Xian Zhang has been hired as music director of the Seattle Symphony, becoming the first woman conductor to head a major West Coast orchestra and filling a post that had been vacant since Thomas Dausgaard quit abruptly in January 2022. Zhang agreed to a five-year contract starting in 2025-26, the orchestra said Thursday. She becomes music director designate this season. She first conducted the orchestra at Benaroya Hall in June 2008 and has returned several times, including for performances of Orff’s “Carmina Burana” in 2023 and Copland’s “Appalachian Spring” this April.