# t000__ep034__blocks

- **suite / variant:** `` / ``
- **instruction:** Stack the yellow block on the wooden block
- **success:** False
- **control steps:** 930  (18.5s at 50 Hz)
- **policy inferences:** 160  (replan_steps=6)
- **video:** `blocks/ep034/rollout.mp4`
- **features:** `160` prefix tensors (`prefix`; model=``)

## Semantic timeline

| seconds | control_step | policy_step | phrase |
|---|---|---|---|
| 0.0–3.0 | 0–150 | 0–25 | reaching for and grasping yellow block |
| 3.0–6.0 | 151–301 | 25–50 | lifting yellow block; misplacing on table |
| 6.0–9.0 | 302–452 | 50–75 | releasing block; hovering low near table |
| 9.0–12.0 | 453–603 | 75–100 | hovering near misplaced block; idle |
| 12.0–15.0 | 604–754 | 100–125 | holding position near table; idle |
| 15.0–18.0 | 755–905 | 125–150 | remaining stationary near block |
| 18.0–18.5 | 906–929 | 151–154 | remaining stationary at rollout end |

## Failure

- **yes**
- **onset type:** obvious_mistake
- **onset:** 5.09920634920635 s (00:05.1)
- **frame / control_step:** 257 (policy_step=42, chunk_index=5)
- **coarse onset:** 6.0 s (refined=True)
- **mode:** placement_or_insertion_failure
- **reason:** The robot successfully picked up the yellow block and brought it toward the wooden block, but misplaced it off the edge of the wooden block onto the table instead of stacking it directly on top.
  Summary: misaligned placement; yellow block placed on table beside wooden block
- **recovery:** Re-grasp the yellow block from the table surface, lift it above the wooden block, align it over the top center of the wooden block, and release.
  Summary: re-grasp yellow block; center and stack on wooden block
- **prevention:** Maintain sufficient clearance height above the wooden block during approach and align the yellow block centered over the top surface before releasing.
  Summary: maintain clearance; center yellow block over wooden block before release
- **justification:** Around 6.0 seconds (frame 00:06), the robot lowers the yellow block, but misses the top surface of the wooden block and places it onto the table adjacent to it. The yellow block remains on the table for the rest of the rollout, failing the stacking goal.