Prompt Layout Filler

If you've ever built a prompt out of separate pieces - subject, pose, background, lighting - you've probably done it with a chain of string-concat nodes and cursed at the commas. PromptLayoutFiller is the cleaner version: you write a template once, with {0}, {1}-style placeholders, and then plug each piece into a slot. It's mail-merge, but for prompts.

How it works

Write the template in the template field:

character, {0:position}, {1:background}, {2:lighting}

The {0:position} syntax is the important bit - the number is the slot index, and the word after the colon is just a visual label that never reaches the output. Then connect nodes to the matching slots: slot_0, slot_1, slot_2. At execution each placeholder is replaced by its connected value. Slots appear one at a time as you connect the previous one, so the node stays tidy instead of dumping ten empty inputs on you.

The natural sources are PromptOptionPicker nodes - one for poses, one for backgrounds, one for lighting, each managing its own list. Slot lengths don't need to match, so you can swap a 3-option lighting picker for a 9-option one without touching the template. When you want to change what the prompt says, you edit a picker, not the template.

The inputs that matter

• template - multiline, with {N} or {N:label} placeholders. Gets a highlighted editor: green for placeholders whose slot is connected, red for ones you've referenced but haven't wired up. That red is your early warning.
• cleanup - default on, same cleanup rules as the rest of the pack. Vital when a slot outputs an empty string and leaves you with character, , , dark-style debris; it scrubs the residual commas and empty parens.
• slot_0 through slot_9 - connectable STRING inputs.
• preset_data - internal storage for the preset system; you don't touch it.

One output: text, the fully resolved prompt, ready for a text encoder.

Presets - the underrated feature

This node can remember whole slot configurations as named presets, and they're stored inside the workflow. The header buttons are ➕ (new preset from current values), 💾 (overwrite), 🗑️ (delete), plus 📋 Export and 📥 Import which move all presets as JSON via clipboard. Recalling a preset pushes its saved values back into the connected source nodes - so if you've saved "outdoor day" and "indoor night" as two setups, you're one dropdown away from either.

The catch, honestly documented: recalling pushes values into source nodes, so if a source no longer offers that value, or a source got disconnected, it errors rather than guessing. That's the trade-off for the two-way sync.

Installing it

It's in ComfyUI-RE-CustomUtils. ComfyUI Manager → search the pack, or:

cd ComfyUI/custom_nodes
git clone https://github.com/relhamdi/ComfyUI-RE-CustomUtils

Restart ComfyUI. No extra packages, no model downloads - the pack's only declared dependency is torch.

Where people get burned

• Referenced-but-disconnected placeholders error out. That's by design - it refuses to run with a hole in the template - but it means you can't temporarily unplug a slot and still test. Leave a picker in place even if you don't want its value.
• Index 9 is the ceiling. A placeholder beyond slot_9 fails validation. Ten slots is plenty, but know the limit.
• Empty template stops the workflow too.

The one-two punch this pack is built around is PromptOptionPicker → PromptLayoutFiller → text encoder: pick your pieces, fill the template, generate. If that's the workflow you want, this is the node that makes it feel like one thing instead of ten.