I am a chemist by training, though not an expert in photographic chemistry. However, I was reading about properties of developers one day and it occurred to me that an ascorbate/para aminophenol developer adjusted to pH 9 or so should activate the para aminophenol (perhaps weakly) but not the ascorbate, and that the ascorbate should regenerate the para aminophenol under these conditions. Does this sound something like what you are describing?
One more thing. I understand that when ascorbate is oxidized it increases the acidity of the solution. If so would a developer such as I outlined above have a compensating effect by lowering the local pH in the gel in the areas of most active development, thereby inhibiting development in those areas?
Yes, this might work. It is not super additivity but rather probably fits into the realm of the ET (Electron Transport) developer mechanisms. However, if the pH drops then the activity could fall off overall.