Parent State ID: 1
State Depth: 2
Action Taken: stack(block_a, block_d)
Action Reasoning: To move closer to the goal state where 'a' is on 'c', we should stack 'a' onto 'd', which is clear. This allows us to eventually free the hand to unstack 'd' from 'b', creating a clear path to place 'a' on 'c'.
State Description: Block 'a' is stacked on block 'd' and is clear. Block 'd' now supports block 'a' and is no longer clear. Block 'b' is still supporting block 'd'. Block 'c' remains supporting block 'b'. The hand is now empty.
Action Path: ['unstack(block_a, block_d)', 'stack(block_a, block_d)']

INACTIVE REASON: action path invalid: The last action `stack(block_a, block_d)` is valid in terms of preconditions and effects, but it does not move us closer to the goal state of having `block_a` on `block_c`. The current state's description and visualization are accurate, but the action sequence does not logically progress towards the goal.
