comfyui-frontend-extensions

name	comfyui-frontend-extensions
description	Authoring ComfyUI v2 frontend extensions with @comfyorg/extension-api — defineNode/defineExtension/defineWidget, shell UI (sidebar tabs, commands, hotkeys), typed events, and handles. Use when writing or editing ComfyUI web-UI extension code (custom node JS, sidebar panels, widgets). Use when this capability is needed.
metadata	{"author":"artokun"}

ComfyUI v2 Frontend Extension API

The v2 extension API is the published npm package @comfyorg/extension-api. It replaces the legacy app.registerExtension() / nodeType.prototype monkey-patching model with a typed, tree-shakeable, import-based API.

If you are converting an existing v1 extension, read references/migrate-v1-to-v2.md for a pattern-by-pattern mapping.

Mental model

v1 (legacy)	v2 (@comfyorg/extension-api)
One giant app.registerExtension({...}) call	One defineX per concern, each independently disposable
window.app / app.* globals	Direct import from the package; no window.app at module-eval time
nodeType.prototype.onExecuted = ... patching	node.on('executed', fn) on a NodeHandle
Mutate widget.value, assign widget.callback	widget.setValue(v) / widget.on('valueChange', fn)
api.addEventListener('execution_start', fn)	execution.on('start', fn) (typed namespaces)
Manual removeEventListener bookkeeping	Every subscription returns Unsubscribe; every defineX returns DisposableHandle

Core principles baked into the API:

• Import, don't reach for globals. import { defineNode } from '@comfyorg/extension-api'. No window.app dependency at module evaluation time.
• Read via getters, write via command-dispatch setters. getValue() reads; setValue() dispatches an undo-able, serializable command. Read-only invariants (set at construction) are readonly accessors (node.type, widget.name).
• Observe via typed on(...) subscriptions. Each returns an Unsubscribe cleanup function. No Vue refs/signals are ever exposed — Vue reactivity is the internal engine only.
• Everything is disposable. Every defineX returns a DisposableHandle with an idempotent, synchronous dispose().

Registration entry points

All imported from @comfyorg/extension-api:

Function	Purpose	Returns
defineNode(opts)	Primary entry — react to node lifecycle (replaces prototype patching)	NodeExtensionOptions
defineExtension(opts)	App-scoped lifecycle (init/setup) + shell UI host	ExtensionOptions
defineWidget(opts)	Register a custom widget type (DOM via mount)	WidgetExtensionOptions
defineSidebarTab(opts)	Add a left-sidebar tab (Vue or custom)	DisposableHandle
defineBottomPanelTab(opts)	Add a bottom-panel tab	DisposableHandle
defineToolbarButton(opts)	Add an action-bar button	DisposableHandle
defineCommand(opts)	Register an invokable command	DisposableHandle
defineHotkey(opts)	Bind a key combo to a command id	DisposableHandle
defineSetting(opts)	Add a settings-menu entry	DisposableHandle
defineAboutBadge(opts)	Add a badge to the About page	DisposableHandle

Imperative carve-outs (fire-and-forget, NOT defineX, no handle): toast, notify.

A single extension file typically exports a default defineExtension/defineNode result and calls the shell-UI defineX functions inside setup() (or at module scope — they queue safely before the app boots).

defineNode — the primary entry point

Reacts to node lifecycle. nodeCreated fires once per node instance (typed in, pasted, duplicated, or loaded without an existing workflow). loadedGraphNode fires once when a node is restored from a saved workflow (widget values already populated). Exactly one of them fires per node entity — never both.

import { defineNode, onNodeMounted, onNodeRemoved } from '@comfyorg/extension-api'

export default defineNode({
  name: 'my-org.executed-logger',
  // Filter to specific comfyClass names. Omit to receive every node type.
  nodeTypes: ['KSampler', 'KSamplerAdvanced'],

  // MUST be synchronous. Runs inside a Vue EffectScope; everything registered
  // here (subscriptions, onNodeMounted) auto-disposes when the node is removed.
  nodeCreated(node) {
    // Read-only invariants
    console.log(node.type, node.comfyClass, node.id)

    // Subscribe to backend execution completion (replaces onExecuted patching)
    node.on('executed', (e) => {
      console.log('output:', e.output) // Record<string, unknown>
    })

    // Lifecycle hooks — call SYNCHRONOUSLY (never after an await)
    onNodeMounted(() => {
      // Node fully mounted; DOM/canvas ready.
    })
    onNodeRemoved(() => {
      // Cleanup: abort fetches, close sockets. Does NOT fire on subgraph promotion.
    })
  },

  loadedGraphNode(node) {
    // Node restored from a saved workflow; widget values are already set.
  }
})

NodeHandle surface (Phase A)

Member	Kind	Notes
id: string	readonly	Opaque token. Compare with node.equals(other), never by slicing.
equals(other)	method	Canonical identity comparison.
type: string	readonly	LiteGraph node type.
comfyClass: string	readonly	Backend class name.
getProperty<T>(key) / getProperties() / setProperty(key, v)	methods	Per-instance props (migration shim — prefer widget values).
getInputs() / getOutputs()	methods	ReadonlyArray<Readonly<SlotInfo>> — frozen views.
on('executed', fn)	method	Execution complete → NodeExecutedEvent { output }.
on('removed', fn)	method	Node deleted (not subgraph promotion).
on('configured', fn)	method	Loaded from saved workflow (after widget values restored).
on('beforeSerialize', fn)	method	Deprecated — use widget-level beforeSerialize (ADR-0010).

Position/size/title/mode getters and slot/connection events are deferred in Phase A (excluded per the project's AXIOMS). Do not rely on getPosition, setSize, getMode, on('connected'), etc. — they are not yet on the surface.

Nodes cannot enumerate or reference their widgets (node.getWidget(name) was removed). To attach per-widget behavior, register a widget type with defineWidget and use the mount context's ctx.widget handle.

defineExtension — app lifecycle + shell UI

Use for app-wide setup and to host shell-UI registrations. setup() runs at the early registration point; use the imported onMounted hook for work that needs the app fully initialized.

import {
  defineExtension,
  onMounted,
  onUnmounted,
  execution,
  toast
} from '@comfyorg/extension-api'

export default defineExtension({
  name: 'my-org.my-extension',
  setup() {
    // Register late-lifecycle work via onMounted (called synchronously here).
    onMounted(() => {
      const off = execution.on('start', () => {
        toast.show({ severity: 'info', summary: 'Run started' })
      })
      onUnmounted(off) // tidy teardown
    })
  }
})

setup() signature note. The source-of-truth surface uses implicit-context hooks: import onMounted/onNodeMounted/etc. and call them synchronously inside setup() (mirrors Vue's Composition API). An early package draft showed a setup(ctx) { ctx.onNodeMounted(...) } context-argument style; prefer the imported-hook form above, which is what the current API exports.

Context-scoped lifecycle hooks are imported and called synchronously inside defineExtension's setup(): onBeforeMount, onMounted, onUnmounted, onActivated, onDeactivated. Note: defineSidebarTab/defineBottomPanelTab take no setup field — don't add one (it's a type error). onActivated/onDeactivated fire when the surrounding tab/panel is shown/hidden.

defineWidget — custom widget types with DOM

Widgets are declared in the Python node's INPUT_TYPES, never created at runtime (node.addWidget is forbidden). defineWidget registers a type and the DOM mount hook the runtime invokes against a host <div> it owns. mount is optional — omit it for value-only widgets that render through the native renderer.

import { defineWidget, type WidgetCleanup } from '@comfyorg/extension-api'

export default defineWidget({
  name: 'my-org.color-picker',
  type: 'COLOR_PICKER', // referenced from Python INPUT_TYPES

  // The SOLE DOM seam. Capture host + constructed DOM via closure — there is
  // no widget.element accessor.
  mount(host, ctx): WidgetCleanup {
    const input = document.createElement('input')
    input.type = 'color'
    input.value = String(ctx.widget.getValue() ?? '#000000')
    input.addEventListener('input', () => ctx.widget.setValue(input.value))
    host.appendChild(input)

    // ctx.widget / ctx.node are the only legal handles here.
    ctx.widget.on('valueChange', (e) => {
      input.value = String(e.newValue ?? '#000000')
    })

    // Optional cleanup — fires once on widget destruction (NOT on host remount).
    return  input.()
  }
})

WidgetMountContext also exposes onUnmount(fn), onBeforeRemount(fn), and onAfterRemount(fn => ...) for host-move scenarios (graph↔app mode, subgraph promotion). The mount body is not re-invoked across a remount — only the remount hooks fire.

WidgetHandle surface

Member	Kind	Notes
id / equals(other)	readonly / method	Opaque identity.
name / widgetType / label	readonly	Set from INPUT_TYPES schema.
getValue<T>() / setValue(v)	methods	setValue dispatches an undo-able command.
options	readonly	Readonly<WidgetOptions> snapshot. Writes raise TS errors.
getOption<K>(key) / setOption(key, v)	methods	Per-instance overrides (e.g. min/max/step).
setHeight(px)	method	Resize the reserved host height (DOM widgets).
on('valueChange', fn)	method	WidgetValueChangeEvent { oldValue, newValue }.
on('optionChange', fn)	method	WidgetOptionChangeEvent { key, oldValue, newValue }.
on('beforeSerialize', fn)	method	Only async-allowed event. e.value + e.setSerializedValue(v).
on('beforeQueue', fn)	method	Pre-queue validation. Call e.reject(msg) to cancel.

// Serialization override (the SOLE serialization interface in v2):
widget.on('beforeSerialize', (e) => {
  e.setSerializedValue(processDynamicPrompt(widget.getValue()))
})

// Async serialization (e.g. capture a webcam frame before queueing):
widget.on('beforeSerialize', async (e) => {
  e.setSerializedValue(await captureFrame())
})

// Pre-queue validation (replaces app.queuePrompt monkey-patching):
widget.on('beforeQueue', (e) => {
  if (!widget.getValue()) e.reject('Prompt text is required before queueing.')
})

Typed event namespaces

Four module-level singletons replace api.addEventListener('...'). Each on() returns an Unsubscribe. Subscriptions made inside a setup() body auto-dispose on unmount; subscriptions made elsewhere are the caller's responsibility.

Namespace	Events (canonical)	Wire mapping
execution	start, end, error, interrupted, cached, executing, progress, preview	execution_<evt>
graph	changed, …	graph:<evt>
server	status, logs, reconnected, feature_flags, assets, + custom-node events	raw event name
workbench	notification, …	workbench:<evt>

import { execution, server } from '@comfyorg/extension-api'

const off = execution.on('progress', (e) => console.log('progress', e))
// Custom-node events ride the `server` namespace with arbitrary names:
server.on('my-org.my-node.update', (e) => console.log(e))
// later:
off()

Payloads default to unknown today. Narrow them with TS module augmentation:

declare module '@comfyorg/extension-api' {
  interface ExecutionEventPayloads {
    start: { promptId: string }
    progress: { value: number; max: number }
  }
  interface ServerEventPayloads {
    'my-org.my-node.update': { nodeId: string; text: string }
  }
}

The augmentable interfaces are GraphEventPayloads, ExecutionEventPayloads, ServerEventPayloads, and WorkbenchEventPayloads.

Shell UI registrations

Each returns a DisposableHandle. Safe to call at module scope (they queue until the app boots) or inside setup().

import {
  defineCommand,
  defineHotkey,
  defineToolbarButton,
  defineSetting,
  defineAboutBadge
} from '@comfyorg/extension-api'

// Command — id, function, optional label/icon/tooltip.
const cmd = defineCommand({
  id: 'my-org.do-the-thing',
  label: 'Do The Thing',
  function: () => { /* ... */ }
})

// Hotkey — binds a key combo to an already-registered command id.
// `mod` = cmd on macOS, ctrl elsewhere.
defineHotkey({ keys: 'mod+shift+k', commandId: 'my-org.do-the-thing' })

// Action-bar button — id (for dispose), icon, onClick.
defineToolbarButton({
  id: 'my-org.help',
  icon: 'pi-question-circle',
  tooltip: 'Get help',
  onClick: () => openHelp()
})

// Setting — widen the id when not augmenting the Settings keymap.
defineSetting({
  id: 'my-org.enabled' as never,
  name: 'Enable my extension',
  type: 'boolean',
  defaultValue: false
})

// About-page badge.
defineAboutBadge({
  label: 'GitHub',
  : ,
  : 
})


cmd.() 

CommandDefinition fields: id (required), function: (metadata?) => void | Promise<void> (required), optional label / icon / tooltip (each string | (() => string)), menubarLabel, versionAdded.

defineSidebarTab — embedded panels (e.g. a chat panel)

A sidebar tab is the substrate for a rich embedded UI such as a chat panel. Two flavors: type: 'vue' (mount a Vue component) or type: 'custom' (imperative render(container) / destroy()). Both share the base fields id, title, optional icon, iconBadge, tooltip, label.

Vue component tab

import { defineSidebarTab } from '@comfyorg/extension-api'
import ChatPanel from './ChatPanel.vue'

const chatTab = defineSidebarTab({
  id: 'my-org.chat',
  title: 'Chat',
  type: 'vue',
  icon: 'pi-comments',
  component: ChatPanel
})
// chatTab.dispose() removes the tab.

Custom (framework-free) chat panel

When you don't want a Vue dependency, use type: 'custom' and build the DOM yourself. render receives the container; destroy is your teardown.

import {
  defineExtension,
  defineSidebarTab,
  execution,
  server,
  type Unsubscribe
} from '@comfyorg/extension-api'

export default defineExtension({
  name: 'my-org.chat-panel',
  setup() {
    const subscriptions: Unsubscribe[] = []

    defineSidebarTab({
      id: 'my-org.chat',
      title: 'Chat',
      type: 'custom',
      icon: 'pi-comments',

      render(container: HTMLElement) {
        const log = document.createElement('div')
        log.className = 'chat-log'

        const form = document.createElement('form')
        const input = document.createElement('input')
        input.placeholder = 'Ask something…'
        const send = document.createElement('button')
        send.type = 'submit'
        send. = 
        form.(input, send)

          = () => {
           line = .()
          line. = 
          log.(line)
          log. = log.
        }

        form.(,  {
          ev.()
           text = input..()
           (!text) 
          (, text)
          input. = 
          
        })

        container.(log, form)

        
        subscriptions.(
          server.(,  (, (e)))
        )
        
        subscriptions.(
          execution.(,  (, ))
        )
      },

      () {
         ( off  subscriptions) ()
        subscriptions. = 
      }
    })
  }
})

defineBottomPanelTab has the same vue / custom shapes (base fields id, optional title/titleKey, optional targetPanel: 'terminal' | 'shortcuts').

Toasts

toast and notify are inline imperative (no defineX, no handle). Call from any setup() body or hook closure.

import { toast } from '@comfyorg/extension-api'

toast.show({ severity: 'error', summary: 'Workflow failed', detail: err.message, life: 4000 })
toast.removeAll()

notify({ kind, message, detail, life }) is a deprecated 1:1 wrapper over toast.show — prefer toast.show directly.

Node identity helpers

For referencing nodes across subgraph boundaries or execution runs, use the branded identity primitives rather than raw integer node IDs:

import {
  createNodeLocatorId, parseNodeLocatorId, isNodeLocatorId,
  createNodeExecutionId, parseNodeExecutionId, isNodeExecutionId,
  type NodeLocatorId, type NodeExecutionId
} from '@comfyorg/extension-api'

const locator: NodeLocatorId = createNodeLocatorId(subgraphUuid, localNodeId)
// NodeExecutionId encodes a node's path through nested subgraphs as an array of node ids
// (joined with ':'). Pass the array, not positional args:
const execId: NodeExecutionId = createNodeExecutionId([localNodeId])

if (isNodeLocatorId(maybe)) {
  // parseNodeLocatorId returns { subgraphUuid: string | null; localNodeId: NodeId }
  const { subgraphUuid, localNodeId } = parseNodeLocatorId(maybe)
}

NodeLocatorId arrives from workflow JSON; NodeExecutionId arrives from websocket frames. You receive these from event payloads — that's why they're public (unlike the internal *EntityId brands, which are not exported).

Disposal contract

Every defineX returns DisposableHandle { dispose(): void }:

• Idempotent — calling dispose() again is a safe no-op.
• Synchronous — teardown happens synchronously inside dispose().
• Independent — disposing handle A does not affect B or C. Sequence calls explicitly when teardown order matters (e.g. drop a hotkey before its command).
• Pre-mount safe — disposing before the app boots removes the spec from the pending queue so it never mounts.

const handles = [
  defineCommand({ id: 'my.cmd', function: () => {} }),
  defineHotkey({ keys: 'mod+k', commandId: 'my.cmd' }),
  defineSidebarTab({ id: 'my.tab', title: 'Tab', type: 'vue', component: MyTab })
]
// Full teardown:
for (const h of handles.reverse()) h.dispose()

Common mistakes

1. Calling lifecycle hooks after await. onNodeMounted / onMounted / onUnmounted rely on implicit scope context and must be called synchronously inside the setup()/nodeCreated body. After an await the scope is gone — throws in dev, silent no-op in prod. Kick off async work in the body, but register hooks first.
2. Reaching for window.app or app.*. v2 has no window.app dependency at module-eval time. Import everything from @comfyorg/extension-api.
3. Patching nodeType.prototype. Replaced by defineNode + node.on(...). Prototype patching does not interoperate with the v2 handle model.
4. Mutating reads. node.getInputs(), widget.options, and Point/Size tuples are frozen/Readonly — assignment raises TS errors. Use the setter methods (widget.setOption, widget.setValue).
5. Assigning widget.value / widget.callback / widget.serializeValue. Use setValue(), on('valueChange'), and on('beforeSerialize'). serializeValue is read-only on the v2 surface.
6. Trying to disable widget serialization. There is no serialize: false and no skip() in v2. If a widget should not contribute to the payload, it should not be a widget. The only serialization interface is widget.on('beforeSerialize', fn) + e.setSerializedValue(v).
7. Creating widgets at runtime. node.addWidget(...) / node.addDOMWidget(...) are removed. Declare widgets in the Python INPUT_TYPES; render custom DOM via defineWidget({ mount }).
8. Enumerating widgets from a node. node.getWidget(name) / node.getWidgets() were removed (nodes cannot reference widgets). Use a mount context's , or share state via the event bus.

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Source: artokun/comfyui-mcp — distributed by TomeVault.