Combine Pixaroma

Loops in ComfyUI have a chicken-and-egg problem: round two of a loop needs the output of round one, but the loop has to start somewhere. Combine Pixaroma is the accumulator that makes that work. It takes two inputs and joins them into one - so inside a loop you feed it "everything gathered so far" on one side and "this round's result" on the other, and it hands back the growing pile for the next round. It's the difference between a loop that builds a video in chunks or stacks a batch of images, and one that just errors.

How it works

• any1 / any2 - wire any two things in. Images and video frames get stacked into one batch, latents get batched, numbers and text get gathered into a list. It works with any wire type, which is what makes it a general-purpose accumulator rather than an image-only tool.
• batch - the two inputs joined. Images/frames come out as one bigger batch; numbers/text as a list.

The detail that makes it loop-safe: if one side is empty, it passes the other side straight through. In a loop, round one has nothing accumulated yet - an empty any1 doesn't crash, it just forwards round one's result and starts the pile. Trying to join two things that genuinely don't fit (an image and some text) stops with a clear, plain message instead of a cryptic type error, which is a small mercy you'll appreciate at 2am.

Where it fits

Its natural partner is the pack's Loop Start / Loop End - the standard pattern is:

Loop Start → [do work on this round] → Combine(any1=carried over, any2=new result) → Loop End → back to Combine's any1

With that in place you can build a long video in chunks (each round appends its frames to the batch) or pile up a batch of images until the loop ends. Outside loops it's also just a handy two-to-one merge: stack two image batches, gather two lists of numbers, batch two latents - a less fiddly alternative to the built-in batch-concat math in common cases.

The honest take

This node only earns its keep if you're looping or batch-building, and for that it's quietly essential - it's the state that carries forward. On its own it's a two-input merge you could half-replicate with core nodes, but the loop-safety (empty side passes through) and the friendly type-error are exactly the polish the loop use-case needs. Works in both the classic and the new node interface.

Install

Part of the Pixaroma pack:

cd ComfyUI/custom_nodes
git clone https://github.com/pixaroma/ComfyUI-Pixaroma

or ComfyUI Manager → Pixaroma → install, restart. No extra dependencies. If the pack was recently updated and a loop node misbehaves, the standing advice applies: hard-refresh the browser (Ctrl+Shift+R) - the cache, not the code, is usually the culprit.