Need to see better pictures of the entire area but this will need to be a real kludge for both up and down railings and in reality looks quite dangerous with railings making the entire area much more congested, and tighter.

Any chance of moving the door over a few inches? Having trouble seeing how you'll anchor a railing without interfering with the door otherwise.

This looks not particularly well planned out and as a result pretty challenging. I'd have wanted to lag posts into the joists at both the top and bottom of that short run prior to adding the subfloor at the least.

You will probably need to go with a very thin metal railing. Maybe the railing could be attached to the side (to the floor joist) instead of the floor but that might not be possible if it cuts into the needed headroom space down the stairs.

You'd better hope your local division of inspection doesn't stop by; I can smell a red tag.

this is a 100 year old house, that's how they are mostly. and an inspector was here actually for the basement recently.

@palimpsest thank you for the illustration! metal is an interesting idea.

Consider installing a side-mounted metal cable railing. This option preserves the usability of the staircase and maintains an unobstructed view, which is especially important in smaller spaces to prevent collisions. However, it's essential to review a comprehensive photo of the entire area to determine the optimal installation location. Here’s an example with a space similar to yours.