neo4j-nvl-skill— agent skill

When to Use

• Rendering a Neo4j graph in a browser (vanilla JS, React, Vite) with custom interactions, rendering, or data shapes
• Visualizing driver.executeQuery results as an interactive graph
• Wiring zoom, pan, drag, click, hover, lasso, or box-select interactions
• Embedding NVL inside an existing app and synchronizing graph state

When NOT to Use

• Pre-styled embedded graph view with default behavior, no custom interactions → GraphVisualization from @neo4j-ndl/react (Neo4j Needle / NDL design system) — wraps NVL with default Neo4j styling. See Use NVL or the Needle Component? below.
• Python / Jupyter notebook graph visualization → neo4j/python-graph-visualization (the Python port of NVL)
• Writing/optimizing Cypher → neo4j-cypher-skill
• Driver setup / executeQuery / sessions → neo4j-driver-javascript-skill
• Server-side data fetching with no rendering → neo4j-driver-javascript-skill
• GDS algorithm execution → neo4j-gds-skill or neo4j-aura-graph-analytics-skill
• GraphQL API → neo4j-graphql-skill

Use NVL or the Needle Component?

If the answer is the first row, install and use the Needle component instead of NVL — do not duplicate styling work.

Install

npm install @neo4j-nvl/base                  # core (required)
npm install @neo4j-nvl/interaction-handlers  # standard interactions (optional, vanilla JS)
npm install @neo4j-nvl/react                 # React wrappers (optional)

Peer requirements: React 19 for @neo4j-nvl/react. The published peerDependency range still permits React 18, but mixing major versions is not recommended — target 19. @neo4j-nvl/layout-workers is a transitive dependency — never install directly. neo4j-driver is a peer of @neo4j-nvl/base only when using nvlResultTransformer.

Starter templates: https://github.com/neo4j-devtools/nvl-boilerplates — official per-framework scaffolds; prefer these over hand-rolled setups.

License: NVL ships under the Neo4j Visualization Library License — for use with Neo4j products only. Cannot be used against other graph backends.

Pick the Right Paradigm

Pick the Right Renderer

const nvl = new NVL(container, nodes, rels, { renderer: 'webgl' })
nvl.setRenderer('canvas')   // swap at runtime

NVL 2.0 requires WebGL2 for the GPU renderer and force-directed physics engine. When GPU acceleration is unavailable, NVL can fall back to Canvas rendering and non-GPU layout implementations; use disableWebGL: true to explicitly avoid WebGL.

Container Setup

The container must have an explicit width AND height. Missing height → container collapses to 0 → graph invisible. Most-reported NVL bug.

<!-- ❌ height defaults to 0; graph invisible -->
<div id="viz"></div>

<!-- ✅ explicit dimensions -->
<div id="viz" style="width: 100%; height: 600px;"></div>

Vanilla — Base Library

import { NVL } from '@neo4j-nvl/base'

const container = document.getElementById('viz')
const nodes = [{ id: '1' }, { id: '2' }]
const relationships = [{ id: '12', from: '1', to: '2', type: 'KNOWS' }]

const nvl = new NVL(container, nodes, relationships)

With options + callbacks:

import { NVL } from '@neo4j-nvl/base'

const options = {
  initialZoom: 1.0,
  minZoom: 0.1,
  maxZoom: 8,
  layout: 'forceDirected',
  renderer: 'canvas',
  styling: { defaultNodeColor: '#0e86d4', defaultRelationshipColor: '#888' }
}
const callbacks = {
  onInitialization: () => console.log('NVL ready'),
  onLayoutDone: () => nvl.fit([]),
  onError: (err) => console.error('NVL error', err)
}

const nvl = new NVL(container, nodes, relationships, options, callbacks)

// On teardown — always:
nvl.destroy()

NVL constructor signature: new NVL(frame, nvlNodes?, nvlRels?, options?, callbacks?). All but frame are optional and default to empty.

Vanilla — Interaction Handlers

Compose handlers onto an existing NVL instance. Each handler registers callbacks via .updateCallback(name, fn) and must be torn down with .destroy().

import { NVL } from '@neo4j-nvl/base'
import {
  ZoomInteraction, PanInteraction, DragNodeInteraction,
  ClickInteraction, HoverInteraction, BoxSelectInteraction,
  LassoInteraction, KeyboardInteraction
} from '@neo4j-nvl/interaction-handlers'

const nvl = new NVL(container, nodes, relationships)

const zoom  = new ZoomInteraction(nvl)
const pan   = new PanInteraction(nvl)
const drag  = new DragNodeInteraction(nvl)
const click = new ClickInteraction(nvl, { selectOnClick: true })
const hover = new HoverInteraction(nvl, { drawShadowOnHover: true })

click.updateCallback('onNodeClick',         (node, hits, evt) => console.log('node',  node.id))
click.updateCallback('onRelationshipClick', (rel,  hits, evt) => console.log('rel',   rel.id))
click.updateCallback('onClusterClick',      (cluster, hits, evt) => console.log('cluster', cluster.id))
click.updateCallback('onCanvasClick',       (evt)             => console.log('canvas'))
hover.updateCallback('onHover',             (el, hits, evt)   => el && console.log('over', el.id))
drag.updateCallback('onDragEnd',            (nodes, evt)      => savePositions(nodes))
zoom.updateCallback('onZoomAndPan',          (level, panX, panY) => console.log(level, panX, panY))

// Teardown — destroy all handlers, then the NVL instance
function teardown() {
  for (const h of [zoom, pan, drag, click, hover]) h.destroy()
  nvl.destroy()
}

Disable an event without removing the handler: click.removeCallback('onCanvasClick'). Passing true instead of a function enables the event with a no-op (useful for default selection behavior).

React — InteractiveNvlWrapper

Pre-wires every interaction handler. Toggle events with mouseEventCallbacks (function = on + callback; true = on, no-op; false/omit = off).

import { InteractiveNvlWrapper } from '@neo4j-nvl/react'
import type { MouseEventCallbacks } from '@neo4j-nvl/react'
import { useRef } from 'react'
import type { NVL, NvlOptions } from '@neo4j-nvl/base'

export function GraphView({ nodes, rels }) {
  const nvlRef = useRef<NVL>(null)

  const nvlOptions: NvlOptions = { initialZoom: 1, renderer: 'canvas' }

  const mouseEventCallbacks: MouseEventCallbacks = {
    onNodeClick:         (node, hits, evt) => console.log('node',  node.id),
    onRelationshipClick: (rel,  hits, evt) => console.log('rel',   rel.id),
    onClusterClick:      (cluster, hits, evt) => console.log('cluster', cluster.id),
    onCanvasClick:       (evt)             => console.log('canvas'),
    onHover:             (el, hits, evt)   => {
      if (el) console.log('hover', el.id)
      if (hits.clusters[0]) console.log('cluster hover', hits.clusters[0].data.id)
    },
    onDragEnd:           (nodes, evt)      => persist(nodes),
    onZoomAndPan: true,                                 // enable, no callback
    onPan:  true
  }

  return (
    <div style={{ width: '100%', height: 600 }}>
      <InteractiveNvlWrapper
        ref={nvlRef}
        nodes={nodes}
        rels={rels}
        nvlOptions={nvlOptions}
        interactionOptions={{ selectOnClick: true, drawShadowOnHover: true }}
        mouseEventCallbacks={mouseEventCallbacks}
        onInitializationError={(err) => console.error('NVL init', err)}
      />
    </div>
  )
}

ref resolves to the underlying NVL instance — call any method on it: nvlRef.current?.fit([]), nvlRef.current?.setRenderer('webgl'), nvlRef.current?.saveToFile().

NVL 2.0 — Layout Clustering

clusterBy groups nodes whose callback returns the same string or number. Return undefined for independent nodes. Keep the callback reference stable in React with useCallback.

Force-directed clustering nests all clustering settings under layoutOptions.clustering:

const clusterBy = (nodeId) => categoryByNodeId[nodeId]

const nvl = new NVL(container, nodes, relationships, {
  layout: 'forceDirected',
  layoutOptions: {
    seedingMethod: 'circle',
    clustering: {
      clusterBy,
      drawOutline: true,
      drawHalo: true,
      crossClusterRelationshipMultiplier: 0.2
    }
  },
  minFps: 3,
  maxFps: 30
})

crossClusterRelationshipMultiplier is experimental, capped to 0..1, and can destabilize highly connected graphs near 1. It affects cross-cluster spring pull only; intra-cluster edges remain full strength.

Hierarchical clustering places clusterBy directly in layoutOptions:

const nvl = new NVL(container, nodes, relationships, {
  layout: 'hierarchical',
  layoutOptions: {
    direction: 'down',
    clusterBy
  }
})

Cluster decorations and cluster hull interactions apply to force-directed layoutOptions.clustering. A Cluster is not a graph element; it has { id: string | number, nodeIds: string[] }. Cluster callbacks fire only for empty space inside a cluster hull; node and relationship hits retain priority.

Migrating from NVL 1.x to 2.0

• Move React wrapper layout and layoutOptions props into nvlOptions:

<InteractiveNvlWrapper nvlOptions={{ layout, layoutOptions }} />.

• Replace interaction callback onZoom with onZoomAndPan(zoom, panX, panY, event).
• Remove intelWorkaround and Cytoscape-related layout settings; they no longer exist.
• Treat WebGL as WebGL2-only and do not expect captions in the WebGL renderer.
• getNodes() and onLayoutStep return NodeWithClientPosition[]: x/y are layout coordinates and clientPosition is relative to the canvas element.
• Use styling.overlayLineColor; styling.minimapViewportBoxColor is deprecated.

React — BasicNvlWrapper + Ref

No interactions wired. The ref exposes every NVL method via IncludeMethods<NVL> — use when building custom interaction logic in React.

import { BasicNvlWrapper } from '@neo4j-nvl/react'
import type { NVL } from '@neo4j-nvl/base'
import { useRef } from 'react'

export function MiniGraph({ nodes, rels }) {
  const nvlRef = useRef<NVL>(null)

  return (
    <div style={{ width: '100%', height: 400 }}>
      <BasicNvlWrapper
        ref={nvlRef}
        nodes={nodes}
        rels={rels}
        nvlOptions={{ initialZoom: 2 }}
        nvlCallbacks={{ onLayoutDone: () => nvlRef.current?.fit([]) }}
      />
      <button onClick={() => nvlRef.current?.fit(['1', '2'])}>Zoom to 1,2</button>
    </div>
  )
}

Wiring a Neo4j Driver Result

@neo4j-nvl/base exports a ResultTransformer for the JS driver that deduplicates nodes/relationships across any record shape.

import neo4j from 'neo4j-driver'
import { NVL, nvlResultTransformer } from '@neo4j-nvl/base'

const driver = neo4j.driver(process.env.NEO4J_URI,
  neo4j.auth.basic(process.env.NEO4J_USERNAME, process.env.NEO4J_PASSWORD))

const { nodes, relationships } = await driver.executeQuery(
  'MATCH (a)-[r]-(b) RETURN a, r, b LIMIT 25',
  {},
  { database: 'neo4j', resultTransformer: nvlResultTransformer }
)

const nvl = new NVL(document.getElementById('viz'), nodes, relationships)

// ❌ raw EagerResult — records are not Node/Relationship objects
const result = await driver.executeQuery('MATCH (a)-[r]-(b) RETURN a, r, b')
new NVL(container, result.records, [])   // breaks

// ✅ use the transformer
const { nodes, relationships } = await driver.executeQuery(
  'MATCH (a)-[r]-(b) RETURN a, r, b',
  {},
  { database: 'neo4j', resultTransformer: nvlResultTransformer }
)
new NVL(container, nodes, relationships)

For driver lifecycle, session management, Integer handling, and TypeScript types → neo4j-driver-javascript-skill.

Updating the Graph

Diff updates use PartialNode / PartialRelationship — only id is required:

nvl.updateElementsInGraph(
  [{ id: '1', color: '#f00', selected: true }],   // PartialNode
  [{ id: '12', width: 4 }]                         // PartialRelationship
)

Hit Testing (Manual)

Use when NOT using the interaction-handlers package. In 2.0, getHits() resolves nodes, relationships, and force-directed cluster hulls. Its default targets are ['node', 'relationship', 'cluster'].

const nvl = new NVL(container, nodes, rels)

container.addEventListener('click', (evt) => {
  const { nvlTargets } = nvl.getHits(evt, ['node', 'relationship', 'cluster'], { hitNodeMarginWidth: 4 })
  const hitNode = nvlTargets.nodes[0]
  const hitRel  = nvlTargets.relationships[0]
  const hitCluster = nvlTargets.clusters[0]
  if (hitNode) console.log('hit node', hitNode.data.id)
  else if (hitRel) console.log('hit rel', hitRel.data.id)
  else if (hitCluster) console.log('hit cluster', hitCluster.data.id, hitCluster.data.nodeIds)
  else console.log('hit canvas')
})

HitTargetNode / HitTargetRelationship carry element hit data. HitTargetCluster carries data, pointerCoordinates, and the fitted convex hull. See references/api-surface.md.

Common Mistakes

References

Load on demand:

• references/api-surface.md — complete 2.0 NVL method table; clustering, FPS, seeding, NodeWithClientPosition, hit target and interaction callback types; React props; named exports; nvlResultTransformer
• references/troubleshooting.md — zero-height container, WebGL2 and Canvas trade-offs, clustering configuration, 1.x migration errors, worker fallback, context loss, telemetry, lifecycle, layout and hit-testing issues

Canonical web documentation (use WebFetch when references above are insufficient):

• https://neo4j.com/docs/nvl/current/ — user guide (installation, base library, interaction handlers, React wrappers)
• https://neo4j.com/docs/api/nvl/current/ — TypeDoc API reference
• https://neo4j.com/docs/api/nvl/current/examples.html — runnable examples
• https://github.com/neo4j-devtools/nvl-boilerplates — official starter templates per supported framework
• https://github.com/neo4j/python-graph-visualization — Python port of NVL (use this skill only for the JavaScript/browser path)

Checklist

• [ ] Container has explicit width AND height CSS
• [ ] Correct paradigm chosen from the decision table (vanilla / handlers / React)
• [ ] Renderer matches expected node count (Canvas ≲1k / WebGL 100k+)
• [ ] Canvas selected whenever captions are required
• [ ] React layout and layoutOptions nested inside nvlOptions
• [ ] Zoom handlers use onZoomAndPan, not removed onZoom
• [ ] clusterBy is stable in React and placed correctly for the selected layout
• [ ] Driver executeQuery results piped through nvlResultTransformer
• [ ] database specified on every executeQuery call (delegate to neo4j-driver-javascript-skill)
• [ ] All interaction handlers .destroy()-ed before nvl.destroy() on teardown
• [ ] nvl.destroy() called on React unmount (manual instances only — wrappers handle it)
• [ ] disableTelemetry: true set when in regulated / offline environments
• [ ] disableWebWorkers: true set when bundler / CSP blocks worker construction
• [ ] Graph updates use addAndUpdateElementsInGraph / updateElementsInGraph — not restart
• [ ] License compatible: target is a Neo4j product