Space") if heldFor and State.keyRepeatFired("Space", { delay = 0.4, period = 0.08 }) then -- charge-attack tick, key-repeat menu navigation, etc. end ``` ## Notes - Mouse-button indices are 0-based and follow `InputResource.mouse_buttons[]` (0=left, 1=right, 2=middle). Winit's `0=L, 1=M, 2=R` is converted in Rust before reaching Luau. - `mousePosition` / `mouseDelta` return two numbers, not a table. - Held-time / repeat state is updated by the `Zin.tick` coordinator via `_observeEvent` — without a tick, those queries return `nil` / `false`. - `keyRepeatFired` advances state on every call — call once per frame per consumer. - All entry points are no-ops or return zero values when `__zero_input` is missing (off-host execution). - Gameplay subscribes to controls through an activated `.inputMap`; this module is the raw snapshot layer those bindings evaluate against, used directly by rebind capture, the emulation floor, and dev tooling. Polling it from a world makes that world keyboard-only and draws the `engine-raw-key-poll` diagnostic at author time.

# surface Active input-surface classification. Answers "what device class is the player using right now" — `"touch"` or `"kbm"` — and notifies on change; backs `Zin.surface`. Virtual touch controls mount whenever the surface is `"touch"`, in edit and play alike. ## The frame rule Resolution runs once per engine frame from the `Zin.tick` pipeline: a per-event observer collects which device classes produced events this frame, and the frame resolver applies one rule — **touch wins a frame that contains any touch event**. The primary touch contact also drives the mouse path (a projected `mouse.down`/`move`/`up` in the same frame), so classifying by the latest single event would flip to `kbm` on every tap; the frame rule keeps projection-generated mouse events from masking the touch that caused them. ## Capability default Before any input arrives, the class defaults to `"touch"` on sessions with a touch source (`touch_capable` — latched by the first contact or declared at boot by Android / the web client) and `"kbm"` otherwise, so touch-first devices present touch controls from the first frame. ## Exports - `M.current() -> string` — the active surface class, `"touch"` or `"kbm"`. - `M.onChange(fn: (string, string?) -> ()) -> number` — subscribe to class flips; `fn(now, prev)` where `prev` is the previously reported class (the first-tick capability default when no event had resolved yet). Returns a handle. - `M.off(handle: number) -> boolean` — unsubscribe an `onChange` handle. - `M._beginFrame()` — internal: clear this frame's per-class flags; wired by `Zin.tick`. - `M._observeEvent(ev: any)` — internal: per-event observer; wired by `Zin.tick`. - `M._resolveFrame()` — internal: resolve this frame's class and fire `onChange` on a flip; wired by `Zin.tick`. - `M._reset()` — test-only: clear resolution state and subscriptions. Types: - `SurfaceClass = "touch" | "kbm"` ## Usage ```luau local Surface = require("@builtin::modules.zinput.surface") if Surface.current() == "touch" then showTouchOverlay() end Surface.onChange(function(now, prev) print("surface flipped to", now) end) ``` ## Notes - `onChange` fires from the `Zin.tick` pipeline on the frame the class flips; without a tick, resolution never advances and `current()` keeps returning the capability default. - The change signal compares against the last reported class, whose initial value is the capability default captured on the first tick of the session — a phone's first contact confirms the default silently, while a desktop touchscreen's first contact reports kbm→touch. - Handler errors during `onChange` dispatch are caught and logged, not propagated.

# test Test-input helpers that simulate keyboard / mouse / scroll events and yield one engine frame so the queued events drain into the next snapshot. Backs `Zin.test`. Helpers do NOT call `Zin.tick()` — explicit dispatch control is left to the caller. ## Exports - `M.runFrame()` — yield one engine frame so simulated events drain. - `M.pressKey(code: string)` — hold the key DOWN and leave it held. A second `pressKey` on a held key produces no new press edge — pair every `pressKey` with a `releaseKey`, or use `tapKey` for a full press. - `M.releaseKey(code: string)` — simulate a key release. - `M.tapKey(code: string, duration: number?)` — press + optional hold + release. The helper for "the player taps a key". - `M.pressMouse(button: (number | string)?)` — simulate a mouse button press (default 0 = left). The index and the name (`"left"`/`"right"`/`"middle"`) reach the same button. - `M.releaseMouse(button: (number | string)?)` — simulate a mouse button release. - `M.clickMouse(button: (number | string)?, x: number?, y: number?, duration: number?)` — full click, optionally moving the cursor to `(x, y)` first and holding for `duration` seconds. - `M.moveMouse(x: number, y: number)` — set absolute cursor position. - `M.moveMouseBy(dx: number, dy: number, steps: number?)` — move the pointer by a relative motion. The motion lands in this frame's `mouse_delta` and the position advances by the same amount, so the same `(dx, dy)` repeated keeps producing look movement. `steps` spreads it over that many frames, each carrying its share; 1 when omitted. - `M.scroll(dy: number)` — simulate a wheel scroll. ## Usage ```luau local Test = require("@builtin::modules.zinput.test") Test.tapKey("KeyM") -- press + release Zin.tick(1 / 60) -- explicit dispatch assert(#Zin.scheme.fired() > 0) Test.pressKey("Space") -- key goes DOWN and stays held... Zin.tick(1 / 60) Test.releaseKey("Space") -- ...until released Test.clickMouse(0, 100, 200) ``` ## Notes - Each helper queues the simulated event and yields one frame (`task.wait(0)`) so the snapshot reflects the input on return. - Simulated key state persists like real key state: after `pressKey` the key stays held until `releaseKey`, and only the release re-arms the next press edge. `tapKey` is the edge-per-call helper. - Helpers do NOT call `Zin.tick()` — a test that relies on a control's handlers, or on `Zin.input.on*` / `Zin.actions.bind`, must run a tick itself. `Zin.scheme.fired()` is what turns a simulated input into an assertion: it reports which controls fired since it last read, and from which device class. - Mouse button index is 0-based (0=left, 1=right, 2=middle) following the `InputResource.mouse_buttons` convention. - All helpers are no-ops when the `__zero_input.simulate*` FFI is missing (off-host execution).

# text Requiring this module raises a fatal error: `zinput.text` is not available in this build. ## Exports None — the module raises on `require`.

# touch Per-finger touch contacts. Thin wrapper over the `touches` array of the internal `__zero_input.snapshot()` FFI plus pre-baked `touch.*` event listeners; backs `Zin.touch`. ## Exports - `M.slots() -> { TouchPoint }` — all active contacts this frame, in begin order. - `M.count() -> number` — number of active contacts this frame. - `M.byId(id: number) -> TouchPoint?` — look up an active contact by finger id. - `M.primary() -> TouchPoint?` — the primary contact (slot 0), if a finger is down. - `M.capable() -> boolean` — whether the session has (or has declared) a touch source. - `M.onBegan(fn, opts?) -> handle` — subscribe to `touch.down` events. - `M.onMoved(fn, opts?) -> handle` — subscribe to `touch.move` events. - `M.onEnded(fn, opts?) -> handle` — subscribe to `touch.up` events. - `M.onCancelled(fn, opts?) -> handle` — subscribe to `touch.cancel` events. - `M.off(handle)` — unsubscribe a handle returned by any `on*` function. Types: - `TouchPoint = { id: number, slot: number, x: number, y: number, dx: number, dy: number, pressure: number, phase: string, pointer: boolean }` ## Contact record fields | Field | Meaning | |---|---| | `id` | The platform's stable finger id for the contact. | | `slot` | Lowest index free when the contact began; 0 = primary (also drives the mouse path). | | `x`, `y` | Screen position. | | `dx`, `dy` | This frame's accumulated delta. | | `pressure` | Normalized 0..1 (1 when the platform reports none). | | `phase` | `"began"` \| `"moved"` \| `"stationary"` \| `"ended"` \| `"cancelled"` (ended/cancelled contacts survive exactly one frame). | | `pointer` | Whether the contact drives the UI's pointer, so a widget under it can take its press. The primary contact does, unless it began on a region an on-screen control holds (`input.setTouchClaims`) or is a simulated contact for the game alone. | ## Usage ```luau local Touch = require("@builtin::modules.zinput.touch") for _, t in ipairs(Touch.slots()) do print(t.slot, t.x, t.y) end local h = Touch.onBegan(function(ev, gpe) print(ev.id, ev.x, ev.y) end) ``` ## Notes - `onBegan` / `onMoved` / `onEnded` / `onCancelled` are pre-baked kind filters over `Zin.events.on` — handlers dispatch from the `Zin.tick` pipeline and receive `(ev, gpe)` where `gpe` is the UI-focus flag at fire time. Return `"sink"` to stop lower-priority handlers from seeing the same event. - All entry points return empty / falsy values when `__zero_input` is missing (off-host execution).

# touchControls On-screen touch overlay: a renderer + worker, not an event-driven widget net. The worker reads raw touches (`Zin.touch.slots()`) and routes them into zone geometry derived from the live bindings, writing `Zin.virtual` (stick/button/drag). `Zin.tick` runs the worker early — after `Virtual._beginFrame()` clears the previous tick's drag deltas and before the binding evaluators read `Zin.virtual` — so the touch binding kinds consume those values on the SAME tick they're written. The renderer (a `canvas` screen declaring `pointerEvents = "none"`) only draws and takes no pointer, so every widget beneath it, in any screen at any layer, still receives the presses that land on it. Backs `Zin.touchControls`. ## Who a contact belongs to - A contact that begins on a drawn button, the fan or an open sheet entry is that control's alone. The overlay states those circles to the input layer with `input.setTouchClaims` (in the window pixels contacts arrive in), and a contact beginning inside one drives no pointer: no widget beneath the button is pressed by it, and no mouse button reads held. - A contact that begins anywhere else drives the pointer as the primary contact always does, and the UI decides whether a widget takes its press. When one does, the contact is the widget's: on the tick after it began, the stick or look zone that took it lets it go before it has moved anything. - Everything left falls to the stick and look zones below. ## Coordinate space Touch contacts (`Zin.touch.slots()` — `t.x`/`t.y`/`t.dx`/`t.dy`) carry PHYSICAL framebuffer pixels — `InputResource` keeps the raw platform coordinates unconverted, the same space `getViewportSize()` reports. Every widget geometry computation — button/stick positions, the canvas root's `style.width/height` — lives in `ui.screenSize()`'s LOGICAL space (the space `ui.registerScreen` / `ui.getLayoutInfo` use), which differs from the physical space whenever the display's `pixels_per_point ~= 1` (HiDPI). An internal `logicalScale` helper computes the `screenSize / viewportSize` ratio once per tick, and every touch coordinate this module reads is scaled by it before use. ## Safe area Every control keeps inside the part of the overlay no system bar, display cutout or on-screen keyboard covers. `ui.safeArea()` states that part of the picture the overlay's screen lays out in (the scene viewport's, at `ui.screenSize()`), and the overlay takes it into its own space, which leaves a safe rect `L`/`T` in from the left and top edges, `SW` x `SH` in size (the whole picture where the picture lies inside the window's safe area, as a Scene panel does). The zones, the button column and the stick all lie inside it, a contact beginning outside it starts none of them, and `layout().safe` reports it. ## Size on the glass Every radius, inset and gap is in the points `ui.screenSize()` reports. On a phone or a tablet a point covers at least the display's density (`ui.displayScale()`), so the controls keep one physical size on every phone and in both orientations: a 40 point "small" button is 80 dp across, past the 48 dp touch target. `layout()` reports the radii in points; multiply by the pixels one of the overlay's points covers for their size on the glass: the width `ui.getLayoutInfo("zin_touch_controls_canvas")` gives its canvas, over `layout().safe.width`, times `ui.pixelRatio()`. Button labels are canvas text sized from the button's radius, so the user's text scale leaves them inside their circles. ## Zone geometry (fractions of the safe rect, `SW`/`SH`) - **stick** - activation region `x < L + 0.4*SW and y > T + 0.4*SH` (left 40%, bottom 60%). A floating stick: the base spawns at the touch's start point, the thumb clamps to a 96px radius, and the vector fed to `Zin.virtual.setStick` is `offset / 96` with `y` screen-down positive (matching `setStick`'s documented convention). - **buttons** — one circle per `touchButton` binding among the LIVE bindings (`Zin.scheme.bindings()` — what awake components asked for, so every button corresponds to a control some world actually consumes), budgeted into a two-column band along the safe rect's right edge, between 45% of its height and its bottom edge less the inset. Buttons sort by `(priority, id)` - the touchButton's `priority` option, authored default 50, synthesized default 100 — with same-`group` buttons kept adjacent, then fill the two columns growing inward from the bottom-right corner. Each circle is the radius ITS OWN `size` option names (`small` 40px, `medium` 56px, `large` 72px), so a scheme mixing a `large` action button with a `small` pause pip draws them at 72 and 40 whatever else is live; the largest of those radii is the slot pitch and the row budget the column packs on, so the set decides where a button sits and the button's own declaration decides how big it is. More than 4 authored buttons walk every button one step down its own size, which `layout()` reports as `appliedSize`. Anything past the two-column budget doesn't render individually — the last slot becomes a `...` fan button; tapping it opens a rows-of-3 grid sheet holding the overflow (same tap/hold behavior as a regular button), and tapping the fan again, or any layout-invalidating context/map change, closes it. - **drag** - everything else in the safe rect at `x >= L + 0.4*SW` (accumulates into `Zin.virtual.addDrag` every tick from the contact's per-frame delta). - the remaining top-left quadrant (`x < L + 0.4*SW and y <= T + 0.4*SH`) is unclaimed - free for other UI. A control is drawn only when it is live AND subscribed: a button offered for a control nothing listens to is an offer that cannot be kept, so the layout tracks `Zin.scheme.subscriberEpoch()` alongside `Zin.scheme.generation()`. Only bindings whose `context` matches the current input context (`Zin.context.current()`) contribute controls, so a vehicle-context Brake button neither renders nor claims touches while the default context is on top. The layout rebuilds when the live set, the subscriber count, the context, the screen size or the safe area changes. A record-shaped map applied through `Zin.map.activate` contributes its touch classes too. A control whose name is already live as an asset is skipped, so a world carrying both never draws the same control twice under two ids. A contact is assigned to a region on its `began` phase only (a contact-id -> assignment map) and released on `ended` / `cancelled` / vanishing from `Zin.touch.slots()`. Button circle hit-tests (visible buttons, the fan, the open sheet's entries) take precedence over the stick/drag zone checks — a button is a precise target and wins wherever it lands, including inside a zone (the open sheet grows leftward and can reach the stick zone on a narrow screen). A contact claimed by the stick or a button never also feeds the drag zone (a contact is assigned to exactly one region), so its projected-mouse / `touchDrag` state never competes with a look/aim consumer reading `Zin.virtual.drag` — no extra suppression is needed beyond the region assignment itself. A pinch and the drag region share the same space, so the two are arbitrated once per tick. The contacts the stick and the buttons hold are published to `Zin.gestures`, which forms its two-finger pair out of what is left; while the active map declares a `touchPinch` control and that pair is down, the drag region reports nothing. A pinch made over the look surface therefore reaches the pinch control alone, a thumb resting on the movement stick is no part of a pinch so the other thumb keeps looking, and lifting one finger from a pinch drags again. ## Rendering One screen (`"zin_touch_controls"`, layer 200) whose root is a single transparent `canvas` sized to the safe rect, taking no pointer. The screen lays out inside the safe area, so the canvas starts at the rect's corner and every command is drawn from there. Commands rebuild only when the draw state actually changed (a dirty flag) — buttons are always drawn while mounted; the stick draws only while a stick contact is live. ## Auto-mount Every `_advance()` checks `Zin.surface.current()` — `"touch"` registers (lazily, once) and shows the screen; anything else hides it. Visibility is purely the surface class, in edit and play alike. `M._forceMount(true)` bypasses the surface gate for headless testing. Touch routing itself is unconditional: it runs every tick regardless of mount state, so a forced or real touch always drives `Zin.virtual` even before the overlay is visible. ## Adding a control while the world runs The overlay draws a button for a control that is live and subscribed, so adding one at runtime is adding a control asset, activating it, and subscribing to it — the three steps a component takes in `awake`, in one call: ```luau local h = Zin.touchControls.addControl({ name = "cast", label = "Cast", kbm = Zin.bindings.key("KeyF"), gamepad = Zin.bindings.padButton("north"), onPressed = function() castSpell() end, }) Zin.touchControls.removeControl(h) ``` The control becomes a real `<name>.inputMap/<name>.inputBinding/` under `/source/runtimeControls/`, so it is inspectable, rebindable and publishable like any other, and its name is its id in `Zin.scheme.bindings()` / `Zin.scheme.fired()`. `removeControl` releases it — off the screen, out of the live set, every subscription dropped — and leaves the asset, so re-adding the same name reuses it and its guid. `M.button(opts)` is the same idea against a record-shaped map applied through `Zin.map.activate`, in two flavors: - `{ action = "jump" }` attaches an extra touchButton binding to an existing action on the active map. - `{ emit = "KeyF", label = "Cast" }` registers an overlay-only button: a synthetic `emit:KeyF` action carrying both the kbm key binding and the touchButton, so the emulation floor drives `KeyF` through the same binding/emulation path every other control uses. Both return a handle for `M.removeButton(handle)`. ## Exports - `M.addControl(opts: ControlOpts) -> number` / `M.removeControl(handle) -> boolean` — add or release a control while the world runs. - `M.controls() -> { { handle, name, path } }` — every control `addControl` currently holds, in the order they were added. - `M.button(opts) -> number` / `M.removeButton(handle) -> boolean` — the button API described above. - `M.claimed() -> { number }` — the contact ids currently claimed by the stick, a button, or the drag zone. - `M.primaryClaimed() -> boolean` — whether an on-screen control owns the primary contact. `Zin.bindings` consults this so a thumb on the stick or the look area does not also fire whatever the world bound to left-click. - `M.layout() -> { buttons, fan?, stick?, drag?, pinch?, width, height, safe }` - the current control layout (a copy): `buttons` is the budgeted, VISIBLE stack in draw order, each entry `{ id, label, actionName, priority, size, appliedSize, group, cx, cy, radius }` in `ui.screenSize()` space — `size` is the step the binding declared and `appliedSize` the one `radius` came from, which differ only where a rich scheme's step-down moved a button one size down; `fan` is nil unless the button set exceeded the two-column budget, else `{ open, cx, cy, radius, buttons }` — `open` is whether the overflow sheet is expanded, `buttons` the overflowed entries at their sheet positions (tappable only while `open`); `stick` / `drag` name the axis + virtual zone each region feeds, and `pinch` the axis the two-finger recognizer feeds; `safe` is the safe rect `{ x, y, width, height }` every control keeps inside. Backs custom control-placement UI and headless tests that aim simulated touches at a button's (or the fan's) center. - `M._advance()` — internal: one tick (touch routing, layout, auto-mount, repaint). Wired into `Zin.tick`, before `Zin.emulation._advance()`. - `M._forceMount(on: boolean)` — test-only: force mounting regardless of `Zin.surface.current()`. - `M._setViewportOverride(w?, h?)` — test-only: override the logical screen size the layout budget/fan math reads, without resizing the real window. Pass nil/nil to clear. - `M._reset()` — test-only: unmount, clear routing/layout state, drop buttons, release every runtime control, close the fan, and clear the viewport override.

# utils Pure helpers for the `Zin` input library. Mouse-button name↔index conversion, key-code normalization, held-modifier matching against a frame snapshot, and the shaping a reading passes through on its way to a consumer. No FFI; safe to call from any context. Stateless. ## Exports - `M.buttonName(idx: number) -> string?` — convert a 0-based mouse button index to its name. - `M.buttonIndex(name: string) -> number?` — convert a mouse button name to its 0-based index. - `M.normalizeKey(code: string) -> string` — canonicalize a key code: a single ASCII letter becomes its `Key<L>` code, a single digit its `Digit<N>` code; multi-character codes pass through. - `M.matchModifiers(snapshot: Snapshot, mods: Modifiers) -> boolean` — test whether the snapshot's held keys match the requested modifier set. - `M.applyCurve(curve, x: number) -> number` — apply a response curve to a reading. - `M.applyDeadzoneScalar(x: number, deadzone: number?) -> number` — 0 below the threshold, the reading at or above it. - `M.applyDeadzoneVector(v: Vector2, deadzone: number?) -> Vector2` — the same, measured **radially** on the magnitude of the pair. - `M.shapeScalar(x: number, deadzone: number?, curve, invert: boolean?) -> number` — deadzone, then curve, then inversion. - `M.shapeVector(v: Vector2, deadzone: number?, curve, invert: boolean?) -> Vector2` — the same for a pair. - `M.smoothToward(current: number, target: number, dt: number, tau: number) -> number` — one step of an exponential approach with time constant `tau`. A `curve` is `"linear"`, `"quadratic"`, `"cubic"`, a function of the reading, or `nil` for linear. Types: - `Snapshot = { [string]: any }` — the raw frame-snapshot table returned by `Zin.state.get()`. - `Modifiers = { ctrl: boolean?, shift: boolean?, alt: boolean? }` — modifier subset to require in `matchModifiers`. - `Vector2 = { x: number, y: number }` — a two-component reading. ## Shaping The order is deadzone, curve, invert, then the approach toward the shaped target. A scalar takes its deadzone per value; a pair takes it radially, so a diagonal is not clipped into a cross by two independent thresholds. `"quadratic"` squares while keeping the sign, so a half-pushed stick reads a quarter in the direction it was pushed. A curve function that raises, or answers with anything other than a number, leaves the reading as it was. This is the one implementation of that shaping: `Zin.axes` reads it for a registered axis and `Zin.scheme` for an `axis1` / `axis2` control, so an axis and a control declaring the same numbers read the same. ## Usage ```luau local Utils = require("@builtin::modules.zinput.utils") local name = Utils.buttonName(0) -- "left" local idx = Utils.buttonIndex("right") -- 1 local key = Utils.normalizeKey("w") -- "KeyW" local hit = Utils.matchModifiers(snap, { ctrl = true, shift = false }) ``` ## Notes - Pure functions — no state, no side effects. - Mouse-button indexing is 0-based and matches `Zin.state.mouseButtonDown(idx)` (0=left, 1=right, 2=middle). - `matchModifiers` ignores fields set to `nil` in `mods` — only `true`/`false` are constraints. - `normalizeKey` rejects any other single character: no bound key code is one character long, so `"?"` raises rather than resolving to a phantom key nothing consumes.

# virtual Per-tick virtual-control values. On-screen controls (and tests) write stick vectors, button states, and drag deltas here; the `touchStick` / `touchButton` / `touchDrag` / `touchPinch` binding kinds in `Zin.bindings` read them. Backs `Zin.virtual`. Three families, each keyed by the control's binding identity: - **Sticks** — zone string (`"left"`, `"right"`, ...). A vector clamped to `[-1, 1]` per component, persisting until set again or reset. - **Buttons** — id string: a `touchButton`'s `id` (stamped with the control's name when its map activates), else its `label`, else its `zone`. A held boolean; `buttonPressed` / `buttonReleased` derive edges from the previous frame boundary. - **Drags** — zone string. A delta vector that accumulates within a tick (`addDrag` sums repeated calls) and clears at the next frame boundary — the same per-frame-delta semantics as `Zin.state.mouseDelta()`. ## Edge-at-frame-boundary semantics `_beginFrame()` shifts `_buttons` into `_buttonsPrev` and clears drag deltas. It runs once per engine frame from the `Zin.tick` coordinator's gated begin block, before any binding evals happen. On-screen overlay code (script phase) calls `setButton` earlier in the same frame it wants the press recognized; `buttonPressed` reads true starting the frame `_beginFrame` next observes the transition — matching how a real key's press edge surfaces on the frame after the OS event, not the same frame the write happened. ## Exports - `M.setStick(zone: string, x: number, y: number)` — set a stick's vector (clamped). - `M.stick(zone: string) -> (number, number)` — read a stick's `(x, y)`; `(0, 0)` when unset. - `M.setButton(id: string, held: boolean)` — set a button's held state. - `M.button(id: string) -> boolean` — held state. - `M.buttonPressed(id: string) -> boolean` — press edge this frame. - `M.buttonReleased(id: string) -> boolean` — release edge this frame. - `M.addDrag(zone: string, dx: number, dy: number)` — accumulate a drag delta. - `M.drag(zone: string) -> (number, number)` — read a zone's accumulated `(dx, dy)` this frame. - `M._beginFrame()` — internal: frame-boundary edge shift + drag clear, called by `Zin.tick`. - `M._reset()` — test-only: clear all virtual state. ## Usage ```luau local Virtual = require("@builtin::modules.zinput.virtual") Virtual.setStick("left", 0.4, -0.9) local x, y = Virtual.stick("left") Virtual.setButton("Jump", true) if Virtual.buttonPressed("Jump") then -- fires once, on the frame after the set end ```

# Component (asset type) A component is a reusable behavior + data unit attached to an entity. The component file declares public fields, methods, and lifecycle callbacks; the engine instantiates one per attachment and drives its hooks every frame. Components are the primary unit of gameplay code — movement, AI, animations, UI panels, network sync, and per-entity state all live here. ## When to use one - You need per-entity state that survives across frames. - You need per-entity behavior driven by engine lifecycle hooks (`start`, `update`, `destroy`). - You want to expose configurable fields to designers / `entity.spawn` callers / scenes without code changes. If you need a global service that outlives any entity, use a `.service` instead. If you need a stateless pure-function library, use a `.module`. ## Where it lives - Source: `/zero/source/.../<Name>.component/` - Identity: `<Name>` (the `.component` suffix strips from the identity, but the folder retains the suffix on disk). - Folder shape: - `init.luau` (or `init.lua`) — declares the component. **Required.** - `README.md` — instance-level documentation. **Required.** - `.metadata` — agent-editable tags + free-form fields. **Required.** The structural contract is enforced by `asset.validate` against this type's `type.yaml`. ## How to create one Always start with the scaffold — it guarantees the folder shape matches `type.yaml` from the moment it's on disk: ```luau asset.create("component", "<Name>") -- Creates: /zero/source/<Name>.component/ -- init.luau (canonical declare + public block + hooks stubbed) -- README.md (instance README template) ``` After scaffolding, edit `init.luau` to fill in the actual fields and behaviour. The component registers as soon as the file is written — hot-reload is automatic; no engine restart required. ## How it operates 1. **Registration.** Writing `init.luau` into a `.component/` folder indexes the asset, mints a guid (in the `.meta` sidecar), and surfaces the type to the engine's component registry. Same-frame visible to `entity.component.add`. 2. **Attachment.** `entity(id).component.add(name, data)` (or the batch form `tools.use("entityOps", "addComponents", targets, { [name] = data })`) attaches an instance. The `data` table's fields override the component's declared defaults; omitted fields take the declared default. The `data` values are copied into `public.*` BEFORE `awake()` runs. 3. **Lifecycle.** The hooks run in this order: - `awake()` — same frame as attach, immediately after the data copy. Initialise state, set up native bridges, register with other systems. Other components on the same entity may not have awoken yet. - `start()` — the next frame. Every component on the entity has completed `awake()` by then, so cross-component setup is safe here. - `update(dt)` — same frame as `start()`, then every frame after, for as long as the gameplay clock is running. `fixedUpdate(dt)` runs beside it on the fixed timestep; `editorUpdate(dt)` runs while the clock is held. Which of them ticks is decided by `engine.mode` AND `engine.paused` together — see **Per-frame hooks and the two axes** below, and `man modes`. - `onDestroy()` — when the component is removed via `component.remove` or when the owning entity is despawned. Release resources, drop native ECS components. For the full list (`onEnable`, `onDisable`, `fixedUpdate`, `editorUpdate`, `onPropertyChanged`, `onAssetReload`, `onModuleReload`, `onBeforeSave`, …) and the timing details, **read `man components` — that is the canonical lifecycle reference. Generic component patterns (declare blocks, public fields, sync, ECS bindings, typed methods) all live there.** 4. **Public surface.** Fields declared in `public` are inspectable, editable in the inspector, and persist with the entity. Methods are declared on that same table with a colon — `typed function public:method(args)` — and every one of them takes the component ref as `self`, so a caller invokes it with a colon too: `entity(id).component.get(name):method(args)`. That is the one calling convention a component ref answers to: the reflection methods `ref:fields()` / `ref:getField(name)` / `ref:setField(name, value)` take the same spelling. A function the chunk declares at file scope (`function helper()`) is the component's own, reachable from its hooks under its bare name; `public` is what the ref carries. 5. **Settings and the Inspector card.** `type.yaml` names the component's settings schema as `settings: { schema: { instance: "init.luau", export: "public" } }`: the `public` table IS the schema, and its values live on each entity the component is on, so `asset.schema(componentRef)` answers the Field descriptors and no values file exists. On an entity the Inspector shows the component as a card whose generic `settings` section edits those fields as typed controls, each edit checked against the schema and written to the live component as one undoable operation. `type.yaml` also names `inspector: { instance: "inspector.luau" }`: a component that ships an `inspector.luau` beside its `init.luau` shapes its card — the file returns `{ sections, replace, order }` (see `assetTypes/README.md`, "`inspector:`"), each section's `build(ctx)` reading `ctx.component` (the live component) and `ctx.selection.id` (the entity). `SceneModule.component/inspector.luau` replaces `settings` with the bound module's declared inputs. 6. **Events.** An `events` block declares typed moments the component fires from inside — `events = { onHit = Event({ dmg = Field.number(0, NoSync) }) }`. The owner fires with `events.onHit:fire({ dmg = 10 })`; outside code subscribes through the proxy's subscribe-only facade, `entity(id).component.get(name).events.onHit:connect(fn)` (`:once` / `:wait` too). Pass `Sync` as the event's second argument to replicate a fire to other peers. Events let one component react to another's moments without polling. Full reference: **`man components`**, Events section. 7. **Hot reload.** Editing `init.luau` reloads the component definition; live instances are reconciled with the new declaration in-place, and each crosses one lifecycle boundary: `onDestroy()` ends the running life, then `awake()` and `start()` construct the one that replaces it, and `update()` resumes on the next frame. `public` and `private` values carry across; module-level `local`s belong to the chunk, so the new life starts with them at their initial values and its `awake`/`start` are what fill them in. Whatever the old life handed elsewhere — a subscription, a shared registration, a spawned entity — is released in `onDestroy`, the call that pairs with the construction about to run. An edit that leaves the source byte-identical crosses no boundary at all. A field carries its value across when something stated it: a key of the `data` table the instance was attached with (a scene record's data is that table), or a write made since. Every other field takes the edited source's declared default, so changing a default reaches every instance that left the field to it. An instance that states its own value for a field whose default the edit changed keeps that value, and the reload logs a `[HotReload]` warning naming the field, the entity, the value kept and both defaults. ## Discovery - `asset.list("component")` — every registered component (engine + world + libraries). - `asset.inspect("<name>")` — identity, scope, public fields, lifecycle methods, source path, and this type README. `detail` carries the component's declared `fields`, `methods`, and `events`, parsed from its source — `tools.use("assets","describe", "<name>")` renders it as markdown, so a component's events are visible without opening its source. - `ls /zero/source/<Name>.component` lists the files the folder holds. - `entity(id).component.list()` — components attached to an entity. ## Per-frame hooks and the two axes `engine.mode` (`"edit"` / `"play"`) and `engine.paused` (the gameplay clock) are independent, and the per-frame hooks read them separately: - `update(dt)` / `fixedUpdate(dt)` tick while **the gameplay clock is running** — whichever mode the engine is in. - `editorUpdate(dt)` ticks while **the clock is held** — because the mode is `edit`, or because play is paused — and also alongside `update` whenever edit is running. Which gives four states, and this table is the contract: | `engine.mode` | `engine.paused` | hooks that tick | |---|---|---| | `edit` | `true` | `editorUpdate` | | `edit` | `false` | `update`, `fixedUpdate`, `editorUpdate` | | `play` | `false` | `update`, `fixedUpdate` | | `play` | `true` | `editorUpdate` | Entering edit sets `paused = true` and entering play sets it back to `false`, so a session that never writes `engine.paused` only ever sees rows 1 and 3 — which is where the shorthand "`update` is the play tick, `editorUpdate` is the edit tick" comes from. It is the two default rows of a four-row table, not the rule. **Row 2 is the one that surprises.** With `engine.paused = false` in edit — set by hand, or by a tool that advances the gameplay clock to sample it, such as a `capture.collage` given a `duration` — `update` and `editorUpdate` both fire, once each, every frame. A component that declares both and routes them to one body therefore runs that body **twice per frame**: ```luau local function drive(dt) ... end function update(dt) drive(dt) end function editorUpdate(dt) drive(dt) end -- twice per frame in row 2 ``` Nothing reports the doubling; it reads as an animation running at twice its intended speed. To get exactly one tick per frame in every row, ask which axis you meant and answer it in the body: ```luau function update(dt) drive(dt) end function editorUpdate(dt) if engine.paused then drive(dt) end end ``` A scene `entrypoint.luau` declaring the same two hook names is dispatched by the scene loader, not by this table: there `update` needs play AND running, `editorUpdate` needs edit, and play-paused ticks neither. Read `man scenes` before carrying a component's rule to an entrypoint. ## Authoring conventions - Annotate public fields with `--!desc` so the inspector + LSP show documentation alongside the field name. - Declare lifecycle hooks (`start`, `update`, `destroy`) explicitly rather than relying on engine defaults — readers can see at a glance what runs when. - Keep `update(dt)` cheap — it runs every frame per instance. Move heavy work to `start`, to a service, or behind a job (`man jobs`). - For multi-entity batching, prefer `tools.use("entityOps", "addComponents", targets, components)` over a loop of `entity(id).component.add` — it takes many targets and many components in one call. ## Common pitfalls - **Naming.** The component identity is the folder stem with `.component` stripped (e.g. `<Spinner>.component/` → identity `Spinner`). Don't repeat the suffix in the identity passed to `component.add`. - **`init.lua` vs `init.luau`.** Either is accepted (it's a `one_of_group: "entrypoint"`), but `.luau` is canonical. Mixing both in one folder is invalid. - **`update` in edit mode.** It runs whenever the gameplay clock is running, and entering edit stops that clock — so `update` is idle in a freshly-entered edit session and ticks again the moment anything sets `engine.paused = false`. Use `tools.use("wld", "play")` to test update logic under the mode it ships in; `tools.use("wld", "edit")` to return. See **Per-frame hooks and the two axes** above. - **Renaming.** Renaming the folder changes the identity. Update every `component.add(<oldname>, ...)` call and the scene JSON entries that reference it. ## Related types - `.module` — pure-function library, no per-entity state. - `.service` — globally-scoped behavior, no per-entity state. - `.preset` — a captured component configuration, replayable into `component.add` without re-typing fields. - `.bundle` — entity hierarchies that may carry component attachments as part of the bundle. ## In the Inspector Fields: its execution order, hooks, and how many methods and events it declares, then the fields its `public` table declares as read-only typed controls holding their defaults, with **Check** and **Open** for its entry file. Instances: a link to every entity carrying it. What its card shows on an entity comes from the component's own `inspector.luau`.

# modules.api.engine.dirty_hot_reload Picks up dirty-overlay changes from disk while a scene is loaded in edit mode, applies them to the live entities, and keeps the in-memory representation in lockstep with `scene_dirty/` files. Pairs with `scene_saver` (writes deltas) + `scene_loader` (composes canonical + overlay at load time). ## Parents A record's `parent` names the entity it stands under: the entity whose id is that text, else the entity whose display name is exactly that text. A `*` or `?` in it is a character of the name, never a pattern. A record whose parent no entity provides waits. An entity that does not stand yet is not built, one that already stands keeps its state, the layer logs the record once, and `debugState(guid).waiting` maps its id to the parent it names. While a record waits, the scene saver leaves it as it stands rather than writing a standing entity's older state over it, until an author edits that entity, which the saver then records as it stands. When a record builds an entity, the records waiting on that entity's id or display name are built under it, so a child record that arrives before its parent's record lands where a load of both places it. Each waiting record is built as its overlay file states it at that moment, so a record rewritten while it waited, including by this session's own saver, builds from its current bytes. A load gives the same account of a record whose parent stays missing: the loader abandons it with `parentMissing`.

# playerSetupValidation Agent-facing validation for authored player setups. A player-spawn scene is built from PlayerSpawn entities (each naming a PlayerPrototype subtree to instantiate on join) and PlayerPrototype roots (marked PrototypeOnly, carrying a Camera in their subtree and a `body` field naming the entity to adopt). `checkEntity` inspects one such entity and returns human-readable messages that name what is wrong and what to do about it; `checkScene` validates the scene's player intent against its PlayerSpawn / Camera counts; `checkActiveScene` runs both across the live active-layer scene and returns a flat `{ entity, message }` list — the queryable surface an agent reads to see what to fix. `checkActiveScene` answers for the settled scene: it holds while a scene load or a mode-flip transition is rebuilding the live tree, then judges what the rebuild lands on. Each PlayerSpawn's prototype resolves wherever the materialisation holds it — the live entity in edit, and in play, where the loader keeps authored prototype subtrees out of the scene, the captured authored template each joining player is cloned from — so the same rules run over the same authored structure in both modes, and a prototype removed from a scene that materialises prototypes reads as the missing reference it is. Location: `src/lua/lib/modules/api/engine/playerSetupValidation.module`

# json JSON encode/decode library for Luau. Encodes Lua values to JSON strings and decodes JSON strings back to Lua values. Used for communication with the Rust side of the engine, the VFS read/write bridge, and any wire-format that needs JSON. Pure Luau, no engine dependencies. Compact and pretty-printed encoders, plus a hand-rolled decoder that streams the input by position so it works under WASM as well as native. ## Exports - `Json.encode(value: any, indent?: string, currentIndent?: string) -> string` — compact encode. Functions / unknown types and NaN/Inf encode as `null`. - `Json.encodePretty(value: any, indentStr?: string) -> string` — pretty-printed encode with sorted object keys (diff-friendly). - `Json.encodeArgs(...: any) -> string` — encode varargs as a JSON array. - `Json.decode(str: string) -> any` — decode a JSON string. Returns the decoded value, or `nil` + error message on failure. ## Usage ```luau local Json = require("@builtin::modules.json") local widget = { type = "button", text = "Click Me" } local compact = Json.encode(widget) -- '{"text":"Click Me","type":"button"}' local pretty = Json.encodePretty(widget, " ") local decoded = Json.decode(compact) local v, err = Json.decode("oops") -- v = nil, err = error message ``` ## Notes - Object keys are sorted alphabetically in both encoders for consistent output across runs. - Numeric keys on objects are stringified at encode time (JSON has no numeric keys). Pure-integer key sets get detected as arrays via `isArray` and encoded with brackets. - NaN, +Inf, -Inf encode as `null` — JSON has no representation. Round trips through `decode` recover `null` (Lua `nil`), so they don't preserve. - Unicode `\uXXXX` escapes decode to UTF-8 by hand to stay WASM-safe. Only the BMP is covered; supplementary planes via surrogate pairs are not. - Functions encode as `null`. - Decode is character-streamed — no regex, no `string.match` patterns on the whole input — so the line-and-column information needs to be reconstructed from the position offset.

# scene_build Turns builder code into scene records, and scene records into scene entities. `run(builder)` opens an entity capture scope, calls `builder`, and composes every entity it created into records — then despawns them. The builder writes ordinary spawn code; what comes back is data. A builder that raises leaves nothing behind. What a component the builder attached creates while running its own lifecycle belongs to that component: the record names the COMPONENT, and the same lifecycle runs again wherever the record is put back. That is what makes a nested build one build — a placement the builder makes runs its own module and owns what it lands, and the build around it describes the placement. `reconcile(records, target, owner)` applies records to the scene under `target`, writing `owner` and the record's place in the hierarchy onto each entity it places as the `buildOwner` / `buildKey` attributes. A rebuild reads that pair back off the entities under `target` and lands on the same ones, so nothing has to be remembered between two rebuilds — the pair is in the scene, and a reload brings it back with the entity. It returns the ids it landed on, keyed by record identity. A record is identified by its place in the hierarchy — the chain of names from the build root down to it, `base/coin_3` — so dropping a line from the middle of a builder, inserting one, or emitting two entities in the other order leaves every other entity's id where it was. Children of one parent that share a name carry their rank among those, `base/crate#2`, counted in the order the builder created them. Together these are the bake: code in, durable static-id scene content out. ## Who states an entity An entity names the build that placed it, so `ownerOf(id)` answers which build owns it — and answers nil for an entity an author spawned. `sourceOf(owner)` names the file that build is written in, from the `source` the reconcile running it passed. That pair is what makes ownership legible where an author meets it. A build states its entities in full every time it runs, so a value set on one of them holds until the next run. `notePreview(id, values)` records what the entity carries after such a change and `takePreview(id)` reads it back exactly once — in the run that states the entity again, which is where what the author set and what the build says can be named side by side.

# `scene.shared.loader` Luau-side scene loader. Reads `scene.json` v6, dispatches to engine FFIs, runs the sibling `entrypoint.luau`. ## Public surface ```lua local loader = require("@builtin::assetTypes.scene.shared.loader") loader.load(ref, opts?) -- ref: AssetRef<scene> | identity string | VFS path -- opts.layer: layer name (default "main") -- Returns: the Scene proxy (with player_config + camera_config attached). loader.unload(layerName) -- Wrapper around layers.unload(name); symmetric to M.load. -- Cannot unload "main". ``` ## Behavior 1. Resolve `ref` to a VFS path; append `/scene.json` if needed. 2. `vfs.read` + `Json.decode` (from `modules.json`) → body table. 3. Version check — refuse anything but `version: 6`. 4. Attach `body.player` + `body.camera` to the Scene proxy as `player_config` / `camera_config` (consumed by player_spawner + camera_spawner). 5. Activate the target layer via `layers.find(layerName)` (the loader threads the layer through `entity.spawn` opts), spawn `body.entities` in two passes (shells + transforms first, parents + components second), then restore the previous active layer. 6. Apply `body.lighting` via `lights.setup` + `lights.addPointLight`. Field name mapping: `directional` → `sun`, `clear_color` → `clearColor` (both engine API names and v6 field names are accepted). 7. Auto-discover sibling `entrypoint.luau` via `vfs.exists`; if present, compile with `loadstring` + run. ## Performance ~5 ms for a 1000-entity scene (≈5k FFI calls × ~1 µs each). Acceptable for a load-time operation. If a particular call class becomes hot, batch primitives can be added in a narrow follow-up. ## Why pure Luau Per § 10 of the unification integration design, the scene format is data + dispatch — no Rust-only primitives needed. The existing ECS FFI (`entity.spawn`, `entity(id).component.add`, etc.) covers everything. Keeping the loader in Luau means iteration speed, auditability, and hot-reload. ## FFI corrections vs. the original plan The plan was drafted against assumed API names. The actual engine FFIs differ: | Plan assumed | Actual engine API | |---|---| | `json.parse(s)` | `require("..json").decode(s)` (`modules.json`) | | `json.encode(t)` | `require("..json").encode(t)` | | `entity.spawn(n, { layer }).id` | layer activation via `layers.find(layer)` + `entity.spawn(n, opts).id` | | `entity.setParent(id, pid)` | `entity(id).setParent(pid)` | | `unloadLayer(name)` | `layers.unload(name)` | | `lights.setup({ directional })` | `lights.setup({ sun })` | | `lights.setup({ clear_color })` | `lights.setup({ clearColor })` | | `lights.addPointLight(table)` | `lights.addPointLight(name, x, y, z, opts)` | The loader accepts both the v6 field names and the engine API names for the lighting fields so that round-tripping through the scene saver and back works without a conversion step.

# scene_observe The record of what a scene load did, and what each loaded scene costs. Backs `layers.observe`, `layers.lastLoad`, `layers.lastUnload`, `layers.loadHistory`, `layers.problems`, `layers.whyPartial`, `layers.inventory`, `layers.cost` and `layers.resetCostWindow`, and the `scene` toolbox's `observe`, `whyPartial` and `cost` above them. `layers` and `scene_loader` are its writers. ## One record per load A load opens a record; the loader, the lifecycle dispatchers and the scene's own build write their failures and phase timings into it; the load's own completion point closes it with the duration the engine already measured for its `DONE` line. Reading is lazy — nothing here walks the world, and the only writer that runs every frame is `noteUpdate`, which the entrypoint tick calls once per scene that declares one. ```lua local r = layers.lastLoad() print(r.name, r.outcome, r.durationMs) print(r.entities.added, "arrived,", r.entities.removed, "left") print(r.phases.teardown, r.phases.instantiate, r.phases.settle) ``` `outcome` is `"ok"` when everything the scene declared was produced, `"partial"` when the load finished with failures in it, `"failed"` when the load raised and left no layer, and `"unchanged"` when the scene asked for was already the active root — that load rebuilt nothing, so the layer keeps the record of the load that built it and still answers why it is not whole. `reason` names the nearest cause from the closed set — `loaderRaised`, `entrypointCompileFailed`, `entrypointBodyRaised`, `entrypointRaised`, `buildRaised`, `entityFailed`, `parentMissing`, `parentRefused`, `parentAbandoned`, `componentUnresolved`, `componentRefused`, `subscriberRaised`, `updateRaised` — ranked so it names the thing to fix rather than the last thing to break. ## Failures reach the layer they belong to Every write of a failure calls the subscriber `layers` registers through `M.onFailure`, which republishes the record onto that layer's proxy: `ok` false, `failures` the records, and `"partial"` in place of `"ready"` once the layer has settled. A tick that starts raising on frame 400 moves the layer the same way one raised during the load does. A failure identical to one already held raises that one's `count`, so a tick raising every frame keeps one record. `FAILURE_LIMIT` bounds the distinct records a report holds, and `failuresOmitted` states how many arrived past it. ## Cost `noteUpdate` accumulates each layer's entrypoint tick into a per-guid entry — calls, total, last, max, average and how many raised — summed across the window `M.window()` reports. `M.resetWindow()` opens a new one, leaving the load history alone. An unload drops the layer's entry.

# `scene.shared.saver` Luau-side scene saver. Writes `scene.json` v6 — **authored intent only**. No captured runtime state. ## Public surface ```lua local saver = require("@builtin::assetTypes.scene.shared.saver") saver.save(name, opts?) -- name: logical scene name ("main") OR full VFS path -- opts.layer: layer name to read from (default layers.active.name or "main") -- Returns: the absolute VFS path written. ``` ## What is captured | Field | Source | Notes | |---|---|---| | `format`, `version` | constants | Always `"scene"` + `6`. | | `entities` | `entity.findAll()` walk | Excludes `temporary` entities + the spawner-managed Player + primary Camera. | | `entities[].transform` | local position / rotation / scale | NOT world transform — local only. | | `entities[].components` | component.list + component.get | Strips `_`-prefixed runtime fields. | | `entities[].attributes` | `attribute.list` + `attribute.get` | The entity's key/value bag, written as a `{ [key] = value }` map; omitted for an entity that holds none. Holds the authored keys — a `_`-prefixed key is the engine's own session bookkeeping. | | `lighting` | `lights.snapshot()`, filtered | Scene-level `clear_color` + `sky` only. Directional / ambient / point lights persist as `Light` entities in `entities[]`. | | `player` | `sceneProxy.player_config` | Carried forward from load-time, authored only. | | `camera` | `sceneProxy.camera_config` | Carried forward from load-time, authored only. | ## What is NOT captured - Local player's position / rotation. Runtime drift; not authored intent. - Primary camera's transform. Runtime; behavior-driven. - Any entity flagged `temporary = true`. Debug helpers, runtime markers. - Internal component fields prefixed with `_` (e.g. `_velocity` on CharacterController). The spawner-managed entities (Player + primary Camera) are excluded because they're created on load by player_spawner / camera_spawner from the scene's declarative `player` + `camera` blocks. Saving them would double them on the next load. ## When to use `layers.active:save(name)` (Phase 6) routes through this module. Callers that want a state snapshot (save-game systems, undo stacks) should use `world.debugSaveToDisk(...)` instead — that captures runtime state by design.

# @builtin::assetTypes.scene.shared.swapOrchestrator Owns the user-scope orchestration for scene swaps: leaves the prior scene's multiplayer room, gates concurrent loads via the `__scene_load.begin/finish` token, drives `scene_loader.M.load` for the new scene, and joins the new scene's room. Keeps the swap atomic from a multiplayer-sync standpoint (room transition + entity churn happen inside a single barrier).

# Model Loads and displays a 3D mesh on an entity. Disabling the component hides the mesh. Supports procedural meshes (`cube`, `sphere`, ...), model files, and remote URLs. Tint and outline are shader effects applied to the mesh. **Material lives on this component.** There is no standalone `Material` component — a material only renders where there is a mesh to render it on, so the `material` field is part of Model (and SkinnedModel). Set it at add time or assign the field later; properties are registry-wide. Public fields: `model`, `material` (`AssetRef<material>`), `tintR/G/B`, `tintBlend`, `outlineR/G/B`, `outlineIntensity`. Methods: `:setTint(color, blend?)` (color: `{r, g, b}` array or `{r=, g=, b=}` map), `:clearTint()`, `:setOutline(color, intensity?)`, `:clearOutline()`, `:setMaterialProperty(prop, value)`, `:getMaterialProperty(prop)`, `:getMaterialPropertyNames()`. ```luau entity(id).component.add("Model", { model = "cube", material = "gold" }) entity(id).component.get("Model").material = "checkerboard" -- swap material entity(id).component.get("Model"):setTint({1, 0, 0}, 0.5) entity(id).component.get("Model"):setMaterialProperty("roughness", 0.2) ```

# PlayerPrototype Marks the root of a player-setup subtree — the entity and children that define what a joining user becomes (avatar slot, spawn behaviour, controller). On awake it flips the entity to PrototypeOnly participation, so the prototype lives in the editor and drives spawning without being saved as a world entity itself; `kind` and `label` describe it for authoring surfaces. In edit mode it draws a cyan silhouette outline so the prototype root is easy to pick out, and surfaces its own setup-validation messages (missing camera, avatar slot, or wrong participation) on the component's error channel. Location: `src/lua/lib/components/PlayerPrototype.component`

# BoxCollider (component) A box collision shape. Works with or without a `Physics` component: on its own it is static collision geometry, and alongside one it moves with the body. ## Sizing `half` is the box's half-extents in the entity's local space, multiplied by the entity's world scale. Leave it unset and the box derives from the entity's model bounds, so a bare `BoxCollider` matches what is rendered at any scale. ```lua entity.find("crate").component.add("BoxCollider", {}) -- fits the mesh entity.find("wall").component.add("BoxCollider", { half = { 2, 4, 0.2 } }) -- authored ``` ## Fields | Field | Meaning | |-------|---------| | `half` | Half-extents. Unset derives from model bounds. | | `isTrigger` | Report overlaps without blocking. | | `friction` | Surface friction. | | `restitution` | Bounciness. | ## Composing A collider on a child entity attaches to the nearest ancestor carrying a `Physics` component, so a body made of several shapes puts each on its own entity and each keeps its own material and trigger flag. Past a few dozen boxes sharing one material, `CompoundCollider` is cheaper: it is a single broadphase volume where separate components are one each.

# Physics Adds rigid body dynamics to an entity. Body kind is `"dynamic"` (affected by forces), `"static"` (immovable), or `"kinematic"` (moved by script, affects other bodies). Public fields: `kind`, `gravityScale`, `mass`, `linearDamping`, `angularDamping`, `ccd`, `interpolation`, `lockRotationX/Y/Z`, `lockTranslationX/Y/Z`. `ccd` (continuous collision detection) sweeps the body along its motion so it cannot pass through thin geometry between two steps. It is off by default: the sweep runs on every body that travels further than its own thickness in one step — most of a collapsing structure or a debris burst — and it dominates the physics budget when a scene has many such bodies. Turn it on for the individual bodies that would visibly tunnel: bullets, thrown props, a wrecking ball. ```luau entity(id).component.add("Physics", { kind = "dynamic", ccd = true }) ``` `mass` is the body's total mass in kilograms. At its default of 0 the mass comes from the collider volume at 1 kg per cubic metre, so a bigger collider makes a heavier body; a value greater than zero sets the total mass exactly. Methods: `:applyForce(x, y, z)`, `:applyImpulse(x, y, z)`, `:applyTorque(x, y, z)`, `:setVelocity(x, y, z)`, `:addVelocity(dx, dy, dz)`. ```luau entity(id).component.add("Physics", { kind = "dynamic" }) entity(id).component.get("Physics"):applyImpulse(5, 0, 0) ```

# Light Adds a light source to an entity. The entity's world transform determines the light's position (point) or direction (directional). Point light positions are auto-synced from that world transform, so a light on a child entity burns where the entity stands — the position `entity.position` reports. A point light's `intensity` is on one scale with the `SpotLight` component's `intensity`/`brightness`: the same number at the same `radius`/`range` puts the same light on a surface either kind faces from the same place, and a spot spends it on the cone it opens on rather than all around itself. Kinds: `"point"`, `"spot"`, `"directional"` (the scene's sun), `"ambient"`, `"distant"` (a parallel light beside the sun). Public fields: `kind`, `colorR/G/B`, `intensity`, `radius`, `directionX/Y/Z`, `castsShadows`, `lightChannels`, `mobility`. `range`, `color` and `direction` are aliases accepting the composite/renamed forms. Methods: `:setColor(color)` (color: `{r, g, b}` array or `{r=, g=, b=}` map), `:setIntensity(i)`, `:setRadius(r)`, `:setDirection(dir)`, `:setKind(lightKind)`. `kind = "spot"` opens a cone along the entity's forward axis, at the engine's default 30° outer and 20° inner half-angles; the `SpotLight` component is the one that carries the cone angles and the `face` axis as fields. `"directional"` and `"distant"` are parallel lights: they arrive from the same direction at every point in the world and no distance attenuates them, so their `intensity` reads against the sun's rather than against a point light's. The `SpotLight` README carries the rest of how to balance a mixed point-and-spot rig. ```luau entity(id).component.add("Light", { kind = "point", intensity = 2, radius = 10 }) entity(id).component.add("Light", { kind = "directional", direction = {-0.5, -1, -0.3} }) ```

# ProceduralSky The editable atmospheric sky: a day/night gradient with a sun disc, glow, stars and a moon, all derived procedurally from the directional light's elevation. Add it to an entity like a light: ```lua entity.spawn("sky").component.add("ProceduralSky", { timeOfDay = 18.5 }) entity.spawn("sky").component.add("ProceduralSky", { preset = "sunset" }) entity.spawn("sky").component.add("ProceduralSky", { zenithColor = { r = 0.05, g = 0.1, b = 0.3 }, horizonColor = { r = 0.9, g = 0.4, b = 0.2 }, }) ``` A `ProceduralSky` owns its material outright: it registers a **runtime GPU material** of its own over the builtin procedural-sky shader and pushes every visual parameter (colours, sun, stars, moon, turbidity, exposure) straight to that record. The component's fields **are** the material definition — no `.material` asset backs it, so retuning a scene's sky changes that scene's sky and nothing else. The renderer reads the values from the material's group(1) uniform like any other material — there is no sky-specific render path. Those values also travel the native `Sky` bridge into the scene sky config, alongside the time-of-day / auto-cycle / sun-sync controls. That config is what `sky.get()` reports and what a saved scene records, so both name the sky being drawn. With `syncSunToLight` on (the default), the sky's `timeOfDay` is what the scene is lit by: the scene's directional light takes its direction, colour and intensity from the sun's position, so the sun in the sky and the sun the scene is lit by are the same sun through a whole day/night cycle. Turn it off for a light the sky leaves alone. The intensity that arrives is the day/night curve between night and noon, and `sunPeakIntensity` is the noon end of it — `1.0`, the sky's own daylight, unless a scene asks for more. A harder sun on water or snow is stated here; setting the light itself does not survive, because the sky writes over it every time the hour moves. Like the directional light, the sky is conceptually **singular per scene**. A `ProceduralSky` fully defines its material on `awake` (every parameter from its own fields), so switching scenes never inherits a previous scene's overrides. Day/night comes from the sun's elevation, so evening presets render dark — drive the look by `timeOfDay` (which orients the sun). ## Fields | Field | Type | Default | Meaning | |---|---|---|---| | `preset` | string | `""` | Named look applied before explicit fields: `clear_day`, `sunset`, `sunrise`, `overcast`, `night`. | | `timeOfDay` | number | `14.0` | 0..24 hours; orients the sun and the day/night gradient. | | `autoCycle` | bool | `false` | Advance `timeOfDay` each frame. | | `cycleSpeed` | number | `60.0` | Game-seconds per real-second for the auto cycle. | | `syncSunToLight` | bool | `true` | Drive the directional light from the sun. | | `sunPeakIntensity` | number | `1.0` | What the sun's light measures at noon; the day/night curve runs from night up to this. | | `zenithColor` / `horizonColor` / `groundColor` | color | — | Sky gradient colours. | | `sunSize` / `sunIntensity` | number | `0.02` / `20.0` | Sun disc size + brightness. | | `starsIntensity` | number | `1.0` | Night star-field intensity. | | `moonSize` | number | `0.03` | Moon disc size. | | `turbidity` | number | `4.0` | Atmospheric haziness. | | `exposure` | number | `1.0` | Sky exposure multiplier. | ## Methods | Method | Description | |---|---| | `sky:setTimeOfDay(hours)` | Set the time of day (0..24). | | `sky:applyPreset(name)` | Apply a named look. | | `sky:setZenithColor(c)` / `setHorizonColor(c)` / `setGroundColor(c)` | Set a gradient colour (`{r,g,b}` array or map; >1 auto-scales /255). |

# Lit Checkerboard A static, lit checkerboard surface built on `@builtin::shaders.lit_checkerboard` — the default ground material for newly seeded worlds. It uses a neutral light-grey base colour (`0.85, 0.85, 0.85`) with a grey emissive tint (`0.35, 0.35, 0.35`) so the pattern stays readable in dim scenes, high roughness (`0.7`), no metallic, opaque, and instanced. ## Inputs - `colors.base_color` (`0.85, 0.85, 0.85, 1.0`) — neutral grey checker palette. - `colors.dark_color` (`0.35, 0.35, 0.35, 1.0`) — the dark square colour, close enough to the base that the pattern stays readable in low light. - `floats.roughness` (`0.7`) — mostly diffuse surface. - `render.instancing` (`true`) — supports instanced draws.

# Asset Promote the bundle's spawned children from temporary to permanent scene state and remove the Asset component, "baking" the bundle's contents directly into the owning scene. Subsequent saves persist the baked entities verbatim and stop replaying the bundle template. Location: `src/lua/lib/components/Asset.component`

# PlayerSpawn A world entity that spawns players from a prototype. It carries the fields describing how spawning happens: which `prototype` to instantiate, the `team` and `role` assigned to spawned players, a `maxPlayers` cap (0 = unbounded), the `spawnPolicy` (how many players spawn from this point), and the `placement` (where a spawned player is positioned). The entity's own transform is the spawn point when `placement` is `at_spawn_transform`. In edit mode it draws an orange silhouette outline at the spawn point and surfaces its own setup-validation messages (missing or mis-targeted prototype) on the component's error channel. Location: `src/lua/lib/components/PlayerSpawn.component`

# lamp_post (bundle) A lamp post: a slim post, a lit head sitting on top of it, and the point light it casts. Four entities under one root — `post`, `head` and `glow` — built from builtin meshes and materials, so the bundle carries no geometry of its own. Its foot sits at `y = 0` and it stands 2.53 units tall, so placing it at a position on the ground puts it on the ground. ```lua asset.resolve("@builtin::bundles.lamp_post", "bundle"):instantiate(nil, { position = { 4, 0, 2 }, rotation = { 0, 30, 0 }, scale = 1.2, }) ``` ## What it is for It is the prop a starting scene places to show what placing an asset does: one call brings a whole hierarchy in as the scene's own entities, and the `Light` riding along shows that a bundle carries behaviour and not only shape. Reach for it whenever a scene needs a light source that reads as an object rather than as a floating value.

# orbital_follow Three-ring orbit camera. Framing is authored as three rings around the follow target — a bottom, a centre and a top, each with a `height` above the target's origin and a `radius` out from its axis. Vertical look slides the camera along the spline through those rings; horizontal look orbits around them. The shape of the orbit is geometry you can see and edit rather than a pair of pitch limits you cannot. Public fields: `follow`, `ringBottom` / `ringCenter` / `ringTop` (each `{ height, radius }`), `verticalAxis` (0 at the bottom ring, 1 at the top), `horizontalAxis` (the world heading the camera looks along, in radians about +Y from world +Z), `radiusScale`, `aimHeight` (the aim point above the target's origin), `damping` (per-axis time constants in seconds), `cameraRadius` (radius of the pull-in sweep; `0` turns the pull-in off), `cameraIgnore` (entities whose colliders the pull-in passes through), `sensitivity`, `invertY` (off by default: pushing the mouse forward looks UP, drawing the camera toward the bottom ring; on pitches the other way), `zoomSpeed`, `minRadiusScale`, `maxRadiusScale`. The rig owns that heading. Binding a follow target aims it along the subject's facing, so the shot opens from behind whoever the camera is told to follow, and look input turns it from there — the subject's facing is never read again. That is what makes the camera steerable for a character who turns to face where it is walking: hold "forward" and the character walks the line the camera looks down, instead of chasing a heading that moves as it turns. The default rings frame a roughly 1.8 m humanoid standing at its origin: the centre ring sits above head height at the widest radius for a resting shot from behind and slightly above, the bottom ring drops to knee height and pulls in to look up, and the top ring climbs and tightens for a near-overhead look down. Writing any framing field re-poses the rig immediately with damping bypassed, so editing a ring moves the camera to the shot that ring describes. `follow` falls back to the `Camera.follow` slot when it is empty, so a rig selected through `Camera.behavior` tracks whatever that camera already follows. Controls: mouse to orbit and to slide along the rings (play mode requests pointer lock, so no button is held), scroll to scale the ring radii. ```luau local cam = entity(id).component.get("Camera") cam.behavior = asset.ref("@builtin::controller.orbital_follow", "component") entity(id).component.get("controller.orbital_follow").ringCenter = { height = 2.6, radius = 6 } ``` ## The camera pulls in when a collider is in the way Each frame the rig sweeps a sphere of `cameraRadius` from the point it aims at out to where its framing puts the camera, and stands the camera where the sphere first meets a collider. Every collider in the world stops that sweep, whether or not anything draws it: an invisible walk bound (a `BoxCollider` with no `Model`), a trigger volume and a solid wall all pull the camera in alike. The follow subject is the one entity the sweep passes by default. So a camera that snaps in close to the player, or collapses onto it, while nothing visible stands behind the player is meeting a collider nobody can see. Two fields settle it: - `cameraIgnore` lists the entities whose colliders the camera sees through. Name the walk bounds and gameplay volumes there and the sweep passes them as it passes the subject, while walls the player can see still pull the camera in. Each entry is an entity (or its id), and it is the collider's own entity that is listed. - `cameraRadius = 0` turns the pull-in off: the camera stands where its framing puts it, through every collider. ```luau local rig = entity(camId).component.get("controller.orbital_follow") rig.cameraIgnore = { entity.find("NorthBound"), entity.find("SouthBound") } -- or drop the pull-in entirely rig.cameraRadius = 0 ``` ## Attach through `Camera.behavior` The Camera owns the behavior slot, so assigning the rig there is what lets the Camera tell it when `follow` changes. A rig added straight onto the entity with `component.add` still poses, but the Camera does not know about it and a `follow` assigned afterwards will not reach it. ## Player cameras: leave `follow` unset Entering play drops and respawns `PlayerPrototype` subtrees, so the body is recreated with a NEW entity id. A `follow` authored on the rig keeps pointing at the original, which is no longer live, and the camera freezes at its last pose instead of tracking the player. For a player camera, set the target on the **Camera** and leave the rig's own `follow` empty: ```luau entity(rigId).component.get("Camera").follow = body -- PlayerPrototype rebinds this on every spawn ``` `PlayerPrototype` refreshes `Camera.follow` to the live body each time it clones, and the rig reads that slot whenever its own `follow` is empty. Set the rig's `follow` only for a camera that watches a fixed, non-respawning subject.

# Plastic Red A glossy red plastic — a non-metallic PBR surface with a saturated red base colour (`0.8, 0.1, 0.1`) and mid roughness (`0.5`) for a soft dielectric sheen. Built on `@builtin::shaders.pbr`. Opaque, back-face culled, queue `2000`. ## Inputs - `colors.base_color` (`0.8, 0.1, 0.1`) — the red plastic tint. - `floats.roughness` (`0.5`) — soft, semi-glossy highlight. - `floats.metallic` (`0.0`) — dielectric (non-metal) response. - `floats.emissive` (`0.0`) — no self-illumination.

# UI Templates — main scene The startup scene for the **UI Templates** world. `scene.json` materializes a ground plane, ambient + directional lighting with a procedural sky, and the standard multiplayer player setup (a `PlayerPrototype` with body + `CameraRig` under `PlayerSetups`, and a `PlayerSpawn` under `Spawns`). `entrypoint.luau` holds the lifecycle callbacks (all commented out by default). This world collects reusable, ready-to-read **UI screen templates** authored against the `ui.*` CSS-parity surface. Each template is a self-contained script under `/source/ui/` that registers and shows an `ui` screen. Current templates: - `ui/p5_menu.luau` — a Persona 5 main-menu lockup: a font-family list resolving the bundled **Arial Black** face for the blocky title, clip-path polygons for the torn wedge / octagon badges / row tears, CSS transforms, `-webkit-text-stroke`, text-shadow, and a repeating-linear-gradient halftone field. Run it with `execute { file = "/source/ui/p5_menu.luau" }` to display the screen.

# Tessellation Showcase Every surface in this scene starts as a **flat two-triangle plane**. The `Tessellation` component subdivides each triangle into thousands of GPU micro-triangles and displaces them along their normals from a **height map**, turning flat geometry into rich relief — no authored high-poly meshes. The entrypoint drives the same component with four procedural height maps: | Piece | Height source | What it shows | | --- | --- | --- | | Rocky mountains | 5-octave value-noise fBm | Natural terrain from a flat plane | | Sand dunes | Low-frequency swells | Smooth rolling forms | | Ocean swell | Crossed sine waves | Repeating wave crests | | Before / after | Bold ridge grid | Same box, flat vs. tessellated | ## What it demonstrates `Tessellation` sits next to a `Model` + `Material`. It reads the entity's current mesh, subdivides each triangle into `4^level` micro-triangles, and displaces them from the material's displacement map — the entity's PBR material renders the result. A single flat box + a height map becomes a detailed surface entirely on the GPU. ## Running Load the scene and enter play mode. The height maps are generated procedurally on load, so the showcase is fully self-contained.

# assetType runtime The machinery that reads a `<typename>.assetType/behavior.luau` and turns its declarations into live behaviour. A `behavior.luau` is a table of declarations — `ref` methods, `modules` shared code, an `events` schema, a `namePattern`, `refShapes`, and the `onCreate` / `onRegister` / `onChange` / `onDelete` / `validate` / `settingsDefaults` / `settingsCorrections` hooks. None of it runs itself. This is the code that runs it, and it lives here because reading a type's declarations is the **assetType type's own behaviour** — the same way `material.assetType` owns what a `.material` does. ## Sub-modules | Module | Reads | Responsibility | |---|---|---| | `ref.module` | `ref`, `modules` | Builds every `AssetRef` envelope, attaches the shared metatable, and dispatches per-type methods and shared modules onto it. Also owns edit-mode write-behind persistence. | | `create.module` | `onCreate`, `namePattern`, `validate` | Backs `asset.create`: resolves the type, checks the name against its pattern, runs `onCreate` (or clones `template/`), and writes the instance. `validate.module` beside it checks a creation `opts` table against the type's `createSchema`. Before running `onCreate`, resolves the type's settings chain (below) and hands the result to the hook as `opts.settings`. | | `settings.module` | `settings`, `settingsDefaults`, `settingsCorrections` | A type's declared settings schema and where its values live (`type.yaml`'s `settings:` block). `Settings.resolveForCreate` layers the schema's own defaults, the type's own `settingsDefaults(name, opts, asked)` hook (a DEFAULT the schema can't express — a name-derived convention, a fact read off a payload the caller handed it, a value following a field `asked` shows a higher layer naming; any later layer overrides it), the Preset Manager, an importer's settings, the caller's `settings` table, then the type's own `settingsCorrections(values, name, opts)` hook (a CROSS-FIELD CONSTRAINT the schema can't express, applied last over the fully merged values). A correction over a default/preset/importer value lands silently; a correction that would override what the caller's own `settings` table explicitly asked for refuses the creation instead, naming the field and why. Neither hook is ever handed a table to mutate; each returns what it wants changed (`settingsCorrections` may also return a `{ [field]: reason }` table for that refusal message). `Settings.cloneValues` deep-copies a values table — `create.module` hands `onCreate` a copy, never the table it stamps. `Settings.valuesOf` / `writeValues` read and write an asset's own values file. | | `typeYaml.module` | `type.yaml` | The folder a type lives in and its parsed `type.yaml`, decoded once per content version of the file. `settings.module` and `inspector.module` read their blocks through it. `about` / `aboutAt` read a type's `about.yaml` (`intent`, `function`, `usage`), leaving out any key that is empty or still starts with `[[describe]]`; `aboutRows` and `aboutMarkdown` lay the texts out for the Inspector and the `types/<name>` guide. | | `inspector.module` | `type.yaml`'s `inspector:` block | Which inspector a type declares for its assets (`inspector: { type: ... }` or `{ instance: ... }`), and the declaration that file returns — the sections it adds, the generic ones it replaces, and their order — or the problem that kept it from loading. | | `onRegister.module` | `onRegister` | Fires an instance's once-only registration hook — on arrival, on world load, and for `@builtin` library instances. | | `changeDispatch.module` | `onChange`, `onDelete`, `refShapes` | Routes a VFS source write or a folder delete to the enclosing typed asset's type hooks. | | `refShapes.module` | `refShapes`, `ref` | Publishes what every `AssetRef<category>` answers to, so a member read on an asset-typed value is checked against that category's real surface. | | `events.module` | `events` | The per-asset event runtime behind `ref.events`. | | `instantiable.module` | `ref.instantiate` | The instantiation contract an asset type opts into: `root` stands the root entity, `place` applies the base placement opts to one the type adopted, and `result` shapes the `(root, idMap)` every `instantiate` returns. Also registers the `sceneInstantiable` field-constraint validator. | | `declaration.module` | `type.yaml` | The type's decoded declaration, read once and held until a write inside an `.assetType` folder; what every question about a type as a whole reads. | | `previewRecipe.module` | `type.yaml` `preview:` | How an instance's `preview.png` is produced: which of the four recipes (`instantiate`, `image`, `surface`, `custom`) the type declares, and what that recipe needs. | ## Reaching it ```luau local rt = require("@builtin::assetTypes.assetType.shared") rt.ref.loadTypeBehavior("material") ``` Fields resolve lazily. The prelude requires the sub-modules directly, in dependency order (`ref`, then `changeDispatch`, `onRegister.install()`, `refShapes.install()`) — a table that required all six on load would take that ordering away from it.