⚗ Alchemica Save Image (pick the folder) [old, use Alchemica Save Image (drive + folder + workflow name)]

Two nodes in one name, both hidden, both still working. Here's which one you're looking at and what to use instead.

What it is

AlchemicaSaveImage is the English restyle of the AlchemicaSampler pack's original Save Image: pick a subfolder from a menu instead of typing it into filename_prefix, keep everything else about ComfyUI's Save Image the same. It appears as "⚗ Alchemica Save Image (pick the folder) [old, use Alchemica Save Image (drive + folder + workflow name)]" - the pack's 1.1 release then marked it superseded in favour of AlchemicaSaveImagePath.

That's because the original design had a real flaw the changelog doesn't hide: the folder list was built by enumerating the subfolders of ComfyUI's output directory at startup, so as your output folder accumulated a hundred folders the menu "looked random", and a workflow saved with a folder that had since been deleted failed validation. The replacement solves both by giving you a drive menu, a proper browse button and a prefix built from the workflow name.

So the honest summary: if you have a saved workflow that uses this node, it will keep running and it does its job fine. If you're building new, use ⚗ Alchemica Save Image (drive + folder + workflow name). There is nothing this node does that the new one doesn't.

What it does

Same PNG output as ComfyUI's own Save Image, same embedded metadata - the prompt and workflow chunks, so dragging the PNG back onto the canvas rebuilds the graph. That convention is the whole reason to save PNG rather than WebP or JPEG if you want your work to be reloadable: re-encoding loses the graph, PNG text chunks keep it.

Its one improvement over core Save Image is validation. It declares validation as always-true, so a workflow pointing at a folder that no longer exists queues anyway and the folder is recreated at save time, instead of refusing with a validation error about a menu option that vanished. That's a small thing that saves real annoyance when you move images around.

Inputs and outputs

• images - the IMAGE you're saving.
• folder - dropdown: (output root), every subfolder in ComfyUI's output directory, or (new folder).
• new_folder - the name for a new folder. Only used when folder is (new folder).
• filename_prefix - base filename, defaulting to immagine. The counter makes it immagine_00001_.png, immagine_00002_.png, and so on. A slash in it still creates subfolders, as in core.

No outputs - it's a terminal node.

Installing it

ComfyUI Manager, search "AlchemicaSampler", or:

cd ComfyUI/custom_nodes
git clone https://github.com/Nessuno76/ComfyUI-AlchemicaSampler
# restart the ComfyUI server so the nodes register

No extra Python dependencies (the pack declares none at all). ComfyUI 0.36.0+ is the pack's requirement, though a save node isn't where that constraint bites.

Where it goes wrong

• Your folder isn't in the dropdown. The list is captured when the server starts. Create the folder and restart.
• You can't save outside ComfyUI's output folder. Correct - and it's the specific gap AlchemicaSaveImagePath closes, with a drive menu on top.
• (new folder) with an empty name. It raises. Choose a name or an existing folder.
• The saved file has no workflow in it. Check whether your ComfyUI was started with --disable-metadata, or whether something re-saved the PNG afterwards; both delete the chunk.