A2 Prompt

A2Prompt is the positive-prompt half of the ComfyUI-SkyReels-A2 pack, and like its sibling NegativePrompt it does almost nothing: it takes the string you type, stamps it with a custom PROMPT type, and hands it to A2VideoGenerator. No API calls, no API keys, no processing. If you've ever loaded a SkyReels-A2 workflow and wondered what this node contributes beyond a text box - that's the honest answer. It exists because the pack's generator demands a PROMPT-typed input and refuses to accept a bare string, so the workflow needs a bridge node.

Where this node stops being trivial is in what you type, because SkyReels-A2 is a compose model and prompting it is not like prompting a normal image-to-video. The model already knows who (subject reference), what (object reference), and where (environment reference) from the ReferenceImages node. The text prompt's job is the composition and the action: "A man is holding a teddy bear in the forest," which is the shipped default, is a perfect example - the references carry the identity, the prompt carries the verb and the layout.

How to prompt it well

Follow the same discipline people use with Wan 2.1 I2V (SkyReels-A2 is a fine-tune of it): describe the motion and the interaction plainly, don't narrate every pixel of your references back at the model, and skip adjectives like "beautiful" or "stunning" - describe what happens, not how you feel about it. If your reference is a specific person and you want them doing something, the action phrase matters more than re-listing their appearance, which the model already has in the clip encoder's pocket.

Inputs and outputs

One input, input_prompt (default "A man is holding a teddy bear in the forest."), one output, prompt, which wires into A2VideoGenerator's prompt slot. Note you need both A2Prompt and NegativePrompt - the generator requires both typed inputs before it will run.

Installing it

It's part of Yuan-ManX/ComfyUI-SkyReels-A2, so installing the pack covers it: ComfyUI Manager → search "SkyReels", or

cd ComfyUI/custom_nodes
git clone https://github.com/Yuan-ManX/ComfyUI-SkyReels-A2.git
cd ComfyUI-SkyReels-A2
pip install -r requirements.txt

Restart ComfyUI afterward. Heavy dependencies (flash_attn, diffusers from git) make the first install the slow part, not the node itself.

Gotchas

The one real trap is treating it as a normal ComfyUI text node: its PROMPT output won't connect to KSampler or standard conditioning, and it has no effect outside this pack's own generator. It's also worth knowing the generator's PROMPT type is entirely separate from the NEGATIVEPROMPT type - wiring the wrong node into the wrong slot is the most common "why won't it run" error with this pack.