Some of the semi permanents (NOT demi permanents which may contain small amounts of harsh chemicals) are just in a conditioner base, I am using UK brand La Riche Directions which leaves my hair really glossy and supple after three hours. I do this over a permanent blonde box dye to lift the roots a couple of shades so it will take, which is obviously less gentle (!) but still a great improvement on box dying the whole head each time.
Ingredients are "Aqua, cetearyl alcohol, distearoylethyl hydroxyethylmonium methosulfate and cetearyl alcohol, ceteareth-20, butylene glycol, glyceryl stearate, citric acid, methylparaben
Whilst I don't much like using parabens, that is CG friendly AFAIK
no polyquats or cones or anything that coats the hair, no sulphate surfactants. And I can CO-wash off the excess!