I'm halfway in on a six-month disaster contract where I'm converting a massive site written over 7~8 years to a new system. Manager has had us restart about 4 times and there are other departments who want to take over. The deadline is so tight that I've stuck with the original plan and kept my code flexible to be changed if the manager wants to go with the other teams' ideas. ("Okay, manager: here's a clone, tell the other team to prove that works") The lead dev, to my horror, didn't write any code and was let go in November.

Manager hired a new dev part-time whose commitment is on something entirely separate that is required in order for the deadline to be pushed to Summer. (new thing for old thing)

New dev has an attitude, basically wants to start over, and is already acting like I'm his subordinate, very patronizing, very dodgy when asked to explain a strong opinion (THIS IS A SECURITY PROBLEM!!!1). I really have no idea what my manager promised to him. Also found out that manager hired an agency to create a roadmap of the project (WHY?!!! WHY NOW?!). I've been burned once already with the previous lead, and I'm not wild about working with yet another person who wants to burn the whole thing to the ground and start completely over, especially not someone who wants to engage in a dick-measuring contest.

Do you guys have any advice? I mean, other than quitting? I'm going to see this through, but I'm burned out.