@vizij/node-graph-wasm

Vizij’s node graph engine for JavaScript.

This package ships the WebAssembly build of vizij-graph-core together with a TypeScript wrapper, schema helpers, and sample graphs. Load Vizij GraphSpecs, stage host inputs, evaluate outputs, and update node parameters from any modern JS runtime without compiling Rust.

Table of Contents

1. Overview
2. Key Concepts
3. Installation
4. API
5. Usage
6. Samples & Fixtures
7. Development & Testing
8. Related Packages

Overview

• Built from vizij-graph-core with wasm-bindgen; the npm package is the canonical JavaScript distribution maintained by the Vizij team.
• Provides a high-level Graph class, low-level bindings, TypeScript definitions, and ready-to-use fixtures.
• Supports both browser and Node environments—init() chooses the right loader and validates the ABI (abi_version() === 2).
• Ships GraphSpec normalisers and schema inspection helpers so editors and tooling can speak the same language as Vizij runtimes.
• Bakes the node registry (metadata/registry.json) straight from the Rust core so build-time tooling and authoring UIs stay in sync with the runtime.

Key Concepts

• GraphSpec – Declarative JSON describing nodes, parameters, and the explicit edges array that connects node outputs to inputs (selectors, output keys). The package normalises shorthand specs automatically.
• Graph Runtime – The Graph class owns a GraphRuntime, handling loadGraph, stageInput, setParam, step, and evalAll. Structural parameter changes (e.g., Split.sizes) invalidate the wasm plan cache and the JS wrapper resets its delta baseline automatically so the next eval re-establishes a full snapshot before returning to deltas.
• Plan caching & invalidation – The wasm engine caches a compiled execution plan (topological order + port layouts + input bindings) for performance.
  • The cache is reused across frames when the graph layout is unchanged.
  • Only structural edits (changes that can affect port layouts or bindings) invalidate the plan. In practice today this includes Split.sizes; most other param changes are non-structural and do not force a plan rebuild.
  • GraphSpec.specVersion (and fingerprint) are treated as plan-validity keys (not a generic "state version"). The wrapper auto-fills them and bumps them only for structural changes, so ordinary value tweaks do not degrade steady-state performance.
• Staged Inputs – Host-provided values keyed by TypedPath. They are latched until you replace or remove them.
• Evaluation Result – evalAll() returns per-node port snapshots plus a WriteBatch of sink writes (each with Value + Shape metadata).
• Node Schema Registry – getNodeSchemas() exposes the runtime-supported nodes, ideal for palettes/editors.
• ABI Guard – abi_version() ensures the JS glue and .wasm binary are compatible. Rebuild when versions change.

Installation

npm install @vizij/node-graph-wasm
# or pnpm add @vizij/node-graph-wasm

For local development inside Vizij:

pnpm run build:wasm:graph
cd npm/@vizij/node-graph-wasm
pnpm install
pnpm run build

Link into vizij-web while iterating:

(cd npm/@vizij/node-graph-wasm && pnpm link --global)
(cd ../vizij-web && pnpm link @vizij/node-graph-wasm)

Bundler Configuration

Like the other Vizij wasm packages, this module now exports an ESM wrapper that first attempts a static import of the wasm-bindgen JS glue. Bundlers that support async WebAssembly (Webpack 5, Vite, etc.) should treat pkg/vizij_graph_wasm_bg.wasm as an emitted asset. For Next.js configure:

// next.config.js
module.exports = {
  webpack: (config) => {
    config.experiments = { ...(config.experiments ?? {}), asyncWebAssembly: true };
    config.module.rules.push({
      test: /\.wasm$/,
      type: "asset/resource",
    });
    return config;
  },
};

If you host the wasm binary elsewhere, pass a string URL to init():

await init("https://cdn.example.com/vizij/node_graph_wasm_bg.wasm");

Passing a string avoids Webpack’s RelativeURL helper, which previously attempted to call .replace() on a URL object.

API

async function init(input?: InitInput): Promise<void>;
function abi_version(): number;
async function normalizeGraphSpec(spec: GraphSpec | string): Promise<GraphSpec>;
async function getNodeSchemas(): Promise<Registry>;
function getNodeRegistry(): Registry;
function findNodeSignature(typeId: NodeType | string): NodeSignature | undefined;
function requireNodeSignature(typeId: NodeType | string): NodeSignature;
function listNodeTypeIds(): NodeType[];
function groupNodeSignaturesByCategory(): Map<string, NodeSignature[]>;
const nodeRegistryVersion: string;
async function logNodeSchemaDocs(nodeType?: NodeType | string): Promise<void>;
const graphSamples: Record<string, GraphSpec>;

class Graph {
  constructor();
  loadGraph(
    specOrJson: GraphSpec | string,
    opts?: { hotPaths?: string[]; epsilon?: number; autoClearDroppedHotPaths?: boolean }
  ): void;
  unloadGraph(): void;
  stageInput(path: string, value: ValueInput, shape?: ShapeJSON, immediateEval?: boolean): void;
  setHotPaths(paths: string[], opts?: { epsilon?: number; autoClearDroppedHotPaths?: boolean }): void;
  stageInputs(paths: string[], values: Float32Array, shapes?: (ShapeJSON | null)[]): void; // routes through smart staging
  stageInputsBySlotDiff(indices: Uint32Array, values: Float32Array, epsilon?: number): void;
  clearSlot(idx: number): Promise<void>;
  clearInput(path: string): Promise<void>;
  clearStagedInputs(): void;
  applyStagedInputs(): void;
  evalAll(): EvalResult;
  evalAllFull(): EvalResult; // resets the delta baseline
  getOutputsDelta(sinceVersion?: number): EvalResult & { version: number };
  setParam(nodeId: string, key: string, value: ValueInput): void;
  setTime(t: number): void;
  step(dt: number): void;
  getWrites(): WriteOpJSON[];
  clearWrites(): void;
  waitForGraphReady?(): Promise<void>; // only populated when used through React provider
}

Normalization, Schema & Docs Helpers

• normalizeGraphSpec(spec) – round-trips any GraphSpec (object or JSON string) through the Rust normaliser so shorthand inputs/legacy inputs maps come back with explicit edges, typed paths, and canonical casing.
• getNodeSchemas() / getNodeRegistry() – runtime and baked access to the node registry (including ports and params) for palette/editor usage.
• findNodeSignature(typeId) / requireNodeSignature(typeId) – quick lookups into the baked registry.
• listNodeTypeIds() / groupNodeSignaturesByCategory() – helpers for palettes or UI grouping.
• logNodeSchemaDocs(nodeType?) – pretty-prints the schema docs for every node or a specific NodeType right to the console (handy while prototyping editors).
• graphSamples – curated ready-to-load specs that already reflect the canonical edges form and typed path parameters.

Each registry entry exposes:

| Field | Description | |-------|-------------| | doc / short_doc | Human-readable description for node palettes and tooltips. | | inputs / outputs | Port metadata (label, doc, shape hints) useful for editors. | | params | Parameter schema with expected value types and default values. | | categories | Optional grouping tags for UI organisation. |

Types (GraphSpec, EvalResult, ValueJSON, ShapeJSON, etc.) are exported from src/types.

Performance guardrails:

• Structural param edits that change port layouts (e.g., Split.sizes) rebuild the plan; the wrapper drops its cached baseline and will emit a full snapshot on the next eval before returning to deltas.
• The Graph wrapper automatically picks the optimized slots + delta path; calling inner.eval_all_js / other legacy exports bypasses these optimizations and is slower.

Delta semantics (baseline resync)

getOutputsDelta(sinceVersion?) is designed for long-running loops where you want to transfer only the ports that changed since a version token.

• Pass 0 (or omit the argument) for the first call to establish a baseline snapshot.
• If the caller's sinceVersion does not match the runtime's cached baseline (including when the wasm runtime resets versions after loadGraph, clear, or a structural edit), the runtime returns a full snapshot flagged with full: true.
• When full: true, treat the payload as a replacement baseline (do not merge it with an older snapshot).

The Graph wrapper handles baseline management automatically for the common case; this section is mainly relevant if you call low-level bindings directly.

Usage

import {
  init,
  Graph,
  normalizeGraphSpec,
  graphSamples,
  valueAsNumber,
} from "@vizij/node-graph-wasm";

await init();

const graph = new Graph();
const spec = await normalizeGraphSpec(graphSamples.vectorPlayground);
graph.loadGraph(spec);

graph.stageInput("demo/path", { float: 1 }, undefined, true);
const result = graph.evalAll();

const nodeValue =
  result.nodes["const"]?.out?.value ?? { type: "float", data: NaN };
console.log("Node value", valueAsNumber(nodeValue));

for (const write of result.writes) {
  console.log("Write", write.path, write.value);
}

Hot-path fast staging (unified)

const graph = new Graph();
graph.loadGraph(spec, { hotPaths: ["demo/a", "demo/b"], epsilon: 0, autoClearDroppedHotPaths: true });
// setHotPaths is still available; loadGraph can now register the hot list for you.

const paths = ["demo/a", "demo/b", "demo/rare"];
const values = new Float32Array([1, 2, 3]);

// Routes hot paths through slots (diffed after first call), others through path batch.
graph.stageInputs(paths, values);
const frame = graph.evalAll(); // first call returns full snapshot; subsequent calls use delta internally

// Debug visibility
graph.setDebugLogging(true);
console.log(graph.inspectStaging());

Note: The hot-path fast lane currently targets numeric scalars. Non-scalar or explicitly shaped inputs in the hot list will fall back to path staging for that call (log in debug mode). Use clearSlot / clearInput to stop replaying cached values.

Fast-path loop with deltas (slots-only eval)

let version = 0n;
const inputs = new Float32Array(paths.length);
const indices = graph.registerInputPaths(paths);
graph.prepareInputSlots(indices);

function tick(frame) {
  inputs.fill(frame);
  graph.stageInputsBySlotDiff(indices, inputs); // only sends changed slots
  graph.setTime(frame / 60);
  graph.step(1 / 60);
  const delta = graph.getOutputsDelta(Number(version));
  version = BigInt(delta.version);
  // delta.nodes contains only changed ports when the baseline matches.
  // When the baseline does NOT match (first call, after loadGraph, after structural edits),
  // the runtime will return a full snapshot and the wrapper will replace its cached baseline.
}

Manual time control (force a full baseline refresh when needed):

graph.setTime(0);
graph.step(1 / 60);
graph.evalAllFull(); // resets delta baseline

Staging inputs lazily:

graph.stageInput("demo/path", { vec3: [0, 1, 0] });
graph.applyStagedInputs();
graph.evalAll();

Performance tips

• Batch steady frames: If inputs remain constant for N ticks, prefer graph.evalSteps(N, dt) to advance time and return only the final outputs/writes. This collapses N JS↔WASM calls into one. Don’t use it when you need to inject new inputs every frame.
• Avoid JSON for numeric streams: For hot numeric inputs, call the underlying wasm export graph.inner.stage_input_f32(path, float32Array) to skip JSON encode/decode. To read numeric outputs without JSON, use graph.inner.get_output_f32(nodeId, outputKey) to receive a Float32Array. Keep the JSON/ValueJSON path for mixed or non-numeric data.
• One call per frame: Even with per-frame inputs, batch all staging calls, then a single evalAll (or evalSteps when valid) per frame to minimize boundary crossings.

Custom loader options

init(input?: InitInput) accepts any input supported by @vizij/wasm-loader:

import { init } from "@vizij/node-graph-wasm";
import { readFile } from "node:fs/promises";

// Host wasm from your CDN
await init(new URL("https://cdn.example.com/vizij/node_graph_wasm_bg.wasm"));

// Node / Electron / tests
const bytes = await readFile("dist/node_graph_wasm_bg.wasm");
await init(bytes);

This is useful for service workers, Electron, or any environment that needs explicit control over fetch behaviour.

Samples & Fixtures

The package exports several ready-to-run specs:

• graphSamples map (e.g., vectorPlayground, oscillatorBasics, logicGate).
• Named exports (oscillatorBasics, nestedTelemetry, etc.) for convenience.
• Helpers:

  import { loadNodeGraphBundle } from "@vizij/node-graph-wasm";
  
  const { spec, stage } = await loadNodeGraphBundle("urdf-ik-position");
  graph.loadGraph(spec);
  if (stage) {
    for (const [path, payload] of Object.entries(stage)) {
      graph.stageInput(path, payload.value, payload.shape);
    }
  }

Fixtures originate from @vizij/test-fixtures so tests and demos share the same assets.

Troubleshooting

• Selector mismatch – Errors such as selector index 5 out of bounds mean the GraphSpec referenced an array element that does not exist. Normalise the spec and confirm upstream nodes emit the expected shape.
• set_param validation – Parameters enforce specific value types (float, text, tuple pairs). Coerce values with normalizeValueJSON before calling setParam to avoid runtime throws.
• ABI mismatch – Re-run pnpm run build:wasm:graph if abi_version() differs from the expected version logged by the package.
• Missing fixtures – loadNodeGraphBundle resolves names from @vizij/test-fixtures. Ensure pnpm run build:shared has been executed in local development.

Development & Testing

pnpm run build:wasm:graph          # regenerate pkg/
cd npm/@vizij/node-graph-wasm
pnpm test

The Vitest suite runs sample graphs through the wasm bridge, checking evaluation results and write batches. For Rust-side coverage, run cargo test -p vizij-graph-wasm.

Related Packages

• vizij-graph-wasm – Rust crate producing the wasm build.
• vizij-graph-core – underlying evaluator.
• @vizij/node-graph-react – React integration built on this npm package.
• @vizij/value-json – shared value helpers used during staging.

Need assistance or spot a bug? Open an issue—robust bindings keep Vizij graphs portable. 🧠

Inspecting Schema Documentation

Each NodeSignature in the schema registry now ships with human-friendly descriptions for the node itself, its ports, and parameters.

import { getNodeSchemas, logNodeSchemaDocs } from "@vizij/node-graph-wasm";

await init();

// Fetch the registry and inspect docs programmatically.
const registry = await getNodeSchemas();
for (const node of registry.nodes) {
  console.log(node.name, node.doc);        // node.doc is a plain string
  for (const port of node.inputs) {
    console.log("  input:", port.label, port.doc);
  }
}

// Or print a nicely formatted summary for all nodes…
await logNodeSchemaDocs();

// …or just a single node type.
await logNodeSchemaDocs("remap");

The same documentation is embedded in the wasm JSON (get_node_schemas_json) so downstream tools can consume it without relying on these helpers.