Parent State ID: 20
State Depth: 7
Action Taken: stack(d, b)
Action Reasoning: The goal state requires block `d` on top of block `b`. Since block `d` is clear and on the table, the best action is to stack block `d` on block `b`, as they meet all preconditions.
State Description: Block `a` is on the table and clear. Block `b` is on the table and supports block `d`. Block `c` is on block `b` and is clear. Block `d` is on block `b` and is clear. The hand is empty.
Action Path: ['unstack(d, a)', 'put-down(d)', 'unstack(a, c)', 'put-down(a)', 'pick-up(d)', 'put-down(d)', 'stack(d, b)']

INACTIVE REASON: deactivated because diagram generation failed or invalid action chosen: Preconditions for "stack(d, b)" are not met; block `b` is not clear, and the hand is not holding block `d`.
