Reverse List Ovum

Reverse List Ovum returns a new list with the elements in reverse order, and it works on Python list objects rather than graph-level batches. First element becomes last, last becomes first, input untouched. Simple, non-mutating, and part of the comfy-ovum pack's Python-list utility family.

Python list vs. graph batch, one more time

The comfy-ovum list nodes come in three flavors, and which one you grab depends entirely on what you're feeding:

• ovum/lists/comfy (the "Batch" nodes) declare OUTPUT_IS_LIST - the engine treats the output as a batch and fans it out to list-aware consumers.
• ovum/lists/python (the "Ovum" nodes, including this one) return a Python list as a single value on the wire. They're built for other list-utility nodes: splices, slices, joins, editors, index lookups.
• ovum/lists/any (the bare ReverseList, RepeatItem, StringListEditor) is deprecated in the source - the old family, superseded by the two above.

So this node is the one you want when the thing on the other end of the wire expects an actual Python list object and you need it reversed.

When you'd reach for it

You're composing list data - building a list with the pack's editors or repeat nodes, then transforming it before feeding a loop, a joiner, or a custom node. If your list of prompts, seeds, or paths needs to come out in the opposite order, this is the drop-in.

How it works

Backend is list(reversed(py_list)) - a new list, reversed, with the input untouched. No OUTPUT_IS_LIST flag here, so the result stays a single list value. Like the rest of the pack's utility nodes it inherits NewPointer, meaning IS_CHANGED returns NaN and it's never cached away. And like its batch sibling, it raises ValueError if you feed it something that isn't a Python list.

Inputs and outputs

• py_list (required, *) - the list to reverse.
• * (output) - the reversed Python list, as a single value.

Installing it

Part of the comfy-ovum pack:

cd ComfyUI/custom_nodes
git clone https://github.com/sfinktah/comfy-ovum

Restart ComfyUI, or use ComfyUI Manager → search "comfy-ovum" → Install. No models, no GPU footprint.

Common gotchas

• Wrong dialect = confusing failures. Feed a graph-batch to a Python-list consumer (or vice versa) and the mismatch shows up as a weird runtime error, not a clean message. Pick the family that matches your downstream node.
• It reverses, it doesn't sort. There are no options here, by design.
• Non-list input raises. If you see a ValueError about a Python list, check what's actually connected - it's probably a scalar or a wrapped batch, not a list object.