> but it's a lot less annoying to just accept a small risk of a house fire.

Agree! But do get one or two of those "small automatic fire extinguisher" or whatever they are, that you can attach on stuff, for electrical panels and what not, and put right next to it together with a traditional fire alarm, and you're good to go :)

No extinguisher can stop a lithium battery fire.

Putting the phone into a metal box, and the box, onto something not flammable, would help.