ComfyUI MultiPreview

日本語版はこちら / Japanese README

MultiPreview is a custom ComfyUI node for previewing multiple image inputs in a single node.

It supports dynamic image pins, per-pin preview switching, batch image navigation, and immediate preview updates while a workflow is running.

Features

• Multiple image inputs in one preview node
• Dynamic imageN input pins
  • A new empty pin is automatically added as needed
  • Empty pins remain available for connection
• Dynamic preview buttons
  • Buttons are shown only for pins that have an active connection or retained preview state
• Switch preview by pin button
• Batch image support
  • Each pin keeps its own batch image index
  • Switching between pins restores that pin's previous batch position
• Immediate preview updates
  • Images are displayed as soon as each pin finishes
  • The node does not need to wait for all connected inputs to finish
• Auto latest mode
  • Optional auto_latest toggle
  • When enabled, the preview automatically switches to the pin that most recently received an image
• Stable state handling
  • Disconnecting a pin does not immediately clear the current preview
  • Old state is cleaned up on the next execution
• Node run button fallback
  • The node still supports normal execution behavior
• Image preload/cache handling
  • Reduces flicker when switching pins or receiving new images

Installation

1. Download or clone this repository into your ComfyUI custom nodes directory:

ComfyUI/custom_nodes/ComfyUI-MultiPreview

2. Restart ComfyUI.

3. Hard refresh your browser.

4. Add the node from:

image / MultiPreview

Usage

Connect image outputs to the image1, image2, image3, ... inputs.

Image source A ──▶ image1
Image source B ──▶ image2
Image source C ──▶ image3

MultiPreview will show a button for each connected image pin.

Click a button to switch the preview target.

If a connected input produces a batch, use the normal ComfyUI preview navigation to move through the batch images.

Auto Latest

The auto_latest toggle controls whether the preview should automatically switch to the newest arriving pin.

• OFF: Keep showing the currently selected pin
• ON: Automatically switch to the pin that most recently received an image

Notes

MultiPreview injects internal receiver nodes at execution time. These receivers save per-pin preview images and notify the frontend with a custom event so the parent MultiPreview node can update immediately.

The internal receiver nodes are injected automatically and do not need to be placed manually.

Temporary Preview Files

MultiPreview uses ComfyUI's standard temporary preview image mechanism through PreviewImage.save_images().

This means preview files are handled in the same general way as standard ComfyUI preview nodes.

v1.2.8

Maintenance release with a guarded state cache for ComfyUI tab/view switching.

• Added in-memory frontend state cache for MultiPreview nodes
• Restores preview images after ComfyUI tab/view switching
• Restores selected pin and per-pin batch index
• Restores preview buttons after node UI rebuilds

MultiPreview Auto

MultiPreview Auto is a simplified node variant.

• Dynamic image pins only
• No pin buttons
• No manual preview switching
• Always switches to the pin that most recently received an image
• Uses the same internal receiver mechanism as MultiPreview

Use this node when you only want a compact live preview of the latest completed branch.

State Restoration

MultiPreview keeps an in-memory frontend state cache for each node.

When ComfyUI rebuilds the node UI after switching tabs or views, MultiPreview attempts to restore:

• saved preview images
• selected pin
• per-pin batch index
• preview buttons

This state is session-local and is not intended to be a workflow serialization format.

Restoration timing fix

v1.2.3 fixes a case where ComfyUI could call node setup hooks before the final node id/state was available. MultiPreview now delays marking a node as restored until a valid cached state is actually found, and also runs one deferred restore pass after widget setup.

State cache guard

v1.2.4 prevents empty transient UI state during tab/view switches from overwriting a previously cached preview state. It also searches both the current canvas graph and root graph when restoring nodes.

Debug Build

This debug build enables verbose console logging for MultiPreview lifecycle, state save/restore, receiver payloads, and pin selection.

Search the browser console for:

[MultiPreview v1.2.8]

Debug log noise reduction

v1.2.8 disables the 1-second periodic persistence log by default. State is still saved on receiver updates, pin selection, lifecycle events, blur, visibilitychange, and beforeunload.

Restore retry fix

v1.2.8 allows state restoration to run again when a tab/view switch clears the live pin image state while cached preview images still exist.

v1.2.8

Stale preview cleanup and state-cache safety release.

• Clears preview images, node image arrays, and restore cache when executing with no connected image inputs
• Prevents all-disconnected runs from restoring stale previews
• Adds connection snapshot checks before restoring cached preview state
• Includes graph identity in the state cache key when available
• Disables verbose debug logging by default

v1.2.9

Batch index retention fix.

• Tracks node.imageIndex changes and immediately stores the current batch index for the selected pin
• Prevents the initial graph/configure pass from clearing restored per-pin batch indexes

v1.2.10

Clear-preview crash fix.

• Fixes a crash when executing MultiPreview after disconnecting all image inputs
• Clears node.imgs / node.images by deleting the properties instead of assigning empty arrays
• Keeps the v1.2.9 batch index retention fix

v1.2.11

Clear-preview safety placeholder fix.

• Uses a transparent 1x1 placeholder instead of an empty node.imgs state while ComfyUI's standard preview widget is being removed
• Extends delayed cleanup for asynchronously recreated standard preview widgets
• Clears legacy app.nodeOutputs image fields when available

v1.2.12

Clear-preview behavior adjustment.

• Removes the transparent 1x1 placeholder used in v1.2.11
• Does not assign empty node.imgs / node.images arrays when all image inputs are disconnected
• Keeps the previous non-empty preview array briefly if ComfyUI's standard preview widget is still visible, matching normal Preview Image behavior
• Keeps stale restore cache suppressed for all-disconnected runs

v1.2.13

Batch index cache timing fix.

• Saves the selected pin's batch index to the restore cache immediately after node.imageIndex changes
• Uses a microtask-based saveNodeStateSoon() to avoid losing the latest batch page during fast tab/view switching
• Keeps the v1.2.12 all-disconnected clear behavior

v1.2.14

No-input execution behavior fix.

• Raises an execution error when MultiPreview runs with no connected image inputs, so the node turns red like ComfyUI's normal Preview Image behavior
• Preserves the current visible batch page when clearing stale preview state after all inputs are disconnected
• Keeps stale restore cache suppression and batch index cache timing fixes

v1.2.15

No-input execution display behavior adjustment.

• If a previously executed MultiPreview is run after all image inputs are disconnected, the current preview display is preserved while the node turns red
• If a fresh MultiPreview with no previous preview is run without image inputs, it simply turns red with no preview image
• Keeps per-pin batch index state when entering the no-input error state

v1.2.16

Error message adjustment.

• Changes the no-input execution error message to Required input is missing: images
• Keeps the v1.2.15 behavior where a previously displayed preview remains visible while the node turns red

v1.2.17

Light flicker reduction pass.

• Defers pin switching whenever the target image is not loaded yet, even when there is no current node.imgs preview
• Removes the 500ms delayed standard-preview-widget cleanup sweep
• Uses a lightweight state initialization path for receiver updates after the node widgets are already ready
• Keeps the v1.2.16 no-input error message behavior

v1.2.18

Small stability cleanup.

• Adds a schedule guard to onConnectionsChange so dynamic pin reconciliation cannot queue repeated overlapping passes
• Clears evicted image cache entries more explicitly by dropping handlers, clearing img.src, and emptying waiter callbacks
• Keeps the v1.2.17 flicker reduction changes

v1.2.19

Unified receiver state pipeline.

• Internal receivers now include a stable state_key
• Receiver payloads always update the global preview state store first, whether the workflow tab is visible or not
• If the live node is available, the same stored state is then applied to the node UI
• Preview persistence, selected pin state, and per-pin batch index restoration now use a single state-key-based path

v1.2.20

State-key fallback and cache eviction safety fix.

• Cache eviction now removes only the Map reference and no longer clears img.src or waiter callbacks, preventing visible previews or deferred selections from being broken
• Adds a prompt-node fallback state key so receiver payloads can still be stored when the live graph node is unavailable during prompt injection
• Restore now checks both the graph-based state key and the prompt fallback state key
• Keeps the v1.2.19 unified receiver state pipeline

v1.2.21

Review fixes.

• Fixes an undefined fallback constant in injectInternalReceiversIntoPrompt()
• Adds a schedule guard to removeStandardPreviewWidgetsSoon() to coalesce repeated cleanup timers
• Adds a clarifying comment for intentionally unused onExecuted hook variables
• Keeps the v1.2.20 state-key fallback and safe cache eviction behavior

v1.2.22

Node removal cleanup.

• Adds an onRemoved lifecycle hook for MultiPreview nodes
• Clears graph-based and prompt-fallback preview state keys from globalStateStore() when the node is removed
• Keeps the v1.2.21 review fixes and v1.2.20 state-key fallback behavior

Note: if a future ComfyUI frontend fires onRemoved during workflow-tab unload rather than actual node deletion, this cleanup may need a stricter deletion guard.

v1.2.23

0x0 flicker reduction for auto-update replacement.

• syncContextMenuImages() now keeps the previous node.imgs until the whole replacement batch has loaded
• Prevents ComfyUI's standard preview widget from briefly rendering newly assigned but still-unloaded images as 0x0
• Restore and fallback execution paths now use deferred pin selection
• Keeps the v1.2.22 onRemoved cleanup behavior

v1.2.24

Batch grid view restoration fix.

• Preserves ComfyUI's node.imageIndex = null grid-view state instead of coercing it to page 0
• Fixes the standard preview X button not returning batch previews to grid view
• Stores and restores grid-view state per pin together with per-pin batch page state
• Keeps the v1.2.23 0x0 flicker guard behavior

v1.2.25

Default batch index fix.

• Treats undefined imageIndex as the default first page (0)
• Keeps explicit null imageIndex as ComfyUI's batch grid-view state
• Prevents fresh/default previews from starting in grid mode while preserving the X button grid behavior

v1.2.26

Safe workflow configure/reconnect input handling.

• ensureWidgets() no longer prunes dynamic image inputs during onNodeCreated / onConfigure
• reconcileDynamicInputs() now supports allowRemove: false for load-time safe reconciliation
• Input pruning is limited to explicit connection-change and execution paths, avoiding link/slot corruption while LiteGraph restores workflows
• Keeps the v1.2.25 default index/grid behavior