How strong perfect-information assumptions do you need to guarantee that rational decision-making can never lead both sides in a conflict to precommit to escalation, even in a situation where their behavior has signaling implications for other conflicts in the future? (I don't know the answer to this question, but my hunch is that even if this is possible, the assumptions would have to be unrealistic for anything conceivable in reality.)

And of course, as you note, even if every conflict is resolved by perfect Coasian bargaining, if there is a significant asymmetry of power, the practical outcome can still be little different from defeat and subjugation (or even obliteration) in a war for the weaker side.