https://www.wikidata.org/wiki/Q171416 has error

contemporary constraint The entities Battle of Trafalgar and Horatio Nelson should be contemporary to be linked through participant, but the latest end value of Horatio Nelson is 1805 and the earliest start value of Battle of Trafalgar is 21 October 1805.

This is also true of states, see the Battle of Waterloo, https://www.wikidata.org/wiki/Q48314

Expected behaviour: comparison of dates with different levels of precision should always expand the less qualified date to the start or end of the period depending on the comparison.