Parent State ID: 11
State Depth: 6
Action Taken: stack(d, b)
Action Reasoning: The hand is holding block `d`, and according to the goal state, block `d` should be on top of block `b`. Block `b` is clear (since `c` is on top of it, but this action conveniently places `d`), so the correct next step is to stack `d` onto `b`.
State Description: Block `a` is on the table and clear. Block `b` is on the table supporting block `d` and is no longer clear. Block `c` is on the table and clear. Block `d` is on block `b` and clear. The hand is empty.
Action Path: ['unstack(d, a)', 'put-down(d)', 'unstack(a, c)', 'put-down(a)', 'pick-up(d)', 'stack(d, b)']

INACTIVE REASON: deactivated because diagram generation failed or invalid action chosen: Block `b` is not clear, violating the precondition for stacking.
