ScarlotSoft Concatenate

A string_a, a string_b, a boolean, and one STRING output. That is the whole node, and the only thing it does is glue two text boxes together with either a space or a blank line, depending on the toggle. bool_on_off on = blank-line join, off = single space. That's the mechanism - no token limits, no clever parsing, just f"{a}{delimiter}{b}".

Simple as it is, this is the kind of plumbing that quietly powers prompt-assembly graphs. You keep a quality/style prefix in string_a, drop your subject into string_b from a randomizer or a file reader, and out comes a combined prompt you feed to a CLIP encoder. The blank-line mode is the one worth knowing: ComfyUI's CLIP tokenizer treats a line break as a genuine pause between prompt regions, which is a real (if subtle) way to structure a prompt - especially on the SDXL anime lineage where comma-bags are the norm and a paragraph break reads differently. For day-to-day tag prompts the space mode is what you want.

Where this node fits next to the rest of the suite matters more than the node itself. ScarlotSoft's philosophy is "your prompt is a thing you assemble," so this works hand-in-glove with EasyLineFromFile (feed a random line in as string_b), Concatenate stacking into CLIPTextEncodeModular, or the Prompt Builder loaders that assemble whole files. It's also a plain-language alternative to the core String concat nodes if you dislike their extra dials.

Two things to know before you reach for it. First, there's no delimiter choice beyond space-or-blank-line - if you want commas or pipes, you're back to a string-concat node. Second, all three inputs are widgets, not sockets, so if you want the toggle or one of the strings to come from elsewhere in the graph you'll use right-click → Convert widget to input. That's standard ComfyUI fare, not a bug in this node.

Install as part of the suite - ComfyUI Manager, search ScarlotSoft, install, restart:

cd ComfyUI/custom_nodes
git clone https://github.com/scarlotsoft/ComfyUI_ScarlotSoft

No dependencies to speak of. It gets the suite's dark theme automatically; if it renders wrong after a UI-mode switch, hard-refresh (Ctrl+Shift+R).

Honest verdict: you don't install this pack for this node. You install the pack, and this is one of the small pieces that make prompt-building graphs read cleanly. It's a competent two-box concat with a tidy toggle and no surprises - which is exactly what you want from plumbing. If you're copying a ScarlotSoft workflow, you'll meet this node constantly, and now you know the toggle means "space vs. blank line."