Drain & Vent for Toilet

Attached is a crude drawing of a proposed drain and vent for a toilet. Do you see anything wrong with it? Any help would be appreciated. Thanks.

I dont know about your local code but you might have a problem because you are running the vent horizontally.

Your combo T is upsidedown

Are there any fixtures draining in that stack from an upper floor?. If not, the extra vent is not required. It will use the stack as a vent "Stack vented"
If so, most juresditions will require you to wet vent the toilet if the Y is placed verticle , the way you are showing in the pic

In my drawing I neglected to show this but the horizontal part of the vent actually slopes upward approximately 1" and it is about a foot long, does that still make it illegal? The vent is the main vent for the toilet. This is a single story house nothing draining into it. And I'm a bit confused about the combo. It is actually a combination wye with 1/8 bend connecting to the main 3" drain pipe on the ground. The direction of flow in the drawing of the drain pipe on the ground is up.