trace_id string | example_id int64 | rollout_number int64 | task null | prompt list | completion list | answer null | reward float64 | score null | correct null | num_steps null | total_time float64 | latency_ms int64 | created_at string | info dict | difficulty_score int64 | pytest_reward float64 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
hosted-7 | 0 | 1 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef flatten(items):\n \"\"\"Flatten nested iterables into a flat list of elements.\"\"\"\n result = []\n for x in items:\n if isinstance(x, (str, bytes)):\n result.append(x)\n elif hasattr(x, '__iter__'):\n result.e... | null | 1 | null | null | null | 15.326358 | 15,326 | 2026-06-03T19:17:55.715324Z | {
"id": "flatten-iterable-trap",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "iteration_protocol",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original cases must still work\nassert flatten([1, [2, 3], [4, [5, 6]]]) == [1, 2, 3, 4, 5, 6]\nassert flatten([]) == []\n# S... | 4 | 1 |
hosted-8 | 0 | 2 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\nimport collections.abc\n\ndef flatten(items):\n \"\"\"Flatten nested iterables into a flat list of elements.\"\"\"\n result = []\n for x in items:\n if isinstance(x, collections.abc.Iterable) and not isinstance(x, (str, bytes)):\n re... | null | 1 | null | null | null | 15.326181 | 15,326 | 2026-06-03T19:17:55.715324Z | {
"id": "flatten-iterable-trap",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "iteration_protocol",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original cases must still work\nassert flatten([1, [2, 3], [4, [5, 6]]]) == [1, 2, 3, 4, 5, 6]\nassert flatten([]) == []\n# S... | 4 | 1 |
hosted-9 | 0 | 3 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef flatten(items):\n \"\"\"Flatten nested iterables into a flat list of elements.\"\"\"\n result = []\n for x in items:\n if isinstance(x, (str, bytes)):\n result.append(x)\n elif hasattr(x, '__iter__'):\n result.e... | null | 1 | null | null | null | 15.326015 | 15,326 | 2026-06-03T19:17:55.715324Z | {
"id": "flatten-iterable-trap",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "iteration_protocol",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original cases must still work\nassert flatten([1, [2, 3], [4, [5, 6]]]) == [1, 2, 3, 4, 5, 6]\nassert flatten([]) == []\n# S... | 4 | 1 |
hosted-4 | 1 | 1 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef find_first(arr, target):\n \"\"\"Return index of FIRST occurrence of target in sorted arr, or -1 if absent.\"\"\"\n lo, hi = 0, len(arr) - 1\n result = -1\n while lo <= hi:\n mid = (lo + hi) // 2\n if arr[mid] == target:\n ... | null | 1 | null | null | null | 5.996807 | 5,997 | 2026-06-03T19:17:48.342127Z | {
"id": "find-first-with-duplicates",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "algorithm_variant",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original cases\nassert find_first([1, 3, 5, 7, 9], 5) == 2\nassert find_first([1, 3, 5, 7, 9], 4) == -1\nassert find_firs... | 4 | 1 |
hosted-5 | 1 | 2 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef find_first(arr, target):\n \"\"\"Return index of FIRST occurrence of target in sorted arr, or -1 if absent.\"\"\"\n lo, hi = 0, len(arr) - 1\n result = -1\n while lo <= hi:\n mid = (lo + hi) // 2\n if arr[mid] == target:\n ... | null | 1 | null | null | null | 5.9967 | 5,997 | 2026-06-03T19:17:48.342127Z | {
"id": "find-first-with-duplicates",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "algorithm_variant",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original cases\nassert find_first([1, 3, 5, 7, 9], 5) == 2\nassert find_first([1, 3, 5, 7, 9], 4) == -1\nassert find_firs... | 4 | 1 |
hosted-6 | 1 | 3 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef find_first(arr, target):\n \"\"\"Return index of FIRST occurrence of target in sorted arr, or -1 if absent.\"\"\"\n lo, hi = 0, len(arr) - 1\n result = -1\n while lo <= hi:\n mid = (lo + hi) // 2\n if arr[mid] == target:\n ... | null | 1 | null | null | null | 5.996597 | 5,997 | 2026-06-03T19:17:48.342127Z | {
"id": "find-first-with-duplicates",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "algorithm_variant",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original cases\nassert find_first([1, 3, 5, 7, 9], 5) == 2\nassert find_first([1, 3, 5, 7, 9], 4) == -1\nassert find_firs... | 4 | 1 |
hosted-1 | 2 | 1 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef group_by_first_letter(words):\n \"\"\"Group words by their first letter.\"\"\"\n letters = set(w[0] for w in words if w)\n groups = {letter: [] for letter in letters}\n for w in words:\n if w:\n groups[w[0]].append(w)\n ret... | null | 1 | null | null | null | 4.869977 | 4,870 | 2026-06-03T19:17:45.060802Z | {
"id": "fromkeys-shared-list",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "mutable_aliasing",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Multiple words per group reveals the shared-list bug\nr = group_by_first_letter(['apple', 'ant', 'bat', 'ball'])\nassert r == {'... | 4 | 1 |
hosted-2 | 2 | 2 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef group_by_first_letter(words):\n \"\"\"Group words by their first letter.\"\"\"\n letters = set(w[0] for w in words if w)\n groups = {k: [] for k in letters}\n for w in words:\n if w:\n groups[w[0]].append(w)\n return groups... | null | 1 | null | null | null | 4.869836 | 4,870 | 2026-06-03T19:17:45.060802Z | {
"id": "fromkeys-shared-list",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "mutable_aliasing",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Multiple words per group reveals the shared-list bug\nr = group_by_first_letter(['apple', 'ant', 'bat', 'ball'])\nassert r == {'... | 4 | 1 |
hosted-3 | 2 | 3 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef group_by_first_letter(words):\n \"\"\"Group words by their first letter.\"\"\"\n letters = set(w[0] for w in words if w)\n groups = {letter: [] for letter in letters}\n for w in words:\n if w:\n groups[w[0]].append(w)\n ret... | null | 1 | null | null | null | 4.868134 | 4,868 | 2026-06-03T19:17:45.060802Z | {
"id": "fromkeys-shared-list",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "mutable_aliasing",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Multiple words per group reveals the shared-list bug\nr = group_by_first_letter(['apple', 'ant', 'bat', 'ball'])\nassert r == {'... | 4 | 1 |
hosted-10 | 3 | 1 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef variance(nums):\n \"\"\"Return the sample variance of nums; 0.0 for n < 2.\"\"\"\n n = len(nums)\n if n < 2:\n return 0.0\n mean = sum(nums) / n\n return sum((x - mean) ** 2 for x in nums) / (n - 1)\n```\n",
"reasoning_content": "... | null | 1 | null | null | null | 17.29032 | 17,290 | 2026-06-03T19:17:59.194987Z | {
"id": "variance-numerical-stability",
"level": 3,
"difficulty": "Adversarial",
"included": true,
"category": "numerical_stability",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original well-conditioned cases must still pass\nassert abs(variance([1, 2, 3, 4, 5]) - 2.5) < 1e-9\nassert vari... | 5 | 1 |
hosted-11 | 3 | 2 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef variance(nums):\n \"\"\"Return the sample variance of nums; 0.0 for n < 2.\"\"\"\n n = len(nums)\n if n < 2:\n return 0.0\n mean = sum(nums) / n\n return sum((x - mean) ** 2 for x in nums) / (n - 1)\n```\n",
"reasoning_content": "... | null | 1 | null | null | null | 17.29015 | 17,290 | 2026-06-03T19:17:59.194987Z | {
"id": "variance-numerical-stability",
"level": 3,
"difficulty": "Adversarial",
"included": true,
"category": "numerical_stability",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original well-conditioned cases must still pass\nassert abs(variance([1, 2, 3, 4, 5]) - 2.5) < 1e-9\nassert vari... | 5 | 1 |
hosted-12 | 3 | 3 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef variance(nums):\n \"\"\"Return the sample variance of nums; 0.0 for n < 2.\"\"\"\n n = len(nums)\n if n < 2:\n return 0.0\n mean = sum(nums) / n\n return sum((x - mean) ** 2 for x in nums) / (n - 1)\n```\n",
"reasoning_content": "... | null | 1 | null | null | null | 17.290021 | 17,290 | 2026-06-03T19:17:59.194987Z | {
"id": "variance-numerical-stability",
"level": 3,
"difficulty": "Adversarial",
"included": true,
"category": "numerical_stability",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original well-conditioned cases must still pass\nassert abs(variance([1, 2, 3, 4, 5]) - 2.5) < 1e-9\nassert vari... | 5 | 1 |
hosted-13 | 4 | 1 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef chunked(iterable, size):\n \"\"\"Yield successive lists of `size` items from iterable; final chunk may be smaller.\"\"\"\n if not isinstance(size, int) or size <= 0:\n raise ValueError(\"size must be a positive integer\")\n \n chunk = []... | null | 1 | null | null | null | 27.328798 | 27,329 | 2026-06-03T19:18:07.209516Z | {
"id": "chunked-eager-materialization",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "lazy_iteration",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original cases\nassert list(chunked([1, 2, 3, 4, 5], 2)) == [[1, 2], [3, 4], [5]]\nassert list(chunked([], 3)) == []\n# S... | 4 | 1 |
hosted-14 | 4 | 2 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef chunked(iterable, size):\n \"\"\"Yield successive lists of `size` items from iterable; final chunk may be smaller.\"\"\"\n if not isinstance(size, int) or size <= 0:\n raise ValueError(\"size must be a positive integer\")\n items = list(ite... | null | 0 | null | null | null | 27.32872 | 27,329 | 2026-06-03T19:18:07.209516Z | {
"id": "chunked-eager-materialization",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "lazy_iteration",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original cases\nassert list(chunked([1, 2, 3, 4, 5], 2)) == [[1, 2], [3, 4], [5]]\nassert list(chunked([], 3)) == []\n# S... | 4 | 0 |
hosted-15 | 4 | 3 | null | [
{
"role": "system",
"content": "You are a Python expert and bug fixer. When shown a buggy Python function or class and a SAMPLE of tests it must pass, identify the underlying bug — which may involve API misuse, numerical stability, lifecycle or resource management, comparator semantics, lazy vs eager iterat... | [
{
"role": "assistant",
"content": "\n```python\ndef chunked(iterable, size):\n \"\"\"Yield successive lists of `size` items from iterable; final chunk may be smaller.\"\"\"\n if size <= 0:\n raise ValueError(\"size must be a positive integer\")\n items = list(iterable)\n for i in range(0,... | null | 0 | null | null | null | 27.328643 | 27,329 | 2026-06-03T19:18:07.209516Z | {
"id": "chunked-eager-materialization",
"level": 3,
"difficulty": "Subtle",
"included": true,
"category": "lazy_iteration",
"task_bank_version": "v5-asymmetric-tests",
"test_code": "# Original cases\nassert list(chunked([1, 2, 3, 4, 5], 2)) == [[1, 2], [3, 4], [5]]\nassert list(chunked([], 3)) == []\n# S... | 4 | 0 |
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