How far does coffee drinking or cultivation in Ethiopia predate the earliest 15th-century documented evidence from Yemen?

The popular account of coffee origin, a goatherd named Kaldi noticing his goats grow lively after eating coffee berries, was first put into writing in 1671 by Antoine Faustus Nairon, nearly a thousand years after Kaldi supposedly lived, and no earlier written trace of the story exists; it is folklore, not history. The earliest solid documentary and archaeological evidence for coffee drinking and cultivation as a prepared beverage instead comes from Sufi monasteries and coffeehouses in 15th-century Yemen. Coffea itself is native to the Ethiopian highlands, and Ethiopian oral tradition and later regional use are widely assumed to predate the Yemeni record, but no dated textual or archaeobotanical evidence currently closes the gap between the plant's native range and the first solid 15th-century documentation of it being deliberately cultivated and brewed.