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asset⌬ modulemoduleprimary: init.luau·originates fromworld 07158574-5…

jobs

Substrate job registry. Wraps the `__jobs` FFI surface with a typed Luau API and a JobHandle metatable. Every registered job returns a stable handle; the `__index` lookup hits a small METHODS table, so each operation makes exactly one FFI crossing — none of the methods snapshot t…

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

jobs

Substrate job registry. Wraps the __jobs FFI surface with a typed Luau API and a JobHandle metatable. Every registered job returns a stable handle; the __index lookup hits a small METHODS table, so each operation makes exactly one FFI crossing — none of the methods snapshot the full registry.

Exposed as the jobs Luau global via --!global. Authored scripts call jobs.register, jobs.list, jobs.find, jobs.inspect directly without a require.

Exports

  • jobs.register(descriptor: table) -> JobHandle? — register a job. Dispatches by executor.kind: "kernel" / "stub" → __jobs.register (JSON-only descriptor), "luau" → __jobs.register_luau so the run function survives the JSON crossing as a stable registry ref. Auto-fills origin with the calling script's VFS path.

  • jobs.list(phase: string?) -> { JobInfo } — list registered job summaries, optionally filtered to a single phase.

  • jobs.find(name: string) -> JobHandle? — look up a registered job by name; returns a handle or nil.

  • jobs.inspect(target: JobHandle | string) -> JobInfo? — return a snapshot row by handle or by name.

  • jobs.dispatch(module: string, entry: string, args: any, opts?) -> PromiseHandle — run the function entry of the module module (a require path, read from the calling line as require reads it) on a worker thread, and answer a promise of its result. opts = { deadline: number?, name: string?, key: string?, supersede: boolean? }: the key the item runs as and whether it supersedes the key's items that have not started (see "Keep state in a worker: keys" below), the deadline in seconds (default and at most the longest hold on one run, 60 seconds on every platform, native and browser alike: it may be lowered and never raised, and a larger one is refused at the call naming the cap; the longest one run of the item may take between a resume and the next yield, counted per run on monotonic time and never summed across runs) and what a rejection calls the item.

  • jobs.parallelFor(module: string, entry: string, over: number | { first, last } | buffer, args: any, opts?) -> PromiseHandle — split a loop across the worker pool; the promise settles with the chunks' results in chunk order. opts = { deadline: number?, name: string?, chunks: number?, stride: number? }.

  • jobs.release(key: string) -> boolean — end the binding of a key to its worker VM once the key's items dispatched before the call have settled; that VM's jobs.onRelease watchers run with the key. False for a key the pool does not hold.

  • jobs.onRelease(watcher: (key: string) -> ()) -> () -> () — hold a watcher in the calling VM that runs once per release of each key bound to it; answers the function that removes it.

  • jobs.warm(module: string, entry: string) -> PromiseHandle — run entry of module once in every worker VM, before items need what it builds; the promise settles once every VM up at the call has run it.

  • jobs.context() -> { worker, key?, fresh }? — on a worker, the running item's worker slot, key and whether it is the first of its key in this VM since the key bound; nil on the engine thread.

Handle methods (called via :):

  • job:pause() / job:resume() — skip / resume the job on subsequent ticks.
  • job:status() -> JobStatus? — "pending" / "running" / "errored" or nil.
  • job:valid() -> boolean — whether the substrate still tracks this job.
  • job:info() -> JobInfo? — full snapshot row.
  • job:cancel() / job:destroy() — drop one refcount; last drop unregisters.

Types:

  • JobStatus = "pending" | "running" | "errored"
  • ResourceAccess = { resource = { kind, id?, component?, field?, entity? }, mode? = "r"/"w"/"rw", type? }
  • JobExecutor = KernelExecutor | StubExecutor | LuauExecutor | ComputeExecutor
  • JobOrdering = { after? = { string }, before? = { string } }
  • JobDescriptor = { name?, phase, reads?, writes?, executor, ordering?, pure?, origin?, metadata? }
  • JobInfo = { id, name?, phase, executor, executor_detail, status, paused, refcount, last_error?, origin?, metadata, pure, ordering, reads, writes, key?, waited_for_vm_ms? }
  • DispatchOptions = { deadline?, name?, key?, supersede? }
  • JobContext = { worker?, key?, fresh }
  • JobHandle = { id, pause, resume, status, info, valid, cancel, destroy }

Usage

local job = jobs.register({
    phase    = "main",
    executor = {
        kind = "kernel",
        kernel = "copy_buffer",
    },
    reads  = {{ resource = { kind = "buffer", id = src.id }, mode = "r" }},
    writes = {{ resource = { kind = "buffer", id = dst.id }, mode = "w" }},
})

-- Luau-kind executor — the dispatcher invokes `run` once per frame.
local tick = jobs.register({
    phase    = "main",
    executor = { kind = "luau", run = function() print("tick") end },
})

job:pause()
local rows = jobs.list("main")
local info = jobs.inspect("animation_blend_main")

Work on a worker thread

jobs.dispatch runs one function of a module on a worker thread, so a computation that would hold a frame for tens or hundreds of milliseconds holds none. The module and the modules it requires run in a worker VM that boots the prelude and requires modules as the engine thread's VM does, so it has the same globals and modules/api modules; the entry computes from its arguments and returns a value, and the code awaiting the promise applies it to the world.

A call to a function only the engine thread serves (one that reads or changes the ECS world, the component instances its VM holds, or a table the engine thread has not published yet) is forwarded. The task that made the call waits as it waits on a promise, the worker keeps serving its other tasks, and the time parked never counts toward the deadline. The engine thread runs the same function with the same arguments after every write the job recorded before the call, as the principal the job runs as, and the answer returns to the job; an error the call raises raises in the job. Each forwarded call takes at least one engine frame to answer, so a loop of them costs a frame each; tasks that wait at once are answered in the same frame. Arguments and answers cross as copies (nil, booleans, numbers, strings, buffers, vectors and tables of those). A call whose argument holds a function, coroutine or userdata handle, whose answer holds an object of the engine thread's VM, or that is made where the script cannot wait (a metamethod, the top level of a module being required, a batch or queue body) raises an error naming the function and the reason. job:info().forwarded_calls counts a worker job's forwarded calls, and profiler.counters("system.schedule.frame.forwarded_calls") and profiler.stats("system.schedule.frame.forwarded_call") report the calls the engine thread served each frame and the milliseconds they took.

A watcher the module registers (engine.onModeChange, modules.watch, world.on, vfs.watch and the other engine events) is kept by the worker VM and fires when that VM next starts an item, for the events raised since it registered. save.onMarksLanded is refused on a worker, because the engine reads the value its callback returns inside its own frame. A function the module hands the engine through renderfeature.setTick, jobs.register (the luau and worker kinds) or httpserver.route stays in the worker VM that registered it, and that VM stays in service for it after the item returns: the engine posts each call to the worker and never waits for it, and reads the output of the latest call that completed. A tick or a job body runs once per frame, and what a tick enqueues is drawn one frame after the tick that made it; a job's input result is read, and its apply runs, one frame after the call that made them. A frame whose call is still running keeps the last completed output, and the call it would have made is a late call, counted in the workers report, in jobs.inspect(job).worker.lateCalls and in the profiler count system.schedule.frame.worker_late_calls. A route's handler runs on the worker once per request and the request waits for its value, as it waits on the engine thread. The function runs as the job that registered it. The registration lives until it is unregistered, or the world changes or the scripting state resets, whatever became of the job that made it; the worker's thread serves it for that long. The entry is a task of the worker VM's own scheduler: it waits on time (task.wait), on frames (task.waitFrames) and on promises (task.await), starts tasks and scopes, and returns its result. The promise settles once the engine thread has applied every write the entry and the tasks it started made before it returned, so the code awaiting it reads all of those writes, as it would after making the same calls on the engine thread. An entry whose last write the engine thread applies in the frame the entry returned settles as soon as one that writes nothing; otherwise it settles one frame later. It waits as long as the writes do (while no world is open, say) and then resolves with the entry's result. It rejects only when the engine resets the scripting state or changes its world first, and then none of those writes is applied. The tasks it started keep running until they end or the item's deadline ends them, or a run of one passes the deadline; the deadline is for one call, one run from a resume to the next yield, and time parked never counts. A write one of those tasks makes after the entry returned is not part of what the promise waits for. A promise the worker makes settles on that worker (delay, http.* and jobs.dispatch serve one), and a call whose promise an engine-thread system settles (queue, shell.run of a command it would queue) is refused, naming it.

An item runs as the task that dispatched it: its caller key and its whole call context (the actor token of the agent whose call began the chain) are captured at the dispatch, carried by the item's task and every task, watcher callback, nested jobs.dispatch and jobs.parallelFor chunk it starts, and nothing in Luau can state another. A write the item records is applied by the engine thread as that caller, so a component it adds, a publish it makes and a metered service call it issues belong to the dispatcher. A callback runs as the caller that registered it (none when none did), from the worker's own loop and never inside the call of another task, and one run of it is bound by the same hold as an item's run. No run of Luau on a worker thread is unbounded: a task's resume, a watcher or handler the worker's loop fires, and a call nothing routed each have the hold, and a run that has not armed one is given it from its first safepoint. A worker VM ends when the engine resets its scripting state or its world changes: its tasks, watchers and handles end, the item it serves fails naming the reset, and the next item runs on a new VM over the modules the engine holds then. /runtime/workers names what a worker keeps serving after its item returned (serving: the item, its owner tag, the caller, and the tasks and watchers it holds).

The pool runs several workers, each with a VM of its own, and an item dispatched without a key runs on whichever worker takes it. A module's top-level state stays in the VM that set it; items that keep state there for the next one run with a key (below).

-- /source/terrain/noise.luau
local M = {}
function M.heights(args)
    local out = buffer.create(args.size * args.size * 4)
    for i = 0, args.size * args.size - 1 do
        buffer.writef32(out, i * 4, math.noise(i % args.size / 16, i // args.size / 16, args.seed))
    end
    return out
end
return M
local heights = jobs.dispatch("@root::terrain.noise", "heights", { size = 256, seed = 7 }):await()
  • The pool's size is its share of the engine's one thread budget (the hardware threads less the engine thread, shared among the compute-task, data-parallel, off-frame, luau-workers and pipeline-build pools by weight, at least one thread each), so that many items run at once; /runtime/workers/pool reads the number as max_workers, and __threads.budget() lists every pool's share and size.
  • The promise is a future (core/scripting-and-tasks): code that must not wait, a component's update among it, reads p:state() ("pending", "resolved", "rejected", "cancelled") each frame and takes the value with p:await() once it has settled, which then returns at once.
  • A promise settles when the engine thread takes in finished items, once a frame, so a round trip lasts at least a frame however small the entry: an item is worth sending when its work outweighs that frame.
  • args and the result cross as copies: nil, booleans, numbers, strings, buffers, vectors and tables of those. Any other value (a function, an entity, a cyclic table) is refused at the call, naming its key path (args.fn).
  • The promise rejects with the entry's error and its stack, or names the deadline when one run of the entry takes longer than opts.deadline; an entry that keeps yielding has no lifetime limit.
  • p:cancel() halts a running entry, and keeps a queued one from running; the awaiter raises the cancellation task.isCancellation recognises.
  • An edit of the module reaches the next dispatch.

Keep state in a worker: keys

An item dispatched with opts.key runs in the worker VM its key is bound to, so the state a module keeps for the key (a cache, a plan, a parsed asset, a compiled rule set) is there for the key's next item:

-- /source/paths/graph.luau
local graphs = {}
local M = {}

jobs.onRelease(function(key)
    graphs[key] = nil
end)

function M.route(args)
    local ctx = jobs.context()
    local graph = graphs[ctx.key]
    if graph == nil then
        graph = buildGraph(args.map)
        graphs[ctx.key] = graph
    end
    return graph:route(args.from, args.to)
end

function M.loadTables()
    loadSharedTables()
end

return M
jobs.warm("@root::paths.graph", "loadTables")
local route = jobs.dispatch("@root::paths.graph", "route", { map = map, from = a, to = b }, { key = "level3" }):await()
jobs.release("level3")
  • The first item of a key binds the key to a worker VM: an idle worker holding the fewest keys; when none is idle, a worker the pool starts for it while it is under its cap, or else the worker holding the fewest keys. Every later item of the key runs in that VM. A key holds no worker: between the key's items the VM serves other items, keyed or not.
  • The items of a key run one at a time, in the order they were dispatched: the next starts once the one before it has settled and the writes it made have applied, so it reads them, also when that one waits and its worker serves other work meanwhile. An item that awaits an item of its own key is refused at the await, naming the key: the awaiting item holds the key's turn, and the awaited item starts only after it settles. Dispatching to its own key without awaiting (queueing a next stage) runs that item after it. A cycle through other keys (an item of a awaiting one of b that awaits one of a) waits for itself in the same way and is not refused.
  • A worker waiting inside an item takes queued work of the principal that item runs as, and the queued entries of keys that item itself awaits, or that a task of its VM belonging to no item (a watcher, a tick, a route handler) awaits, whatever principal queued them, since an entry bound to the worker can run on no other. An entry of a key none of those awaits waits for a worker of its own.
  • A key's item waits for its VM even while other workers are idle: that wait is the price of the state it finds there. /runtime/workers reports it per key (keys[].waited_for_vm_ms), and job:info().waited_for_vm_ms for a keyed worker job.
  • opts.supersede = true with a key rejects every item of the key that has not started, each naming the item that replaced it; the running item is untouched. An edit stream sends each request with it and runs only the newest.
  • jobs.context() answers, on a worker, { worker, key, fresh }: the pool slot of the worker, the running item's key (nil for an item dispatched without one, and outside an item, as in a watcher), and fresh, true for the first item a key runs in this VM since the key bound, so a module tells a cold cache from a missing entry. On the engine thread it answers nil.
  • A binding ends when jobs.release(key) reaches it (after the key's items dispatched before the call have settled), when its VM ends (the world changes, the scripting state resets, an item panics in the engine, a browser worker is lost), or when the pool ends. The key's next item binds anew and runs fresh; an item waiting for its turn when the VM ended is not lost with it. A key with items queued or running, bound or not yet bound (the pool binds a key to the worker that takes its first item), is released after them, and jobs.release answers true; it answers false, doing nothing, only for a key with no binding and no item queued or running (a key whose only entry is a release under way among them). Items of a key queued before the world changes or the scripting state resets are refused unrun, naming the reset, as every queued item is: they belong to the state that was reset. The key's items dispatched after it run.
  • jobs.onRelease(watcher) holds the watcher in the VM of the module that registers it, as a worker VM holds its engine.on* watchers: it runs as a task of that VM's scheduler, once per release of each key bound to the VM, and drops what the module keeps for the key. It answers the function that removes it. Without a release, a VM keeps each key's state for as long as it lives; /runtime/workers lists the keys each worker holds (workers[].keys).
  • jobs.warm(module, entry) runs entry of module once in every worker VM, to build the state the module keeps in its own VM (a registry, a parsed asset, a table it loads) before an item needs it. The pool starts every worker it may start, each VM up runs the entry as its next item, and a VM made later runs it before its first item, whichever boot made it. The promise settles once every VM up at the call has run it: it resolves when every run ended well, and rejects naming each worker whose run raised, panicked or ran past the warm bound, and its error. A second call for the same module and entry, for the life of the scripting state, runs nothing more and answers the same.
  • A warm entry builds state in its own VM and does not wait on the pool. It runs under the hold on one run (60 seconds from a resume to the next yield), and its whole run, waits included, under the warm bound: 60 seconds of wall time from its start to its end, on every platform. The bound is read between runs, so a run in progress at the bound goes on to its next yield: an entry that does not yield runs at most the bound plus one hold, about 120 seconds. It may wait on time and frames (task.wait, task.waitFrames). An await of a jobs.dispatch, a jobs.parallelFor or a jobs.warm promise by the entry or a task it started, while the entry runs, raises, naming what it awaited, whether or not the promise has settled; so does making a future combinator over one, at the call. Tasks the entry leaves behind await freely once it is over. Dispatching without awaiting is fine: the item runs once the VM is warm, so an entry that waits for that item another way (polling a flag it sets, popping a queue it fills) runs to the warm bound.
  • No item starts on a VM until its warm pass is over, keyed or not. Tasks the VM already holds, those of items that started earlier and its watchers, ticks and route handlers, go on between the entry's waits, and their awaits are their own.
  • An entry that raises is logged with its module, entry and worker, and the VM serves on. An entry that panics the engine, or runs past the warm bound, runs on no later VM until the scripting state resets: it is logged once and ended, and a VM it panicked is followed by one that runs the rest of the pass before any item. A panic in code outside the entry while it runs (the VM's boot, a watcher, a task another entry left behind) ends that VM, and the VM made next runs the pass once more. These endings are counted per entry, across every worker of the pool, for the epoch: the second one fails the entry for the epoch, naming the panic. A VM that cannot be made is reported with that reason, and an item that waited for it fails naming it when it cannot be made a second time.
  • An item may call jobs.warm, awaited or not, whatever principal it runs as: its worker runs the warm job for its own VM before the item resumes. A module calls it as it is first used in a world, so a world that never uses the module pays nothing; the entry runs on workers only. /runtime/workers lists each worker's warm runs with their milliseconds, and the failed ones with why, those of a VM that ended included (workers[].warm); a keyed item that waited behind a warm pass counts that time in waited_for_vm_ms.
  • A kind = "worker" job takes executor.key: every item of the job runs as that key.
  • A key is a string of 1 to 256 bytes, and the pool holds at most 65,536 keys at once; a dispatch past either bound is refused at the call, naming it. A bound key stays until it is released or its VM ends, so a key names a thing that persists (a graph, a map, an asset), and a module releases it when the thing goes.

Split a loop across the workers

jobs.parallelFor(module, entry, over, args, opts?) cuts a loop into chunks that run on the pool's workers and answers one promise, which settles when every chunk is done with the chunks' results in chunk order. over is a count of indices (1..over), a { first, last } range of whole numbers, or a buffer whose elements are opts.stride bytes each (default 1). Each chunk calls entry with one table:

-- /source/sim/reduce.luau
local M = {}
function M.sumChunk(chunk)
    local sum = 0
    for i = chunk.first, chunk.last do
        sum += i * chunk.args.scale
    end
    return sum
end
return M
local sums = jobs.parallelFor("@root::sim.reduce", "sumChunk", 100000, { scale = 2 }):await()
local total = 0
for _, s in sums do total += s end
  • chunk is { index, count, first, last, args, data }: the chunk's place among count chunks, the first and last index it covers (for a buffer, element numbers from 1), a copy of args, and for a buffer data, the chunk's slice of it. Every index is in exactly one chunk.
  • opts.chunks is the number of chunks (default four per worker, at most one per index or element, at most 4096); chunks are as even as the range divides.
  • opts.deadline (seconds, default and at most the hold on one run: 60 seconds on every platform) bounds one run of each chunk between a resume and the next yield; opts.name is what a rejection calls the call.
  • A chunk that raises or runs past its deadline rejects the promise, naming the chunk (chunk 3 of 8) and its error, and cancels the other chunks. p:cancel() cancels every chunk.
  • It runs from the engine thread and from inside a worker entry. A worker that awaits the promise runs queued chunks itself while it waits, so a chunk may call parallelFor again and complete with every worker busy.
  • The promise settles once every chunk has returned and the engine thread has applied every write the chunks made before they returned.
  • Everything else (the worker VM, copied values, module edits) follows jobs.dispatch. Splitting is worth its cost when each chunk's work outweighs the frame a round trip takes.

Work every frame on a worker thread

A kind = "worker" job runs the same kind of module entry every frame, pipelined: the engine thread pays only for input and apply.

local job = jobs.register({
    name = "crowd",
    phase = "main",
    executor = {
        kind = "worker",
        module = "@root::crowd.sim",
        entry = "step",
        input = function() return snapshot() end,       -- engine thread
        apply = function(result) write(result) end,      -- engine thread, the frame it lands
        deadline = 2,                                   -- seconds one run of an item may take between a resume and the next yield (default and at most the hold on one run: 60 seconds on every platform)
    },
})
  • At the job's phase each frame, a result that has landed goes to apply(result); then, when no item is in flight, input() runs and its value is copied to a worker, where entry runs on it. An input that returns nil queues no item that frame, so a job with work only some of the time returns nil until it has some.
  • One item is in flight at a time. A frame whose item has not returned runs no input; job:info() reports in_flight, frames_behind (the frames waited on the current item) and last_ms (how long the last item held its worker) and forwarded_calls (the calls its items made to functions only the engine thread serves).
  • The module follows the jobs.dispatch rules: a worker VM that boots the engine's prelude, copied values, and an edit reaching the next item.
  • Without executor.key, two items of one job can run on different workers, and module state stays in the worker VM that set it, so what one item hands the next travels through the result and input: apply keeps it on the engine thread and input sends it back. With executor.key, every item runs as that key, in the VM the key is bound to, and finds the state the item before it left there.
  • An entry that raises, runs past its deadline, or whose input value cannot be copied errors the job with the message (job:info().last_error, and once in the engine's error log, naming the job); job:resume() runs it again. An apply that raises errors its own job and no other.
  • Destroying, pausing or erroring the job stops its item, and apply never runs for it. input and apply run as the principal that registered the job, and so does each item.
  • /runtime/workers reads the pool (pool) and each worker that has run an item (0, 1, ...): its state (running, idle, or lost for a worker lost while it ran an item), the item it is running, its item count and busy time.
  • __threads.pools() reports the luau-workers pool: its workers, the items queued and running, and the workers lost.

Share state with the game while a job runs: jobs.shared

jobs.dispatch hands its result back when the entry returns. State that has to cross while a job runs (progress, partial results, a flag the game sets, work handed from one job to another) lives in jobs.shared: tables and queues that the engine's VM and every worker VM read and write. Process memory, not persisted and not replicated: runtime_data and synced component fields are the persisted, replicated stores.

-- /source/terrain/build.luau   (runs in a job)
local M = {}
function M.run(args)
    local regions = jobs.shared.table("terrain.regions")
    for index = 1, args.count do
        regions[index] = buildRegion(index)         -- a table of numbers, strings, buffers
        jobs.shared.atomic(jobs.shared.table("terrain.progress"), "done", function(n) return (n or 0) + 1 end)
    end
    return true
end
return M
-- the game, each frame
local regions = jobs.shared.table("terrain.regions")
local progress = jobs.shared.table("terrain.progress")
local seen = 0
task.loop(function()
    local now = jobs.shared.revision(regions)
    if now ~= seen then
        seen = now
        for index, region in regions do showRegion(index, region) end
    end
end)
  • jobs.shared.table(name) is a table every VM reads and writes: t.x = 1, t.player.hp -= 5, #t, for k, v in t, pairs, ipairs, next, table.insert, table.remove, table.sort, table.concat, table.find, table.unpack, table.clone, table.clear, rawget, rawset, and type(t) == "table" behave as on an ordinary table. It holds nil, boolean, number, integer, string, vector, buffer and tables of those. Assigning a table copies it in: later edits of the local table are not seen. A function, coroutine, userdata, or a table with a metatable raises, naming the key path.
  • t.a where t.a is a table is that table, so t.a.b = 1 writes through and t.a == t.a. A table that was replaced or removed raises on any use, naming where it was.
  • Each access is atomic on its table. A loop walks the table as it stood when the loop started: it never sees a torn table and never holds a writer up. A change that spans keys is one jobs.shared.atomic on the parent key.
  • jobs.shared.atomic(t, key, fn) reads, changes and writes one key without a race. fn(current) returns the new value; if another write reached the table meanwhile fn runs again on the newer value (up to 256 attempts, then the call raises naming the table and key), so fn is quick, pure and does not yield. A call that lost four attempts in a row takes its turn at the table: the other atomic calls on a worker wait for it, so atomic calls never starve one another, and the 256 attempts bound only a storm of plain writes. Counters, flags and compare-and-set are this call.
  • jobs.shared.revision(t) is one number that every write to the table or to any table nested in it advances: game code that polls each frame reads the table only when the number moved. jobs.shared.snapshot(t) is a plain deep copy.
  • jobs.shared.queue(name, { capacity = 1024 }) is a bounded first-in-first-out queue (at most 65,536 values). q:push(v) copies v in from anywhere; q:pop() takes the front value and waits for one (a worker parks and uses no cpu; on the engine thread only the calling task suspends, so no frame is held); q:tryPop() never waits and answers nil when empty; q:length() counts. A full queue raises naming the queue and its capacity: it never drops a value.
  • Created on first use; it lasts until the world changes or the scripting state resets (entering play keeps it). After that a held table or queue raises naming the reason, and tasks parked on pop are rejected with it.
  • Bounds: a table holds at most 1,048,576 entries and 64 MiB (32 MiB in the browser), nested at most 64 deep; the process holds at most 4,096 names and 256 MiB (128 MiB in the browser). A write past a bound raises and changes nothing.
  • Reach: the engine's VM and worker VMs, not the trusted VM.

Notes

  • JobHandles are cached by id with weak values — looking the same id up again returns the same handle table.
  • JobHandle is sealed: rawset on the handle and __newindex both raise. The id is the only field, exposed via direct access.
  • cancel and destroy are aliases for symmetry with other resource handles (entity:destroy(), buffer:destroy()); both drop one refcount.
  • origin is auto-filled by register with the calling script's VFS path unless the descriptor already supplies one — surfaced under /zero/runtime/jobs/<phase>/<key>/origin.txt for agent traceability.
  • register's descriptor parameter is typed table rather than JobDescriptor because the LSP doesn't yet narrow string literals to their literal types in record fields, which would reject the tagged-union executor discriminator on every call site. Runtime validation in __jobs.register enforces the actual structure.

Interface

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

conforms to

zero/source-extract/v2

global jobs

jobhandle_pause(self: JobHandle) → boolean

Pause the job — skipped on subsequent ticks but stays registered.

argtypedescription
selfJobHandleJobHandle returned by `jobs.register`.

examples

local job = jobs.register({...}); job:pause()

jobhandle_resume(self: JobHandle) → boolean

Resume a paused or errored job (clears `Errored` → `Pending`).

argtypedescription
selfJobHandleJobHandle returned by `jobs.register`.

examples

job:resume()

jobhandle_status(self: JobHandle) → JobStatus

Read the job's current scheduler status.

argtypedescription
selfJobHandleJobHandle returned by `jobs.register`.

examples

local s = job:status() -- "pending"

jobhandle_valid(self: JobHandle) → boolean

Whether the substrate still tracks this job (false after :cancel/:destroy).

argtypedescription
selfJobHandleJobHandle returned by `jobs.register`.

examples

if not job:valid() then return end

jobhandle_info(self: JobHandle) → JobInfo

Latest snapshot row for this job (id, name, phase, status, origin, metadata, reads, writes…). Single FFI crossing — pulls only this job's row, not the full registry.

argtypedescription
selfJobHandleJobHandle returned by `jobs.register`.

examples

local info = job:info(); print(info.origin)

jobhandle_cancel(self: JobHandle) → boolean

Cancel the job — drops one refcount, last drop unregisters and the dispatcher stops invoking it. Symmetric with `vfs.remove("/runtime/jobs/<phase>/<id>")`.

argtypedescription
selfJobHandleJobHandle returned by `jobs.register`.

examples

job:cancel()

__newindex(_: any, k: any) → void

argtypedescription
_any
kany

__index(self: any, key: string) → void

The typed JobHandle struct is closed — method-cache rawset fields like `__m_pause` would fail strict-shape checks on subsequent typed calls (the typed function preprocessor rejects unknown self-fields). Skip the cache; METHODS is a plain hash lookup, ~constant cost.

argtypedescription
selfany
keystring

build_handle(job_id: number) → JobHandle

argtypedescription
job_idnumber

computeExecutorKey(shader: any) → any

The registration key for whatever `executor.shader` names. A reference asks the computeShader assetType for its key, so the job dispatches under exactly the key the shader compiled under.

argtypedescription
shaderany

register(descriptor: table) → JobHandle

Register a substrate job. Returns a JobHandle on success, nil on validation failure. Dispatches by `executor.kind`:\n - `"kernel"` / `"stub"` → standard `__jobs.register` (JSON-only descriptor).\n - `"luau"` → `__jobs.register_luau(descriptor, executor.run)` so the Luau function survives the JSON crossing as a stable registry ref. The dispatcher invokes the run closure once per frame; the closure captures any bindings/buffers it needs.\n - `"compute"` → the shader reference resolves to its registration key, and the job queues one dispatch per frame.\n - `"worker"` → `__jobs.register_worker(descriptor, executor.input, executor.apply)`: each frame `input()` runs on the engine thread, its value is copied to a worker where the `module`'s `entry` runs, and the result reaches `apply(result)` on the engine thread the frame it lands, one item in flight at a time. An `input` that returns nil queues no item that frame. A job that errors logs its name and message once, and `job:info().last_error` holds it. Without a `key`, its items can run on different workers, each with module state of its own, so what carries from one item to the next travels through the result and `input`. `key` (a string of 1 to 256 bytes) runs every item of the job as that key, in the worker VM the key is bound to, so module state one item leaves there is there for the next (see `jobs.dispatch`); `job:info().waited_for_vm_ms` is the time its items waited for that VM. A job registered from a worker VM keeps its function (`run`, or `input` and `apply`) in that VM: the dispatcher posts each frame's call to the worker and never waits for it, the writes it records apply one frame later, a raise marks the job errored one frame later, and `job:info().worker` reports the calls, the late calls and the failed calls. A worker job whose `input` or `apply` is not a function, whose `deadline` is not a number of seconds above 0 and at most the hold on one run (60 seconds on every platform), or whose `key` is not a string of 1 to 256 bytes, is raised at the call, naming why. `deadline` (default and at most that hold: it may be lowered and never raised) is the longest one run of an item may take between a resume and the next yield, counted on monotonic time per run and never summed across runs.\n\n`origin` is auto-filled with the VFS path of the calling script unless the descriptor already supplies one — surfaced under `/zero/runtime/jobs/<phase>/<key>/origin.txt` for agent traceability. Single FFI crossing — auto-origin runs Rust-side via `lua_getinfo`, no separate stack-inspection trip.

argtypedescription
descriptortableJob declaration with the `JobDescriptor` shape — `name?`, `phase`, `reads?`, `writes?`, `executor`, `ordering?`, `pure?`, `origin?`, `metadata?`. Param is typed as `table` rather than `JobDescriptor` because the LSP doesn't yet narrow string literals to their literal types in record fields, so a `JobDescriptor` annotation rejects the tagged-union `executor` discriminator on every call site (literal `kind = "kernel"` infers as `kind: string`, doesn't subtype `KernelExecutor.kind: "kernel"`). Runtime validation in `__jobs.register` enforces the actual structure; see the `JobDescriptor` type alias above for the canonical shape.

examples

local job = jobs.register({ phase = "main", executor = { kind = "kernel", kernel = "copy_buffer" }, reads = {{resource={kind="buffer",id=src.id},mode="r"}}, writes = {{resource={kind="buffer",id=dst.id},mode="w"}} })
local job = jobs.register({ phase = "main", executor = { kind = "luau", run = function() print("tick") end } })
local job = jobs.register({ phase = "main", executor = { kind = "compute", shader = asset.resolve("carve", "computeShader"), buffers = { "heights" }, workgroups = { 64 } } })
local job = jobs.register({ name = "crowd", phase = "main", executor = { kind = "worker", module = "@root::crowd.sim", entry = "step", input = function() return snapshot() end, apply = function(result) write(result) end } })

list(phase: string?) →

List registered job summaries. Pass a phase name to filter to a single phase. Single FFI crossing — only the requested rows cross the bridge.

argtypedescription
phasestring?Optional phase filter — nil returns every job.

examples

local rows = jobs.list("main")

find(name: string) → JobHandle

Look up a registered job by name. Returns a JobHandle or nil for anonymous / unknown names. Single FFI crossing — returns the id directly, no registry snapshot.

argtypedescription
namestringJob name supplied to `jobs.register`.

examples

local job = jobs.find("animation_blend_main")

inspect(target: JobHandle | string) → JobInfo

Return a snapshot row by job handle or by name without retrieving a full handle. Single FFI crossing — pulls only the matching row.

argtypedescription
targetJobHandle | stringJobHandle, or job name string.

examples

local info = jobs.inspect("animation_blend_main")

dispatch(module: string, entry: string, args: any, opts: DispatchOptions?) → PromiseHandle

Run the function `entry` of the module `module` on a worker thread and answer a promise of its result, so a long computation holds no frame. `module` is a require path, read from this line as `require` reads it. The module and the modules it requires run in a worker VM that boots the prelude and requires modules as the engine thread's VM does, so it has the same globals and `modules/api` modules: the entry computes from its arguments and returns a value, which the code awaiting the promise applies to the world. A call to a function only the engine thread serves (one that reads or changes the ECS world, the component instances its VM holds, or a table the engine thread has not published yet) is forwarded: from a job it runs on the engine thread, with the same arguments, after every write the job recorded before it, as the principal the job runs as, and its answer or its error returns to the job. The task that made it waits as it waits on a promise, so the worker keeps serving its other tasks and the time parked never counts toward the deadline; each forwarded call takes at least one engine frame, and `job:info().forwarded_calls` and the `system.schedule.frame.forwarded_calls` profiler count report them. Arguments and answers cross as copies; a call whose argument holds a function, coroutine or userdata handle, whose answer holds an object of the engine thread's VM, or that is made where the script cannot wait (a metamethod, the top level of a module being required, a `batch` or `queue` body) raises an error naming the function and the reason. A watcher the module registers (`engine.onModeChange`, `modules.watch`, `world.on`, `vfs.watch` and the other engine events) is kept by the worker VM and fires when that VM next starts an item, for the events raised since it registered; `save.onMarksLanded` is refused there, because the engine reads the value its callback returns inside its own frame. A function the module registers with `renderfeature.setTick`, `jobs.register` or `httpserver.route` stays in the worker VM that registered it, and that VM stays in service for it after the item returns, until the function is unregistered or the world changes or the scripting state resets: the engine posts each call to the worker and never waits for it, and reads the latest completed output (a tick's passes are drawn one frame after the tick that made them, and a frame whose call is still running keeps the last completed output and counts a late call). The entry is a task of the worker VM's own scheduler: it waits on time (`task.wait`), on frames (`task.waitFrames`) and on promises (`task.await`), starts tasks and scopes, and returns its result. The promise settles once the engine thread has applied every write the entry and the tasks it started made before it returned, so the code awaiting it reads all of those writes, as it would after making the same calls on the engine thread; an entry whose last write the engine thread applies in the frame the entry returned settles as soon as one that writes nothing, and otherwise one frame later. It waits as long as the writes do (while no world is open, say) and then resolves with the entry's result. It rejects only when the engine resets the scripting state or changes its world first, and then none of those writes is applied. The tasks it started keep running until they end or the item's deadline ends them; a write one of them makes after the entry returned is not part of what the promise waits for. A promise the worker makes settles on that worker (`delay`, `http.*` and `jobs.dispatch` serve one), and a call whose promise an engine-thread system settles (`queue`, `shell.run` of a command it would queue) is refused, naming it. An item runs on whichever worker takes it. With `opts.key` (a string of 1 to 256 bytes) it runs in the worker VM the key is bound to, after every item of the key dispatched before it has settled and its writes have applied, one at a time and in order, so module state an item of the key leaves (a cache, a plan, a parsed asset) is there for the next; `jobs.context().fresh` tells the first item of a key in a VM since the key bound, `jobs.release` ends the binding, and `jobs.warm` runs a module's one-time setup in every worker VM before items need it. A key's item waits for its VM even while other workers are idle, and `/runtime/workers` reports the wait per key. An item awaiting an item of its own key is refused at the await, naming the key: the awaiting item holds the key's turn, and the awaited item starts only after it settles; dispatching to its own key without awaiting runs that item after it. Items of a key queued before the world changes or the scripting state resets are refused unrun, naming the reset. `opts.supersede = true` with a key rejects every item of the key that has not started, naming this one; the running item is untouched. The pool holds at most 65,536 keys at once, and a dispatch with a key past that is refused at the call, naming the bound. `args` and the result cross as copies: nil, booleans, numbers, strings, buffers, vectors and tables of those, and any other value is refused at this call naming its key path. The promise rejects with the entry's error and stack, or names the deadline when one run of the entry, from a resume to the next yield, takes longer than `opts.deadline` seconds (default and at most the longest hold on one run, 60 seconds on every platform, native and browser alike; any number above 0 up to it, which a caller may lower and may not raise: a larger one is refused at the call naming the cap). The clock starts at each resume and stops at each yield, so time parked on a promise, `task.wait` or a frame never counts, every yield resets it, and no sum across runs is kept: an entry that keeps yielding runs until it returns or is cancelled. The tasks it resumed are held to the same deadline. Cancelling the promise (`p:cancel()`) halts a running entry and keeps a queued one from running. An edit of the module reaches the next dispatch.

argtypedescription
modulestringRequire path of the module, as `require` takes it.
entrystringName of the function in the module's export table.
argsanyThe value the entry receives, copied.
optsDispatchOptions?Optional `{ deadline: number?, name: string?, key: string?, supersede: boolean? }`: the deadline in seconds, what a rejection calls the item, the key it runs as, and whether it supersedes the key's items that have not started.

examples

local heights = jobs.dispatch("@root::terrain.noise", "heights", { size = 256, seed = 7 }):await()
local p = jobs.dispatch("@root::sim.solver", "solve", state, { deadline = 2, name = "solver" }); p:cancel()
local route = jobs.dispatch("@root::paths.graph", "route", { map = "level3", from = a, to = b }, { key = "level3" }):await()
local preview = jobs.dispatch("@root::graph.cook", "cook", edit, { key = graphId, supersede = true })

release(key: string) → boolean

End the binding of `key` to its worker VM once the items of the key dispatched before this call have settled. That VM then runs its `jobs.onRelease` watchers with the key, each as a task of its scheduler, and the key's next item binds anew and runs with `jobs.context().fresh` true. Without a release, a VM keeps each key's state for as long as it lives (until the world changes or the scripting state resets); `/runtime/workers` lists the keys each worker holds. Runs from the engine thread and from a worker.

argtypedescription
keystringThe key, as `jobs.dispatch` was given it in `opts.key`.

examples

jobs.release(graphId)

onRelease(watcher: (key: string) →

Hold `watcher` in the VM of the module that calls it: each time a key bound to that VM is released (`jobs.release`), `watcher(key)` runs there as a task of the VM's scheduler, once per release, so the module drops what it keeps for the key. A worker VM keeps its own watchers, as it keeps `engine.on*` watchers; a module registers at its top level, which every worker VM that requires it runs. The engine thread's VM holds no key, so a watcher there is held and never called. Answers the function that removes the watcher.

argtypedescription
watcher(key: stringCalled with the released key.

examples

jobs.onRelease(function(key) plans[key] = nil end)

warm(module: string, entry: string) → PromiseHandle

Run the function `entry` of the module `module` once in every worker VM, to build the state the module keeps in its own VM (a registry, compiled rules, a table it loads) before an item needs it. The pool starts every worker it may start; each VM up runs the entry as its next item, and a VM made later (after a panic, or one the pool starts later) runs it before its first item, whichever boot made it. The entry is called with nil and builds state in its own VM: it runs under the hold on one run (60 seconds from a resume to the next yield), and its whole run, waits included, under the warm bound of 60 seconds of wall time from its start to its end, read between runs, so a run in progress at the bound goes on to its next yield: an entry that does not yield runs at most the bound plus one hold, about 120 seconds. It may wait on time and frames, and it does not wait on the pool: an await of a `jobs.dispatch`, a `jobs.parallelFor` or a `jobs.warm` promise by the entry or a task it started, while the entry runs, raises, naming what it awaited, whether or not the promise has settled, and so does making a `future` combinator over one, at the call (dispatching without awaiting is fine: the item runs once the VM is warm). No item starts on the VM until its warm pass is over; tasks the VM already holds go on between the entry's waits. The promise settles once every VM up at the call has run it: it resolves when every run ended well, and rejects naming each worker whose run raised, panicked or ran past the warm bound, and its error. It is kept for the life of the scripting state: a second call for the same module and entry runs nothing more and answers the same. An entry that raises is logged, naming its module, entry and worker, and the VM serves on. An entry that panics the engine or runs past the warm bound runs on no later VM until the scripting state resets: it is logged once and ended, and the VM made after a panic runs the rest of the pass before any item. A panic in code outside the entry while it runs (the VM's boot, a watcher, a task another entry left behind) ends that VM, and the VM made next runs it once more; these endings are counted per entry, across every worker of the pool, for the epoch, and the second one fails the entry for the epoch, naming the panic. The entry runs on workers only; the calling thread pays the dispatch. Call it from the engine thread or from an item, awaited or not, whatever principal the item runs as: the item's worker runs the warm job for its own VM before the item resumes. Call it when the module is first used in a world, so a world that never uses it pays nothing; `/runtime/workers` lists each worker's warm runs with their milliseconds, and the failed ones with why.

argtypedescription
modulestringRequire path of the module, as `require` takes it.
entrystringName of the function in the module's export table.

examples

jobs.warm("@root::graph.nodes", "buildRegistry")
jobs.warm("@root::paths.graph", "loadTables"):await()

context( ) → JobContext

What the running item runs as, on a worker: `worker`, the pool slot of its worker; `key`, the item's key (nil for an item dispatched without one, and outside an item, as in a watcher); `fresh`, true for the first item a key runs in this VM since the key bound, so a module tells a cold cache from a missing entry. On the engine thread it answers nil, which is also how code asks whether it runs on a worker.

examples

local ctx = jobs.context(); if ctx and ctx.fresh then cache = {} end

parallelFor(module: string, entry: string, over: number | { first: number, last: number } | buffer, args: any, opts: { deadline: number?, name: string?, chunks: number?, stride: number? }?) → PromiseHandle

Split a loop across the worker pool and answer a promise of the chunks' results in chunk order, so a loop over many indices or many elements of a buffer holds no frame and uses every worker. `over` is a count of indices (`1..over`), a table `{ first = a, last = b }` of whole numbers, or a buffer whose elements are `opts.stride` bytes each (default 1). The range is cut into `opts.chunks` runs (default four per worker, at most one per element), as even as it divides, and each run is an item the pool's workers take: `entry`, a function of the module `module`, is called with one table `chunk` = `{ index, count, first, last, args, data }`, where `first` and `last` are the run's indices (for a buffer, its element numbers from 1), `args` is a copy of `args`, and `data` is the run's slice of a buffer. The promise settles once every chunk has returned and the engine thread has applied every write the chunks made before they returned, with `{ chunk 1 result, chunk 2 result, ... }` in chunk order whichever chunk finished first. A chunk that raises, or runs past its deadline (`opts.deadline` seconds for one run of each chunk between a resume and the next yield, default and at most the hold on one run, 60 seconds on every platform), rejects the promise naming the chunk (`chunk 3 of 8`) and cancels the chunks still queued or running; cancelling the promise (`p:cancel()`) cancels every chunk. It runs from the engine thread and from a worker: a worker that awaits the call runs queued chunks itself, so a call made inside a chunk completes however many workers are busy. The module, its worker VMs, `args` and result copies follow the rules of `jobs.dispatch`.

argtypedescription
modulestringRequire path of the module, as `require` takes it.
entrystringName of the function in the module's export table; it receives the chunk table.
overnumber | { first: number, last: number } | bufferA count of indices, a `{ first, last }` range, or a buffer.
argsanyA value every chunk receives as `chunk.args`, copied.
opts{ deadline: number?, name: string?, chunks: number?, stride: number? }?Optional `{ deadline: number?, name: string?, chunks: number?, stride: number? }`: the deadline in seconds of one run of each chunk, what a rejection calls the call, the number of chunks, and the bytes in one element of a buffer.

examples

local sums = jobs.parallelFor("@root::sim.reduce", "sumChunk", 100000, { scale = 2 }):await()
local out = jobs.parallelFor("@root::pixels.tint", "tint", pixels, nil, { stride = 4, chunks = 16 }):await()

sharedBinding( ) → any

push(_self: any, value: any) → void

argtypedescription
_selfany
valueany

tryPop(_self: any) → any

argtypedescription
_selfany

pop(_self: any) → any

argtypedescription
_selfany

length(_self: any) → number

argtypedescription
_selfany
⌬ Types
JobStatus = "pending" | "running" | "errored"ResourceAccess = {KernelExecutor = {StubExecutor = { kind: "stub" }LuauExecutor = {ComputeExecutor = {WorkerExecutor = {DispatchOptions = {JobContext = {ParallelChunk = {JobExecutor = KernelExecutor | StubExecutor | LuauExecutor | ComputeExecutor | WorkerExecutorJobOrdering = { after: { string }?, before: { string }? }JobDescriptor = {JobInfo = {JobHandle = {SharedTable<T> = { [string | number]: T }SharedQueueOptions = { capacity: number? }SharedQueue<T> = {

Sub-parts

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34+items
·
assettype · born here
❒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**.
▲ 0↑ born
▣
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.
▲ 0↑ born
·
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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# 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.
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module · born here
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# 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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module · born here
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# 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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module · born here
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# 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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backing path · modules/api/engine/jobs.module

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