SamplerDPMPP_SDE_motorway_edition

Every sampler family has its wild child, and for DPM++ that's the plain SDE version. SamplerDPMPP_SDE_motorway_edition is a clone of ComfyUI's built-in SamplerDPMPP_SDE, the first-order stochastic sampler that the whole SDE line is named after. Where the multistep variants (2M, 3M) mostly converge, this one stays noisy by design: it injects fresh random noise at every step, so it never settles into one stable answer. The image keeps a bit of life and variation all the way through - great for texture-heavy styles, slightly maddening if you're trying to dial in a pixel-perfect repeat.

It's a sampler factory, not a drawing node. Give it a model and it produces a SAMPLER object for SamplerCustom's sampler port. In the SD 1.5 / SDXL world this is the "creative chaos" option, and it's a common answer in the "which sampler for detailed output" threads - run it at higher step counts and you can get a lushness that the more analytic samplers sand off. It also has one knob the other DPM++ editions don't:

• r (default 0.5) - the extra-noise coefficient that tunes how much stochasticity the SDE keeps. Push it toward 0 and the process leans more deterministic; 0.5 is the usual starting point and most people never move it.
• eta (default 1.0) - scales the SDE noise injected each step.
• s_noise (default 1.0) - per-step noise strength; the other dial on how "stochastic" it behaves.
• noise_device - gpu (faster, default) or cpu (frees VRAM headroom by generating noise on the CPU).

What it does on the Motorway

This node is one of the generated *_motorway_edition clones from the ComfyUI_agilly1989_motorway pack. The pack's core concept is a named-key data bus - the Motorway (that MOTORWAY 🚌💨 socket) - where values are stored under typed key names and fetched back later, instead of being wired port-to-port. MotorwayStart creates the bus, Motorway AxB ramps store and retrieve keys, and every motorway-edition node is a clone of a built-in ComfyUI node re-plumbed to read its inputs from the bus by key and write its outputs back by key. It always returns the bus so the chain continues.

The model arrives from the bus under the family's INPUT_…_key convention (see INPUT_model_key, default model, on the SDTurboScheduler edition), and the finished sampler is written back to the bus under your OUTPUT_SAMPLER_key - default SAMPLER. A later SamplerCustom_motorway_edition pointed at that key picks it straight off the bus.

Installing it

It's part of ComfyUI_agilly1989_motorway, not a standalone download. ComfyUI Manager: search ComfyUI_agilly1989_motorway, install, restart. Or:

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

No extra Python dependencies, no model files. It's pure glue around ComfyUI's own nodes.

The catch

The standard pack gotcha applies: release 1.1.7 ships with the clone nodes disabled - the two ClonedNodeMapping lines in custom_nodes/ComfyUI_agilly1989_motorway/__init__.py are commented out. Uncomment them and restart, or this node simply won't be in your menu. And keep the README's own warnings in mind: the top line is literally "BIG BROKEN WITH ASYNC WILL FIX WHEN I GET THE TIME/MOTIVATION", it's flagged as an in-development beta, and the author only promises "most" of the cloned nodes work. A fun experiment from a solo dev, but not infrastructure. If a key you reference hasn't been written to the bus yet, you'll get a KeyError: "Key: 'x' doesn't exist in motorway" - that's the signal to check your key names.