MMH3 Last Quadrant Patch

Every node in this pack exists because stitching separate MiniMax H3 video generations together is mostly about seams. MMH3 Last Quadrant Patch exists because one specific layout - the 4_quadrants_expand mode in MMH3 Spatial Extend Video - is where the automatically-derived seam masks stop being trustworthy. The author just calls it what it is: a bug patch. If you've run a four-quadrant H3 pan-out and watched a corner tile come back with a hard seam or a wrong patch of neighbour content bleeding in, this is the intended fix.

Why four quadrants are special

A four-quadrant expansion has a center tile (tile 0) with four corner tiles around it - TL, TR, BL, BR. Each corner tile doesn't have one seam, it has two: against the center tile, and against whichever neighbouring corner it was sampled after. The auto-derived masks can get the geometry of that second seam wrong, which is exactly the kind of edge case a tiling author ships a fix for. Note the 4_quadrants_expand layout needs exactly five tiles, so you'll see this paired with the Spatial Tile Editor set to that plan.

What the node does

It's a small config builder, not a sampler. You set it, and its single output (bug_patch) plugs into MMH3 Spatial Extend Video's bug_patch input. There, it replaces the noise mask of any corner tile you've enabled with the explicit widths you set here - frozen bands that pin already-stitched content exactly (mask 0), plus fade bands that let the new tile blend in. If you wire it up on any other layout, Extend Video ignores it with a console note. And if you enable no tiles at all, it's a silent no-op - the output dict just contains all-false toggles.

The inputs that matter are the four booleans and the width pairs:

• apply_tile1 … apply_tile4 - one toggle per quadrant (TL, TR, BL, BR). Enable only the tiles whose seams are actually misbehaving.
• center_mask_w_freeze / center_mask_h_freeze and center_mask_w_fade / center_mask_h_fade - the frozen and following fade widths along the tile's seam against the center. They're split into width and height because the center overlap rect isn't square.
• edge_mask_freeze / edge_fade - the same two bands at a tile's seams against its neighbouring corner tiles.

All widths are in pixels, step 32, and the rule to remember is that frozen + fade must fit within the tile's overlap width, or the band walks out of the seam entirely.

When to reach for it (and when not to)

Only for 4_quadrants_expand, and only after you've seen a bad seam. It's a niche fix for a niche layout inside an already-niche pack, so treat it as reactive rather than prophylactic - if your quadrant stitch looks clean, adding it gains you nothing. And it's the youngest part of an explicitly under-development pack (0.0.1), so treat its defaults as provisional. It's cheap to experiment with: widths are just integers you can raise, lower, or toggle per tile until the corner seams disappear.

How to install

It ships in the same pack as the nodes it fixes:

cd ComfyUI/custom_nodes
git clone https://github.com/bbaudio-2025/Comfyui-MMH3-UltimateExtend

then restart ComfyUI (ComfyUI Manager may list it by the pack title "Comfyui-MMH3-UltimateExtend" once it's in the registry). No Python dependencies, no model files of its own - everything else you need is whatever MMH3 Spatial Extend Video already requires, which starts with the actual MiniMax H3 weights. One caveat before you set any of that up: H3's community licence doesn't grant running rights in the US, EU, UK or South Korea, so the geofence is worth checking first.