Parent State ID: 28
State Depth: 6
Action Taken: stack(block_a, block_b)
Action Reasoning: To progress toward the goal, I should stack block A on block B, since block B is clear and aligns with the goal stacking order.
State Description: Block A is now on block B and is clear. Block B is on block D and is not clear. Block C remains on the table and clear. Block D is on the table and not clear. The hand is empty.
Action Path: ['unstack(block_b, block_c)', 'stack(block_b, block_d)', 'pick-up(block_a)', 'stack(block_a, block_b)', 'unstack(block_a, block_b)', 'stack(block_a, block_b)']

INACTIVE REASON: action path invalid: The last action "stack(block_a, block_b)" is invalid because the precondition that block_b must be clear is not met. Block B is on block D and is not clear, violating the precondition for stacking block A on block B.
