Why does qpos have a num_envs dimension but xpos does not

[bfmat]

Intro

Hi!

I am a recent Stanford grad and using Mujoco MJX for my robotics research.

My setup

Mujoco 3.2.7, Python, latest macOS

My question

I wish to get the site_xpos for each env in my 1024-env MJX environment.

I run print(state.qpos.shape, state.xpos.shape, state.geom_xpos.shape, state.site_xpos.shape) and get the following:
(1024, 55) (57, 3) (68, 3) (17, 3)

Is this a bug? Why is there no envs dimension on xpos?

Minimal model and/or code that explain my question

print(state.qpos.shape, state.xpos.shape, state.geom_xpos.shape, state.site_xpos.shape)

Confirmations

• I searched the latest documentation thoroughly before posting.
• I searched previous Issues and Discussions, I am certain this has not been raised before.