Flux 2 / Klein Prompt Builder (Official BFL 8-Layer Encyclopedic)

This node writes your entire Flux 2 / Klein prompt for you. Not magic - you're still the one choosing between "3D Disney Pixar Animated" and "Renaissance Chiaroscuro" - but it's a real time-saver if you've ever sat at a blank CLIP Text Encode box wondering what to type for Klein. It's the flagship of the ComfyUI-StudioPromptDirector pack, and it shows: fifteen dropdowns, eleven labeled override boxes, and two string outputs (positive_prompt, negative_prompt) that drop straight into your text encoder.

The thing that makes it work is luck plus design. Klein's text encoder is a Qwen3 LLM that reads your prompt like an instruction - a chat turn, not CLIP tag soup. masterpiece, best quality does nothing on it; a descriptive sentence does. So when the pack's README says this implements the "exact 8-slot structural formula mandated by Black Forest Labs" ([SUBJECT], [LOCATION], [STYLE], [CAMERA], [LIGHTING], [COLORS], [EFFECT], [ADDITIONAL ELEMENTS]), take the word "mandated" with salt - that's the author's framing, not a published BFL spec. What's true is that the 8-slot approach produces long, structured, sentence-shaped prompts, which is exactly the format Klein rewards. The name may oversell the "official" bit; the method is sound.

The inputs that actually matter

You'll fiddle with style_art_form first - it's the big one, 42 choices from Pixar-ish CGI to 70mm IMAX to Hokusai woodblock. After that, the dropdowns are pleasantly opinionated: ethnicity_origin, age_group, gender_and_physique, facial_expression, hair_preset, wardrobe_preset, location_environment, camera_framing, lens_and_optics, lighting_engine, color_palette_preset, visual_effect_preset, and additional_elements_preset. Set character_name to "Maya" or anything you like - it's threaded through the subject core.

The real power is in the eleven optional 🏷️_ boxes. They're slot-by-slot overrides: leave a slot's dropdown alone and type something better into 1_Custom_Style_and_Art_Medium or 5_Custom_Camera_and_Framing, and the node uses yours. Two to remember: Negative_Prompt_Custom_Additions appends to your chosen negative preset, and Full_Override_Positive_Prompt bypasses every dropdown entirely - type anything there and it ships straight to the output. That's your escape hatch when the assembled prompt fights you.

The negative prompt question

negative_prompt_preset offers seven guards - anatomy/anti-deformation, 3D-CGI clean, photoreal preserver, that sort of thing. Honest take: these are classic SD-style tag negatives (bad anatomy, bad hands, worst quality), and Flux-family models barely lean on negatives the way SD does, especially at Klein's default CFG 1. They're harmless, and if your workflow routes a negative text encode you'll want them, but don't expect them to carry the load. If Klein's anatomy is misbehaving, the community fix is more practical: run the distilled checkpoints at 8 steps with CFG nudged to 1.2–1.5, and don't fight the tag weighting - Klein's encoder ignores ((parentheses)) emphasis anyway.

Install

Two ways, both painless - this is a pure-Python node pack with no dependencies and no model downloads (the shipped requirements.txt is a comment):

# Via ComfyUI Manager: search "ComfyUI-StudioPromptDirector" and install
# Or manual clone:
cd ComfyUI/custom_nodes
git clone https://github.com/nexusfinancial-dev/ComfyUI-StudioPromptDirector.git

Restart ComfyUI and the nodes appear under the StudioPromptDirector category. It's a young, small pack with zero community footprint so far, but it's genuinely dependency-free, so the install risk is basically nil.

Gotchas

Wire positive_prompt into whatever text encoder your Klein workflow uses and negative_prompt into the negative one if it has one. If your output looks off, remember the override box - the assembled prompt is only as good as your weakest dropdown, and "Custom Origin (Use Labeled Box Below)" exists for a reason. And if you're coming from SD tag habits, unlearn them here: on Klein, "a hyper-realistic portrait of Maya, 24yo, warm honey olive skin, shot with an 85mm f/1.2" beats "realistic, detailed, 8k, masterpiece" every time. This node builds the former. Let it.