A year in a Failure Analysis lab aside, I would say that the dolls head cracked well before it finally let go. The rust in the fracture indicates the early failure and the clean, albeit crystalline surface is the continuation of the original crack.
Replace the entire rib extension, or take what you have to a micro welder, build the entire end up with weld metal, and machine the dolls head out of the welded portion. Not an insurmountable job off the gun.
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