SolidMask_motorway_edition

SolidMask is ComfyUI's way of making a mask out of nothing: a full-frame rectangle filled with one value. You set the size and the brightness, and out comes a mask. It sounds trivial until you realize how often you need exactly that - a solid white mask to say "regenerate everything," a solid black one to say "touch nothing," or a mid-gray one as the seed of a mask operation you're about to blur and threshold into something interesting.

This _motorway_edition version just does that on the Motorway. Because SolidMask has no upstream connections - no image, no latent, nothing to read - this node is one of the rare motorway-ed nodes where the MOTORWAY input is optional. Leave it disconnected and it acts like its own little Motorway start: it creates the mask, writes it to the pipe under your key, and hands you the pipe to continue from. That makes it a handy source node for kicking off a mask-heavy flow.

What to set

Everything on this one is a widget, plus one output key:

• value (default 1, 0–1) - the mask's brightness. 1 is fully white (fully masked/affected), 0 is fully black.
• width / height (default 512 × 512) - the mask dimensions. Match your latent or you'll get a shape mismatch downstream.
• OUTPUT_MASK_key (default MASK) - the Motorway key the mask is written under.

Output is the MOTORWAY with MASK in the pipe. If you already have a Motorway running, plug it in and it'll just add the mask to what's flowing; if you don't, it works standalone.

Installing it

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

Restart ComfyUI; it shows up under agilly1989 Nodes → Motorway-ed → mask. ComfyUI Manager has the pack as well. No pip dependencies - nothing extra gets installed.

Where people get burned

The size gotcha is the real one. width/height default to 512, and if your latent is 1024 the mask silently won't line up, and composite/mask ops downstream will behave oddly. Set the size to match your generation resolution explicitly.

The other classic: you're new to the Motorway and expecting a wire to carry the mask. On the Motorway it travels as a value under the MASK key, so whatever node reads it (say a SetLatentNoiseMask motorway-ed edition) must be told the same key name - case-sensitive, exact. And a word on the pack: it's a beta, actively developed, and the author has disabled the auto-cloned motorway-ed nodes in some releases. If you update and they vanish from the menu, that's the pack changing, not your install breaking.