Kanye West's ex-executive/personal assistant is adding to her previous claims about the mogul ... claiming not only was she sexually harassed by Ye -- but, she alleges the rapper drugged her at a studio session cohosted by Diddy, too.
Lauren Pisciotta -- who filed a lawsuit against against Kanye back in June claiming he fired her after sending vile sexual texts and and videos -- amended the lawsuit with several new claims ... including saying she attended a studio session with the "Donda" rapper and Diddy.
Pisciotta says she and her former artist management client -- who's name is not in the lawsuit -- were invited by Ye to the session he cohosted with Diddy.
According to the lawsuit, soon after they arrived "drinks were served to her and others in attendance, followed by an announcement that everybody had to drink, if they wanted to stay."
LP says she drank, but ... "After a few small sips of the beverage, poured at the direction of Kanye West a.k.a. Ye by a studio assistant and then served to her by Kanye West, Plaintiff suddenly started to feel disoriented."
Pisciotta says she woke up the next day remembering almost nothing of what took place at the alleged studio session and felt "immense shame and embarrassment."
LP says years later, while working with Kanye, she claims West brought up the night in question ... saying they did hook up and preceding to provide further details of the alleged incident.
Before Kanye allegedly provided those details, Lauren says she thought she simply got roofied and embarrassed herself at a work function.
As we told you ... Lauren was already suing Kanye for allegedly sending her dirty text messages in which she claims he wrote things like, "see my problem is I be wanting to f*** but then after I f*** I want a girl to tell me how hard they been f***ed while I'm f***ing them. Then I want her to cheat on me ..." followed by even more graphic language.
Pisciotta also claims Kanye would masturbate while on the phone with her ... and, he allegedly fixated on the penis size of her boyfriends.
Diddy was arrested last month and charged with racketeering conspiracy, sex trafficking by force, fraud or coercion, and transportation to engage in prostitution. He's denied all major sexual assault allegations made against him.
Worth noting ... Lauren is claiming Kanye drugged her at the studio session cohosted by Diddy. She is not accusing Diddy of any alleged wrongdoing.
We've reached out to Diddy team and Kanye's team ... so far, no word back.