Door light relay wiring

Hi All, New to the forum. Although I have used it many times for help on various projects. I am currently looking to use a negative ground actuated door wire to activate a relay to then turn on some under dash LEDs. I think I have gotten the wiring of the relay for the most part. Basically when the door opens, the negative ground trigger wire to 85 activates the relay and lights up the LEDs connected to 87. My question is, and where I am stumped, is where would I place a diode to prevent any kickback when the relay deactivates from flowing back through the door trigger? Would it still be across the coil at 85 and 86? Would it go elsewhere since the 12v is on 86 and 30? Thanks so much.