Add Default color when Unlit

I’m trying to add a default color to a pixel when the pixel is not lit by any lights in the scene.

I tried to use the finalcolor modifier of a surface shader and set the color when the color of the pixel is 0,0,0 but this seems to blend the results of the base color and the pixel color when the pixel is lit.

Any ideas on how this could be implemented?

I found some documentation on forward rendering that helps to clear this up. Apparently it does call the shader multiple times, one for each light source (including the ambient one).

Thanks for the help.