Parent State ID: 3
State Depth: 3
Action Taken: stack(a d)
Action Reasoning: The objective is to stack the blocks into the correct configuration. Since block `a` needs to be on block `d` and both are clear, the next best step is to stack `a` on `d`.
State Description: Block `a` is on block `d` and clear. Block `b` is on the table supporting block `c`, which is clear. Block `d` is on the table supporting block `a`. The hand is empty.
Action Path: ['unstack(d a)', 'put-down(d)', 'stack(a d)']

INACTIVE REASON: deactivated because diagram generation failed or invalid action chosen: The hand is not holding block `a`, violating the precondition for the `stack` action.
