I have a situation in my county where a JP agreed not to issue warrants on some Class C tickets so long as the def. was cooperating as an informant with local SO. DPS Trooper issued the tickets and is upset that no warrant has been issued and is questioning the legality of the deal. Is this done in your county and, if so, do you know of any authority for it?

Only prosecutors can make deals about nonprosecution. Judges, as I recall, are impartial and are told it is unethical to engage in plea bargaining.