Re: Fragile source code
Agile sounds like it has too much bureaucracy in it, and an oxymoronic name.
What you really need is a bunch of mad scientist types (like me), a decent engineer as a manager, a clear goal, and a sufficient slot of time. Generally can get it all done under budget that way with as much as 10:1 productivity (or even better, depending), so long as you have a competent engineer dividing up the tasks in a sane manner [and as few meetings as possible].
You know, OLD school! And NO rapid/radical direction changes. Those go into "rev 2".