SamplerEulerCFGpp_motorway_edition

Here's the short version of CFG++: what if you could get classifier-free guidance's prompt adherence without running a separate unconditional pass and without a negative prompt? That's the idea this sampler is testing. SamplerEulerCFGpp_motorway_edition is a clone of ComfyUI's experimental SamplerEulerCFGpp, and the _for_testing in its category is ComfyUI's own flag, not this pack's - this is upstream's experimental code, cloned wholesale.

The practical difference you'd notice: in a CFG++ workflow, your negative prompt field is largely a formality. Guidance is applied as a positive-only correction to the prediction, so the whole "push away from the empty prompt" dance disappears, and it can behave differently at low CFG. Enthusiasts like it for workflows where negative prompting fights the image (some styles, some distilled models) or where they want to save the second forward pass. The catch is it's still experimental and community consensus hasn't canonized it - you'll find it in "interesting but nobody's default" territory. The KB's sampler guidance sums up the mood: for normal SD 1.5/SDXL work, DPM++ 2M Karras or Euler remain the boring, reliable choices.

The one widget worth knowing:

• version - regular or alternative. Two implementations of the CFG++ guidance math. Regular is the straightforward version; alternative uses a slightly different correction. If one gives you weird artifacts, try the other - there's no universal "right" answer.

It's a sampler factory like the rest of the family: model in, SAMPLER out, for SamplerCustom's sampler port.

What it does on the Motorway

Another generated *_motorway_edition clone from ComfyUI_agilly1989_motorway. The pack's deal is a named-key data bus - the Motorway - where values ride under typed key names instead of wires. MotorwayStart starts the bus, Motorway AxB ramps store and fetch keys, and every motorway-edition node reads its inputs from the bus by key and writes its outputs back by key, always returning the bus. The model comes in via the family's INPUT_…_key convention (default model), and the sampler is parked back under your OUTPUT_SAMPLER_key (default SAMPLER).

Installing it

Ships inside ComfyUI_agilly1989_motorway - no separate install. ComfyUI Manager: search ComfyUI_agilly1989_motorway, install, restart. Or:

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

No extra dependencies, no model files.

The catch

Double experimental: the underlying CFG++ sampler is ComfyUI's own _for_testing code, and the pack layer is a beta. Release 1.1.7 has the clone nodes switched off - uncomment the two ClonedNodeMapping lines in custom_nodes/ComfyUI_agilly1989_motorway/__init__.py and restart to get any *_motorway_edition node to appear. The README's opening line - "BIG BROKEN WITH ASYNC WILL FIX WHEN I GET THE TIME/MOTIVATION" - is your honest warning about how finished this is. Fun to tinker with CFG++ on the bus; don't ship a workflow on it.