Yet if you want to bring timing into play, a reagent needs to have a witness for the absence of other reagents that it might react with during an interval of time in order for us to know that it persists across that interval.
I wonder if some species of focussing discipline would constrain proofs to consider all possible interactions between the current set of hypotheses, so that a reagent running through the whole gamut would indeed have sufficient evidence to conclude that it merely sticks around unreacted.
