Reactor Helios Segment

Helios doesn't do cuts, and that's the whole character of this node. You don't get a scene change; you get a scene that keeps going and quietly becomes something else because you changed the prompt. Chain five segments and you get one uninterrupted take that evolves.

What it's for

This is the model you use when a cut would break the spell - a slow transformation, a mood shift, a camera that never stops rolling while the weather turns. Because there's no kind input on the node at all, you can't accidentally cut: every segment continues the shot, and the prompt is the only thing steering it. That's a real limitation and a real feature depending on what you're shooting.

The other thing Helios gives you that most of this pack doesn't is a graded reference image. Not just on the first segment - on any segment - with an image_strength dial you can move between segments. Drop a reference in at segment four and turn it to 0.4 and the scene pulls toward it without slamming into a hard match.

How it works

Helios is chunked at 33 frames at 24fps, so frames steps by 33 and both ends of a segment round to the nearest chunk. Everything is prompt-driven inside those chunks, and image_strength is a mid-run setting: it holds its value until a later segment changes it, so you set it once and the whole tail of your timeline inherits it. Same for the image itself - a reference stays in effect until you change it on a later segment.

Worth knowing before you fall in love with it: Reactor serves Helios at a small canvas in this plugin, 640×384-ish, and the pack explicitly asks the model for its small native size rather than upscaling. It's a low-resolution, mood-and-motion model. If you need detail, render here and upscale, or pick a different model in the pack.

The inputs that matter

• prompt - what this stretch of the scene looks like. Since there are no cuts, the prompt is doing double duty as your edit.
• frames - default 132, stepping by 33.
• image (optional) - a reference image, and unlike most models here, Helios can read one on any segment.
• image_strength - 0 to 1, default 1, steps of 0.05. Holds until a later segment changes it. This is the dial that makes the node interesting: low values tint the scene, high values lock it.
• sequence - the earlier segments; empty on the first.
• REACTOR_SEQUENCE (output) - the next segment, then Reactor Render.

Install

Manager search comfyui-reactor-api, or:

cd ComfyUI/custom_nodes
git clone https://github.com/reactor-team/comfyui-reactor-api
pip install -r comfyui-reactor-api/requirements.txt

No weights, no CUDA, one dependency (reactor-sdk>=1.6). Add REACTOR_API_KEY (environment or config.ini under [API]), restart, and the pack's nodes show up under Reactor. Copy example_inputs/ into ComfyUI's input folder for the bundled templates.

Where people get burned

You cannot cut. The compiler will refuse a hard cut on Helios. If your story needs a scene change, either accept the soft morph or build that stretch with LongLive-2.0 instead.

frames isn't free-form. 100 frames becomes the nearest chunk multiple, and a segment shorter than half a chunk collapses to zero. Use the visualizer if you're tuning lengths by hand.

Image strength is sticky. Set image_strength to 0.2 on segment two and every segment after it stays at 0.2 until you set it back. People set it once, forget, and then wonder why the last third of the render looks washed toward a reference they'd stopped thinking about.

Small canvas, honest expectations. The output is around 640×384 and 24fps. Judging it at 200% zoom will only make you sad.