Alex Hughes hit an unbeaten 67 and Ben Slater added 52 as Derbyshire closed Day Two just 76 runs behind Glamorgan with seven wickets in hand.
Slater and Hosein (35) added 90 for the first wicket and Wayne Madsen (41) and Hughes continued to press on as Derbyshire ended the day on 207-3.
Earlier Tony Palladino claimed his 398th first-class wicket and his 12th five-wicket haul to dismiss Glamorgan for 283 after Salter (72 not out) rallied for the hosts.
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