# blobs Generic binary staging for handing bytes to native components. Content reads a file's bytes (`vfs.read`, binary-safe, yields until the blob is resident), stages them with `set`, and passes the returned handle through a component field; the native consumer takes the bytes back by that handle and owns its copy. Component field values travel as JSON (UTF-8 only), so a raw binary payload rides as a staged handle — the CPU-side analogue of the mesh/texture GPU upload. ## Methods - `blobs.set(bytes) -> handle` — stage a binary payload, get a short string handle to pass through a component field. - `blobs.get(handle) -> bytes?` — read back a copy of the staged bytes without removing them; nil for an unknown or already-cleared handle. - `blobs.clear(handle)` — drop a staged payload that will not be consumed, freeing its memory. ## Usage ```luau local bytes = vfs.read(clipPath .. "/data.zaud") local handle = ecs.blobs.set(bytes) ecs.insertSync(id, ecs.AudioSource { clip = clip, bytesHandle = handle }) ```

# ecs.components Component-spec namespace — re-exports every native ECS component spec under `ecs.components.<Name>`. Each spec describes one native component: its public name, the Rust type it maps to, and the per-field entries the generic `ecs` verbs use to build and read Rust-shaped values. The sibling `ecs` module registers each spec to mint its typed constructor (`ecs.Mesh`, `ecs.Transform`, ...). ## Spec shape Each spec is a table with: - `name` — the public component name (`"Mesh"`). - `rust` — the native type it maps to (`"MeshInstance"`). - `entries` — per-field descriptors `{ luau, rust?, kind, expand? }`. `luau` is the camelCase field a caller writes; `rust` is the underlying snake_case field; `kind` is the conversion kind (`string`, `bool`, `number`, `vec3`, `meshHandle`, `materialHandle`, `textureHandle`, `assetRef`, `struct`); `expand` lists the rust scalars a `vec3` expands into. - `behavior(id) -> { method = fn }` — optional per-entity imperative methods the `ecs.get` handle exposes. - `static = { fn = function(id, ...) end }` — optional component-level operations that take an explicit entity id. ## Members `Mesh`, `Material`, `Transform`, `Physics`, `Light`, `Collider`, `CollisionGroups`, `PhysicsJoint`, `WheelCollider`, `SoftBody`, `AudioSource`, `Camera`, `Sky`, `PlayerOwned`, `Skeleton`, `TransformConstraints`. Each lives in its own `.module/` folder. ## Usage ```luau local Specs = require("modules.api.engine.ecs.components") for name, spec in Specs do print(name, spec.rust) end ```

# handle Lazy handle over a present component, returned by `ecs.get(id, ecs.<Name>)`. It retains a bind accessor per field (resolved once, reused, revalidated) and closes over the component's compiled conversion plan, so reads and writes stay live without re-crossing into the native substrate. ## Reads Index the handle by the public (mapped) field name you construct with — `h.castsShadows`, `h.tint` — or by the underlying rust field name — `h["casts_shadows"]`, `h["tint_r"]`. Public names win when both resolve. A `vec3` field recomposes into `{ x, y, z }` (also mirrored to `[1]`, `[2]`, `[3]`). Reads are live, never stale. ## Writes Assign to the same names you read: `h.castsShadows = false`, `h.tint = { 1, 0, 0 }`. The assignment writes the component's row, so the read after it answers what the component holds. `handle:set(key, value)` is the same write in method form. The component's row is the handle's only store — a name the component does not have raises, and a value the field will not take leaves the field as it was and warns, naming the component, the field under the name you wrote it as, and the value refused. ## Methods - `handle:set(key, value) -> handle` — write a field by public or rust name; resolves and coerces handle-typed fields, and expands a `vec3` into its three scalars. Returns the handle. - `handle:read() -> table` — batch-read every rust field in one pass (point-in-time copy keyed by rust field name). - `handle:release()` — destroy the retained bind accessors. A behavior-bearing component (e.g. `Physics`) also attaches its per-entity imperative methods directly on the handle, each bound to this entity's id. ## Usage ```luau local body = ecs.get(id, ecs.Mesh) local visible = body.visible body.castsShadows = false body:set("tint", { 1, 0, 0 }) ```

# handles Loads the native components a saved record lists. A record (a scene entity, a bundle `entity_template` entry) states its native components beside its script components as `ecs = { { type = "<public name>", data = <row> } }`: `type` is the name the component answers to under `ecs`, and `data` is the row `ecs.snapshot` answers for it. Every field that holds a GPU handle is written as the guid of the ASSET the handle came from, because the guid outlives the session and the handle does not. Loading resolves each of those guids to the handle the component holds (`ref:handle()`, the call a `Model` makes, which puts the asset on the GPU) and inserts one value into every entity that states the same entry. ## Exports - `M.handleFields(typeName) -> { { rust, category } }?` - the fields of a native component that hold a GPU handle, each with the asset category its guid names (`mesh`, `material` or `texture`). nil for a name `ecs` does not hold. - `M.value(entry) -> value` - the component value one `{ type, data }` entry states, ready for `ecs.insert`. A guid that names no asset of the field's category raises, naming the component and field. - `M.insertAll(specs) -> failures` - inserts `{ id, type, data }` specs, one `ecs.insertMany` per distinct `(type, data)`. Answers one `{ type, ids, message }` per entry that did not land. ## Usage ```luau local handles = require("modules.api.engine.ecs.handles") local failed = handles.insertAll({ { id = a, type = "Mesh", data = { mesh = meshGuid } }, { id = b, type = "Mesh", data = { mesh = meshGuid } }, { id = a, type = "Material", data = { id = materialGuid } }, }) for _, failure in ipairs(failed) do log.error(failure.type .. ": " .. failure.message) end ``` The scene loader and `bundle:instantiate` call `insertAll` after a record's script components are added.

# plan Compiles a per-component spec into a reusable conversion plan and formats Luau input into the Rust-shaped payload the `ecs` verbs apply. A plan is compiled once per component at module load; `format` is the only per-call work. ## Exports - `M.compile(spec) -> plan` — builds a plan from a spec's `entries`: `{ rust, entries, byLuau, rustFields }`, where `byLuau` maps each public field name to its entry and `rustFields` is the set of underlying rust field names. - `M.format(plan, input) -> table` — converts Luau input to the rust-shaped payload. Expands `vec3` fields into their three rust scalars (reading `{r,g,b}`, `{x,y,z}`, or array form), resolves handle fields to their guid, passes scalars through, and raises on an unknown field. - `M.resolveMeshHandle(value) -> string` — reads the live GPU registry guid off a `MeshHandle`, raising on a category mismatch or a missing guid. - `M.resolveMaterialHandle(value) -> string` — reduces any of the forms that identify a material to the one string rust holds: a `MaterialHandle` (its guid), a registry key or asset guid string (passed through), or an `AssetRef` (its `__ref`). These are the forms `renderer.mesh.drawInstanced` takes for the same job. A handle or envelope naming another category raises — a handle names its category in `category`, an `AssetRef` names it in `type`, and both are read. - `M.resolveTextureHandle(value) -> string` — accepts a typed `TextureHandle` (returns its guid), a bare guid string (passed through), or `nil` / `""` to clear. ## Usage ```luau local plan = require("modules.api.engine.ecs.plan") local compiled = plan.compile(spec) local payload = plan.format(compiled, { visible = true, tint = { 1, 0, 0 } }) ```

# 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**.

# ecs.AudioListener Spec for the `AudioListener` component, which maps to the native AudioListener. The entity carrying it is the "ears" of the scene: its transform sets where spatial audio is heard from. Attach it to whatever should hear — a camera, a character, a listener rig. ## Fields - `active` — whether this listener drives the ears. It is live: writing it takes effect on the next frame, so clearing it on the listener holding the ears hands them to another active listener, and clearing it everywhere leaves spatial sources playing centered. When several are active one of them drives the ears — the same one every frame — and `audio.observe().listener.entity` names it. ```luau entity(id).component.add("AudioListener", { active = true }) ```

# ecs.AudioSource Spec for the `AudioSource` component, which maps to the native AudioSource. Plays a `.soundClip` asset from an entity, with optional 3D spatial attenuation. Spatial sources are heard relative to the scene's `AudioListener`. ## Fields - `clip` — the `.soundClip` asset to play, referenced by guid. - `bytesHandle` — the staging handle the mixer takes the clip's audio bytes from. - `streaming` — stream the compressed payload vs decode it fully on load. - `sourceType` — an `AudioSourceType` variant name. - `volume`, `pitch` — playback gain and pitch. - `looping` — repeat playback. - `spatial` — enable 3D distance attenuation. - `maxDistance` — the distance a spatial source fades to silence at, in world units. It is at full volume within one unit of the listener. - `rolloff` — exponent of that fade: the amplitude is `(1 - t)^rolloff` for a source `t` of the way through the window, so `1` fades linearly, higher drops off sooner, and `0` holds full volume to the edge. - `state` — a `PlaybackState` variant name. - `stopRequested` — a stop asked for on the source, taken up by the mixer. - `autoplay` — start playing on add. - `channel` — the mixer channel name. ## Usage The `Audio` script component owns this one. It resolves the clip, stages the clip's bytes under `bytesHandle` so the mixer has something to play, installs the source, and keeps the source in step with its own fields as they change. Adding `Audio` is how a clip sounds from an entity. ```luau entity(id).component.add("Audio", { clip = themeClip, looping = true, autoplay = true }) ``` A playback setting written on that component reaches the source it installed, including one that is already sounding: ```luau local music = entity(id).component.get("Audio") music.volume = 0.5 ```

# ecs.Camera Spec for the `Camera` component, which maps to the native Camera. Makes an entity a render viewpoint, with a configurable projection, render priority, layer selection, and an optional offscreen render target. ## Fields - `enabled` — whether the camera renders. - `fov`, `near`, `far` — perspective projection parameters. - `priority` — orders multiple cameras. - `textureHandle` — a `renderer.texture.create({ width, height })` handle the camera renders into; absent means the main viewport. - `layerIncludeMask` — render-layer include bitmask; a layer draws into this camera only when its bit is set. The `Camera` component resolves its `renderLayers` name spec (e.g. `"all !ui"`) down to this raw mask. - `debugChannel` — debug visualization channel. ## Methods - `scheduleRender(output, priority, fov, near, far)` — schedule a single render of this camera into `output` (the `"viewport"` target or a named offscreen handle) for the current frame, at the given priority and projection. ```luau entity(id).component.add("Camera", { fov = 60, near = 0.1, far = 1000 }) entity(id).component.Camera:scheduleRender("viewport", 0, 60, 0.1, 1000) ```

# ecs.Collider Component spec for `ecs.Collider`, which maps to the native Collider — an entity's collision shape. The constructor `ecs.Collider{...}` builds a value the generic ecs verbs (`ecs.insert` / `ecs.set` / `ecs.get`) apply. `size` and `heightfieldExtent` are single Vec3 fields; `children` (compound shapes) and `heights` (heightfield grid) are arrays — all pass through verbatim. ## Fields - `shape: string?` — `"Box"` | `"Sphere"` | `"Capsule"` | `"Compound"` | `"Heightfield"` | ... - `size: { number }?` - `isTrigger: boolean?` - `friction: number?` - `restitution: number?` - `name: string?` - `children: { EcsColliderChild }?` — compound child shapes. - `heights: { number }?` — heightfield grid samples. - `heightfieldExtent: { number }?` ## Types - `EcsColliderChild = { shape: string, size: { number }, offset: { number }? }` ## Usage ```luau ecs.insert(id, ecs.Collider{ shape = "Box", size = { 2, 4, 0.2 } }) ```

# ecs.CollisionGroups Component spec for `ecs.CollisionGroups`, which maps to the native CollisionGroups — the bitmask membership/filter that decides which colliders interact. Two colliders collide only when `(a.membership & b.filter)` and `(b.membership & a.filter)` are both set. The constructor `ecs.CollisionGroups{...}` builds a value the generic ecs verbs apply, and the component is behavior-bearing: `ecs.get` exposes per-collider group methods. ## Fields - `membership: number?` — the groups this collider belongs to. - `filter: number?` — the groups this collider tests against. ## Handle methods `ecs.get(id, ecs.CollisionGroups)` returns the generic data handle plus these methods, each bound to the entity's id. - `apply(membership, filter)`: store the membership/filter masks on this component and push them onto this entity's colliders. The engine holds the colliders of the entity's rigid body or standalone collider to the stored masks as the body is built and before every physics step, so a body built or rebuilt later takes them too. - `ignore(otherEntityId, ignore?)`: set pairwise collision ignore against another entity (`ignore` defaults to `true`). ## Usage ```luau ecs.insert(id, ecs.CollisionGroups{ membership = 0x1, filter = 0x2 }) local groups = ecs.get(id, ecs.CollisionGroups) groups:ignore(otherId) ```

# ecs.Light Component spec for `ecs.Light`, which maps to the native Light. One component backs point, directional, ambient, and spot lights, selected by `lightType`. The constructor `ecs.Light{...}` builds a value the generic ecs verbs (`ecs.insert` / `ecs.set` / `ecs.get`) apply. `color`, `direction`, and `face` are vec3 composites; the cone angles apply to spot lights. ## Fields - `lightType: string?` — `"Point"` | `"Directional"` | `"Ambient"` | `"Spot"`. - `color: { number }?` — `{r, g, b}`. - `intensity: number?` - `radius: number?` - `direction: { number }?` — `{x, y, z}`. - `coneInnerDeg: number?` — spot cone inner angle (degrees). - `coneOuterDeg: number?` — spot cone outer angle (degrees). - `face: { number }?` — `{x, y, z}`. - `castsShadows: boolean?` ## Usage ```luau ecs.insert(id, ecs.Light{ lightType = "Point", color = { 1, 1, 1 }, intensity = 5, radius = 10 }) ```

# ecs.Material Component spec for `ecs.Material`, which maps to the native MaterialRef — the material bound to an entity's mesh. The single field `material` takes a GPU MaterialHandle obtained from `materialRef:handle()`. The constructor `ecs.Material{...}` builds a value the generic ecs verbs (`ecs.insert` / `ecs.set` / `ecs.get`) apply. ## Fields - `material: MaterialHandle` — the GPU material to apply. ## Usage ```luau local handle = materialRef:handle() ecs.insert(id, ecs.Material{ material = handle }) ```

# ecs.Mesh Component spec for `ecs.Mesh`, which maps to the native MeshInstance — the renderable mesh attached to an entity. The constructor `ecs.Mesh{...}` builds a value the generic ecs verbs (`ecs.insert` / `ecs.set` / `ecs.get`) apply. `mesh` takes a GPU MeshHandle obtained from `meshRef:handle()`; the remaining fields cover visibility, tinting, outline, morph weighting, and shadow participation. ## Fields - `mesh: MeshHandle` — the GPU mesh to render. - `visible: boolean?` - `weightInfluence: number?` — morph-target weight influence. - `tint: { number }?` — `{r, g, b}`. - `tintBlend: number?` - `outline: { number }?` — `{r, g, b}`. - `outlineIntensity: number?` - `castsShadows: boolean?` - `receivesShadows: boolean?` ## Usage ```luau local handle = meshRef:handle() ecs.insert(id, ecs.Mesh{ mesh = handle, tint = { 1, 0, 0 }, castsShadows = true }) ```

# ecs.MorphWeights Spec for the `MorphWeights` component, which maps to the native MorphWeights. How strongly an entity blends each morph target its mesh carries: weight `i` scales target `i`'s per-vertex deltas, and the surface drawn is the mesh's base shape plus the sum of them. Weights are ordered as the mesh's targets are, one per target the mesh carries. `0` leaves a target out, `1` applies it whole, and values between (or past) either end blend it proportionally. Driving a weight over time deforms the surface, and the motion it makes is reported like any other movement. ## Fields - `weights` — one blend weight per morph target, in target order. ```luau ecs.insertSync(id, ecs.MorphWeights { weights = { 1.0, 0.25 } }) ecs.set(id, ecs.MorphWeights { weights = { 0.5, 0.5 } }) ``` ## Driving a shape by name A mesh's targets carry the names they were authored under — for an imported model, the ones its source file gave its blend shapes. Read them in target order with `renderer.mesh.morphTargets(mesh)`, and build this array from weights named by shape with `renderer.mesh.morphWeights(mesh, byName)`: ```luau local mesh = entity(id).component.SkinnedModel.model for i, name in renderer.mesh.morphTargets(mesh) do print(i, name) end ecs.set(id, ecs.MorphWeights { weights = renderer.mesh.morphWeights(mesh, { Eyes_Blink = 1, ["Visemes_Body.AA"] = 0.6 }), }) ``` Shapes left out of `byName` sit at 0, and a name the mesh does not carry errors listing the ones it does.

# ecs.Physics Component spec for `ecs.Physics`, which maps to the native Physics rigid body. It is the first behavior-bearing ecs component: it declares both stored configuration fields (driven through the generic `ecs.insert` / `ecs.set` / `ecs.get` verbs) and a per-entity behavior factory whose imperative methods the `ecs.get` handle exposes. The split follows the behavior tier: stored config goes through the constructor and verbs; per-entity runtime dynamics go through the handle methods below; world queries (raycasts, overlaps) live in the `physics` capability namespace. ## Fields - `bodyType: string?` — `"Static"` | `"Dynamic"` | `"Kinematic"`. - `gravityScale: number?` - `mass: number?` - `linearDamping: number?` - `angularDamping: number?` - `ccd: boolean?` — continuous collision detection, off by default. Sweeps the body along its motion so it cannot pass through thin geometry between steps; costly on any body travelling further than its own thickness per step, so turn it on per body (bullets, thrown props, a wrecking ball). - `interpolation: boolean?` - `lockRotationX / lockRotationY / lockRotationZ: boolean?` - `lockTranslationX / lockTranslationY / lockTranslationZ: boolean?` ## Handle methods `ecs.get(id, ecs.Physics)` returns the generic data handle plus these imperative methods, each bound to the entity's id. A vec3 argument accepts `{x, y, z}` or `{a, b, c}` array form and raises on malformed input. - `applyForce(force)` - `applyImpulse(impulse)` - `applyTorque(torque)` - `applyForceAtPoint(force, point)` - `setVelocity(velocity)` - `addVelocity(delta)` - `getVelocity() -> { x, y, z }?` - `setAngularVelocity(velocity)` - `getAngularVelocity() -> { x, y, z }?` ## Usage ```luau ecs.insert(id, ecs.Physics{ bodyType = "Dynamic", mass = 2, ccd = true }) local body = ecs.get(id, ecs.Physics) body:applyImpulse({ 0, 10, 0 }) ```

# ecs.PhysicsJoint Component spec for `ecs.PhysicsJoint`, which maps to the native PhysicsJoint — a constraint binding this entity's body to another. `connectedEntityId` names the other body; the anchors and axis are single Vec3 fields. The constructor `ecs.PhysicsJoint{...}` builds a value the generic ecs verbs apply, and the component is behavior-bearing: `ecs.get` exposes a motor drive. ## Fields - `jointType: string?` — `"Fixed"` | `"Hinge"` | `"Ball"` | `"Prismatic"` | `"Spring"`. - `connectedEntityId: string?` — the other body to bind to. - `anchorSelf: { number }?` — `{x, y, z}`. - `anchorOther: { number }?` — `{x, y, z}`. - `axis: { number }?` — `{x, y, z}`. - `breakForce: number?` - `stiffness: number?` - `damping: number?` - `restLength: number?` - `regionSelf: { [string]: any }?`: when this entity is a soft body, the particles the joint is anchored on: `{ kind, min, max, point, world }`, `kind` `"Whole"` (the body's frame, the default), `"Box"` (the particles between `min` and `max`) or `"Nearest"` (the particle nearest `point`), in the entity's local space or, with `world = true`, in world space. - `regionOther: { [string]: any }?`: the same for the connected entity, when it is a soft body. ## Handle methods `ecs.get(id, ecs.PhysicsJoint)` returns the generic data handle plus this method, bound to the entity's id. - `setMotor(targetVelocity, maxForce)` — drive the joint motor. ## Usage ```luau ecs.insert(id, ecs.PhysicsJoint{ jointType = "Hinge", connectedEntityId = otherId, axis = { 0, 1, 0 } }) local joint = ecs.get(id, ecs.PhysicsJoint) joint:setMotor(2, 50) ```

# ecs.PlayerOwned Spec for the `PlayerOwned` component, which maps to the native PlayerOwned. Marks an entity as owned by a player. ## Fields - `ownerIdentity` — the owning player's identity (empty for a local marker). ## Usage ```luau ecs.insertSync(id, ecs.PlayerOwned{ ownerIdentity = identity }) ```

# EcsRetargetProfile Spec for `ecs.RetargetProfile` → the native `RetargetProfile` component. The canonical role→bone map that lets a clip authored on one rig drive this body through the shared role vocabulary. A separate component from `Skeleton`: its **presence** on an entity is the gate that says "this rig participates in retargeting" (a humanoid today). A skeleton with no `RetargetProfile` is still a fully working skeleton — it plays clips authored on its own rig directly instead of joining the shared retarget pool. Like every spec under `ecs.components.<Name>`, it describes one Rust component (public name, the Rust type it maps to, and the per-field entries the generic `ecs` verbs use to build and read values) and is registered by the `ecs` module to mint its typed constructor.

# ecs.ShaderData Component spec for `ecs.ShaderData`, which maps to the native ShaderData: four `vec4` lanes an entity's draws carry to its material's shader. The shader reads lane `k` back as `zero_object_data(in.instance_id, k)`, so one material serves many entities that differ in what the lanes hold — an age, a seed, a colour, a mask. The engine attaches no meaning to a lane; the shader and whatever writes the lanes agree on it. A procedural graph's elements carry the lanes through the attributes `data0` .. `data3`, one Vec4 each, so a value made per element reaches the shader of whatever the element becomes. ## Fields - `lane0: { x, y, z, w }?` — read by the shader as lane 0. - `lane1: { x, y, z, w }?` — lane 1. - `lane2: { x, y, z, w }?` — lane 2. - `lane3: { x, y, z, w }?` — lane 3. ## Types - `EcsVec4 = { x: number, y: number, z: number, w: number }` ## Usage ```luau ecs.set(id, ecs.ShaderData{ lane0 = { x = 1, y = 0.5, z = 0, w = 1 } }) ```

# ecs.Skeleton Spec for the `Skeleton` component, which maps to the native Skeleton. Binds an entity hierarchy as a skeleton for skinned animation. ## Fields - `rootEntityId` — the root bone entity (the authored field). - `rootBoneIndex`, `rootBoneReferenceY` — engine-managed root-bone hints. - `cachedTransforms` — engine-managed cached bone transforms. ## Usage ```luau ecs.insertSync(id, ecs.Skeleton{ rootEntityId = rootBone }) ```

# ecs.Sky Spec for the `Sky` component, which maps to the native Sky. Backs solid, gradient, procedural, and skybox-texture skies, selected by `skyType`. ## Fields - `skyType` — selects the sky mode. - `materialName` — material used for the sky. - `timeOfDay`, `autoCycle`, `cycleSpeed` — day/night cycle position and animation. - `syncSunToLight` — drive a directional light from the sun position. - `texture` — skybox texture asset. - `exposure`, `rotation` — sky exposure and orientation. - `solid`, `zenith`, `horizon`, `ground` — Vec3 colors (`{ r, g, b }`) for the solid color and gradient stops. - `sunSize`, `sunIntensity` — sun disc size and brightness. - `starsIntensity` — star field brightness. - `moonSize` — moon disc size. - `turbidity` — atmospheric haze for the procedural sky. ## Usage ```luau ecs.insertSync(id, ecs.Sky{ skyType = "gradient", zenith = { 0.1, 0.2, 0.5 }, horizon = { 0.8, 0.7, 0.6 }, ground = { 0.2, 0.2, 0.2 }, }) ``` Two script components drive this one and carry their own authored fields on top of it: `ProceduralSky` for the editable day/night sky, and `Skybox` for a sky expressed as a material. ```luau entity(id).component.add("ProceduralSky", { timeOfDay = 18.5 }) entity(id).component.add("Skybox", { material = "sky_cubemap" }) ```

# EcsSoftBody Spec for `ecs.SoftBody`, the native soft body the `SoftBody` component drives: the `shape` (a generator, `"Box"`, `"Sphere"`, `"Balloon"` or `"Cloth"`, or `"Mesh"`, the entity's own model filled with tetrahedra), `resolution`, `mass`, `stiffness`, `damping`, the cell `model` of a solid (`"Corotational"`, `"NeoHookean"` or `"Volume"`), `poisson`, the plastic fields `plasticYield`, `plasticCreep` and `plasticMax`, `inflation`, `shapeMatching` (the natural frequency in hertz of the pull back toward the rest shape, 0 for none), `selfContact`, the `repairs` count, `preserveVolume`, `friction`, `restitution`, `collisionMemberships`, `collisionFilter`, `canSleep`, and for `"Mesh"` the `cellSize` of its cells and `collideWith` (`"Cage"` or `"Surface"`). The material (`stiffness`, `damping`, `poisson`, the plastic fields, `inflation`, `shapeMatching`, `preserveVolume`, `friction`, `restitution`, the collision groups) is applied to the running body in place, and a raised `repairs` count restores the shape the body was built in. The other fields are read when the body is built, so writing one rebuilds it at the entity's transform. `attachments` (a list of `{ target, region }` records holding regions of the body to rigid bodies) is applied to the built body without rebuilding it, and applied again to a rebuilt one.

# ecs.Tessellation Spec for the `Tessellation` component, which maps to the native Tessellation. Subdivides the entity's current mesh into `4^level` micro-triangles and displaces them along the interpolated normal from the entity material's displacement map, then flips `MeshInstance.mesh` to the result. The entity's Material renders the tessellated surface unchanged. ## Fields - `level` — subdivision level (0..=6); `4^level` micro-tris per source triangle. Under `mode = "adaptive"` this is the ceiling the derived level stays under. - `displacementScale` — world-units of displacement per unit of sampled height. With no displacement map on the material, the surface is subdivided but left flat. - `mode` — `"static"` holds the authored level; `"adaptive"` re-derives it from the entity's screen coverage each frame. Other values report `status = "rejected_mode"`. - `screenError` — target micro-triangle edge in pixels, which `mode = "adaptive"` picks the level for. - `status` *(read-only)* — system-written lifecycle marker: `""` / `"pending"` / `"ok"` / `"clamped"` / `"too_large"` / `"rejected_mode"`. - `activeLevel` *(read-only)* — the level the installed mesh was baked at. - `outputTriangles` *(read-only)* — triangle count of the installed mesh: source triangles × `4^activeLevel`. - `outputVertices` *(read-only)* — vertex count of the installed mesh: source triangles × the `(n+1)(n+2)/2` lattice a patch carries at `activeLevel`, `n = 2^activeLevel`. ```luau entity(id).component.add("Tessellation", { level = 4, displacementScale = 0.05 }) ```

# ecs.Transform Component spec for `ecs.Transform`, which maps to the native Transform — an entity's position, rotation, and scale. Transform is always present on an entity, so it is read and written through `ecs.get` / `ecs.set` (the generic insert/remove verbs do not apply). Each field is a single Vec3 or Quat passed through verbatim. ## Fields - `position: { x, y, z }?` — translation. - `rotation: { x, y, z, w }?` — quaternion. - `scale: { x, y, z }?` ## Types - `EcsVec3 = { x: number, y: number, z: number }` - `EcsQuat = { x: number, y: number, z: number, w: number }` ## Usage ```luau ecs.set(id, ecs.Transform{ position = { x = 0, y = 1, z = 0 } }) ```

# ecs.TransformConstraints Spec for the `TransformConstraints` component, which maps to the native TransformConstraints. Holds a list of constraint entries that drive an entity's transform from a target — position, rotation, scale, look-at, parent, or aim. ## Fields - `constraints` — the list of active constraint entries. ## Constraint options (`EcsConstraintOpts`) - `type` — `"position"`, `"rotation"`, `"scale"`, `"lookat"`, `"parent"`, or `"aim"`. - `targetEntityId` — the entity to constrain to. - `targetPosition` — an explicit `{ x, y, z }` target. - `axes` — `{ x, y, z }` booleans selecting which axes the constraint affects. - `offset` — `{ x, y, z }` offset applied to the target. - `weight` — constraint blend weight. - `tag` — label used to address the entry later. ## Static methods Entries are added, removed, and toggled through the physics system, so these are descriptor methods that take an explicit entity id and create the component if it is absent. - `add(id, opts)` — add a transform constraint entry to an entity. - `remove(id, tagOrIndex?)` — remove entries; a string removes by tag, a number by index, omitted removes all. - `setEnabled(id, tag, enabled)` — enable or disable constraint entries by tag. ```luau local TransformConstraints = require("modules.api.engine.ecs.components.EcsTransformConstraints") TransformConstraints.add(id, { type = "lookat", targetEntityId = target, tag = "face" }) TransformConstraints.setEnabled(id, "face", false) ```

# ecs.VisibilityRange Spec for the `VisibilityRange` component, which maps to the native VisibilityRange. Restricts an entity to a band of camera distances, so it is drawn only while the camera is inside that band. ## Fields - `near` — closest camera distance at which the entity is drawn. - `far` — furthest camera distance at which the entity is drawn. `0` leaves the entity visible at any distance. ## Usage ```luau ecs.insertSync(id, ecs.VisibilityRange{ near = 0, far = 120 }) ecs.set(id, ecs.VisibilityRange{ far = 300 }) ```

# ecs.WheelCollider Spec for the `WheelCollider` component, which maps to the native WheelCollider. A raycast-based wheel that applies a suspension spring, motor/brake torque, and tire friction to the parent rigid body. ## Fields - `suspensionDistance` — suspension travel. - `springRate`, `damperRate` — suspension spring stiffness and damping. - `targetPosition` — rest position along the suspension travel. - `radius`, `width` — wheel dimensions. - `motorTorque`, `brakeTorque` — drive and braking torque. - `steerAngle` — steering angle. - `forwardFriction`, `sidewaysFriction` — tire grip along and across the wheel. - `rollingResistance` — rolling drag. - `is2D` — constrain the wheel to a 2D plane. ```luau entity(id).component.add("WheelCollider", { radius = 0.35, springRate = 35000, motorTorque = 200 }) ```

# 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.

# 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.

# luau_introspect (module) Parses Luau/asset source TEXT into structured declarations. Pure string/pattern parsing (`string.find` / `string.match` / `string.gmatch`) over the literal source — no compiling, no VM spawn, no runtime state, no engine FFI. Given source text, it extracts what is written in the file. This is the shared parser every per-assetType `M.ref.inspect` hook uses to turn a component/module/tool's own source into the structured record `asset.inspect` returns. ## Exports - `docstrings(src) -> DocMap` — scans `--!desc` / `--!arg` / `--!return` / `--!example` comment runs and binds each run to the name of the declaration on the next non-comment line (the identifier after `function`, `public:`, `local function`, or `M.`). - `publicFields(src) -> { FieldEntry }` — parses `public = { name = Field.<kind>(default, mode), ... }` table-literal entries and module-scope `public.<name> = Field.<kind>(...)` assignments. - `events(src) -> { EventEntry }` — parses `events = { name = Event(payloadSchema?, syncMode?), ... }` table-literal entries. - `methods(src) -> { MethodEntry }` — parses `function public:<name>(...)` / `typed function public:<name>(...)` declarations (params + optional return type). - `lifecycleHooks(src, catalog) -> { string }` — top-level `function <name>(` declarations whose name is in the caller-supplied `catalog` array. - `moduleExports(src) -> { ExportEntry }` — parses `M.<name> = function` assignments, `function M.<name>(...)` declarations, and a trailing `return { foo = foo, ... }` export table. - `forSource(src, computeFn) -> any` — memoises `computeFn(src)` keyed on `src` itself in a module-local table. The same source text returns the cached result without re-running `computeFn`; different source text recomputes. Keyed on the source content (not an asset checksum) because composite/container assets (component folders, scene folders, etc.) all hash to the empty-string checksum — a checksum-keyed cache collapses every such asset's detail onto whichever one was inspected first. ## Usage ```luau local Introspect = require("modules.luau_introspect") local src = self:getInitScript() local detail = Introspect.forSource(src, function(s) return { fields = Introspect.publicFields(s), events = Introspect.events(s), methods = Introspect.methods(s), hooks = Introspect.lifecycleHooks(s, lifecycleCatalog), } end) ``` ## Notes - Every function is a pure string→table transform: same source text in, same structured table out, every time. No reads of live component state, no entity/world queries. - Structural scanning runs over a comment- and string-aware **mask** of the source (a same-length copy where comment bodies and string-literal contents are blanked to spaces, delimiters and newlines preserved). Pattern matches and brace/paren balancing run on the mask — so a brace, `Field.`, `Event(`, or a whole entry that appears inside a comment or a string literal never registers — while captured values are sliced from the original source at the same (aligned) indices. This makes the parser robust to apostrophes in comments, commented-out entries, string defaults containing `}` / `Field.` / `Event(`, and `[[ ]]` long strings. - `default` / `category` are raw trimmed source-text slices (with any trailing comment stripped), not evaluated values. - For a **ref constructor** (`Field.assetRef` / `dataRef` / `resource` / `componentRef`) the FIRST positional argument is the category / contract / componentType selector, captured under `category`; the SECOND argument is captured under `default`. - For every **other** Field kind the first argument is the `default` and `category` is nil. - A trailing `Sync` / `NoSync` identifier is captured as `sync`, tolerating a trailing comma or a trailing comment after the last argument. - Field/Event entries whose key is a computed or indirect expression (`[expr] = Field.number(...)`) are omitted — only literal identifier keys are recognised. - `methods` captures a `...` variadic parameter (as `name = "..."`), with its `: <type>` annotation when present. - A `--!desc` written above a field/event declaration (`<name> = Field.<kind>(...)` / `<name> = Event(...)`) or a `public.<name> =` assignment binds to that name in `docstrings`, and is folded into the corresponding `publicFields` / `events` entry's `desc`. - `lifecycleHooks` never hardcodes the lifecycle-callback catalog; the caller passes the list of names to match against. - `forSource`'s memo is bounded (oldest-key eviction) so a long session touching many distinct asset versions can't grow it without limit.

# assetType.shared.ref Builds the metatable every `AssetRef` (the `{ __ref, type, name, guid, identity, path }` envelope returned by `asset.resolve` / `asset.ref`) carries. Replaces the per-call C metatable that used to live in `crates/zero_scripting/src/ffi/bindings/asset.rs::attach_asset_ref_metatable`. ## Public API ```lua local assetRef = require("@builtin::assetTypes.assetType.shared.ref") -- Called by the Rust factory (push_asset_ref_handle) via -- _G.__build_asset_ref_proxy after the envelope fields are set. assetRef.build(envelope) -- attaches AssetRefMT, returns the table ``` The module exposes no invalidation surface — discovery is registry-driven and hot-reload is transparent (see "Discovery and hot-reload" below). ## Method dispatch order `ref.foo` is resolved in this order: 1. **Default methods** — `getSource` / `getBytes` / `getText` / `exists` / `inspect` and the lazy `meta` property. Per-type definitions cannot override these (engine contract from gh#1889). 2. **Per-type `ref` table** — discovered through `asset.resolve(<typename>, "assetType")` + `require(<identity>.behavior)`. The lookup resolves to whichever `<typename>.assetType/` folder is currently registered for the typename (built-in, user, or library-vendored) and pulls its `ref` methods. 3. **Nil** — unknown key, same shape as the original C metatable. ## Adding methods for a new asset type Drop a `behavior.luau` into the type folder: ``` src/lua/lib/assetTypes/<typename>.assetType/ ├── type.yaml -- structural spec (existing) ├── behavior.luau -- ref + global behaviour (new) └── template/ -- placeholder body (existing) ``` `behavior.luau` returns: ```lua return { ref = { --!desc Per-instance method on every `<typename>` AssetRef. myMethod = function(self, ...) ... end, }, global = { -- Reserved for the asset.<typename>.* surface — not consumed -- yet; included so the contract from gh#1889 lands cleanly. }, } ``` Within `ref` methods, `self` is the AssetRef envelope: `self.path`, `self.identity`, `self.guid`, `self.type`, `self.name` are available. Engine-required fields (`guid`, `path`, `identity`, `type`) must not be redefined. ## Discovery and hot-reload Type discovery uses the asset registry, so it doesn't matter where a `<typename>.assetType/` folder lives — engine built-ins under `@builtin::assetTypes.<X>`, user types dropped under `/zero/source/<X>.assetType/`, or types vendored inside an imported library all resolve identically. The dispatcher walks `asset.resolve(<typename>, "assetType")` → canonical identity → `require <identity>.behavior` on every miss; the asset registry is the cache for the resolve half and Luau's `_LOADED` is the cache for the require half. Hot-reload is transparent. When a `<typename>.assetType/behavior.luau` is rewritten through VFS, the engine's `invalidate_require_cache_for_state` re-runs the module and mutates the cached `_LOADED[<identity>.behavior]` table in place. Dispatch reads `mod.ref` on every access (rather than caching a sub-pointer), so existing AssetRefs see the new methods on the very next access — no Rust-side hook into this module is needed, and no invalidation API is exposed for callers to call. The same registry-driven path also handles type **registration** correctness: dropping a new `<typename>.assetType/behavior.luau` updates the asset registry, the next `asset.resolve(<typename>, "assetType")` returns the new ref, and AssetRefs of that type immediately gain the new methods. ## Why Luau, not Rust The asset surface needed per-category behaviour (`material:getProperties()`, `bundle:instantiate(entityId)`, `tool:run(args)`) and the old shape couldn't grow without an FFI change per method. Owning the proxy in Luau means: - Type-specific methods ship as content (the `<typename>.assetType/` folder), not engine code. - Adding a new asset type drops in a new folder; no Rust rebuild. - Methods can call any other Luau global (`vfs`, `asset`, `Material`, `entity`, etc.) directly, instead of going through narrow FFI primitives. ## Consumers - `crates/zero_scripting/src/ffi/bindings/asset.rs::attach_asset_ref_metatable` — the Rust factory that pushes envelopes invokes `_G.__build_asset_ref_proxy` once per push. - Every Luau call site of `asset.resolve` / `asset.ref` / `entity(id).component.X.material` / any binding declared `AssetRef<...>` — they all receive envelopes built through this module.

# yaml.module YAML decode + encode for authored engine content. Pure Luau, no engine dependencies — a general parsing library, not data-system plumbing. ```luau local Yaml = require("@builtin::modules.yaml") local doc = Yaml.decode(vfs.read(path)) vfs.write(path, Yaml.encode(doc)) ``` ## Supported subset - Block mappings (`key: value`) and block sequences (`- item`), nested to any depth. - Compact sequence-of-mapping entries (`- path: x` / ` kind: y`). - Flow collections — `{ a: 1, b: 2 }` and `[1, 2, 3]` — single line. - Plain scalars with type inference: `~` / `null` → nil, `true` / `false` → boolean, numeric literals → number, everything else → string. - Single- and double-quoted strings (`''` escapes a literal quote inside a single-quoted string; `\n` `\t` `\r` `\\` `\"` inside a double-quoted one). A quote opens a quoted scalar where a scalar begins — after `key:`, after a `- ` entry marker, or inside a flow collection — so a plain scalar carries an apostrophe as data (`note: the world's rules`). Quoted keys are read in flow mappings. - `#` comments — honored outside quotes, so a `#` inside a quoted string is kept as data. - Literal (`|`) and folded (`>`) block scalars — the bare indicators only. A block scalar's content is literal text: quotes (balanced or not), `#`, `key: value` and `---` inside it are data. - An optional leading `---` document marker. ## Loud-error contract Constructs outside the subset above raise instead of misparsing: anchors/aliases (`&`, `*`), tags (`!`), directives (`%`), multi-document streams (a second `---`), block-scalar chomping/indentation indicators (`|-`, `|+`, `>-`, `|2`, ...), tab indentation, and inconsistent indentation (both block structure and block-scalar bodies). Every error carries the offending line number (`yaml: line N: ...`), so a bad config points straight at the line to fix. Tab indentation is rejected everywhere — including block-scalar body lines whose leading whitespace contains a tab. A tab after the first non-space character of a line is content and passes through. ## API - `Yaml.decode(text: string): any` — decode a YAML document into a Luau value (table, scalar, or nil for an empty document). Raises on malformed input or an unsupported construct. - `Yaml.decodeWithComments(text: string): (any, boolean)` — decode as `decode` does, and report whether the text carries a comment by the decoder's own rule: a `#` at a line's start or after whitespace, outside a quoted scalar and outside a block scalar. Re-encoding the value drops such comments, so an editor that writes a document back reads this first. - `Yaml.encode(value: table): string` — encode a Luau table as YAML (block style, two-space indent, alphabetically sorted keys). Raises on values YAML can't represent (functions, userdata, non-string mapping keys). A top-level empty table encodes to an empty document, which decodes back to `nil` (the YAML empty-document ambiguity).

# 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.