MatAnyone2 Prompt Start

Every scripted mask in this pack starts the same way: with nothing. MatAnyonePromptStart is the node that creates an empty MATANYONE_PROMPT container - the seed you then feed points into with Add Point or Prompt From Text before handing it to SAM Refine.

If you've used ComfyUI's Empty Latent nodes, the shape feels familiar: a tiny node with no inputs that exists to give the graph a starting value. It has exactly one output, prompt (the empty SAM prompt structure), and it does nothing else. It's the "begin here" stamp for the scripted pipeline - the extended demo wires it as Prompt Start → Add Point (+) → Add Point (−) → SAM Refine.

Why it exists at all

ComfyUI custom types need a concrete producer. The interactive editor builds its prompts internally from clicks, but the scripted path needs a wire that a prompt flows through, and prompts are built incrementally. You can't point SAM Refine at "a prompt that doesn't exist yet," so you start with an empty container and mutate it downstream. That's this node - the plumbing, not the feature.

How to use it

Just add it and wire the output onward. Its one job is being the root of a prompt chain:

• Straight into Add Point if you're building points by hand with coordinates.
• Or into SAM Refine on its own if you want a zero-point run - though honestly, a prompt with no points produces a degenerate mask; you'll almost always add at least one point first.

Install & notes

It ships in the MatAnyone2 Video Matting pack: ComfyUI Manager search "MatAnyone2", or git clone https://github.com/dreamrec/MatAnyone2_ComfyUI into custom_nodes + pip install -r requirements.txt + python install.py + restart.

The one thing that confuses people: it's not required in the interactive path. If you're using the editor, you never touch this node. It only matters for the scripted/programmatic workflow where you want reproducible, click-free masks. Thin node, thin explanation - if you're seeing it in a workflow you didn't build, it just means whoever made it wants the prompts built from coordinates instead of by hand.