Chess960: two move ideas no.13

Lucky 13 in the two move ideas series features a classic development pattern for a queen in the corner when a queen on h3 is safe from attack:

SP465 black to move: try to see white's ideas

Enjoy 960

Hint: b4 reserves a square for Nb3 or Bb3
White develops the queen to h3 intending g4 at some stage
and the queen attacks d7 and can move laterally on the 3rd rank