# jgengine — capability index Reach for these before hand-rolling. Each row is *the thing you need* → *the primitive that already does it*. ## authored-spawn — read spawn points and markers from the editor document - `authoredSpawnPosition` (function) · `import { authoredSpawnPosition } from "@jgengine/shell/gameKit"` ## authored-triggers — schema'd on/action vocabulary on volumes and markers with runtime dispatch - `collectAuthoredTriggers` (function) · `import { collectAuthoredTriggers } from "@jgengine/shell/gameKit"` ## chase-view-cycle — cycle a vehicle camera between chase, hood and cockpit views at runtime - `nextChaseView` (function) · `import { nextChaseView } from "@jgengine/core/runtime/cameraDirector"` ## client-side — input prediction with replay reconciliation - `createPredictionBuffer` (function) · `import { createPredictionBuffer } from "@jgengine/core/runtime/prediction"` ## collider-autofit — hitboxes and physical bodies fit each kind's rendered model bounds automatically — no hand-tuned sizes - `GameContextModels` (interface) · `import { GameContextModels } from "@jgengine/core/runtime/gameContext"` ## command-number — validate finite, bounded numbers and integers at command boundaries - `readInputNumber` (function) · `import { readInputNumber } from "@jgengine/core/runtime/commandInput"` ## command-parse — parse untrusted command input once so every command stage sees typed, bounded values - `defineCommand` (function) · `import { defineCommand } from "@jgengine/core/runtime/commandRunner"` ## command-quantity — validate bounded whole-item counts at command boundaries - `readQuantity` (function) · `import { readQuantity } from "@jgengine/core/runtime/commandInput"` ## default-walk-codes — stock WASD + jump key codes for the shell walk controller - `DEFAULT_WALK_CODES` (const) · `import { DEFAULT_WALK_CODES } from "@jgengine/shell/gameKit"` ## define-game — single public game-authoring path — compose systems, world, presentation, and authored scene in one definition - `defineGame` (function) · `import { defineGame } from "@jgengine/shell/gameKit"` ## define-system — composable game behavior — pure data + hooks the engine schedules; pass via `defineGame({ systems })` - `defineSystem` (function) · `import { defineSystem } from "@jgengine/shell/gameKit"` ## devtools-log-bus — a bounded, per-system-tagged log ring a system writes to and a report reads - `LogBus` (interface) · `import { LogBus } from "@jgengine/core/devtools/logBus"` ## editor-catalogs — Export typed gameplay catalogs for in-editor tuning. - `EditorCatalogDefinition` (interface) · `import { EditorCatalogDefinition } from "@jgengine/shell/gameKit"` ## fire-input — bind a key or mouse button to a named action that runs the same-named command with the aim; repeatMs auto-fires while held - `ActionCodesMap` (type) · `import { ActionCodesMap } from "@jgengine/core/authoring"` ## game-system — declare a composable capability with its own schedule and lifecycle - `SystemDefinition` (interface) · `import { SystemDefinition } from "@jgengine/shell/gameKit"` ## grounded — ground an XZ point onto the world surface as a pose triple - `grounded` (function) · `import { grounded } from "@jgengine/shell/gameKit"` ## headless-runner — play a real game loop with no renderer — tick, feed input, read the world snapshot - `HeadlessRunner` (interface) · `import { HeadlessRunner } from "@jgengine/core/runtime/headlessRunner"` ## host-join-code-gate — membership-or-code gate for private hosted servers - `canJoinPrivateServer` (function) · `import { canJoinPrivateServer } from "@jgengine/core/runtime/hostPolicy"` ## host-join-target — choose or refuse an auto-matched server under a matchmaking mode - `selectJoinTarget` (function) · `import { selectJoinTarget } from "@jgengine/core/runtime/hostPolicy"` ## host-listing-filter — exclude private sessions from public browse results - `isListablePublicly` (function) · `import { isListablePublicly } from "@jgengine/core/runtime/hostPolicy"` ## hud-canvas — the HUD root surface — design-resolution scaling plus live panel-placement editing (F2+C) - `HudCanvas` (function) · `import { HudCanvas } from "@jgengine/shell/gameKit"` ## hud-clock — in-game time-of-day readout bound to the sim clock - `Clock` (function) · `import { Clock } from "@jgengine/shell/gameKit"` ## hud-coins — currency counter widget bound to a currency id - `Coins` (function) · `import { Coins } from "@jgengine/shell/gameKit"` ## hud-hotbar — optional inventory hotbar building block — games own slot chrome - `Hotbar` (function) · `import { Hotbar } from "@jgengine/shell/gameKit"` ## hud-layout — persistent, live-editable HUD panel layout state for `HudCanvas` - `useHudLayout` (function) · `import { useHudLayout } from "@jgengine/shell/gameKit"` ## hud-panel — anchored HUD slot — drop any widget in a named, player-movable panel - `HudPanel` (function) · `import { HudPanel } from "@jgengine/shell/gameKit"` ## hud-stat-bar — optional stat-bound bar building block (health, mana, stamina) — prefer game-owned chrome - `StatBar` (function) · `import { StatBar } from "@jgengine/shell/gameKit"` ## input-recorder — tick-indexed input log for replay, rollback, and regression tests - `createInputRecorder` (function) · `import { createInputRecorder } from "@jgengine/core/runtime/inputRecorder"` ## local-players — Couch co-op seats: devices hot-join into slots, each with its own user id and input snapshot. - `createLocalPlayers` (function) · `import { createLocalPlayers } from "@jgengine/core/runtime/localPlayers"` ## loot-table — validate a loot table definition for use with the registry - `lootTable` (function) · `import { lootTable } from "@jgengine/core/authoring"` ## mount-game — mount a defined game in the browser — ` import("@jgengine/editor")} />` - `GameHost` (function) · `import { GameHost } from "@jgengine/shell/gameKit"` ## multiplayer-offline — explicit solo adapter — omit `multiplayer` instead; offline is the shell default - `offline` (function) · `import { offline } from "@jgengine/shell/gameKit"` ## multiplayer-p2p — serverless co-op over WebRTC — `multiplayer: p2p({ room })` - `p2p` (function) · `import { p2p } from "@jgengine/core/runtime/adapter"` ## multiplayer-ws — server-hosted shared world over WebSocket — `multiplayer: ws({ authority: "server" })` - `ws` (function) · `import { ws } from "@jgengine/core/runtime/adapter"` ## object-slot-inventory — placed objects hold validated per-instance container contents that replicate and save with the placement - `SceneObjectSlots` (interface) · `import { SceneObjectSlots } from "@jgengine/core/runtime/context/objectSlots"` ## placed-object-rehydrate — rebuild live placed objects, with their state and slot contents, from persisted snapshot rows - `fromRuntimeObjectRow` (function) · `import { fromRuntimeObjectRow } from "@jgengine/core/runtime/objectRows"` ## placed-object-rows — a placed object's per-instance state and container contents convert to and from the persisted snapshot row a host stores - `toRuntimeObjectRow` (function) · `import { toRuntimeObjectRow } from "@jgengine/core/runtime/objectRows"` ## pose-interpolation — render entity poses between fixed simulation steps without stutter - `createPoseHistory` (function) · `import { createPoseHistory } from "@jgengine/core/runtime/poseInterpolation"` ## render-fallback-diagnostics — Enable/disable the dev-only placeholder-fallback probe. - `armFallbackSeams` (function) · `import { armFallbackSeams } from "@jgengine/core/devtools/fallbackSeams"` - `armTextureErrors` (function) · `import { armTextureErrors } from "@jgengine/core/devtools/textureErrors"` - `fallbackSeamsSnapshot` (function) · `import { fallbackSeamsSnapshot } from "@jgengine/core/devtools/fallbackSeams"` - `reportFallbackSeam` (function) · `import { reportFallbackSeam } from "@jgengine/core/devtools/fallbackSeams"` - `reportTextureLoadError` (function) · `import { reportTextureLoadError } from "@jgengine/core/devtools/textureErrors"` - `resetTextureErrors` (function) · `import { resetTextureErrors } from "@jgengine/core/devtools/textureErrors"` - `textureErrorsSnapshot` (function) · `import { textureErrorsSnapshot } from "@jgengine/core/devtools/textureErrors"` ## runtime — snapshot interpolation - `createSnapshotBuffer` (function) · `import { createSnapshotBuffer } from "@jgengine/core/runtime/snapshotBuffer"` ## runtime-save — save/load the whole game world through a pluggable backend, autosave or save points - `createRuntimeSave` (function) · `import { createRuntimeSave } from "@jgengine/core/runtime/runtimeSave"` ## scene-ownership — audit a whole ownership manifest for boundary violations - `auditManifest` (function) · `import { auditManifest } from "@jgengine/core/authoring"` - `classifyOwnership` (function) · `import { classifyOwnership } from "@jgengine/core/authoring"` - `collectOwnershipDiagnostics` (function) · `import { collectOwnershipDiagnostics } from "@jgengine/core/authoring"` - `isSceneOwnershipManifest` (function) · `import { isSceneOwnershipManifest } from "@jgengine/core/authoring"` - `ownershipKey` (function) · `import { ownershipKey } from "@jgengine/core/authoring"` ## seeded-random — injected deterministic randomness for game logic — never `Math.random` in a simulation - `seededRng` (function) · `import { seededRng } from "@jgengine/shell/gameKit"` ## sim-loop — fixed-step or variable simulation stepping with tick count, catch-up cap, and interpolation alpha - `createSimLoop` (function) · `import { createSimLoop } from "@jgengine/core/runtime/simLoop"` ## sim-snapshot — capture and restore whole-simulation state for replay, rollback, and regression tests - `createSimSnapshotRegistry` (function) · `import { createSimSnapshotRegistry } from "@jgengine/core/runtime/simSnapshot"` ## typed-keyed-store — a cast-free typed handle onto a per-owner keyed family of reactive game-store slots, replayable and host-authoritative - `defineKeyedStore` (function) · `import { defineKeyedStore } from "@jgengine/shell/gameKit"` ## typed-store — a cast-free typed handle onto one reactive game-store slot, replayable and host-authoritative - `defineStore` (function) · `import { defineStore } from "@jgengine/shell/gameKit"` ## warn-once — emit a dev-only warning a single time per call site - `warnOnce` (function) · `import { warnOnce } from "@jgengine/core/devtools/warnOnce"` ## world-chunk-key — map world positions to persisted chunk keys at a declared cell size - `chunkKeyOf` (function) · `import { chunkKeyOf } from "@jgengine/core/runtime/worldChunks"` ## world-chunk-write — mutate a snapshot's chunk and have the host persist it - `setChunk` (function) · `import { setChunk } from "@jgengine/core/runtime/worldChunks"` ## world-convergence — derive environment coordinate content from the scene document - `environmentContentFromDocument` (function) · `import { environmentContentFromDocument } from "@jgengine/shell/gameKit"` ## world-environment — compose editor/preset-derived outdoor dressing — terrain, weather, water, structures — into a legacy environment feature - `environment` (function) · `import { environment } from "@jgengine/shell/gameKit"` ## world-item-pickup — pick up dropped items: ctx.scene.worldItem nearestInRadius → pickup into the player's inventory - `SceneWorldItemContext` (interface) · `import { SceneWorldItemContext } from "@jgengine/core/runtime/gameContext"`