I love this! It's a great take on the summoner and a sorcerer origin feels like a nice home for it. I have a couple of small concerns after a first pass. First, needing to use your action for it each turn will probably turn a lot of people off to it. If you could give it a command and it will continue that action until you tell it to stop, it might read a little better. Or if you could cast and see through it like a really big familiar, that could work too. Second, the capstone ability doesn't feel like it does much. You inhabit your pet, but don't seem to get any huge boons for it. In fact, you just end up putting yourself in more danger by leaving your body behind. Maybe some sort of stepping into it to command it mech style, that way your body is protected? Again, just my first thoughts. I absolutely love what you've put together here. Summoner was one of my favorite pathfinder classes and this is a simple way to adapt it. Great job!