Where does this get added in HA 2026 version? When I try to add it in configuration.yaml, spits out error:
Integration error: customize - Integration ‘customize’ not found.
Configuration errors
Invalid config for ‘homeassistant’ at configuration.yaml, line 15: Entity ID climate.ds-thermostat is an invalid entity ID ‘customize->climate.ds-thermostat’, got {‘target_temp_step’: 0.5}
The error message says that your climate.ds-thermostat name of the entity_id is invalid. Maybe it should be climate.ds_thermostat?
Have a look at the settings of the corresponding climate card, the correct entity_id name is shown there:
Yes, I was not being very observant. The correction is working.
This is the difference between the security of experience vs the fear and frustration of ignorance. I was quick to doubt the configuration steps, from my new user POV, because of all the changes in HA up to 2026. It seems like every tip from past online posts has something that is now rejected in HA, especially where templating is concerned.
Thank you!
Great, glad you got it working! The devil is often in the details 
Have we got any idea how to get this to the right attention? just having a UI option to configure would obviously be preferred, as well as a min and max temp. Not allowing the kids to go below 18 for the floor heating would be ideal..
Still, as generic as possible would be ideal (as seen in your generic description) as setting this in customize for each room can be quite tedious and errorprone..