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The dataset viewer is not available for this split.
Cannot load the dataset split (in streaming mode) to extract the first rows.
Error code:   StreamingRowsError
Exception:    TypeError
Message:      Couldn't cast array of type list<item: int64> to null
Traceback:    Traceback (most recent call last):
                File "/src/services/worker/src/worker/utils.py", line 147, in get_rows_or_raise
                  return get_rows(
                      dataset=dataset,
                  ...<4 lines>...
                      column_names=column_names,
                  )
                File "/src/libs/libcommon/src/libcommon/utils.py", line 272, in decorator
                  return func(*args, **kwargs)
                File "/src/services/worker/src/worker/utils.py", line 127, in get_rows
                  rows_plus_one = list(itertools.islice(safe_iter(ds, dataset=dataset), rows_max_number + 1))
                File "/src/services/worker/src/worker/utils.py", line 483, in safe_iter
                  yield from ds.decode(False) if ds.features else ds
                File "/usr/local/lib/python3.14/site-packages/datasets/iterable_dataset.py", line 2840, in __iter__
                  for key, example in ex_iterable:
                                      ^^^^^^^^^^^
                File "/usr/local/lib/python3.14/site-packages/datasets/iterable_dataset.py", line 2373, in __iter__
                  for key, pa_table in self._iter_arrow():
                                       ~~~~~~~~~~~~~~~~^^
                File "/usr/local/lib/python3.14/site-packages/datasets/iterable_dataset.py", line 2398, in _iter_arrow
                  for key, pa_table in self.ex_iterable._iter_arrow():
                                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
                File "/usr/local/lib/python3.14/site-packages/datasets/iterable_dataset.py", line 536, in _iter_arrow
                  for key, pa_table in iterator:
                                       ^^^^^^^^
                File "/usr/local/lib/python3.14/site-packages/datasets/iterable_dataset.py", line 419, in _iter_arrow
                  for key, pa_table in self.generate_tables_fn(**gen_kwags):
                                       ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
                File "/usr/local/lib/python3.14/site-packages/datasets/packaged_modules/json/json.py", line 343, in _generate_tables
                  self._cast_table(pa_table, json_field_paths=json_field_paths),
                  ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                File "/usr/local/lib/python3.14/site-packages/datasets/packaged_modules/json/json.py", line 132, in _cast_table
                  pa_table = table_cast(pa_table, self.info.features.arrow_schema)
                File "/usr/local/lib/python3.14/site-packages/datasets/table.py", line 2378, in table_cast
                  return cast_table_to_schema(table, schema)
                File "/usr/local/lib/python3.14/site-packages/datasets/table.py", line 2312, in cast_table_to_schema
                  cast_array_to_feature(
                  ~~~~~~~~~~~~~~~~~~~~~^
                      table[name] if name in table_column_names else pa.array([None] * len(table), type=schema.field(name).type),
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                      feature,
                      ^^^^^^^^
                  )
                  ^
                File "/usr/local/lib/python3.14/site-packages/datasets/table.py", line 1861, in wrapper
                  return pa.chunked_array([func(chunk, *args, **kwargs) for chunk in array.chunks])
                                           ~~~~^^^^^^^^^^^^^^^^^^^^^^^^
                File "/usr/local/lib/python3.14/site-packages/datasets/table.py", line 2068, in cast_array_to_feature
                  _c(array.field(name) if name in array_fields else null_array, subfeature)
                  ~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                File "/usr/local/lib/python3.14/site-packages/datasets/table.py", line 1863, in wrapper
                  return func(array, *args, **kwargs)
                File "/usr/local/lib/python3.14/site-packages/datasets/table.py", line 2152, in cast_array_to_feature
                  return array_cast(
                      array,
                  ...<2 lines>...
                      allow_decimal_to_str=allow_decimal_to_str,
                  )
                File "/usr/local/lib/python3.14/site-packages/datasets/table.py", line 1863, in wrapper
                  return func(array, *args, **kwargs)
                File "/usr/local/lib/python3.14/site-packages/datasets/table.py", line 2016, in array_cast
                  raise TypeError(f"Couldn't cast array of type {_short_str(array.type)} to {_short_str(pa_type)}")
              TypeError: Couldn't cast array of type list<item: int64> to null

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Widget2Code Bench Data v2

Evaluation targets for Widget2Code, rebuilt so that the picture a person reviews is the picture a model is trained on and scored against.

directory samples contents
train-v2/ 1,822 training screenshots and canonical metadata
test-v2/ 1,000 evaluation screenshots and canonical metadata
train-v2/image_0004/
test-v2/image_0001/
├── image.png        # RGB, no alpha channel
└── metadata.json

Why v2 exists

Every target in Widget2Code Data V4.1 is RGBA, and its readers disagreed about what that meant. PIL.Image.convert("RGB") — used by the benchmark, by the training image loader, by the vLLM inference path and by the conversation's own image pipeline — drops the alpha channel and keeps whatever RGB is stored underneath. A browser composites instead. So a person reviewing a target saw one picture while the model was trained and scored on another.

Usually the disagreement was a few antialiased corner pixels. In 61 targets the capture had left a whole neighbouring widget under the mask, and the model was scored on reproducing content no design contains. On those, the reference render — the best answer the source pool has — scored SSIM 0.5532 against the stored target and 0.6990 against the flattened one, against a pool mean of 0.7664.

Every target here is RGB with no alpha, so the three readers now see the same pixels.

What changed from V4.1 train/ and test/

127 of 2,822 targets differ visibly; the rest differ only where antialiased edge pixels were composited.

change targets
hidden content covered by the flat background 61
cropped to the bounding box of non-transparent pixels 108
both 42

The background is white because it was measured, not assumed: on the affected samples the reference render scores 0.7163 against a white-flattened target, 0.6161 against the stored one and 0.5557 against a black-flattened one.

A transparent margin is what the capture left around the widget, not part of the design, so it is cropped away. An opaque white margin is kept — a pixel the capture recorded as opaque is part of the design. 140 targets therefore still carry a white border.

metadata.json

{
  "id": "image_2052",
  "split": "test-v2",
  "sha256": "...",              // of this image.png
  "category": "tools",          // null when not labelled
  "has_chart": null,
  "side_info": {                // prompt-ready, derived from these pixels
    "dims": [243, 293],
    "ocr": "- `\"Hello, Hayat\"` at (19.8%, 8.5%) of widget, font-height ≈ 12.3% ...",
    "palette": "Target widget palette (top-4, after AA-fringe consolidation): ..."
  },
  "flattened_from": {
    "split": "test",
    "original_sha256": "...",
    "stored_size": [434, 444],
    "crop_box": [95, 76, 338, 369],   // null when nothing was cropped
    "transparent_fraction": 0.651254,
    "hidden_colours": 1171,           // distinct RGB values under the mask
    "background": [255, 255, 255]
  }
}

side_info was regenerated from the new pixels with the benchmark 1.2.0 CPU container, the same generator that produced the V4.1 metadata — verified by reproducing V4.1's own side_info byte for byte on all 1,822 of its train targets. CPU output is canonical; GPU OCR follows a different numeric path.

The eval ground-truth feature cache carried by V4.1 is not included: it describes pixels that changed. A benchmark that misses it recomputes those features, which is correct and slower.

Pairing with reference sources

The sft-v4 reference pool in Widget2Code-Data-V4 hard-codes each target's stored canvas in its root width/height, so 108 of those sources no longer match these targets. Regenerate the references against train-v2/test-v2 rather than pairing the two directly.

Download

from huggingface_hub import snapshot_download

snapshot_download(
    repo_id="Djanghao/Widget2Code-Bench-Data",
    repo_type="dataset",
    local_dir="Widget2Code-Bench-Data",
)
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