# scene.clean Clear the active scene down to a protected keep-set. ```lua scene.clean() -- keep only the player setup scene.clean({ keep = { component = { "Light" } } }) -- also keep lighting scene.clean({ keepPlayer = false }) -- full empty scene.clean({ dryRun = true }) -- preview, no changes ``` By default only the player setup survives (every `PlayerPrototype` subtree and every `PlayerSpawn`), so a clean never orphans the player. `keep` protects a CATEGORY of entities — a `scene.find` query on `component` / `attribute` / `tag` / `under` — not a single named entity. A clean is a LIVE mutation only: it does not write the saved `scene.json`, so `scene.revert` undoes it and `scene.save` commits it. If the scene has unsaved edits, clean refuses (to avoid folding its removals into work no revert could restore) — save or revert those edits first. There is no confirm/force flag. The guard does not apply while play mode runs unpaused. Returns `{ removed, kept, intent }`, plus a `warning` when the clean left the scene with no lights.

# scene.cost Which loaded scene is costing the frame time. Ranks every loaded layer by what its entrypoint's `update` / `editorUpdate` costs, timed where the tick runs and attributed to the layer that owns it — the answer to "the scene is slow and the profiler's script rows do not account for it", because a scene entrypoint's per-frame tick is not a component and does not appear among them. `totalMs` is a sum across the window since the last reset (or engine start) and `avgMs` is the per-tick cost, which is the per-frame cost for a tick that runs every frame. Answers in edit mode as well as play.

# scene.create Create a NEW scene from a template and load it. ```lua scene.create("sandbox") -- returns the template catalog scene.create("level_1", "flat") -- ground + lighting, no player scene.create("arena", "player") -- ground + lighting + default player scene.create("title", "menu", { startup = true }) -- a menu scene the world opens into ``` `template` is typed: `"empty"` (blank canvas), `"flat"` (ground + lighting, no player), `"player"` (ground + lighting + the canonical reusable player a joining user's avatar replaces — prefer this over hand-rolling a player), `"menu"` (lighting only, no ground, no player). Omit the template to get the catalog of templates and what each contains; an unknown value errors with the valid choices. Pass `opts.startup = true` to also make the new scene the world's startup scene. The scene is minted as a fresh asset and loaded. Returns `{ scene, template, contains, startup? }`, or `{ templates }` when the template is omitted.

# scene.find The single entity-discovery tool. It reads the flat live population, so it reaches **runtime clones, temporary entities, and detached roots** — the entities a hierarchy walk from a scene root silently misses. Pick a search axis (each a **list**, so many candidates resolve in one call): ```lua scene.find({ name = { "muzzle", "flash" } }) -- name terms (substring by default) scene.find({ component = { "Light", "Camera" } }) -- entities carrying any of these scene.find({ attribute = { name = "team", value = "red" } }) ``` Multiple axes = union; each hit reports **which** criterion matched, so you learn the right wording. Modifiers: - `substring` (default `true`) — case-insensitive name-part matching, so `"muzzle"` reaches `muzzle_light_ent_620d…`. Set `false` for exact. - `includeInternal` (default `false`) — entities marked internal are excluded unless you opt in. - `roots` — top-level entities only. `maxDepth` — cap the hierarchy depth. - `under` — only descendants of these entities (by name or id). `ancestorsOf` — only ancestors of these. - `additive` (default `false`) — search only the active scene, or set `true` to also search loaded overlay (additive) scenes. - `limit` — cap the returned matches; `total` still reports the full count. ## Projections — `include` By default a hit says *which* entity matched. `include` makes the query answer the question outright, so you inspect a set in **one call** instead of querying and then interrogating each entity: ```lua scene.find({ under = { "room" }, include = { "transform", "componentValues" } }) ``` | Projection | Adds to every match | |---|---| | `transform` | `position = { x, y, z }` (world), `rotation = { x, y, z, w }` (world quaternion), `eulerAngles = { x, y, z }` (degrees), `scale = { x, y, z }` (local), each an **array** | | `componentValues` | `componentValues`: each component's **live** field values, keyed by component name | | `attributes` | `attributes`: the entity's attributes as `{ name = value }` | | `scriptComponents` | `scriptComponents`: every script-component instance the live entity carries, as `{ type, identity, instance }` | The `transform` vectors are arrays, the vector shape the scene and entityOps tools take and report, so a projected `position` passes straight to `entityOps.transform`. Read them by index: ```lua local hit = scene.find({ name = { "crate" }, include = { "transform" } }).matches[1] local x, y, z = hit.position[1], hit.position[2], hit.position[3] -- entity(hit.id).position holds the same value keyed x, y, z ``` Every match already carries `components`, the **names** of its components, without `include`; their live values are the `componentValues` projection. Nothing else is added unless `include` names it. An unrecognised projection is an error listing the accepted ones and naming the one to write instead (`include = { "components" }` points at `componentValues` and `scriptComponents`, `"position"` at `transform`). Projections read the **live** entity, so a component added in the same frame reports its values here even though the entity census has not caught up. Returns `{ matches, total, truncated, searchedAxes }`, each match a `{ id, name, parent, depth, components, layer, matched }` with the FULL canonical id and name, plus whatever `include` asked for. ## Writing the query under its parameter name `scene.find`'s one parameter is named `query`, so the search can also be written under that name. Fields written beside the `query` table join it, and both calls below search the same: ```lua scene.find({ query = { name = { "ground" } }, include = { "transform" } }) scene.find({ name = { "ground" }, include = { "transform" } }) ``` A field written both inside `query` and beside it is refused, naming the field. This replaces the old `find`, `findAll`, and `findByComponent`.

# scene.list List the scene snapshots available in the current world. ```lua scene.list() ``` Returns the array of scene-snapshot names registered in the live world.

# scene.load Load a scene snapshot into the live world. ```lua scene.load("main") ``` Loads via `layers.load(name)` and records `name` as the toolbox's last scene name, so a subsequent no-arg `scene.save()` persists back to the same snapshot. Returns `{ loaded = name }`.

# scene.loadedLayers The scene LAYERS loaded into the live world right now. ```lua scene.loadedLayers() ``` Reports the root scene plus any additive overlays (editor UI, effect passes) currently loaded — one record per layer with its `name`, backing `scene`, `status`, `visible`, whether it is `additive`, and whether it is the `root`. This lists loaded LAYERS (the runtime state), not the scenes available to load — for that use `scene.list`. Returns `{ LoadedLayer }`.

# scene.migrate_v6_to_v7 Converts a v6 scene's `scene.json` to the v7 format, in place and user-initiated only — the migration never runs automatically. v6 scenes carry top-level `player{}` and `camera{}` object blocks; v7 replaces both with a single top-level string `player` intent, either `"spawns"` or `"none"`, decided from the v6 `player.required_in_play` flag. On `"spawns"` it injects the final-shape `PlayerSetups`/`Spawns` structure that mirrors the `scene.assetType` template — a `DefaultSocialPlayer` prototype with a child body carrying the avatar asset and an owner-scoped camera rig, and a `DefaultSpawn` pointing back at it — with injected ids derived from the scene folder so no two converted scenes collide. Every existing entity, the lighting, and the `format` are preserved untouched. It also scans the sibling `entrypoint.luau` for references to the removed player/camera flow and returns the flagged call sites for review without ever rewriting the Luau. It is idempotent and safe: a scene already at version 7 or higher is skipped, and a scene with a missing, too-new, or invalid version is reported as an error without being mutated. Reach for it to bring an old scene onto the current player system.

# scene.observe What every scene load did, and what each loaded scene costs. One read carrying the last load's report — what it produced, the root it replaced and the overlays that went with it, the entity counts on each side, how long each phase took, and every failure it produced with the entity, component or lifecycle hook it is about — plus a per-layer inventory of what the engine attributes to each layer and the per-frame cost of each layer's entrypoint tick. Recorded at each load's own completion point and read lazily, so nothing is measured per frame beyond the tick timings themselves. Answers in edit mode as well as play mode.

# scene.player The scene's player setup, in one tool. ```lua scene.player() -- report: intent + prototypes (body/camera wiring) + spawns scene.player("none") -- playerless scene; removes every PlayerPrototype + PlayerSpawn scene.player("spawns") -- player per joining user; authors the default setup if missing scene.player("spawns", { body = "@builtin::avatars.minimal_player" }) -- swap the avatar scene.player("spawns", { behavior = "@builtin::controller.first_person" }) -- first-person scene.player("spawns", { camera = "my_cam" }) -- wire an existing camera entity ``` The intent is typed: `"spawns"` or `"none"`. `"spawns"` on a scene with no PlayerPrototype authors the canonical setup — humanoid body, third-person camera (OwnerOnly), a spawn at the origin — the same shape a fresh scene ships and the `player` template produces. `"none"` strips the player machinery entirely. A `roles` table (second argument) reshapes the player and implies `"spawns"`: - `body` — an entity name/id to adopt, **or** an avatar asset ref (`@builtin::avatars.minimal_player`) that repoints the body's avatar. A joining user's own avatar replaces this body socket, so reuse the canonical setup rather than hand-rolling one. - `camera` — an entity carrying a Camera component; moved under the prototype and scoped OwnerOnly so each joining user gets their own view. - `behavior` — any `cameraBehavior` component (built-in or authored) set on the player camera's `Camera.behavior`. - `prototype` — picks one when the scene has several. Setting anything saves the scene. The report names the root scene layer's `intent` and `scene` path, and lists every PlayerPrototype and PlayerSpawn the loaded layers hold. In play the scene holds each authored prototype as the captured template a joining player is cloned from; the report lists it through the spawn that names it, with `template = true`. With no scene loaded as the root layer the report carries `unloaded` in place of `intent` and `scene`, saying so and how to load one, and the setters refuse until a scene is loaded. The behavior is attached to the player camera's entity as a component of its own type, so it is tuned there: `component.get("<its type>")` on the camera entity and set its fields. A `component.add` of that type writes its values onto the attached instance instead of adding a second one.

# scene.reload Re-run a loaded scene's build. ```lua scene.reload() -- the active root scene scene.reload("main") -- a named scene ``` `scene.load` of a scene that is already loaded and unchanged is an idempotent no-op, so editing an entrypoint and loading it again rebuilds nothing. This unloads and re-loads the layer in place, running the entrypoint's build again — in edit mode, so iterating on a build script does not mean flipping to play and back through the play shadow. A rebuild saves the scene, the way a write to `build.luau` does: `scene.json` holds what the reload built, so the next play loads it, and unsaved edits in the scene are saved with it. A library scene (under `/libs/`) is rebuilt in the live scene alone, and its files stay as the library states them. Returns `{ reloaded = <name>, built = true, content = n, editorOnly = n, saved = bool }` once the layer has been rebuilt (`saved` is false for a library scene), `{ reloaded = <name>, built = false, reason, message }` when the build did not run, or `{ error = "..." }` when no matching layer is loaded.

# scene.remove Remove entities from the active scene. ```lua scene.remove("ground") -- delete the default floor scene.remove({ "probe_a", "probe_b" }) -- several by name/id scene.remove({ component = { "PointLight" } }) -- every entity with that component ``` Targets are entity NAMES or ids, arrays of them, `scene.find` records, or a `scene.find` query — so you delete a selection without looking it up first. Each target is removed with its whole subtree. A remove is a LIVE edit of the scene: `scene.revert` undoes it, and `scene.save` writes it into the scene's `scene.json`, which is the file `zm add` stages and `zm commit` records. To clear a scene while keeping the player setup, use `scene.clean` instead. Returns `removed`, one `{ id, name }` record per removed target, and `playerHint` when a target was part of the player setup.

# scene.replace Replace a loaded scene's **content** with another scene's content. The target scene keeps its identity (guid, name, place in the world); its files — `scene.json`, `entrypoint.luau`, everything else in the scene folder — become copies of the source's, and the scene reloads so the world reflects the swap immediately. ```lua scene.replace("@builtin::scenes.test_arena") scene.replace("my_template", { dryRun = true }) scene.replace("my_template", { scene = "hud_overlay" }) ``` Targets the active scene unless `opts.scene` names another loaded scene. Target content files the source doesn't have are removed; identity sidecars are untouched. `dryRun = true` reports exactly which files would be written and removed, plus the entities the source declares, without touching anything.

# scene.revert Discard a scene's unsaved edits and restore its saved `scene.json`. ```lua scene.revert() -- undo unsaved edits on the active scene scene.revert("main") -- revert the loaded scene named 'main' ``` The undo for `scene.clean` / `scene.remove` and any edit-mode change, and the counterpart to `scene.save`. Every edit since the last save lives in the scene's dirty overlay until you commit it; this throws that overlay away and respawns the scene from its saved state. Because the dirty overlay belongs to the scene ASSET (not the runtime layer), a revert works whether or not the scene is currently loaded — pass a `name` to revert a specific scene, or omit it for the active one. This reverts only the edit-mode dirty overlay; it is not the play-mode baseline restore. Returns `{ scene, discarded }` — `discarded` is true when unsaved edits were thrown away, false when the scene was already clean.

# scene.save Save the loaded scene named `name` back to its own `scene.json`. ```lua scene.save() -- the last-used scene name (initially "main") scene.save("main") ``` Resolves the scene by name via `layers.find` and saves that scene — saving scene A never writes scene B. Errors when no scene by that name is loaded. Returns `{ scene = name }`.

# scene.setStartup Make the currently active scene the world's startup scene. ```lua scene.setStartup() -- pin the active scene as the world's entry point ``` Takes no arguments: it pins whatever scene is live now as the scene the world auto-loads every time it loads, so after building or loading a scene you call this to make it stick across world reloads. There is no clear/unset — a world with no startup scene has no scene context and every script fails, so that is not a valid choice. The current startup scene shows in `scene.summary`. Returns `{ scene }` — the name of the scene now set as the world startup.

# scene.toolbox shared module Cross-tool sharing for the `scene.*` toolbox: the hierarchy snapshot core (`snapshot`, `findAll`, `leaf`) that backs tree / findAll / findByComponent / summary, and the last-scene-name state that save / load share. Tools call these functions; the functions call engine APIs.

# scene.spawns The scene's spawn points. `scene.player` decides whether a scene spawns players and what they become; this decides **where they arrive** — the PlayerSpawn entities themselves. ```lua tools.use("scene", "spawns") -- report every spawn tools.use("scene", "spawns", "add", { position = { 12, 0, -4 } }) tools.use("scene", "spawns", "set", { spawn = "DefaultSpawn", rotation = { 0, 90, 0 } }) tools.use("scene", "spawns", "remove", { spawn = "RedSpawn" }) ``` ## What a spawn decides - **Its transform** — where a joining player's body lands while `placement` is `at_spawn_transform`, and its forward axis is the direction they face. The edit-mode debug overlay draws that as a ring, a heading arrow and a standing capsule, so a spawn is visible where it stands. - **Its prototype** — which PlayerPrototype subtree gets instantiated for the joining user. A spawn whose prototype is unset or no longer resolves cannot spawn anyone; the report says so (`prototypeResolves`) and the overlay draws it red. In play the scene holds the prototype as the captured template each joining player is cloned from, and the spawn's prototype resolves to that template. - **team / role / maxPlayers / spawnPolicy** — the PlayerSpawn component's own fields, carried onto the players it spawns. ## Picking a spawn `opts.spawn` names the spawn to act on, by name or id. With one spawn in the scene it is implied; with several it is required, and an unmatched name is an error listing what the scene has. On `"add"` the same field names the new entity instead. New spawns are parented alongside the spawns already in the scene (else under the scene's `Spawns` container), so spawn points stay collected in one place. Mutating saves the scene.

# scene.summary High-level "what's in the scene" report, and the call that counts the entities in the scene or in one group of it. ```lua scene.summary() scene.summary({ limit = 0 }) scene.summary({ under = "level_1", limit = 5 }) scene.summary({ under = "level_1", fields = { "entityCount" } }) ``` Returns `{ entityCount, rootCount, roots, truncated, more?, under?, activeCamera, player, startupScene }`: the visible entity count, the top-level rows (with their hierarchy fields), the active camera id, the player setup with the verb that changes it, and the world's startup scene. `roots` carries at most `limit` rows, 20 when the call names none. `limit = 0` answers the counts, camera, player and startup scene alone, the read to make when the rows are not the question. `rootCount` is always the full count, and `truncated` with `more` says when rows were left out. An answer to a call naming neither `limit` nor `fields` carries `narrowWith`, the options that shorten it. `under` names entities (an id, a name, a proxy, or an array of them) and scopes the report to what is beneath them: `entityCount` counts their descendants and `roots` holds their children. A reference that names no entity is refused by name. `includeInternal = true` counts entities marked internal too. `fields` keeps only the named fields of the answer: `{ fields = { "entityCount" } }` answers the count alone, the cheapest read to repeat while a scene changes. A name no answer carries is refused, and the refusal lists the fields. For the full structure, `scene.tree` renders the hierarchy itself, and `scene.find { roots = true }` lists every root.

# scene.tree Render the entity hierarchy as an indented tree — the quick "what is the current structure" view. ```lua scene.tree() -- the whole active world, 4 levels scene.tree("player") -- just the player subtree(s) scene.tree(nil, { depth = 2 }) -- roots + their direct children ``` Each line shows the entity's name and its component types; children nest under their parent. Anything deeper than `depth` (or beyond the node budget) is summarized as an explicit `… +N below` count instead of being silently dropped. Options: ```lua { depth = 4, -- levels to expand (1 = just the roots) components = true, -- annotate each entity with its component types includeInternal = false, -- include entities marked internal (and their subtrees) limit = 500, -- node budget } ``` Returns: ```lua { text = string, -- the rendered tree (print this) roots = { { id, name, components?, childCount, children?, omitted? } }, total = number, -- entities in scope (full subtrees) shown = number, -- nodes rendered truncated = boolean, -- depth or budget cut something } ``` The target is an entity id, a name (every matching entity), a proxy, or an array of them; omit it for the whole world from its roots. Children sort by name, so repeated calls give stable output.

# scene.whyPartial Answer why a loaded layer is not whole. Returns the nearest cause from a closed set — `loaderRaised`, `entrypointCompileFailed`, `entrypointBodyRaised`, `entrypointRaised`, `buildRaised`, `entityFailed`, `parentMissing`, `parentRefused`, `parentAbandoned`, `componentUnresolved`, `componentRefused`, `subscriberRaised`, `updateRaised` — with the engine's own words for it and the full list of failures, each naming the entity, component identity or lifecycle hook it is about. A layer that produced everything its scene declared reports `ok = true` and no reason.

# Toolbox (asset type) A toolbox is a namespace folder that groups related `.tool/` children plus shared helpers. Toolboxes are the addressing layer for tools — every tool's identity is `<toolbox>.<name>`, so the toolbox name appears in every callsite. Toolboxes also own a `shared.module/` helper module that the toolbox's tools `require(".shared")` for common utilities (result envelopes, validators, formatters). ## When to use one - You have two or more related tools that belong together (an `anim` toolbox with `play` / `stop` / `list`; an `assets` toolbox with `compose` / `validate`). - You need a shared helper module exclusively used by a tool set. - You want a clean dot-namespaced identity for your tools (`my_tools.foo`, `my_tools.bar`). If you only have one tool and no shared helpers, you still need a toolbox — it's the required parent. ## Where it lives - Source: `/zero/source/.../<Name>.toolbox/` - Identity: `<Name>` (the `.toolbox` suffix strips). - Folder shape (container-style — open child set): - `README.md` — instance documentation. **Required.** - `.metadata` — agent-editable tags + free-form fields. **Required.** - `shared.module/` — optional shared helper module (`init.luau` + `README.md`). - `<x>.tool/` — any number of `.tool/` children. The validator permits unlisted children (`allow_unlisted: true`) so tool subfolders don't need to be declared per-name. ## How to create one ```luau tools.createToolbox({ name = "<Name>", description = "..." }) -- or the generic scaffold: asset.create("toolbox", "<Name>") -- Creates: /zero/source/<Name>.toolbox/ -- README.md (instance README template) -- shared.module/ (ok / fail result-envelope constructors) -- `folder` places it in a subfolder of /source; `into` nests it in a -- resolved `.package`: asset.create("toolbox", "<Name>", { folder = "tools" }) ``` Then add tools under it: ```luau local box = asset.resolve("<Name>.toolbox") asset.create("tool", "<toolName>", { into = box }) ``` ## How it operates 1. **Registration.** Writing into a `.toolbox/` folder indexes the toolbox. It becomes the parent namespace for any `.tool/` children. 2. **Tool identity composition.** Each child `.tool/`'s identity is `<toolbox>.<tool>`. Listing the toolbox's tools enumerates the children. 3. **Shared helpers.** Tools inside the toolbox pull `shared.module/` in via `require(".shared")` (relative require from the tool's `init.luau`). 4. **Hot reload.** Editing `shared.module/init.luau` reloads every tool in the toolbox (they all `require` it). Editing the toolbox folder structure (adding / removing tools) reflects in `tools.list` immediately. ## Discovery - `asset.list("toolbox")` — every registered toolbox. - `asset.inspect("<name>")` — child tools, source, this type README. - `ls /zero/source/<Name>.toolbox` lists the files the folder holds. - `tools.list()` — every tool across every toolbox. ## Authoring conventions - **Per-tool implementation lives in each `<x>.tool/init.luau`.** The tool's full function body — argument validation, the call into engine APIs, the return value — goes in `init.luau` with `--!desc` / `--!arg` / `--!return` / `--!example` annotations above the function. **Every exported function is declared `typed function`** — the keyword compiles to the runtime argument check, so a plain `function` accepts any input and reports success on garbage. Do NOT make `init.luau` a one-line forwarder onto a function defined in `shared.module/`. - Keep `shared.module/` thin: result envelope constructors (`shared.ok(value, formatted)`, `shared.fail(message, exitCode)`), argument validators, common formatters — anything genuinely used by more than one tool. Per-tool logic does NOT belong here. - Group by domain, not by surface — `assets` toolbox holds asset operations, `entity` toolbox holds entity operations. Tools that feel unrelated probably want different toolboxes. - Document the toolbox's surface in `README.md` — what problem space it covers, who calls into it, any shared invariants. ## Common pitfalls - **Missing parent toolbox.** Tools cannot exist outside a toolbox. Always scaffold the toolbox first. - **Cross-toolbox shared.** Each toolbox has its own `shared.module/`. Don't try to share helpers across toolboxes; if you need cross-toolbox helpers, factor them into a standalone `.module`. - **Toolbox identity.** Strip the `.toolbox` suffix in identity references (`my_tools`, not `my_tools.toolbox`). ## Related types - `.tool` — the required child(ren) of a toolbox. - `.module` — for cross-toolbox utilities. ## In the Inspector Tools: how many tools the box holds, whether it ships a shared module, what each tool does, and a link to each tool.

# Tool (asset type) A tool is a single agent-callable function whose schema is its `typed function` signature. Tools are the workflow surface — composed Luau operations that bundle multiple engine APIs into one named call, suitable for agents (and for use from `execute`). Each tool has a declared input shape, return shape, and a strict result envelope (`ZmToolResult`). **Every exported tool function is declared `typed function`.** The `typed` keyword is what makes the signature real: it compiles to a runtime dispatch wrapper that checks each argument against its declared type and raises on a mismatch. A plain `function` — even one carrying Luau type annotations — is checked by nothing at call time, so the tool accepts any input and reports success on garbage. See "The typed signature is the schema" below. ## When to use one - You're composing several engine APIs into a workflow that's worth naming and discovering (`tools.list`, `search_tools`). - You want an agent to be able to call this function by name without reading source code — the typed signature is the API contract. - The operation has clear success / failure modes that fit `{ exitCode, data?, stdout?, message? }`. If the function is just a Luau utility called from other code, use a `.module`. If it's stateful background work, use a `.service`. If it's pure GPU compute, use a compute `.shader`. ## Where it lives Tools nest under a `.toolbox/` parent — toolboxes are the namespace. - Source: `/zero/source/.../<Toolbox>.toolbox/<name>.tool/` - Identity: `<Toolbox>.<name>` (dotted form — the toolbox name is part of the tool identity). - Folder shape: - `init.luau` (or `init.lua`) — exports the function, and carries its schema in `--!desc` / `--!arg` / `--!return` / `--!example` annotations above it. The typed signature IS the tool's signature. **Required.** - `README.md` — instance documentation. **Required.** - `.metadata` — tool-level tier and tags. **Required.** ## How to create one Use the workflow tool that scaffolds the right `.tool/` shape under an existing toolbox: ```luau -- The `tools` global authors a tool inside an existing toolbox: tools.create({ name = "<name>", toolbox = "<Toolbox>", description = "What this tool does, agent-facing.", code = "return shared.ok(true)", -- the function body }) -- Or scaffold the folder manually: local box = asset.resolve("<Toolbox>.toolbox") asset.create("tool", "<name>", { into = box }) ``` Always nest under an existing toolbox — if you don't have one yet, call `tools.createToolbox({ name = "<Name>", description = "..." })` first. ## How it operates 1. **Registration.** Writing `init.luau` into a `.tool/` folder registers the tool with the tools registry. It becomes callable as `tools.use("<toolbox>", "<name>", ...)` from Luau, `use_tool { toolbox, tool, args }` over MCP, and `zero <toolbox> <name> [args]` from the engine shell. 2. **Schema validation.** The `typed function` signature declares the parameter shape. Its runtime dispatch wrapper checks each argument before the body runs and raises a message naming the argument, the expected type, and what arrived. 3. **Return envelope.** Tools MUST return `ZmToolResult`: ``` { exitCode = 0|n, data? = any, stdout? = string, message? = string } ``` `exitCode = 0` means success; non-zero means failure, with `message` carrying the human-readable reason. 4. **Discovery.** The tool surfaces in `tools.list()`, `search_tools { query: "..." }`, and `asset.inspect`'s `exposes:` section (parsed from the typed signature and the `--!` annotations). 5. **Hot reload.** Editing `init.luau` re-registers the tool. Subsequent calls see the new behaviour / schema. ## Discovery - `tools.list()` — every registered tool (any toolbox). - `search_tools { query: "..." }` — MCP-side tool search. - `asset.list("tool")` — same set, asset-style listing. - `asset.inspect("<toolbox>.<name>")` — signature, parameters, return shape, this type README. - `ls /zero/source/<Toolbox>.toolbox/<name>.tool` lists the files the folder holds. ## Authoring conventions - **Implementation lives in `init.luau`.** The tool's full function body — argument validation, the call into engine APIs, the return value — goes in `init.luau`. The toolbox's `shared.module/` is for genuinely cross-tool helpers (`ok` / `fail` constructors, shared parsers / validators), not per-tool logic. Do NOT make `init.luau` a one-line forwarder onto a function defined in `shared.module/`. - Use `shared.module/` in the parent toolbox for `ok` / `fail` result constructors. Don't hand-roll the envelope per tool. Pull it in with `local shared = require(".shared")` from any tool that needs the helpers. - Annotate every public function with `--!desc` / `--!arg` / `--!return` / `--!example` directly above the function — the LSP and toolbox surfaces extract these. - **Declare every exported function `typed function M.name(arg: T, opt: U?): R`.** This is not conditional on the signature being "clear" — a loose argument is the case that needs the checked contract most. Give the argument the type it actually accepts (a union, a named table type, a literal enum) instead of dropping to an unchecked `function`. - Keep tools focused. One tool, one named workflow. Split rather than grow. - Tag tools in the sibling `.metadata` (`{ "tags": [...], "tier": "core|content|specialized" }`) so `search_tools` can find them by domain (e.g. `entity`, `scene`, `assets`, `physics`). ## The typed signature is the schema The `typed` keyword compiles the function into a dispatch wrapper that validates arguments at call time. Without it there is no check at all, so the tool runs its body on whatever arrived and returns a success envelope built from garbage. Type each argument as narrowly as the operation actually accepts: ```luau export type Mode = "edit" | "play" export type SpawnOpts = { position: { number }?, parent: EntityRef?, count: number?, } --!desc Spawn a primitive and return the entities it created. --!arg kind Primitive shape to spawn. --!arg opts Placement and repetition options. --!return The spawned entity refs. --!example "cube", { count = 4 } typed function M.spawn(kind: ("cube" | "sphere" | "plane"), opts: SpawnOpts?): { EntityRef } ``` - **A fixed set of accepted words is a literal union**, never `string`. `("cube" | "sphere")` rejects `"Cube"` at the call and lists the accepted values in the error; `kind: string` accepts `"banana"` and fails somewhere deeper, or not at all. - **A structured argument is a named `export type`**, never `{ [string]: any }`. Naming it puts every field and its type on the tool's page and checks them on entry. - **A named type is only as strong as its fields.** `opts: DrawOpts` where `DrawOpts = { value: any }` passes for a table and checks nothing inside it — the same hole, one level down. The argument checker walks nested fields, so type each one; a type name is not a place to put the work off. - **A dispatch table keyed by an `op` string is several tools.** `{ op: string, [string]: any }` is one unchecked entry point wearing N signatures — split it so each operation carries its own checked arguments. - **An entity or asset argument is `EntityRef` / `AssetRef<kind>`**, never `any` and never a bare name string. - `any` is correct only for a value the tool genuinely does not constrain — a passthrough payload, arbitrary user data. It is not a placeholder for a type not yet written down. ## Common pitfalls - **A plain `function` export.** The tool registers and dispatches, so nothing looks wrong — it just never rejects bad input, and every call reports success. Declare it `typed function`. - **Annotations without `typed`.** `function M.f(x: string)` reads as typed and checks nothing at runtime; the annotation only informs the LSP. The keyword is what enforces it. - **Wrong return envelope.** Returning a raw value instead of `{ exitCode = 0, ... }` will be flagged by callers expecting `ZmToolResult`. - **Tool identity.** The fully-qualified identity is `<toolbox>.<name>`, NOT just `<name>`. Toolbox-less tools don't exist by design. - **Missing dependency.** Tools requiring another package / service must declare it; otherwise the call fails at runtime with a missing-module error. ## Related types - `.toolbox` — the required parent namespace for tools. - `.module` — for Luau libraries with no agent-facing schema. - `.service` — for stateful background work, not callable request/response operations. ## In the Inspector Tool: how the tool is called (its signature), what it does, each argument, what it returns, and its examples, with **Open** for its source.

# 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**.

# shared Cross-tool helpers for the [name] toolbox. Every tool inside the toolbox can pull these in with `require(".shared")`. Holds the small set of helpers that more than one tool needs — typically the `ok(value, formatted?)` / `fail(message, exitCode?)` constructors that produce the canonical `[name]ToolResult` shape, plus any toolbox-wide parsers, validators, or shared state. Per-tool implementation stays inside each `<x>.tool/init.luau`; this module is not a place to forward logic from. ## Exports - `M.ok(value: any?, formatted: string?) -> [name]ToolResult` — success envelope (`exitCode = 0`, `ok = true`). - `M.fail(message: string, exitCode: number?) -> [name]ToolResult` — failure envelope (`exitCode` defaults to 1, `ok = false`). Types: - `[name]ToolResult = { stdout: string, stderr: string, exitCode: number, ok: boolean, value: any? }` - `stdout` — human-readable formatted output; empty when the op produces no text. - `stderr` — error message on failure; empty on success. - `exitCode` — POSIX-style exit code: `0` success, `1` generic failure, `2` bad arguments. - `ok` — `true` iff `exitCode == 0`. - `value` — structured return from the underlying op; `nil` for void ops. ## Usage ```luau local shared = require(".shared") function M.someTool(args) if not args.id then return shared.fail("missing id", 2) end return shared.ok({ id = args.id }, "created " .. args.id) end ``` ## Notes - Pure constructors — no engine calls, no state. Safe to call from any context. - Tools that opt into this shape get a stable envelope every other tool in the toolbox can rely on. Tools that do something custom can return whatever shape they want — `[name]ToolResult` is opt-in. - Per-tool implementations still own their own `--!desc` / `--!arg` / `--!return` / `--!example` annotations even when their result is constructed through these helpers.

# 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.

# volumetrics Volumetric (3D-texture) rendering, end to end, in one package. Built entirely on the engine's generic `compute.*` GPU primitives — no Rust changes are needed to author new volumetric content. ## Layout | Asset | Identity | Role | |---|---|---| | `Volume.component` | `@builtin::systems.volumetrics.Volume` | Attach a 3D voxel texture to an entity; raymarches it through the entity's transform AABB. | | `VolumetricSky.component` | `@builtin::systems.volumetrics.VolumetricSky` | Singleton procedural cloud layer with TAA. | | `ParticipatingMedium.component` | `@builtin::systems.volumetrics.ParticipatingMedium` | Mark an entity as fog/smoke/dust that attenuates the light passing through it. | | `mediaTransmittance.module` | `@builtin::systems.volumetrics.mediaTransmittance` | Light-space optical-depth map: the registry, the settings, and the basis the map is built in. | | `mediaShadow.renderFeature` | `@builtin::systems.volumetrics.mediaShadow` | Builds the optical-depth map and attenuates each surface by the density in front of it. | | `volume.module` | `@builtin::systems.volumetrics.volume` | Builders (`noise`/`sphere`/`box`/`wrap`) + the `.zvol` header reader + occupancy + brick paging + the per-entity raymarch dispatch. | | `VolumeSequence.component` | `@builtin::systems.volumetrics.VolumeSequence` | Play an open volume sequence through an entity's transform AABB. | | `volumeSequence.module` | `@builtin::systems.volumetrics.volumeSequence` | A run of `.zvol` frames streamed through a fixed ring of resident volumes. | | `volumeDemos.module` | `@builtin::systems.volumetrics.volumeDemos` | Shared pipeline for the showcase scenes (fill + emissive raymarch + composite). | | `volumetricSky.module` | `@builtin::systems.volumetrics.volumetricSky` | Cloud volume + raymarch + TAA + composite orchestration. | | `shaders/*.shader` | `@builtin::systems.volumetrics.shaders.*` | `volume_raymarch`, `volume_pages`, `volume_pack`, `cloud_noise[_v3/_v5]`, `cloud_raymarch[_v3/_v4/_v5]`, `cloud_taa`. | | `importers/vdb_to_zvol.importer` | (auto-discovered) | `.vdb` → dense `.zvol` via the `openvdb` WASM plugin (procedural fallback when the plugin isn't loaded). | | `presets/cumulus_default.preset` | `@builtin::systems.volumetrics.cumulus_default` | Canonical full `VolumetricSky` weather preset. | | `demo/*.scene` | `@builtin::systems.volumetrics.demo.*` | `sdf_solids`, `smoke_plume`, `nebula`, `godrays`, `zvol_viewer`, `sky`. | ## Path convention — fully-qualified builtin identities Every intra-package reference uses the asset's fully-qualified builtin identity, the same convention every other builtin package follows: ```luau local Volume = require("@builtin::systems.volumetrics.volume") local Sky = require("@builtin::systems.volumetrics.volumetricSky") local V = require("@builtin::systems.volumetrics.volumeDemos") -- shader identities, e.g. asset.resolve("@builtin::systems.volumetrics.shaders.volume_raymarch") ``` Qualified identities are caller-independent: they resolve identically from a module, a scene entrypoint, or a component. Caller-relative (`.sibling`) requires are deliberately avoided here because the component runtime caller identity is `@builtin::components.<Name>`, so a `.sibling` require from a component resolves against the wrong root. (An earlier revision of this package used a `~volumetrics` package-root alias for relocatability; that alias is not resolvable on current main, so the package uses qualified identities throughout.) ## Usage ```luau -- Per-entity volume. The component resolves the name through `Volume.get`, -- so a volume paged into a brick pool renders from the pool under the same -- name: local Volume = require("@builtin::systems.volumetrics.volume") local cloud = Volume.noise({ name = "cloud", size = 64, scale = 4 }) cloud:buildSparse({ brickSize = 8 }) cloud:releaseDense() entity(id).component.add("Volume", { volumeName = "cloud", density = 6.0 }) -- Procedural sky: local sky = entity.spawn("sky") sky.component.add("VolumetricSky", {}) preset.apply("cumulus_default", { entity = sky.id, component = "VolumetricSky" }) -- VDB import: drop a `.vdb` into the VFS; the importer writes a `.zvol` -- alongside it. Load it with the zvol_viewer demo scene. -- Animated run: one `.zvol` per frame, played through a bounded ring. local Seq = require("@builtin::systems.volumetrics.volumeSequence") Seq.open({ name = "plume", frames = framePaths, resident = 3, fps = 24 }) entity(id).component.add("VolumeSequence", { sequenceName = "plume", density = 6.0 }) ``` ## Plugin dependency The VDB importer delegates real OpenVDB parsing to the `openvdb` plugin in the builtin library, `@builtin::plugins.openvdb`. Without the plugin the importer falls back to a deterministic procedural torus so the pipeline stays functional.

# Baseline Visual Validation harness scene for the [player-camera-unification PR](../../../../docs/plans/2026-05-01-player-camera-unification.md). ## Purpose Visual smoke target for Steps 4–9 of the §17 migration plan. Those steps land *before* §17 step 10 (the generic `camera_spawner` / `player_spawner` that auto-populate scenes with a viewport camera). Without this scene, those intermediate commits have no working viewport to validate against and the boot path produces a single bare `Player` entity that renders nothing. `layers.load("@builtin::scenes.baseline_visual")` brings in: - A `Camera`-bearing entity (`baseline_camera`) at a fixed third-person framing of the origin. Renders to viewport. - A static-collider ground plane (`baseline_ground`) so the character controller has something to stand on. - The engine's default `Player` entity (spawned by `ensure_default_player`) with the two canonical tagged bundles applied: - `@builtin::players.humanoid_visual` — mesh + skeleton + `Locomotion` - `@builtin::players.standard_controller` — `MovementState` + `CharacterController` All spawned entities are `temporary` so `layers.active:save()` doesn't bake them into a persisted `.scene/` file. ## Cleanup path | Step that lands | What changes here | |---|---| | §17 step 10 (`camera_spawner` / `player_spawner`) | The hardcoded camera spawn becomes redundant — drop it; the spawner takes over. Bundle application becomes a no-op smoke check. | | §17 step 3 (`.player/` retirement) | No effect — this scene already references the new tagged bundles. | | End of PR | Either kept as the canonical engine smoke target or deleted in Step 16's test-suite extensions. |

# [scene_name] One-paragraph description of what this scene is — the level, screen or area it represents, and when the world loads it. This README describes *this* scene; what a scene is and how loading works live in the scene assetType README. ## Contents - What the entity hierarchy holds — the terrain, props, lights and spawn points a reader should expect to find. - Which player intent `scene.json` declares (`"spawns"` places the local player and its camera on join; `"none"` leaves both to the entrypoint). ## Entry point - `entrypoint.luau` — what it sets up when this scene loads, and anything a caller has to do before loading it.

# 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.

# hdrChart The synthetic HDR chart as a scene: `@builtin::shaders.post.hdrChart` drawn in place of everything, first in the post chain, so the display path is read against known light with no lighting in between. ## Contents - `HdrChart`: a `PostProcess` holding the chart at priority -1000 as its colour wedge (`pattern = 3`): eleven columns from -4 to +6 stops, the top half a saturated blue light at the column's middle-grey luminance and the bottom half that grey. Change the pattern with `postprocess.setProperty` on the effect, or draw the chart from code with `postMetrics.chart.show`. - `ReferenceCamera`: a camera to hold the viewport; the chart covers the whole frame it draws. The scene's `player` intent is `none`. `postMetrics.chart.reference` builds the picture a display curve should present for the chart, which `postMetrics.flip` holds the presented chart against.

# exposureWedge The exposure reference: known light, read at any exposure. ## Contents - `GreyWedge`: 21 patches of middle grey (0.18) at -10..+10 stops, one stop per patch, left to right (`postReference_greyWedge`, unlit). - `ColorChecker`: the 24 ColorChecker Classic patches, each its published sRGB value as linear reflectance (`postReference_colorChecker`, unlit). - `GreySphereLeft` / `GreySphereRight`: two 18% grey spheres lit by `Sun`, a white directional light of intensity 1 from over the camera's left shoulder. - `ReferenceCamera`: the station every reading is taken from, an isolated camera on black with no ambient term, so the light in the frame is the charts' own and the sun's. The scene's `player` intent is `none`. Put the viewport on the camera with `camera.setEditorOverride(entity.find("ReferenceCamera").id)`, or capture it with `capture.fromCamera`. Sweep `__display__`'s `exposure` by powers of two to walk the wedge through the display curve.

# oceans A sea and the ground under it, as one package: the wave simulation, the surface that renders it, the seabed it is seen through, and the answer to "how high is the water here" that gameplay needs to float things on it. ```lua local Ocean = require("@builtin::systems.oceans.modules.ocean") Ocean.create({ preset = "gale" }) ``` That is a whole ocean — waves out to the horizon, foam on the breaking crests, a seabed below, and a surface that follows whoever is looking at it. To float something on it: ```lua local ocean = Ocean.forEntity(oceanEntityId) boat.position = { x, ocean:sampleHeight(x, z), z } ``` It is a building block. The sun the water glitters under, the ambient its foam sits in and the sky it reflects all come from the scene, through the same directional light and reflection probes every other material in the engine reads — so an ocean drops into a world that already has lighting instead of bringing a second set, and changing the scene's light changes the water with it. ## What it does The simulation is **spectral**: instead of animating individual waves, it builds the sea's energy across every wavelength and direction from an oceanographic spectrum, then inverse-transforms that into a height field. A real sea is what comes out — wind speed alone decides wave height, and it rises with wind the way a fully developed sea does, following the Pierson–Moskowitz law. It runs in **cascades** — independent wave fields over different patch sizes, each band-limited to its own range of wavelengths. A tile of roughly two kilometres carries the long waves and one of a few hundred metres the short ones; they sum into a surface with detail at every scale, and because the bands are disjoint no wavelength is synthesised twice. Above them a **Gerstner bank** adds the swell analytically, which no cascade can hold: a wave longer than its own patch has nowhere to live, and swell arrives from a distant storm on its own heading anyway. **Foam** is not painted on. It comes from the Jacobian of the wave displacement: where the surface folds over itself, the wave is breaking. Whitecaps appear where and when the geometry actually breaks, accumulate into a persistent world-space field, and streak behind the crest as they decay. **Colour and transparency are the same mechanism.** Per-channel Beer–Lambert extinction over the distance light travelled through water gives both — red dies within a metre, blue survives tens. That is why shallow water over sand reads turquoise and the open sea reads near-black blue without switching materials. **The seabed** is one noise field read twice: scaled it is the terrain's relief, unscaled it picks between sand and rock, so outcrops stand on the high ground and sand fills the hollows. The sun's caustic web moves over both, bent by the horizontal displacement of the water directly above it. Bodies land on it: the pass that raises the ground writes the same field out as a height patch that travels with the viewer, so what a body stands on is what the frame drew. Nothing here ships an image. Every map the surface and the seabed sample — the foam patterns, the sand, the rock, the caustics — is grown on the GPU at startup. ## The pieces | Asset | What it is | |---|---| | `components/Ocean` | Puts a sea on an entity. Its fields are the sea state; the simulation is rebuilt from them, so an ocean survives a scene reload. | | `modules/ocean` | The substrate: `attach`, `create`, `forEntity`, `sampleHeight`, `sampleDisplacement`. | | `components/Buoyancy` | Floats a rigid body on the sea. Its fields are the hull: how dense it is, how steady, and what box displaces water. | | `modules/buoyancy` | The forces: `attach`, `forEntity`, `columns`, `submergedFraction`, `restingY`. | | `modules/oceanPresets` | Nine named sea states, from `calmClear` through `gale`. | | `modules/oceanQuality` | The four tiers — how finely a sea is resolved, as distinct from what sea it is. | | `modules/oceanClipmap` | The camera-following ring geometry both the surface and the seabed are built on. | | `modules/oceanFloor` | The seabed: terrain, ground materials, caustics and the ground physics collides with. | | `modules/oceanScene` | The seam between the scene capture and the materials that sample it. | | `shaders/oceanSurface` | The water: cascade normals, absorption, exact dielectric Fresnel, subsurface scattering, sun glitter, foam, and the view from below. | | `shaders/oceanFloor` | The seabed: sand and rock blended by terrain noise, under a caustic web. | | `materials/oceanWater`, `materials/oceanSeabed` | The default looks. | | `renderFeatures/oceanScene` | Copies the frame's colour and depth so the surface can refract what is behind it and measure its own water column. | | `computeShaders/ocean_*` | The ten-stage GPU pipeline. | ## Wind is the control Significant wave height goes as the **square** of wind speed, so that one field does most of the work: | Wind | Sea | Wave height | |---|---|---| | 3 m/s | glassy, a mirror | ~0.2 m | | 11 m/s | working sea, occasional whitecap | ~2.5 m | | 24 m/s | gale, breaking and streaked | ~12 m | Everything else shapes character rather than size: `choppiness` pinches crests into peaks, `standingWaveRatio` runs waves both ways instead of only downwind, `jonswapGamma` sharpens a fetch-limited sea, and the foam layers decide how readily a breaking crest whitens and how long it streaks. Read `documentation/oceans.guide` for the full walkthrough, including the seabed, buoyancy, reflections and what each tier costs.

# banding The banding reference: smooth gradients an 8-bit display path quantises. ## Contents - `ReferenceCamera`: an isolated camera on black at `{0, 0, 6}`, framing the two ramps. - `DarkRamp`: light from 0 at the left edge to 0.1 at the right (`postReference_darkRamp`, unlit): an undithered 8-bit encode climbs it in steps several pixels wide. - `SkyRamp`: a sky-blue ramp from 0.02 to 0.6 (`postReference_skyRamp`, unlit), a clear sky's gradient. - `FogCamera`, `FogGround`, `FogLight` and `DarkFog`: a second station, at `{1000, 1, 0}`, looking down a lit grey ground into dark fog (`@builtin::shaders.post.fog`, density 0.03, fog colour 0.01 / 0.012 / 0.02). The fog is a `PostProcess` box around that station, so it grades the frame only while the viewport camera stands there: the dark fog ramp is the ground fading into it toward the horizon. The scene's `player` intent is `none`. Put the viewport on the station to read (`camera.setEditorOverride(id)`); `postMetrics.banding` reads a ramp's longest flat run, and `postMetrics.scopes.zebra` marks the contours.

# Test Suite (asset type) A **test suite** is a registrable asset that bundles one group of automated engine tests. Each `<name>.testSuite/` folder holds an `init.luau` whose body registers a suite (and its tests) against the test framework this **type** ships in its `shared.module/`, reached with `asset.containing(__FILE__).modules.shared`, plus a `README.md` describing what the suite validates. Test suites are the engine's regression net. Every Luau-facing system — FFI bindings, components, the renderer, the VFS, multiplayer, the input stack — ships its coverage as one or more `.testSuite` assets. Because a suite is an ordinary registrable asset, a new system or package adds its own tests by dropping a `.testSuite` folder next to its code; nothing central (the runner, the shell script, CI) has to be edited. ## When to use one - You added or changed a Luau-facing capability and want a permanent regression guard for it. - You fixed a bug — add a test that reproduces it so it can't silently come back (the `bug_regression` suite is the canonical home for one-test-per-issue guards). - A package or system ships behavior that should be validated on every CI run. If you just want to *manually* exercise something once, use `execute` directly — don't author a throwaway suite. ## Where it lives - Built-in engine suites: `src/lua/lib/tests/suites/<name>.testSuite/` (VFS: `/zero/source/libs/@builtin/tests/suites/<name>.testSuite/`). - Package / system suites: anywhere under the package, e.g. `…/voxelEngine.package/tests/voxel_grid.testSuite/`. - Identity: the folder stem (`strip_suffix: true`), e.g. `vfs`. Suite **names must be unique** across the whole tree — the runner and CI key on the stem. ## Folder shape ``` <name>.testSuite/ ├── init.luau # registers the suite via Test.describe / Test.it ├── README.md # what this suite validates + how to run it └── .metadata # agent-editable tags + free-form fields ``` Suites may also ship fixture files (helper `.module` folders, sample data) alongside `init.luau` — `allow_unlisted: true` permits them. ## How to construct a new suite 1. Create `<name>.testSuite/init.luau`. Reach the framework the type ships, then declare the suite with `Test.describe(name, fn)` and each test with `Test.it(name, fn)`. Documentation is authored as doc-comments the engine's doc parser extracts statically: a top-of-file `--!desc` for the suite, and a `--!desc` (what the test checks) plus `--!pass` (the condition that must hold) directly above each `Test.it`. ```lua --!desc Spawn / despawn / exists / find over the entity API. local Test = asset.containing(__FILE__).modules.shared Test.describe("Entity Lifecycle", function() --!desc entity.spawn(name) creates an entity and returns its proxy. --!pass The returned id is a non-empty string and entity.exists(id) is true. Test.it("spawn returns a stable string id", function() local id = entity.spawn("probe").id Test.expect(type(id)).toBe("string") Test.expect(entity.exists(id)).toBe(true) end) end) return true ``` 2. Create `<name>.testSuite/README.md` describing the suite (what system it covers, notable edge cases, how to run just this suite). 3. That's it. No registration step, no runner edit. The next test run discovers the suite via `asset.list("testSuite")`. See `template/` for a copy-ready skeleton (the templater fills in the `[name]` markers). ## How to run tests - **All suites** (writes `/source/tmp/test_results.md` + `.json`; refused in play mode). A bare `run()` covers the world-authored suites; `"*"` adds the baked `@builtin` library: ```lua return tools.use("tests", "run", "*") ``` - **One suite directly** (instance-direct — runs only this suite): ```lua return asset.resolve("vfs", "testSuite"):run() ``` - **From the shell / CI**: `./scripts/run_luau_tests.sh` (all) or `./scripts/run_luau_tests.sh <name>` (one). `--list` prints every discovered suite. - **From inside the engine** (agent loop): the `tests` toolbox — `tools.use("tests", "list")`, `tools.use("tests", "run", { suite = "vfs" })`, `tools.use("tests", "compare", before, after)` to diff two runs and surface NEW failures. See the toolbox README. ## Discovery commands ```lua asset.list("testSuite") -- every registered suite, as AssetRef handles asset.inspect("vfs") -- summary for one suite asset.resolve("vfs", "testSuite") -- handle { guid, identity, path, type } tools.use("tests", "list") -- { count, suites = { { name, identity, path, origin, testCount? } } } ``` ## Authoring conventions - **One suite per asset.** Keep a suite focused on one system; large systems split into multiple `.testSuite` assets (e.g. `zinput_state`, `zinput_events`, `zinput_actions`). - **No `await()` inside `Test.it()`.** The framework runs synchronously; for multi-frame behavior use the per-test context `t.waitFrames(n)` (see the framework README). - **Clean up.** Entities the runner can't attribute are despawned automatically, but prefer `Test.afterEach` for deterministic cleanup. - **Write fixtures via `Test.tmpPath`.** Any file a test writes to the VFS must go under its per-test sandbox: `Test.tmpPath("Foo.component/init.luau")` → `/zero/source/tmp/tests/<suite>/<test>/...`. That root is under `/source/tmp/` (excluded from world saves + multiplayer sync, so it never clogs the synced VFS) and is torn down per-test and again at end-of-run, regardless of pass/fail/crash. Call it INSIDE the test body. For a fixture shared across tests in one block, write under `Test.TMP_ROOT` directly (survives per-test cleanup, still swept at end-of-run). Never hand-roll a bare `/source/<name>` path — it persists and syncs. - **Idempotent.** A suite must produce the same result run twice and must not depend on ordering between suites. - **Never silence the LSP.** No `--!nocheck` / `---@diagnostic disable` in a suite — fix the underlying type/global instead. ## Common pitfalls - **Duplicate stem.** Two `.testSuite` folders with the same stem collide; the runner warns and skips the duplicate, and `--list` fails. Pick a unique name. - **Forgetting `return true`.** Harmless but conventional — every suite ends with `return true`. - **Deferred mutations.** `despawn` / `setParent` / scene clears apply next frame; verify their effects with `t.waitFrames` or a follow-up query, not in the same frame. ## Related types - **`.module`** — reusable Luau library (a suite often requires the system module under test). - **`.tool`** — agent-callable function; the `tests` toolbox tools are `.tool` assets. - **`.component`** — script component; component behavior is frequently what a suite exercises. ## In the Inspector Tests: how many tests the suite declares and their names, parsed without running it, and **Run**, which runs this suite alone in edit mode and reports its passed, failed, skipped and quarantined counts.

# temporalTorture The temporal reference: the content a temporal resolve gets wrong, under temporal antialiasing. ## Contents - `ReferenceCamera`: the station every reading is taken from, at `{0, 1.5, 9}` looking down -Z; `CutCamera` is a second station (`{6, 3, 6}`, turned 40 degrees toward the scene, priority -1). A camera cut is the viewport going from one to the other (`camera.setEditorOverride(id)`), the frame a resolve has to drop its history on. - `TemporalAntiAliasing`: the scene's temporal antialiasing at its defaults. - `SiemensStar`: 36 spokes of 0.9 on 0.02 (`postReference_siemensStar`, unlit); toward its centre the spokes are narrower than a pixel. - `Wire0`..`Wire4`: horizontal wires 0.016 units thick, thinner than a pixel at this distance (`postReference_white`, unlit). - `FencePost0`..`FencePost16` and `FenceRail0` / `FenceRail1`: a fence of thin white posts at a regular pitch, the pattern a jittered resolve shimmers on. - `Fan` with `FanBlade0`..`FanBlade3`: four white blades turning at 8 radians per second (`Mover.spin`). - `FastObject`: a lit grey cube carried round a 2-unit circle at 3 radians per second (`Mover`) in front of `CheckerBackdrop`, a 64-cell checker (`postReference_checker`). - Everything stands on the scene's dark clear colour, so thin geometry is read against a flat field. - `Sun` and `Ambient` light the lit parts. The movers turn while the engine plays (`engine.mode = "play"`); in edit mode the scene holds still. The scene's `player` intent is `none`. Put the viewport on `ReferenceCamera` and read consecutive frames with `renderer.presentedFrames({ frames = n })`; `postMetrics.temporalVariance` reads how much each pixel changes across them.

# [scene_name] One-paragraph description of what this scene is — the level, screen or area it represents, and when the world loads it. This README describes *this* scene; what a scene is and how loading works live in the scene assetType README. ## Contents - What the entity hierarchy holds — the terrain, props, lights and spawn points a reader should expect to find. - Which player intent `scene.json` declares (`"spawns"` places the local player and its camera on join; `"none"` leaves both to the entrypoint). ## Entry point - `entrypoint.luau` — what it sets up when this scene loads, and anything a caller has to do before loading it.

# 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.

# dofChart The depth-of-field reference: four focus charts at known distances under a lens focused on one of them. ## Contents - `ReferenceCamera`: an isolated camera on black at `{0, 1, 0}` looking down -Z. - `Lens`: a `DepthOfField` focused at 4 units, f/1.4, 50 mm. - `FocusChart2m`, `FocusChart4m`, `FocusChart8m`, `FocusChart16m`: the same chart of bar pairs (`postReference_focusBars`: four rows, 8 pairs across the top row, doubling on each row below, 0.8 on 0.03, unlit) at 2, 4, 8 and 16 units, each scaled with its distance so all four subtend the same angle. The 4-unit chart is in focus; the others are as far out of it as the lens puts them. The scene's `player` intent is `none`. A chart's sharpness is how many of its rows still resolve: `postMetrics.profile` along a row reads the bar contrast.

# bloomEnergy The bloom reference: emitters of known size and light on black, and a specular highlight smaller than a pixel that moves. ## Contents - `ReferenceCamera`: orthographic, 25.6 world units tall, on black with no ambient term. Captured at **256 x 256**, one pixel is 0.1 world units and the frame's centre lies on a pixel corner; every size below is in pixels of that frame. - `Emitter1px`: a single-texel emitter, centred on the pixel 48 from the left and 40 from the top (`postReference_emitter`: 16 times the display's white). - `Emitter4px` and `Emitter16px`: emitters 4 and 16 pixels square, their edges on pixel boundaries, at 4.0 world units above the centre (pixel row 88 from the top), centred at x = 0 and x = 8.0. - `MovingSpecular`: a polished metal sphere lit by `Sun` (directional, intensity 6), its highlight a sub-pixel source; a `Mover` carries it round a circle 0.03 units (0.3 pixel) across at 1.5 radians per second. The scene's `player` intent is `none`. Capture it with `capture.fromCamera` at 256 x 256, or put the viewport on `ReferenceCamera` and read `renderer.presentedFrames`. `postMetrics.ringEnergy` reads the light a bloom spreads around an emitter.

# deprecatedParticles (deprecated) > **Deprecated.** This belongs to the earlier particle substrate. It stays loadable by identity and guid for content that already uses it; nothing new should use it, and search does not offer it. Particles are procgen sim nodes (`sim.spawn`, `sim.particles`, `sim.shader`) played through an effect: use `@builtin::assetTypes.effect`. The package holds the GPU particle engine module (`engine`), the `deprecatedParticles` module over it, the `DeprecatedParticleEmitter` and `DeprecatedSimpleParticleEmitter` components, the shaders, compute shaders and materials they draw with, and a demo scene. The package's `.metadata` carries the deprecation marker, so every asset inside is deprecated.

# 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`

# 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.

# 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`

# 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.

# component_snapshot Serialized snapshots of script-component public data. A component's `public` table is a live proxy — its fields live behind `__iter` / `__index` metamethods, so copying or JSON-encoding the proxy directly yields an empty table. This module materializes the plain, serializable form. It is the script-component parallel to `ecs.snapshot` (native components). ```lua local componentSnapshot = require("modules.component_snapshot") -- one component: live proxy -> plain table local data = componentSnapshot.snapshot(entity(id).component.get("Camera")) -- whole entity: { [type] = data }, named/multi instances nested as -- { [type] = { [instanceName or "__default"] = data } } local all = componentSnapshot.snapshotEntity(entity(id)) ``` `componentSnapshot.plainCopy(value)` materializes ONE live value the same way — a table behind a proxy is walked into a plain table, every other value passes through — for callers reading a single field rather than a whole component. Serialized form: entity refs become id strings, asset refs become `{ __ref, name, type }` envelopes, vectors and colors their plain-table forms; framework functions are omitted. `snapshot` returns nil for a proxy with no serializable fields. Persistence (scene serializer, bundle capture, prototype spawn) and inspection tooling (`debug.inspect`) read component data through this module. Live gameplay reads and writes stay on the proxy itself via `entity(id).component.get` / `getAll`.

# player_prototype_spawn The deterministic spawn core for authored player prototypes. A PlayerSpawn entity names a PlayerPrototype subtree to instantiate; `spawnFor` clones that subtree from its captured authored template, prunes clone-subtree nodes whose networkScope excludes the caller's owner/authority role, marks the clone RuntimeOnly, and turns the clone root into the joining user's hidden UserIdentity, named `user` like every user identity (the prototype keeps its own name, so a lookup by that name reaches the prototype), plugging it into the players registry, join/leave, ownership, and sync. The body named by `PlayerPrototype.body` is adopted as the user's avatar and placed at the PlayerSpawn's world transform; the prototype's CameraRig follows it. `installJoinHook` wires `spawnFor` to a scene's user-join event so a joining user is placed automatically. Location: `src/lua/lib/modules/api/engine/player_prototype_spawn.module`

# opts The contract an options table is held to. A call that reads a fixed set of keys acts on those keys and no others, so a key it does not know names a change the caller asked for and never got — a cube asked for `size = 3` that comes back one unit wide, reporting success. `Opts.check` makes that a refusal carrying what to write instead: the key, the accepted set, and the nearest accepted spelling. The same three parts answer for a name of any kind — `tools.use` names the near-miss toolbox, `MaterialAuthor` names the near-miss shader property — so the distance search lives here too, and every caller ranks candidates the same way. Pure Luau, no engine dependencies. ## Exports - `Opts.check(where: string, value: any, accepted: { string }, inTable?: string)` — raise unless every key of `value` is named by `accepted`. `nil` accepts. - `Opts.forward(where: string, own: { string }, fn, ...) -> ...` — call `fn(...)`, and when it refuses an option, append the vocabulary `where` itself takes. - `Opts.unknown(value, accepted) -> { string }` — the keys `value` carries that `accepted` does not name, sorted. - `Opts.nearest(key: string, candidates: { string }) -> string?` — the candidate `key` is most plausibly a misspelling of, or nil. - `Opts.editDistance(a: string, b: string, limit: number) -> number` — single-character edits between two names, capped at `limit + 1`. ## Usage ```luau local Opts = require("@builtin::modules.opts") -- The keys this call reads, named once. local CUBE_OPTS = { "animate", "scale" } function M.cube(name, x, y, z, opts) Opts.check("primitives.cube", opts, CUBE_OPTS) -- primitives.cube: unknown option 'scail'. Accepted: animate, scale. Did you mean 'scale'? -- The spawn target is handed to `entity.spawn`, so it is that call's -- contract a key is checked against — `own` says what this one takes. local e = Opts.forward("primitives.cube", { "opts.scale", "opts.animate" }, entity.spawn, name) -- entity.spawn: unknown option 'size'. Valid options: name, hidden, … -- (primitives.cube itself takes: opts.scale, opts.animate) end ``` A call taking more than one table names which one the key was written in: ```luau Opts.check("primitives.ground", color, { "r", "g", "b", "a" }, "color") -- primitives.ground: unknown option 'red' in color. Accepted: r, g, b, a. Did you mean 'r'? ``` ## Notes - Refusals raise at level 0: the message is the whole error, so a caller reads the contract rather than the line inside the library that checked it. - A key of any type is reported by how it is written, so the positional form of a named shape (`{ 200, 50, 50 }` for `{ r = , g = , b = }`) names its indices rather than passing as a table with nothing the call reads. - `nearest` is case-insensitive, and a candidate containing the key scores by how much longer it is, so `roughnes` prefers `roughness` over `clearcoat_roughness`. How far a plain misspelling may stray scales with the key's own length — a four-letter key admits two edits, a longer one three — so a short key is not answered with an unrelated short name. - Equal scores go to the shorter candidate, then the alphabetically earlier one, so the answer never depends on the order candidates were listed in. - `forward` matches the phrase both this module and the engine's own option checks use for the condition (`unknown option '<key>'`). Every other error passes through as raised.

# 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.

# ik Look at a rig's bones and at what an IK solve is actually doing. Debugging IK means answering three questions, and none of them can be answered from a screenshot: what are this rig's bones called, where are they right now, and is the chain reaching its target or merely near it. `bones` lists a body's bones with their world positions and parents — the names you need before naming a chain, and the positions you measure against when checking a solve from outside the component. Rigs rarely use the word you would guess: the standard humanoid here calls its feet `Ankle_L` and `Ankle_R`, with no bone containing "foot" anywhere. `reach` reports how far a limb can extend and how far away a point is, both in the same units. A target beyond a limb's reach has no solution — the chain extends straight toward it and stops, which is correct and looks exactly like a broken solver. This is the first thing to check when a solve looks inert. `state` gathers every IK component on an entity and reports what each one is doing, so "is anything solving at all" is one call rather than five.

# 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.