RandomNoise_motorway_edition

RandomNoise is one of those nodes that looks pointless until you're building custom sampling chains. In ComfyUI, "noise" isn't a side effect - it's an input. A sampler needs to know which noise to start denoising from, and RandomNoise is the factory that produces it from a seed. In a stock KSampler, that noise gets created invisibly behind the scenes. In a SamplerCustomAdvanced chain, you have to supply it yourself, and this node is how.

The only thing it does is take a seed and emit a noise generator object. Same seed, same noise, same image - that's the reproducibility contract, and it's the whole reason the node exists.

On the bus

The _motorway_edition clone adds the MOTORWAY 🚌💨 bus to the stock RandomNoise. The MOTORWAY input is optional (it can start a bus if nothing's connected), and there's no INPUT_*_key at all - the original node has no non-primitive inputs. The full input surface is:

• noise_seed (default 0) - the seed that determines the noise. Change it and you change the image; keep it fixed and the sampling chain is reproducible.
• OUTPUT_NOISE_key (default NOISE) - where the noise generator is parked on the bus.

The bus is the only return; the noise object rides inside it under NOISE. Downstream, SamplerCustomAdvanced_motorway_edition reads it via its INPUT_noise_key (default noise) - another one of those case mismatches where NOISE and noise are different keys, so either rename one side or remember which is which.

Install

No Python dependencies, no model downloads - the pack is pure code:

cd ComfyUI/custom_nodes
git clone https://github.com/agilly1989/ComfyUI_agilly1989_motorway

or ComfyUI Manager → search ComfyUI_agilly1989_motorway → install → restart.

The fine print

Beta pack, beta problems: the README says "IF THINGS BREAK ITS BECAUSE I BROKE IT," and the _motorway_edition clones were generated by an auto-cloner that the 1.1.7 build removed. Current installs may not show this node; core RandomNoise always will. If you're only after reproducible sampling, the stock node is the dependable route.

The bus failure mode is the usual KeyError: 'hash_...' doesn't exist in motorway - the sampler asked for a noise key that was never stored. For a node this simple, that's almost always a key spelling or case mismatch between the output key and the sampler's input key, not a real logic problem.

One thing worth knowing even with the plain node: seed reproducibility only holds if everything in the sampling chain is deterministic. Throw in a node that uses random state without a seed and your "same seed" promise quietly breaks. The bus won't save you from that.