First: What is the precise role of bromide in Farmer's Reducer?
I think you mean re-halogenating bleaches. Potassium bromide is used so that when the silver is oxidized it is converted to silver halide again. Such a bleach may be used in connection with an intensifier.
Ag0 - electron --> Ag+ + Br- --> AgBr
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.