Stripped thread on steerer. Who is at fault - me or LBS?
Absolutely.
If they actually put anything but a French headset on a French fork, it should be 100% on them.
Hopefully they will fess up and cover the whole thing.


Just to be clear, measuring the difference between a French fork and the more common ISO/British is super easy. The OD of a French steerer is 25mm, and common 1" is 25.4. The thread pitch is also different. The parts just don't fit right together. Making this mistake and sending it out the door without noticing anything amiss is implausible.

Also, if you did have a French fork and it's being replaced with ISO, they owe you a new stem too because the quill OD/steerer ID is .2mm less on French than ISO.