> Partial seeding of labels, e.g. selecting portions of the incomplete model and artificially limiting the available labels in that area, without collapsing it.

I've done that in my toy WFC to let it generate an output which matches[0] the colours and transparency of a supplied PNG. Handy for generating text / shaped output. Does a pre-pass which only keeps the best N match options for the colour in that cell.

[0] As best it can - my input tileset only really has green, light green, slightly less green, a bit reddy-green, fractionally blue-green, ...