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av

Public Luau surface over the `__av` Internal FFI namespace — audio / video encode and mux control.

byzero-proxy @ DESKTOP-DB3UJOJ·posted 2mo ago
What it does

av Module

Public Luau surface over the __av Internal FFI namespace — audio / video encode and mux control.

Purpose

Wrap the raw __av.* FFI namespace (backed by zero_av) in a typed Luau table that gets auto-injected as _G.av via the prelude. Mirrors libav's split: tier-1 encoder/muxer primitives produce/consume codec-agnostic packets; tier-2 convenience composites (av.record, av.live) wrap both for the common cases.

Always check av.status().supported before kicking off a live stream or recording — encode requires GPU support that some hosts don't have, and unsupported instances return clear errors rather than crashing.

Usage

local s = av.status()
if not s.supported then warn("encode unavailable: " .. s.reason); return end

-- Live spectator stream over a Camera's offscreen texture. The call waits
-- for the engine to open the encoder, so a URL back means the stream is
-- running and a nil carries the reason it is not. A browser engine streams
-- through its WebCodecs encoder, and the proxy serves either engine's stream
-- at /stream/<instance>/live.stream.
local url, why = av.live({
    width = 1280, height = 720, fps = 60,
    texture_handle = spectatorCam.render_target,
})
if not url then warn("no live stream: " .. tostring(why)) end

-- Record a clip to VFS. A relative name records under
-- /zero/runtime/recordings/, so this take is filed at
-- /zero/runtime/recordings/intro.mp4. It runs until it is stopped; pass
-- `max_duration_sec` or `frames` in the opts to bound the take. The call
-- waits for the engine to open the session, so a path back means the
-- recording is running and a nil carries the reason it is not.
local clip, refused = av.record("intro.mp4", { fps = 60, quality = 90 })
if not clip then warn("no recording: " .. tostring(refused)); return end

-- Stop both
av.stop_live()
local stopped, ended = av.stop_recording()
if not stopped and ended then
    warn("the recording had already ended: " .. ended)
end

How a live stream ends

A live stream runs until av.stop_live() ends it or the engine can no longer stream it: its encoder or its frame capture fails, the render device goes out from under it, or, in the browser, a frame step holding it panics and the engine recovers the step and goes on. Every ending reads the same: av.is_live() and av.status().live go false, av.status().liveError names why, and a viewer of the stream sees it close. A request still opening when its stream ends is answered with the reason, and that reason stands on liveError. So av.stop_live() leaves liveError nil once the stream it ends had opened, and names itself there when it ends one still opening: that request is answered with nil and "av.stop_live() ended the stream before it opened". The next av.live opens a stream of its own.

Starting a recording

The encoder is built from the renderer's device on an engine tick, so av.record waits for that tick before it answers: it returns the destination of a session that is open and recording, or nil and the reason there is none: an adapter that cannot encode, a take already running (the reason names its destination), an option the encoder rejects, a resolution the device refuses, a destination the VFS cannot write. Because it waits, it runs where it can yield; from a callback that cannot, wrap it in task.spawn.

The destination is asked the question the film's write will ask, at the call, so a path that write would refuse (a read-only path such as /zero/tmp/..., a directory, engine bookkeeping, a frozen world version) is refused before a frame is encoded, and the reason names the directory a take can always be filed in. A host filesystem path such as /tmp/clip.mp4 is refused the same way: a take is filed in the engine's VFS, and read back with vfs.read or downloaded with the proxy's download_file. Should the terms change while the take runs so that its destination refuses the film when it ends, the film is filed under /zero/runtime/recordings/ at the destination's file name instead, and av.status().recordingError names both the refusal and where the take is.

Recording in the browser

The browser build records through the browser's own WebCodecs VideoEncoder. av.status().backend reads "webcodecs" there, codecs lists what that browser encodes with "h264" first (the codec every engine plays back with video.create), and hardware says whether the browser has a hardware encoder for it. A browser whose WebCodecs encodes none of the codecs the engine offers reports supported = false with the reason "unsupported_browser", and av.record answers with a sentence naming what the browser said.

A take in the browser is the take a native engine records: the same options, refusals, destinations, cadences, bounds, camera and renderLayers, the same MP4, and the same av.status() fields while it runs and after it ends. The browser converts the frames it is handed to YUV itself, so a browser take is 4:2:0 in the code range the browser's encoder chooses, and the colr box of an H.264 or AV1 take states the range its stream was written in: grain above 0, chroma = "444" and any stated range are refused by name.

A browser take with audio left on carries the engine's master mix as an Opus track, encoded by the browser's WebCodecs AudioEncoder, and av.status().recordingAudio reads "opus". The track is the mix the page plays, from the take's first frame to the film's end on the same wall clock as the picture. The engine renders that mix whether or not the page's audio output has been allowed to start, so a take records it either way, and a silent world records a silent track. A browser whose AudioEncoder does not encode Opus records the picture, and recordingAudio reads "none: " with what the browser said.

The browser answers each frame on a later task than the one that drew it, so a take holds only the few frames on their way to the encoder. When the encoder has no room, a "realtime" take leaves that frame slot empty (as a native engine ticking under the requested rate does, and recordingAchievedFps reads it), and a "frame" take holds the engine's next frame until the encoder takes this one, so every step of the timeline is in the film. Closing a take waits for the encoder to hand back its last frames: av.is_recording() goes false once the file is filed.

Which camera a take films

A take draws its film from the presented frame, so what a film holds is what the camera holding the viewport was looking at. In an engine on the editor profile that camera is the editor's own fly camera, whatever priority a scene camera carries — so a take made while authoring films the fly camera unless it says otherwise.

camera says otherwise. It names the camera the take draws from — an entity proxy, an entity id, or an entity name — and that camera holds the viewport for as long as the take runs, above the priority contest and above camera.setEditorOverride:

local film = av.record("film.mp4", {
    fps = 24, frames = 24 * 90, cadence = "frame",
    camera = "FilmCamera",
})

Only frames that camera drew go into the film. A camera that draws no viewport frame — disabled, deactivated, despawned, or rendering into a texture — ends the take with the reason on av.status().recordingError and no frames written, and an id no entity carries is refused at the call. So a take is the view it named, or it is no take.

The camera belongs to the take. Nothing is written to it, and the viewport is back under its own contest the moment the take ends, however it ends — there is nothing to put back.

av.status().recordingCamera reads the camera the take's most recent captured frame was drawn from, and stands as the source of the most recent take once that take has ended. It is read off the frame the engine drew, so it answers "which view did this film?" for a take that named a camera and for one that named none alike.

Where a take lands

A relative destination records under /zero/runtime/recordings/. That directory is the recorder's own: writable in every mode, play included, and outside the world's sync, so a take filed there costs the world nothing and is read back with vfs.read or downloaded with the proxy's download_file for the rest of the session.

A destination under /zero/source/ is world content. The film is filed into the world's source tree when the take ends, and the world's sync uploads it with the rest of that tree, so every collaborator's session receives it and the world carries its size. Record there when the film belongs to the world; record under the recordings directory when it is a take to look at, download or publish elsewhere.

av.record returns where the film will land as a third value, beside the destination path: { durable = true } when the take is filed where the call named it and the next session reads it back, { durable = false, survivesRestart, warning, playShadow, shadowed } when the play shadow takes it: live in this session and discarded on a guarded play-exit unless kept, with survivesRestart saying whether a restart keeps it and playShadow naming the routes that keep it, and { durable = false, survivesRestart = false, warning, scratch } when it is filed in /source/tmp/ scratch, which is gone when the engine stops or restarts. Filming gameplay means filming in play, which is exactly when a /zero/source/ destination belongs to the shadow, so this is the field that says whether such a take survives leaving play; vfs.promotePlayShadow(path) keeps it with play still running.

A take is filed when it ENDS, so the report is the verdict the film's write gets on the terms standing at the call rather than a reading of bytes that are there: the answer vfs.durability(path, { pending = true }) gives, stated at the call because that is where the caller can still act on it. A take outlives those terms when the session enters play while it runs, and the film is filed on the terms in force then: av.status().recordingDurability asks again for the take still running, so that is where a take spanning a mode change reads.

local take, refused, landing = av.record("take.mp4", { fps = 24 })
if not take then warn("no recording: " .. tostring(refused)); return end
if landing and landing.playShadow then
    warn(landing.warning .. " " .. landing.playShadow)
    vfs.promotePlayShadow(take)
end

How a recording ends

A recording ends when it is stopped, or when a bound its caller set is reached. Both write the same complete MP4, so the status table names which happened: av.status().recordingBound is what will end the take in flight, recordingEnd is how the most recent one ended, and recordingError is why one produced no file. av.stop_recording() returns the ending as its second value when there was nothing left to stop, so a take that ran out its bound is distinguishable from one that never started.

A refused request settles the same fields: its reason becomes both recordingEnd and recordingError, and the take report — the frames, bytes, seconds and rate of the take before it — is cleared, so a refusal reads as a recording that produced no file rather than as the earlier take that did. A request refused because a take is already running leaves that take's report where the take put it; recording names the session those numbers belong to.

A take the engine loses on the way ends too. In the browser a frame step that panics is recovered and the page goes on; a take that step held reads recordingEnd "the take was lost", its recordingError names the panic and the path nothing was filed at, and av.is_recording() reads false, so the next av.record opens a take of its own.

Keeping a take

A take lives in /zero/runtime/recordings/ for as long as the engine runs; a browser tab that closes takes it with it. av.save(path) puts a finished take on the device of the person at the screen, byte for byte, under the take's own name (or opts.name). The person decides where it lands:

  • In the browser, the take downloads at once when the save rides a click or key press of the person at the screen, so a "Save clip" button's click handler saves straight to their downloads. A save with no such gesture behind it (an agent, a timer, the end of a take) makes the page show the person an offer, which they save with a click of their own: a browser starts a download only for a person who just acted.
  • A native engine opens the host's save dialog in the person's downloads folder, the take's name filled in, and writes it where they choose. An engine with no window has no person at its screen and refuses.
-- In a button's click handler: the click is the gesture the download rides.
task.spawn(function()
    local ok, where, report = av.save("intro.mp4")
    if not ok then warn("not saved: " .. where) end
    -- report.state is "saved" (on the device) or "offered" (in front of the
    -- person, as the page's offer or the save dialog).
end)

It answers false and why for a take still recording (a take is filed when it ends), a path with no file, a host path, a name with a folder in it, and a take too large for the browser to hold, which the page shows the person too. userfile.save(path) saves any other file the engine holds. In the editor, the Files panel's right-click menu on a file holds "Save to this device", which saves it the same way.

Exports

  • av.status() -> AvStatus
  • av.is_live() -> boolean / av.is_recording() -> boolean
  • av.live(opts?) -> (string?, string?): start the live encoder; the stream URL once it is open, or nil and why it was refused, which also stands on av.status().liveError.
  • av.stop_live() -> boolean
  • av.record(path, opts?) -> (string?, string?, Durability?) — start recording; the destination path of the open session, or nil and why it was refused, and where the film will land. opts.camera names the camera it films.
  • av.stop_recording(handle?) -> (boolean, string?)
  • av.save(path, opts?) -> (boolean, string, SaveReport?): save a finished take to the device of the person at the screen; true, where it went and the report, or false and why it was refused.

Interface

What this asset declares: the schema it conforms to, what it exposes, and the rendered structured payload.

conforms to

zero/source-extract/v2

module av Audio/video encode + mux control — live streaming, recording, encoder/muxer primitives. Public Luau surface over the `__av` Internal FFI namespace. global av global-types require modules/api/engine/av

resolveEntityId(ref: any) → string

Resolve what a caller names a camera by — an entity id, an entity name, or an entity proxy — to the entity id the take is armed with. `entity.find` answers a name quietly, so it is tried behind a pcall and an id passes through unchanged for the engine to accept or refuse.

argtypedescription
refany

status( ) → AvStatus

Report the encoder subsystem's state. Always available regardless of GPU support. `backend` is the encode backend in use: `"vulkan"` or `"vaapi"` on an adapter with a media engine, `"software"` where a native engine encodes on the CPU, and `"webcodecs"` in the browser, where the browser's own WebCodecs encoder takes the frames. `hardware` is true for the first two, and in the browser when the browser reports a hardware encoder for the default codec, so a caller that pays for the take in engine time knows which it is getting. `codecs` lists what the backend encodes with the recording default first (h264 in the browser, which every engine plays back with `video.create`). `reason` is `"supported"`, `"not_probed"` before the engine has asked its encoder, `"unsupported_adapter"` for a native adapter with no encoder, or `"unsupported_browser"` for a browser whose WebCodecs encodes none of the codecs the engine offers. `live` is true while the `av.live` stream is running, and `liveError` is why the most recent stream was refused or ended on a failure: nil while one runs and after `av.stop_live()` ended one that had opened, and the reason that names `av.stop_live()` after it ended one still opening. A take of its own reads back on the recording fields: `recording` is the destination of the take in flight, `recordingBound` what will end it, `recordingEnd` how the most recent one ended, and `recordingError` why one produced no file. `recordingAudio` is the codec the take is writing the master mix with (`"opus"`), or the reason the file carries no audio track — read it to tell a film with a soundtrack from a silent one. `recordingLayers` is the render-layer include spec the armed take is drawing the viewport under, in the words its caller wrote, and nil for a take that stated none — the reading that answers what is in the picture rather than how much of it there is. `recordingCamera` is the entity id of the camera the take's most recent captured frame was drawn from, and stands as the source of the most recent take once that take has ended — it is read off the frame the engine drew, so it answers which view a film holds whether or not the take named a camera. `recordingCadence` is the clock the take stamps its frames from, `"realtime"` or `"frame"`, and so what the tally below is a reading against. What the take produced reads off `recordingFrames`, `recordingBytes` (every byte the take has produced so far, climbing while it runs and ending equal to the size of the file), `recordingSeconds` (the timeline those frames cover), `recordingAchievedFps` (the rate they arrived at) and `recordingRequestedFps` (the rate asked for) — live while a take runs, and its final tally once it ends. On `"realtime"` the requested rate is a ceiling and an engine ticking under it reaches less; on `"frame"` every rendered frame is a slot of the recorded timeline, so `recordingSeconds` is that timeline's length and `recordingAchievedFps` is the rate it plays back at. `recordingDurability` is where the film in flight lands on the terms standing now — the report `av.record` returns as its third value, asked again for the take still running, so a caller polling status learns the play shadow is taking the film in time to keep it, a take that entered play after it opened included. It is present while a take names a destination.

examples

local s = av.status(); print(s.backend, s.hardware, s.recordingAudio)

is_live( ) → boolean

True if a live-stream session is currently active.

examples

if av.is_live() then av.stop_live() end

is_recording( ) → boolean

True if a recording session is currently active.

examples

print("recording:", av.is_recording())

live(opts: LiveOpts?) →

Start the live-stream encoder. The stream is served at `/engine/live.stream` and reverse-proxied at `/stream/<instance>/live.stream` as a binary length-prefixed protocol consumed by the multiviewer UI's WebCodecs decoder. A browser engine encodes it with the browser's WebCodecs encoder, and the proxy reads it over the ZeroMind bridge and serves it at the same `/stream/<instance>/live.stream`. When `texture_handle` is set, the encoder reads from that GPU texture's guid (a Camera pointed at it via `setTargetTexture`) instead of the scene's viewport: that's how spectator cameras work. A stream runs beside an `av.record` take. Returns the stream URL once the encoder is open and streaming, or nil and the reason it is not: no encoder on this engine that streams H.264, a stream already running, an odd dimension, a session the encoder refuses (a size it will not encode, a spectator texture with no size to stream at). The engine opens the encoder, so the call waits for it: run it where it can yield, wrapping it in `task.spawn` from a callback that cannot. The reason also stands on `av.status().liveError`, which is where a stream that ends on a failure later says why.

argtypedescription
optsLiveOpts?Encoder options.

examples

local url, why = av.live({ width = 1280, height = 720, fps = 60 })

stop_live( ) → boolean

Stop any active live-stream session.

examples

av.stop_live()

record(path: string, opts: RecordOpts?) →

Start recording the engine output to a VFS path. Default dir is `/zero/runtime/recordings/` when `path` is not absolute: that directory is writable in every mode and stays out of the world's sync, so a take named relative to it is kept for the session and read back with `vfs.read`. A destination under `/zero/source/` is world content, which the world's sync uploads when the take is filed. The take runs until `av.stop_recording()` unless `opts` bounds it with `max_duration_sec` (seconds of the take's own clock) or `frames` (captured frames); `max_duration_sec` wins when both are given, and the bound in force reads back as `av.status().recordingBound`. With no `chroma`/`range` opts the format defaults to full-range 4:4:4 HEVC where the GPU supports it, else 4:2:0. In the browser the browser's WebCodecs encoder converts the picture itself, so the take is 4:2:0 in the code range that encoder chooses, which an H.264 or AV1 file states, and `grain` above 0, `chroma = "444"` and any stated `range` are refused by name, and the master mix is encoded by the browser's WebCodecs `AudioEncoder`. On the `"software"` backend the take is H.264 encoded on the CPU, which costs the run it records: read `av.status().recordingAchievedFps` against `recordingRequestedFps` to see the rate it reached. What the take did with the master mix reads back as `av.status().recordingAudio`. `cadence` picks the clock the take stamps its frames from. `"realtime"` (the default) stamps each frame with the wall-clock slot it was captured in, so a recorded session is watched back at the speed it happened and an engine ticking under `fps` leaves slots empty. `"frame"` stamps every rendered frame one fixed slot after the last, so a timeline whose own clock advances a step per rendered frame — a cutscene, a scripted demo, anything on a fixed timestep — is delivered at the length that timeline runs to, however slowly the engine drew it: a take of `frames = n` at `fps` is `n / fps` seconds of film, and a `max_duration_sec` bound counts that film's seconds. A `"frame"` take records silent, because the master mix plays in wall-clock seconds and cannot share a file with a fixed-step picture; `recordingAudio` says so, and an explicit `audio = true` beside it is refused. Record the sound as a second `"realtime"` take. `camera` names the camera the take draws its film from — an entity proxy, an entity id, or an entity name. That camera holds the viewport for as long as the take runs, above the priority contest and above `camera.setEditorOverride`, so the film is its view and the frames carry everything the presented frame carries. Only frames that camera drew go into the film, and a camera that never draws the viewport ends the take with the reason on `av.status().recordingError` — so a take is the view it named or it is no take. The camera belongs to the take: nothing is written to it, and the viewport is back under its own contest the moment the take ends. It reads back as `av.status().recordingCamera` while the take runs. Omitted, the take records whichever camera holds the viewport, which in an engine on the editor profile is the editor's own fly camera rather than the scene's. `renderLayers` is the render-layer include spec the viewport is drawn under for as long as the take runs — the same token string a capture takes: `all` seeds every layer, `name` adds one and `!name` drops one, so `"all !EditorUI !debug"` films the scene without the editor's chrome or the authoring overlays (gizmos, light and probe icons, frustums, collider wireframes) over it, and `"all !ui !EditorUI !debug"` drops the authored HUD as well. The viewport admits geometry and screens by that one spec, so it states the whole picture. It belongs to the take: nothing is written to the camera it is stated against, and the moment the take ends — its bound reached, stopped, or refused — the viewport is back under the camera's own spec. While a take states layers, the window shows what the film holds, and `av.status().recordingLayers` reads the spec back. Omitted, the take records the engine output as presented. `width` / `height` are the film's size: the whole of the presented frame (in an editor layout, the rect the scene is drawn into) is resampled to it, and a side left out takes the presented frame's. Returns the destination path of a session that is open and recording, or nil and the reason it is not: an adapter that cannot encode, a take already running, an option the encoder rejects, a resolution the device refuses, a destination the VFS cannot write (a read-only path, a directory, a host filesystem path). The engine opens the session, so the call waits for it: run it where it can yield, wrapping it in `task.spawn` from a callback that cannot. How a take finished reads back as `av.status().recordingEnd`; a refused request puts its reason there and on `recordingError` and leaves no take report behind, while a request refused because a take is already running leaves that take's report as it is. name records under `/zero/runtime/recordings/`. `{ durable = true }` when the take is filed where this call named it and the next session reads it back, `{ durable = false, survivesRestart = …, warning = …, playShadow = …, shadowed = { … } }` when the play shadow takes it: live in this session and discarded on a guarded play-exit unless kept, with `survivesRestart` saying whether a restart keeps it and `playShadow` naming the routes that keep it, and `{ durable = false, survivesRestart = false, warning = …, scratch = { … } }` when it is filed in `/source/tmp/` scratch, which is gone when the engine stops or restarts. The take is filed when it ENDS, so this is the verdict a write landing there gets on the terms standing at THIS call, answered here because here is where a caller can still act on it: a film recorded during play is kept with `vfs.promotePlayShadow(path)` and play keeps running. `durable` is present whatever the answer is, so its absence is never a reading. It is the same answer, in the same words, that `asset.create` returns and the MCP `write_file` / `capture` tools attach to their own results. A take opened in edit that runs on into play is filed on play's terms, so `av.status().recordingDurability` — which answers for the take still running — is where a take spanning a mode change reads.

argtypedescription
pathstringVFS destination path, returned in its `/zero` form; a relative
optsRecordOpts?Encoder options (optional).

examples

local clip = av.record("intro.mp4", { fps = 60 })
local film = av.record("cut.mp4", { fps = 24, frames = 24 * 181, cadence = "frame" })
local clean = av.record("take.mp4", { fps = 24, renderLayers = "all !EditorUI !debug" })
local shot = av.record("film.mp4", { fps = 24, frames = 240, camera = "FilmCamera" })
local take, why, d = av.record("take.mp4", { fps = 24 })
if d and d.playShadow then log.warn(d.warning .. " " .. d.playShadow) end

stop_recording(handle: string?) →

Stop the active recording (or the one for the given promise handle). Returns true when a recording was armed at call time. A false return carries a second value naming how the most recent recording already ended (the bound it reached, or the failure that cut it short), and nil when no recording has run at all. The engine finalizes the take once the call returns. A take stopped before its first frame is captured runs on until that frame lands and ends holding it, and one whose first frame has not landed 120 frames after the stop ends with none. Wait for `av.is_recording()` to go false, then read what it produced off `av.status()`.

argtypedescription
handlestring?Promise handle of a specific recording (optional).

examples

local stopped, ended = av.stop_recording()

save(path: string, opts: SaveOpts?) →

Save a finished take to the device of the person at the screen, so the recording outlives the session: `/zero/runtime/recordings/` is gone when the engine stops (and, in the browser, when the tab closes). `path` names the take the way `av.record` did: a relative name is the take of that name under `/zero/runtime/recordings/`, and any VFS path works too. The person decides where it lands. In the browser the take downloads at once when the save rides a click or key press of the person at the screen, so call it from a button's click handler; a save with no such gesture behind it (an agent, a timer, the end of a take) makes the page show the person an offer they save with a click of their own, because a browser starts a download only for a person who just acted. A native engine opens the host's save dialog in their downloads folder, with the take's name filled in, and writes it where they choose; an engine with no window has no person at its screen and refuses. The call waits for the first answer, so run it where it can yield (`task.spawn` from a callback). Returns true, a sentence saying where the take went, and the report `{ state, detail, name, size, path }` with `state` `"saved"` (on the device) or `"offered"` (in front of the person, as the page's offer or the save dialog); or false and why it was refused: a take still recording (it is filed when it ends), no file at the path, a host path, a name with a folder in it, no window, or a take too large for the browser to hold, which the page shows the person as well. The saved file is the take byte for byte. `userfile.save` saves any other file the engine holds.

argtypedescription
pathstringThe take: its name under `/zero/runtime/recordings/`, or a VFS path.
optsSaveOpts?`{ name }`, the file name the device gets (the take's own when omitted).

examples

local ok, where = av.save("take.mp4")
local ok, where, report = av.save("take.mp4", { name = "boss-fight.mp4" })
⌬ Types
Durability = Vfs.DurabilityAvStatus = {LiveOpts = {SaveOpts = {SaveReport = {RecordOpts = {

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❒asset
# 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**.
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vfs
module · born here
❒asset
# vfs Module Public Luau surface over the `__vfs` Internal FFI namespace — the engine's virtual filesystem. ## Purpose Wrap the raw `__vfs.*` FFI namespace in a typed Luau table that gets auto-injected as `_G.vfs` via the prelude. The standard read / write / move / remove / mkdir / list / exists / readAsync / reload / evict surface, plus trusted-only `watch` / `unwatch` for the bootstrap VM. `vfs.read` yields on a byte-cache miss: the module's last step installs the `vfs_async_read` fallback over the synchronous read, so every VM that holds this namespace, the trusted VM included, reads a path through the same two steps and gets the same bytes for it. ## Usage ```luau -- Read / write local src = vfs.read("@builtin/components/Camera.luau") vfs.write("/zero/source/notes.md", body) -- What a write landed: where the bytes went, and what the static passes -- read in the Luau among them local ok, report = vfs.write("/zero/source/game/Vent.component/init.luau", code) if report.diagnostics then for _, d in report.diagnostics do print(d.severity, d.path, d.line, d.message) end end if not report.durable then log.warn(report.warning) end -- Listing for _, e in ipairs(vfs.list("/zero/source")) do print(e.isDirectory and "[d] " or " ", e.name) end -- Async fetch local png = task.await(vfs.readAsync("/zero/runtime/screenshots/last.png")) -- Reclaim RAM after processing a big binary vfs.evict("/zero/source/textures/imported_huge.png") -- Reload a module after editing its source on disk if vfs.reload("@mylib/utils.helpers") then local m = require("@mylib/utils.helpers") -- sees the new source end ``` `vfs.reload(identity)` answers whether a module was cached under that name and has now been dropped. A `false` says the name matched nothing — either a misspelled identity or a module this VM never required — so the next `require()` returns whatever it would have returned anyway. A module that caches state derived from OTHER files keeps serving the old value when those files are rewritten, since only its own source is watched. Reload it by identity to make the next `require()` recompute. ## Exports - `vfs.read(path, opts?) -> string?` - `vfs.write(path, content, opts?) -> (boolean, WriteReport | string)` - `vfs.move(src, dst, opts?) -> (boolean, WriteReport | string)` - `vfs.copy(src, dst) -> (boolean, WriteReport | string)` - `vfs.remove(path, opts?) -> (boolean, string?)` - `vfs.mkdir(path, opts?) -> boolean` - `vfs.list(path?) -> { VfsListEntry }` - `vfs.exists(path, opts?) -> boolean` - `vfs.readAsync(path, opts?) -> promiseId` - `vfs.reload(modulePath?) -> boolean` - `vfs.evict(path, opts?) -> boolean` - `vfs.mutationSeq() -> number` - Trusted-only: `vfs.watch(path, callback) -> number` / `vfs.unwatch(watcherId) -> boolean`.
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json
module · born here
❒asset
# 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.
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assetType.assetType
assettype · born here
❒asset
# 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.
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luau_introspect
module · born here
❒asset
# 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.
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ref
module · born here
❒asset
# assetType.shared.ref Builds the metatable every `AssetRef` (the `{ __ref, type, name, guid, identity, path }` envelope returned by `asset.resolve` / `asset.ref`) carries. Replaces the per-call C metatable that used to live in `crates/zero_scripting/src/ffi/bindings/asset.rs::attach_asset_ref_metatable`. ## Public API ```lua local assetRef = require("@builtin::assetTypes.assetType.shared.ref") -- Called by the Rust factory (push_asset_ref_handle) via -- _G.__build_asset_ref_proxy after the envelope fields are set. assetRef.build(envelope) -- attaches AssetRefMT, returns the table ``` The module exposes no invalidation surface — discovery is registry-driven and hot-reload is transparent (see "Discovery and hot-reload" below). ## Method dispatch order `ref.foo` is resolved in this order: 1. **Default methods** — `getSource` / `getBytes` / `getText` / `exists` / `inspect` and the lazy `meta` property. Per-type definitions cannot override these (engine contract from gh#1889). 2. **Per-type `ref` table** — discovered through `asset.resolve(<typename>, "assetType")` + `require(<identity>.behavior)`. The lookup resolves to whichever `<typename>.assetType/` folder is currently registered for the typename (built-in, user, or library-vendored) and pulls its `ref` methods. 3. **Nil** — unknown key, same shape as the original C metatable. ## Adding methods for a new asset type Drop a `behavior.luau` into the type folder: ``` src/lua/lib/assetTypes/<typename>.assetType/ ├── type.yaml -- structural spec (existing) ├── behavior.luau -- ref + global behaviour (new) └── template/ -- placeholder body (existing) ``` `behavior.luau` returns: ```lua return { ref = { --!desc Per-instance method on every `<typename>` AssetRef. myMethod = function(self, ...) ... end, }, global = { -- Reserved for the asset.<typename>.* surface — not consumed -- yet; included so the contract from gh#1889 lands cleanly. }, } ``` Within `ref` methods, `self` is the AssetRef envelope: `self.path`, `self.identity`, `self.guid`, `self.type`, `self.name` are available. Engine-required fields (`guid`, `path`, `identity`, `type`) must not be redefined. ## Discovery and hot-reload Type discovery uses the asset registry, so it doesn't matter where a `<typename>.assetType/` folder lives — engine built-ins under `@builtin::assetTypes.<X>`, user types dropped under `/zero/source/<X>.assetType/`, or types vendored inside an imported library all resolve identically. The dispatcher walks `asset.resolve(<typename>, "assetType")` → canonical identity → `require <identity>.behavior` on every miss; the asset registry is the cache for the resolve half and Luau's `_LOADED` is the cache for the require half. Hot-reload is transparent. When a `<typename>.assetType/behavior.luau` is rewritten through VFS, the engine's `invalidate_require_cache_for_state` re-runs the module and mutates the cached `_LOADED[<identity>.behavior]` table in place. Dispatch reads `mod.ref` on every access (rather than caching a sub-pointer), so existing AssetRefs see the new methods on the very next access — no Rust-side hook into this module is needed, and no invalidation API is exposed for callers to call. The same registry-driven path also handles type **registration** correctness: dropping a new `<typename>.assetType/behavior.luau` updates the asset registry, the next `asset.resolve(<typename>, "assetType")` returns the new ref, and AssetRefs of that type immediately gain the new methods. ## Why Luau, not Rust The asset surface needed per-category behaviour (`material:getProperties()`, `bundle:instantiate(entityId)`, `tool:run(args)`) and the old shape couldn't grow without an FFI change per method. Owning the proxy in Luau means: - Type-specific methods ship as content (the `<typename>.assetType/` folder), not engine code. - Adding a new asset type drops in a new folder; no Rust rebuild. - Methods can call any other Luau global (`vfs`, `asset`, `Material`, `entity`, etc.) directly, instead of going through narrow FFI primitives. ## Consumers - `crates/zero_scripting/src/ffi/bindings/asset.rs::attach_asset_ref_metatable` — the Rust factory that pushes envelopes invokes `_G.__build_asset_ref_proxy` once per push. - Every Luau call site of `asset.resolve` / `asset.ref` / `entity(id).component.X.material` / any binding declared `AssetRef<...>` — they all receive envelopes built through this module.
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yaml
module · born here
❒asset
# yaml.module YAML decode + encode for authored engine content. Pure Luau, no engine dependencies — a general parsing library, not data-system plumbing. ```luau local Yaml = require("@builtin::modules.yaml") local doc = Yaml.decode(vfs.read(path)) vfs.write(path, Yaml.encode(doc)) ``` ## Supported subset - Block mappings (`key: value`) and block sequences (`- item`), nested to any depth. - Compact sequence-of-mapping entries (`- path: x` / ` kind: y`). - Flow collections — `{ a: 1, b: 2 }` and `[1, 2, 3]` — single line. - Plain scalars with type inference: `~` / `null` → nil, `true` / `false` → boolean, numeric literals → number, everything else → string. - Single- and double-quoted strings (`''` escapes a literal quote inside a single-quoted string; `\n` `\t` `\r` `\\` `\"` inside a double-quoted one). A quote opens a quoted scalar where a scalar begins — after `key:`, after a `- ` entry marker, or inside a flow collection — so a plain scalar carries an apostrophe as data (`note: the world's rules`). Quoted keys are read in flow mappings. - `#` comments — honored outside quotes, so a `#` inside a quoted string is kept as data. - Literal (`|`) and folded (`>`) block scalars — the bare indicators only. A block scalar's content is literal text: quotes (balanced or not), `#`, `key: value` and `---` inside it are data. - An optional leading `---` document marker. ## Loud-error contract Constructs outside the subset above raise instead of misparsing: anchors/aliases (`&`, `*`), tags (`!`), directives (`%`), multi-document streams (a second `---`), block-scalar chomping/indentation indicators (`|-`, `|+`, `>-`, `|2`, ...), tab indentation, and inconsistent indentation (both block structure and block-scalar bodies). Every error carries the offending line number (`yaml: line N: ...`), so a bad config points straight at the line to fix. Tab indentation is rejected everywhere — including block-scalar body lines whose leading whitespace contains a tab. A tab after the first non-space character of a line is content and passes through. ## API - `Yaml.decode(text: string): any` — decode a YAML document into a Luau value (table, scalar, or nil for an empty document). Raises on malformed input or an unsupported construct. - `Yaml.decodeWithComments(text: string): (any, boolean)` — decode as `decode` does, and report whether the text carries a comment by the decoder's own rule: a `#` at a line's start or after whitespace, outside a quoted scalar and outside a block scalar. Re-encoding the value drops such comments, so an editor that writes a document back reads this first. - `Yaml.encode(value: table): string` — encode a Luau table as YAML (block style, two-space indent, alphabetically sorted keys). Raises on values YAML can't represent (functions, userdata, non-string mapping keys). A top-level empty table encodes to an empty document, which decodes back to `nil` (the YAML empty-document ambiguity).
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shared
module · born here
❒asset
# 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.
▲ 0↑ born
backing path · modules/api/engine/av.module

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