The embattled rapper's back in L.A. County jail after violating his probation in a 2021 assault case, and law enforcement sources tell us he's staying in the administrative segregation area -- meaning he's kept outta gen pop -- and he's got a cell all to himself where he's getting his meals brought to him.

Blue can leave his cell for up to 7 hours a week to participate in education classes or religious services -- assuming they're being offered -- or head to the rooftop yard to call his family or his lawyers.

There's a TV in the shared unit he can watch, and access to the library. Showers are allowed every other day ... unless he's headed to court in which case he's allowed to wash up on that day too.

Blueface will find some commissary options, too ... including Texas beef and cajun chicken ramen, tuna, sliced pepperoni, hot & spicy pork cracklings, hot cheese crunchies, jalapeño peppers, hot tortilla chips and Club crackers.

For dessert, he can choose from Oreos, blueberry and chocolate donuts, chocolate chip cookies or bear claws -- and he can wash it all down with cocoa or coffee.

It's a good thing the food options look tasty ... cause Blue's gonna be locked up for a bit. We broke the story -- he's stuck in prison until at least the summer after violating his probation for a 2021 assault.

We don't know exactly what conditions he violated (his mom's blaming his baby mamas), but there was a hearing last Friday, and now he's in custody until July 2. He was supposed to do a full year, but for every day he serves in county, he'll get credit for another.