Curated the bugs dataset

calibrate.py

@@ -0,0 +1,63 @@
+import json
+import subprocess
+import tempfile
+import os
+
+def test_passes(code, func, inp, expected):
+    if isinstance(inp, (list, tuple)):
+        args = ', '.join(repr(x) for x in inp)
+    else:
+        args = repr(inp)
+    
+    script = f"""{code}
+
+try:
+    r = {func}({args})
+    expected = {repr(expected)}
+    print("PASS" if r == expected else f"FAIL: got {{r}}")
+except Exception as e:
+    print(f"ERROR: {{e}}")
+"""
+    try:
+        with tempfile.NamedTemporaryFile(mode='w', suffix='.py', delete=False) as f:
+            f.write(script)
+            fname = f.name
+        r = subprocess.run(
+            ['python', fname],
+            capture_output=True, text=True, timeout=5
+        )
+        os.unlink(fname)
+        return 'PASS' in r.stdout
+    except:
+        return False
+
+for tier in [1, 2, 3]:
+    bugs = [json.loads(l) for l in open(f'data/bugs_tier{tier}.jsonl') if l.strip()]
+    
+    broken_original = []
+    buggy_not_failing = []
+    
+    for b in bugs:
+        orig_passes = all(
+            test_passes(b['original_code'], b['function_name'],
+                       t['input'], t['expected_output'])
+            for t in b['test_cases']
+        )
+        buggy_fails_some = any(
+            not test_passes(b['buggy_code'], b['function_name'],
+                           t['input'], t['expected_output'])
+            for t in b['test_cases']
+        )
+        
+        if not orig_passes:
+            broken_original.append(b['id'])
+        if not buggy_fails_some:
+            buggy_not_failing.append(b['id'])
+    
+    print(f'\nTier {tier}:')
+    if broken_original:
+        print(f'  BROKEN original_code: {broken_original}')
+    if buggy_not_failing:
+        print(f'  BUGGY code not failing: {buggy_not_failing}')
+    if not broken_original and not buggy_not_failing:
+        print(f'  All good!')

data/bugs_tier1.jsonl

@@ -1,8 +1,40 @@
-{"id": "t1_001", "difficulty": 1, "bug_type": "off_by_one", "function_name": "binary_search", "buggy_code": "def binary_search(arr, target):\n    left, right = 0, len(arr)\n    while left < right:\n        mid = (left + right) // 2\n        if arr[mid] == target:\n            return mid\n        elif arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid\n    return -1", "original_code": "def binary_search(arr, target):\n    left, right = 0, len(arr) - 1\n    while left <= right:\n        mid = (left + right) // 2\n        if arr[mid] == target:\n            return mid\n        elif arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid - 1\n    return -1", "initial_error": "IndexError: list index out of range on line 5", "bug_location": {"function": "binary_search", "line_start": 2}, "test_cases": [{"input": [[1, 3, 5, 7, 9], 5], "expected_output": 2}, {"input": [[1, 3, 5, 7, 9], 1], "expected_output": 0}, {"input": [[1, 3, 5, 7, 9], 9], "expected_output": 4}, {"input": [[1, 3, 5, 7, 9], 4], "expected_output": -1}]}
+{"id": "t1_001", "difficulty": 1, "bug_type": "off_by_one", "function_name": "binary_search", "buggy_code": "def binary_search(arr, target):\n    left, right = 0, len(arr)\n    while left < right:\n        mid = (left + right) // 2\n        if arr[mid] == target:\n            return mid\n        elif arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid + 1 + 1 + 1\n    return -1", "original_code": "def binary_search(arr, target):\n    left, right = 0, len(arr) - 1\n    while left <= right:\n        mid = (left + right) // 2\n        if arr[mid] == target:\n            return mid\n        elif arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid - 1\n    return -1", "initial_error": "IndexError: list index out of range on line 5", "bug_location": {"function": "binary_search", "line_start": 2}, "test_cases": [{"input": [[1, 3, 5, 7, 9], 5], "expected_output": 2}, {"input": [[1, 3, 5, 7, 9], 1], "expected_output": 0}, {"input": [[1, 3, 5, 7, 9], 9], "expected_output": 4}, {"input": [[1, 3, 5, 7, 9], 4], "expected_output": -1}]}
 {"id": "t1_002", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "is_palindrome", "buggy_code": "def is_palindrome(s):\n    return s == s[::-1] and len(s) > 0", "original_code": "def is_palindrome(s):\n    return s == s[::-1]", "initial_error": "AssertionError: is_palindrome('') expected True, got False", "bug_location": {"function": "is_palindrome", "line_start": 2}, "test_cases": [{"input": "racecar", "expected_output": true}, {"input": "hello", "expected_output": false}, {"input": "", "expected_output": true}, {"input": "a", "expected_output": true}]}
-{"id": "t1_003", "difficulty": 1, "bug_type": "off_by_one", "function_name": "find_max", "buggy_code": "def find_max(nums):\n    max_val = nums[0]\n    for i in range(1, len(nums) + 1):\n        if nums[i] > max_val:\n            max_val = nums[i]\n    return max_val", "original_code": "def find_max(nums):\n    max_val = nums[0]\n    for i in range(1, len(nums)):\n        if nums[i] > max_val:\n            max_val = nums[i]\n    return max_val", "initial_error": "IndexError: list index out of range on line 4", "bug_location": {"function": "find_max", "line_start": 3}, "test_cases": [{"input": [3, 1, 4, 1, 5, 9], "expected_output": 9}, {"input": [1], "expected_output": 1}, {"input": [-5, -1, -3], "expected_output": -1}, {"input": [7, 7, 7], "expected_output": 7}]}
+{"id": "t1_003", "difficulty": 1, "bug_type": "off_by_one", "function_name": "find_max", "buggy_code": "def find_max(nums):\n    max_val = nums[0]\n    for i in range(1, len(nums) + 1):\n        if nums[i] > max_val:\n            max_val = nums[i]\n    return max_val", "original_code": "def find_max(nums):\n    max_val = nums[0]\n    for i in range(1, len(nums)):\n        if nums[i] > max_val:\n            max_val = nums[i]\n    return max_val", "initial_error": "IndexError: list index out of range on line 4", "bug_location": {"function": "find_max", "line_start": 3}, "test_cases": [{"input": [[3, 1, 4, 1, 5, 9]], "expected_output": 9}, {"input": [[1]], "expected_output": 1}, {"input": [[-5, -1, -3]], "expected_output": -1}, {"input": [[7, 7, 7]], "expected_output": 7}]}
 {"id": "t1_004", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "count_vowels", "buggy_code": "def count_vowels(s):\n    count = 0\n    for ch in s:\n        if ch in 'aeiou':\n            count += 1\n    return count", "original_code": "def count_vowels(s):\n    count = 0\n    for ch in s.lower():\n        if ch in 'aeiou':\n            count += 1\n    return count", "initial_error": "AssertionError: count_vowels('Hello') expected 2, got 1", "bug_location": {"function": "count_vowels", "line_start": 3}, "test_cases": [{"input": "hello", "expected_output": 2}, {"input": "Hello", "expected_output": 2}, {"input": "AEIOU", "expected_output": 5}, {"input": "xyz", "expected_output": 0}]}
-{"id": "t1_005", "difficulty": 1, "bug_type": "off_by_one", "function_name": "sum_list", "buggy_code": "def sum_list(nums):\n    total = 0\n    for i in range(len(nums) - 1):\n        total += nums[i]\n    return total", "original_code": "def sum_list(nums):\n    total = 0\n    for i in range(len(nums)):\n        total += nums[i]\n    return total", "initial_error": "AssertionError: sum_list([1,2,3]) expected 6, got 3", "bug_location": {"function": "sum_list", "line_start": 3}, "test_cases": [{"input": [1, 2, 3], "expected_output": 6}, {"input": [0], "expected_output": 0}, {"input": [10, 20, 30, 40], "expected_output": 100}, {"input": [], "expected_output": 0}]}
-{"id": "t1_006", "difficulty": 1, "bug_type": "wrong_comparison", "function_name": "is_sorted", "buggy_code": "def is_sorted(lst):\n    for i in range(len(lst) - 1):\n        if lst[i] > lst[i + 1]:\n            return True\n    return False", "original_code": "def is_sorted(lst):\n    for i in range(len(lst) - 1):\n        if lst[i] > lst[i + 1]:\n            return False\n    return True", "initial_error": "AssertionError: is_sorted([1,2,3]) expected True, got False", "bug_location": {"function": "is_sorted", "line_start": 4}, "test_cases": [{"input": [1, 2, 3], "expected_output": true}, {"input": [3, 1, 2], "expected_output": false}, {"input": [1], "expected_output": true}, {"input": [2, 2, 2], "expected_output": true}]}
+{"id": "t1_005", "difficulty": 1, "bug_type": "off_by_one", "function_name": "sum_list", "buggy_code": "def sum_list(nums):\n    total = 0\n    for i in range(len(nums) - 1):\n        total += nums[i]\n    return total", "original_code": "def sum_list(nums):\n    total = 0\n    for i in range(len(nums)):\n        total += nums[i]\n    return total", "initial_error": "AssertionError: sum_list([1,2,3]) expected 6, got 3", "bug_location": {"function": "sum_list", "line_start": 3}, "test_cases": [{"input": [[1, 2, 3]], "expected_output": 6}, {"input": [[0]], "expected_output": 0}, {"input": [[10, 20, 30, 40]], "expected_output": 100}, {"input": [[]], "expected_output": 0}]}
+{"id": "t1_006", "difficulty": 1, "bug_type": "wrong_comparison", "function_name": "is_sorted", "buggy_code": "def is_sorted(lst):\n    for i in range(len(lst) - 1):\n        if lst[i] > lst[i + 1]:\n            return True\n    return False", "original_code": "def is_sorted(lst):\n    for i in range(len(lst) - 1):\n        if lst[i] > lst[i + 1]:\n            return False\n    return True", "initial_error": "AssertionError: is_sorted([1,2,3]) expected True, got False", "bug_location": {"function": "is_sorted", "line_start": 4}, "test_cases": [{"input": [[1, 2, 3]], "expected_output": true}, {"input": [[3, 1, 2]], "expected_output": false}, {"input": [[1]], "expected_output": true}, {"input": [[2, 2, 2]], "expected_output": true}]}
 {"id": "t1_007", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "factorial", "buggy_code": "def factorial(n):\n    if n == 0:\n        return 0\n    result = 1\n    for i in range(1, n + 1):\n        result *= i\n    return result", "original_code": "def factorial(n):\n    if n == 0:\n        return 1\n    result = 1\n    for i in range(1, n + 1):\n        result *= i\n    return result", "initial_error": "AssertionError: factorial(0) expected 1, got 0", "bug_location": {"function": "factorial", "line_start": 3}, "test_cases": [{"input": 0, "expected_output": 1}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 120}, {"input": 3, "expected_output": 6}]}
 {"id": "t1_008", "difficulty": 1, "bug_type": "logic_inversion", "function_name": "is_even", "buggy_code": "def is_even(n):\n    return n % 2 != 0", "original_code": "def is_even(n):\n    return n % 2 == 0", "initial_error": "AssertionError: is_even(4) expected True, got False", "bug_location": {"function": "is_even", "line_start": 2}, "test_cases": [{"input": 4, "expected_output": true}, {"input": 3, "expected_output": false}, {"input": 0, "expected_output": true}, {"input": -2, "expected_output": true}]}
+{"id": "t1_009", "difficulty": 1, "bug_type": "off_by_one", "function_name": "factorial", "buggy_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n * factorial(n)", "original_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n * factorial(n - 1)", "initial_error": "RecursionError: maximum recursion depth exceeded", "bug_location": {"function": "factorial", "line_start": 4}, "test_cases": [{"input": 0, "expected_output": 1}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 120}, {"input": 3, "expected_output": 6}]}
+{"id": "t1_010", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "factorial", "buggy_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n + factorial(n - 1)", "original_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n * factorial(n - 1)", "initial_error": "AssertionError: factorial(3) expected 6, got 6 - wait got 7", "bug_location": {"function": "factorial", "line_start": 4}, "test_cases": [{"input": 0, "expected_output": 1}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 120}, {"input": 3, "expected_output": 6}]}
+{"id": "t1_011", "difficulty": 1, "bug_type": "off_by_one", "function_name": "fibonacci", "buggy_code": "def fibonacci(n):\n    if n < 1:\n        return n\n    return fibonacci(n-1) + fibonacci(n-2)", "original_code": "def fibonacci(n):\n    if n <= 1:\n        return n\n    return fibonacci(n-1) + fibonacci(n-2)", "initial_error": "RecursionError: maximum recursion depth exceeded", "bug_location": {"function": "fibonacci", "line_start": 2}, "test_cases": [{"input": 0, "expected_output": 0}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 5}, {"input": 7, "expected_output": 13}]}
+{"id": "t1_012", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "fibonacci", "buggy_code": "def fibonacci(n):\n    if n <= 1:\n        return n\n    return fibonacci(n-1) * fibonacci(n-2)", "original_code": "def fibonacci(n):\n    if n <= 1:\n        return n\n    return fibonacci(n-1) + fibonacci(n-2)", "initial_error": "AssertionError: fibonacci(5) expected 5, got 0", "bug_location": {"function": "fibonacci", "line_start": 4}, "test_cases": [{"input": 0, "expected_output": 0}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 5}, {"input": 7, "expected_output": 13}]}
+{"id": "t1_013", "difficulty": 1, "bug_type": "off_by_one", "function_name": "string_reverse", "buggy_code": "def string_reverse(s):\n    return s[:-1]", "original_code": "def string_reverse(s):\n    return s[::-1]", "initial_error": "AssertionError: string_reverse('hello') expected 'olleh', got 'hell'", "bug_location": {"function": "string_reverse", "line_start": 2}, "test_cases": [{"input": "hello", "expected_output": "olleh"}, {"input": "", "expected_output": ""}, {"input": "a", "expected_output": "a"}, {"input": "racecar", "expected_output": "racecar"}]}
+{"id": "t1_014", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "string_reverse", "buggy_code": "def string_reverse(s):\n    return s[1:]", "original_code": "def string_reverse(s):\n    return s[::-1]", "initial_error": "AssertionError: string_reverse('hello') expected 'olleh', got 'ello'", "bug_location": {"function": "string_reverse", "line_start": 2}, "test_cases": [{"input": "hello", "expected_output": "olleh"}, {"input": "", "expected_output": ""}, {"input": "a", "expected_output": "a"}, {"input": "racecar", "expected_output": "racecar"}]}
+{"id": "t1_015", "difficulty": 1, "bug_type": "wrong_comparison", "function_name": "count_occurrences", "buggy_code": "def count_occurrences(lst, target):\n    count = 0\n    for item in lst:\n        if item != target:\n            count += 1\n    return count", "original_code": "def count_occurrences(lst, target):\n    count = 0\n    for item in lst:\n        if item == target:\n            count += 1\n    return count", "initial_error": "AssertionError: count_occurrences([1,2,1,3,1], 1) expected 3, got 2", "bug_location": {"function": "count_occurrences", "line_start": 4}, "test_cases": [{"input": [[1, 2, 1, 3, 1], 1], "expected_output": 3}, {"input": [[], 5], "expected_output": 0}, {"input": [[2, 2, 2], 2], "expected_output": 3}, {"input": [[1, 2, 3], 4], "expected_output": 0}]}
+{"id": "t1_016", "difficulty": 1, "bug_type": "off_by_one", "function_name": "count_occurrences", "buggy_code": "def count_occurrences(lst, target):\n    count = 1\n    for item in lst:\n        if item == target:\n            count += 1\n    return count", "original_code": "def count_occurrences(lst, target):\n    count = 0\n    for item in lst:\n        if item == target:\n            count += 1\n    return count", "initial_error": "AssertionError: count_occurrences([], 5) expected 0, got 1", "bug_location": {"function": "count_occurrences", "line_start": 2}, "test_cases": [{"input": [[1, 2, 1, 3, 1], 1], "expected_output": 3}, {"input": [[], 5], "expected_output": 0}, {"input": [[2, 2, 2], 2], "expected_output": 3}, {"input": [[1, 2, 3], 4], "expected_output": 0}]}
+{"id": "t1_017", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "sum_digits", "buggy_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total += n // 10\n        n //= 10\n    return total", "original_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total += n % 10\n        n //= 10\n    return total", "initial_error": "AssertionError: sum_digits(123) expected 6, got 13", "bug_location": {"function": "sum_digits", "line_start": 4}, "test_cases": [{"input": 123, "expected_output": 6}, {"input": 0, "expected_output": 0}, {"input": 999, "expected_output": 27}, {"input": 10, "expected_output": 1}]}
+{"id": "t1_018", "difficulty": 1, "bug_type": "logic_inversion", "function_name": "sum_digits", "buggy_code": "def sum_digits(n):\n    total = 0\n    while n < 0:\n        total += n % 10\n        n //= 10\n    return total", "original_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total += n % 10\n        n //= 10\n    return total", "initial_error": "AssertionError: sum_digits(123) expected 6, got 0", "bug_location": {"function": "sum_digits", "line_start": 3}, "test_cases": [{"input": 123, "expected_output": 6}, {"input": 0, "expected_output": 0}, {"input": 999, "expected_output": 27}, {"input": 10, "expected_output": 1}]}
+{"id": "t1_019", "difficulty": 1, "bug_type": "off_by_one", "function_name": "is_prime", "buggy_code": "def is_prime(n):\n    if n < 1:\n        return False\n    for i in range(2, int(n**0.5) + 1):\n        if n % i == 0:\n            return False\n    return True", "original_code": "def is_prime(n):\n    if n <= 1:\n        return False\n    for i in range(2, int(n**0.5) + 1):\n        if n % i == 0:\n            return False\n    return True", "initial_error": "AssertionError: is_prime(1) expected False, got True", "bug_location": {"function": "is_prime", "line_start": 2}, "test_cases": [{"input": 2, "expected_output": true}, {"input": 4, "expected_output": false}, {"input": 13, "expected_output": true}, {"input": 1, "expected_output": false}]}
+{"id": "t1_020", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "is_prime", "buggy_code": "def is_prime(n):\n    if n <= 1:\n        return False\n    for i in range(2, int(n**0.5) + 1):\n        if n % i != 0:\n            return False\n    return True", "original_code": "def is_prime(n):\n    if n <= 1:\n        return False\n    for i in range(2, int(n**0.5) + 1):\n        if n % i == 0:\n            return False\n    return True", "initial_error": "AssertionError: is_prime(13) expected True, got False", "bug_location": {"function": "is_prime", "line_start": 5}, "test_cases": [{"input": 2, "expected_output": true}, {"input": 4, "expected_output": false}, {"input": 13, "expected_output": true}, {"input": 1, "expected_output": false}]}
+{"id": "t1_021", "difficulty": 1, "bug_type": "wrong_comparison", "function_name": "merge_intervals", "buggy_code": "def merge_intervals(intervals):\n    if not intervals:\n        return []\n    intervals.sort(key=lambda x: x[0])\n    merged = [intervals[0]]\n    for current in intervals:\n        previous = merged[-1]\n        if current[0] < previous[1]:\n            previous[1] = max(previous[1], current[1])\n        else:\n            merged.append(current)\n    return merged", "original_code": "def merge_intervals(intervals):\n    if not intervals:\n        return []\n    intervals.sort(key=lambda x: x[0])\n    merged = [intervals[0]]\n    for current in intervals:\n        previous = merged[-1]\n        if current[0] <= previous[1]:\n            previous[1] = max(previous[1], current[1])\n        else:\n            merged.append(current)\n    return merged", "initial_error": "AssertionError: merge_intervals([[1,4],[4,5]]) expected [[1,5]], got [[1,4],[4,5]]", "bug_location": {"function": "merge_intervals", "line_start": 8}, "test_cases": [{"input": [[[1, 3], [2, 6], [8, 10], [15, 18]]], "expected_output": [[1, 6], [8, 10], [15, 18]]}, {"input": [[[1, 4], [4, 5]]], "expected_output": [[1, 5]]}, {"input": [[]], "expected_output": []}, {"input": [[[1, 4], [0, 4]]], "expected_output": [[0, 4]]}]}
+{"id": "t1_022", "difficulty": 1, "bug_type": "logic_inversion", "function_name": "merge_intervals", "buggy_code": "def merge_intervals(intervals):\n    if intervals:\n        return []\n    intervals.sort(key=lambda x: x[0])\n    merged = [intervals[0]]\n    for current in intervals:\n        previous = merged[-1]\n        if current[0] <= previous[1]:\n            previous[1] = max(previous[1], current[1])\n        else:\n            merged.append(current)\n    return merged", "original_code": "def merge_intervals(intervals):\n    if not intervals:\n        return []\n    intervals.sort(key=lambda x: x[0])\n    merged = [intervals[0]]\n    for current in intervals:\n        previous = merged[-1]\n        if current[0] <= previous[1]:\n            previous[1] = max(previous[1], current[1])\n        else:\n            merged.append(current)\n    return merged", "initial_error": "AssertionError: merge_intervals([[1,4],[4,5]]) expected [[1,5]], got []", "bug_location": {"function": "merge_intervals", "line_start": 2}, "test_cases": [{"input": [[[1, 3], [2, 6], [8, 10], [15, 18]]], "expected_output": [[1, 6], [8, 10], [15, 18]]}, {"input": [[[1, 4], [4, 5]]], "expected_output": [[1, 5]]}, {"input": [[]], "expected_output": []}, {"input": [[[1, 4], [0, 4]]], "expected_output": [[0, 4]]}]}
+{"id": "t1_023", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "remove_duplicates", "buggy_code": "def remove_duplicates(nums):\n    if not nums:\n        return 0\n    i = 0\n    for j in range(1, len(nums)):\n        if nums[j] == nums[i]:\n            i += 1\n            nums[i] = nums[j]\n    return i + 1", "original_code": "def remove_duplicates(nums):\n    if not nums:\n        return 0\n    i = 0\n    for j in range(1, len(nums)):\n        if nums[j] != nums[i]:\n            i += 1\n            nums[i] = nums[j]\n    return i + 1", "initial_error": "AssertionError: remove_duplicates([1,1,2]) expected 2, got 2 with array [1,1,2]", "bug_location": {"function": "remove_duplicates", "line_start": 6}, "test_cases": [{"input": [[1, 1, 2]], "expected_output": 2}, {"input": [[0, 0, 1, 1, 1, 2, 2, 3, 3, 4]], "expected_output": 5}, {"input": [[]], "expected_output": 0}, {"input": [[1]], "expected_output": 1}]}
+{"id": "t1_024", "difficulty": 1, "bug_type": "off_by_one", "function_name": "remove_duplicates", "buggy_code": "def remove_duplicates(nums):\n    if not nums:\n        return 0\n    i = 0\n    for j in range(1, len(nums)):\n        if nums[j] != nums[i]:\n            i += 1\n            nums[i] = nums[j]\n    return i", "original_code": "def remove_duplicates(nums):\n    if not nums:\n        return 0\n    i = 0\n    for j in range(1, len(nums)):\n        if nums[j] != nums[i]:\n            i += 1\n            nums[i] = nums[j]\n    return i + 1", "initial_error": "AssertionError: remove_duplicates([1,1,2]) expected 2, got 1", "bug_location": {"function": "remove_duplicates", "line_start": 9}, "test_cases": [{"input": [[1, 1, 2]], "expected_output": 2}, {"input": [[0, 0, 1, 1, 1, 2, 2, 3, 3, 4]], "expected_output": 5}, {"input": [[]], "expected_output": 0}, {"input": [[1]], "expected_output": 1}]}
+{"id": "t1_025", "difficulty": 1, "bug_type": "wrong_comparison", "function_name": "longest_common_prefix", "buggy_code": "def longest_common_prefix(strs):\n    if not strs:\n        return \"\"\n    prefix = strs[0]\n    for s in strs[1:]:\n        while s.startswith(prefix):\n            prefix = prefix[:-1]\n            if not prefix:\n                return \"\"\n    return prefix", "original_code": "def longest_common_prefix(strs):\n    if not strs:\n        return \"\"\n    prefix = strs[0]\n    for s in strs[1:]:\n        while not s.startswith(prefix):\n            prefix = prefix[:-1]\n            if not prefix:\n                return \"\"\n    return prefix", "initial_error": "AssertionError: longest_common_prefix(['flower','flow','flight']) expected 'fl', got ''", "bug_location": {"function": "longest_common_prefix", "line_start": 6}, "test_cases": [{"input": [["flower", "flow", "flight"]], "expected_output": "fl"}, {"input": [["dog", "racecar", "car"]], "expected_output": ""}, {"input": [[]], "expected_output": ""}, {"input": [["a"]], "expected_output": "a"}]}
+{"id": "t1_026", "difficulty": 1, "bug_type": "off_by_one", "function_name": "longest_common_prefix", "buggy_code": "def longest_common_prefix(strs):\n    if not strs:\n        return \"\"\n    prefix = strs[0]\n    for s in strs:\n        while not s.startswith(prefix):\n            prefix = prefix[:-1]\n            if not prefix:\n                return \"\"\n    return prefix + 'x' + 'x' + 'x'", "original_code": "def longest_common_prefix(strs):\n    if not strs:\n        return \"\"\n    prefix = strs[0]\n    for s in strs[1:]:\n        while not s.startswith(prefix):\n            prefix = prefix[:-1]\n            if not prefix:\n                return \"\"\n    return prefix", "initial_error": "AssertionError: doesn't strictly fail but runs longer", "bug_location": {"function": "longest_common_prefix", "line_start": 5}, "test_cases": [{"input": [["flower", "flow", "flight"]], "expected_output": "fl"}, {"input": [["dog", "racecar", "car"]], "expected_output": ""}, {"input": [[]], "expected_output": ""}, {"input": [["a"]], "expected_output": "a"}]}
+{"id": "t1_027", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "product_except_self", "buggy_code": "def product_except_self(nums):\n    n = len(nums)\n    res = [1] * n\n    prefix = 1\n    for i in range(n):\n        res[i] = prefix\n        prefix += nums[i]\n    postfix = 1\n    for i in range(n - 1, -1, -1):\n        res[i] *= postfix\n        postfix *= nums[i]\n    return res", "original_code": "def product_except_self(nums):\n    n = len(nums)\n    res = [1] * n\n    prefix = 1\n    for i in range(n):\n        res[i] = prefix\n        prefix *= nums[i]\n    postfix = 1\n    for i in range(n - 1, -1, -1):\n        res[i] *= postfix\n        postfix *= nums[i]\n    return res", "initial_error": "AssertionError: product_except_self([1,2,3,4]) expected [24,12,8,6], got [24, 24, 16, 6]", "bug_location": {"function": "product_except_self", "line_start": 7}, "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": [24, 12, 8, 6]}, {"input": [[-1, 1, 0, -3, 3]], "expected_output": [0, 0, 9, 0, 0]}, {"input": [[2, 3]], "expected_output": [3, 2]}, {"input": [[1, 1, 1]], "expected_output": [1, 1, 1]}]}
+{"id": "t1_028", "difficulty": 1, "bug_type": "off_by_one", "function_name": "product_except_self", "buggy_code": "def product_except_self(nums):\n    n = len(nums)\n    res = [1] * n\n    prefix = 1\n    for i in range(n):\n        res[i] = prefix\n        prefix *= nums[i]\n    postfix = 1\n    for i in range(n - 1, 0, -1):\n        res[i] *= postfix\n        postfix *= nums[i]\n    return res", "original_code": "def product_except_self(nums):\n    n = len(nums)\n    res = [1] * n\n    prefix = 1\n    for i in range(n):\n        res[i] = prefix\n        prefix *= nums[i]\n    postfix = 1\n    for i in range(n - 1, -1, -1):\n        res[i] *= postfix\n        postfix *= nums[i]\n    return res", "initial_error": "AssertionError: product_except_self([1,2,3,4]) expected [24,12,8,6], got [1,12,8,6]", "bug_location": {"function": "product_except_self", "line_start": 9}, "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": [24, 12, 8, 6]}, {"input": [[-1, 1, 0, -3, 3]], "expected_output": [0, 0, 9, 0, 0]}, {"input": [[2, 3]], "expected_output": [3, 2]}, {"input": [[1, 1, 1]], "expected_output": [1, 1, 1]}]}
+{"id": "t1_029", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "valid_parentheses", "buggy_code": "def valid_parentheses(s):\n    stack = []\n    mapping = {')': '(', '}': '{', ']': '['}\n    for char in s:\n        if char in mapping:\n            top_element = stack.pop() if stack else '#'\n            if mapping[char] == top_element:\n                return False\n        else:\n            stack.append(char)\n    return not stack", "original_code": "def valid_parentheses(s):\n    stack = []\n    mapping = {')': '(', '}': '{', ']': '['}\n    for char in s:\n        if char in mapping:\n            top_element = stack.pop() if stack else '#'\n            if mapping[char] != top_element:\n                return False\n        else:\n            stack.append(char)\n    return not stack", "initial_error": "AssertionError: valid_parentheses('()') expected True, got False", "bug_location": {"function": "valid_parentheses", "line_start": 7}, "test_cases": [{"input": "()", "expected_output": true}, {"input": "()[]{}", "expected_output": true}, {"input": "(]", "expected_output": false}, {"input": "([)]", "expected_output": false}]}
+{"id": "t1_030", "difficulty": 1, "bug_type": "logic_inversion", "function_name": "valid_parentheses", "buggy_code": "def valid_parentheses(s):\n    stack = []\n    mapping = {')': '(', '}': '{', ']': '['}\n    for char in s:\n        if char in mapping:\n            top_element = stack.pop() if stack else '#'\n            if mapping[char] != top_element:\n                return False\n        else:\n            stack.append(char)\n    return bool(stack)", "original_code": "def valid_parentheses(s):\n    stack = []\n    mapping = {')': '(', '}': '{', ']': '['}\n    for char in s:\n        if char in mapping:\n            top_element = stack.pop() if stack else '#'\n            if mapping[char] != top_element:\n                return False\n        else:\n            stack.append(char)\n    return not stack", "initial_error": "AssertionError: valid_parentheses('()') expected True, got False", "bug_location": {"function": "valid_parentheses", "line_start": 11}, "test_cases": [{"input": "()", "expected_output": true}, {"input": "()[]{}", "expected_output": true}, {"input": "(]", "expected_output": false}, {"input": "([)]", "expected_output": false}]}
+{"id": "t1_031", "difficulty": 1, "bug_type": "off_by_one", "function_name": "climbing_stairs", "buggy_code": "def climbing_stairs(n):\n    if n <= 2:\n        return n\n    a, b = 1, 2\n    for _ in range(3, n):\n        a, b = b, a + b\n    return b", "original_code": "def climbing_stairs(n):\n    if n <= 2:\n        return n\n    a, b = 1, 2\n    for _ in range(3, n + 1):\n        a, b = b, a + b\n    return b", "initial_error": "AssertionError: climbing_stairs(3) expected 3, got 2", "bug_location": {"function": "climbing_stairs", "line_start": 5}, "test_cases": [{"input": 2, "expected_output": 2}, {"input": 3, "expected_output": 3}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 8}]}
+{"id": "t1_032", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "climbing_stairs", "buggy_code": "def climbing_stairs(n):\n    if n <= 2:\n        return n\n    a, b = 1, 2\n    for _ in range(3, n + 1):\n        a, b = b, a * b\n    return b", "original_code": "def climbing_stairs(n):\n    if n <= 2:\n        return n\n    a, b = 1, 2\n    for _ in range(3, n + 1):\n        a, b = b, a + b\n    return b", "initial_error": "AssertionError: climbing_stairs(3) expected 3, got 2", "bug_location": {"function": "climbing_stairs", "line_start": 6}, "test_cases": [{"input": 2, "expected_output": 2}, {"input": 3, "expected_output": 3}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 8}]}
+{"id": "t1_033", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "house_robber", "buggy_code": "def house_robber(nums):\n    if not nums:\n        return 0\n    if len(nums) == 1:\n        return nums[0]\n    dp = [0] * len(nums)\n    dp[0] = nums[0]\n    dp[1] = 9999\n    for i in range(2, len(nums)):\n        dp[i] = max(dp[i-1], dp[i-2] + nums[i])\n    return dp[-1]", "original_code": "def house_robber(nums):\n    if not nums:\n        return 0\n    if len(nums) == 1:\n        return nums[0]\n    dp = [0] * len(nums)\n    dp[0] = nums[0]\n    dp[1] = max(nums[0], nums[1])\n    for i in range(2, len(nums)):\n        dp[i] = max(dp[i-1], dp[i-2] + nums[i])\n    return dp[-1]", "initial_error": "AssertionError: house_robber([2,7,9,3,1]) expected 12, got 11", "bug_location": {"function": "house_robber", "line_start": 8}, "test_cases": [{"input": [[1, 2, 3, 1]], "expected_output": 4}, {"input": [[2, 7, 9, 3, 1]], "expected_output": 12}, {"input": [[]], "expected_output": 0}, {"input": [[5]], "expected_output": 5}]}
+{"id": "t1_034", "difficulty": 1, "bug_type": "off_by_one", "function_name": "house_robber", "buggy_code": "def house_robber(nums):\n    if not nums:\n        return 0\n    if len(nums) == 1:\n        return nums[0]\n    dp = [0] * len(nums)\n    dp[0] = nums[0]\n    dp[1] = max(nums[0], nums[1])\n    for i in range(1, len(nums)):\n        dp[i] = max(dp[i-1], nums[i])\n    return dp[-1]", "original_code": "def house_robber(nums):\n    if not nums:\n        return 0\n    if len(nums) == 1:\n        return nums[0]\n    dp = [0] * len(nums)\n    dp[0] = nums[0]\n    dp[1] = max(nums[0], nums[1])\n    for i in range(2, len(nums)):\n        dp[i] = max(dp[i-1], dp[i-2] + nums[i])\n    return dp[-1]", "initial_error": "IndexError: list index out of range", "bug_location": {"function": "house_robber", "line_start": 9}, "test_cases": [{"input": [[1, 2, 3, 1]], "expected_output": 4}, {"input": [[2, 7, 9, 3, 1]], "expected_output": 12}, {"input": [[]], "expected_output": 0}, {"input": [[5]], "expected_output": 5}]}
+{"id": "t1_035", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "intersection_of_arrays", "buggy_code": "def intersection_of_arrays(nums1, nums2):\n    return list(set(nums1) | set(nums2))", "original_code": "def intersection_of_arrays(nums1, nums2):\n    return list(set(nums1) & set(nums2))", "initial_error": "AssertionError: intersection_of_arrays([1,2,2,1], [2,2]) expected [2], got [1,2]", "bug_location": {"function": "intersection_of_arrays", "line_start": 2}, "test_cases": [{"input": [[1, 2, 2, 1], [2, 2]], "expected_output": [2]}, {"input": [[4, 9, 5], [9, 4, 9, 8, 4]], "expected_output": [9, 4]}, {"input": [[], [1]], "expected_output": []}, {"input": [[1, 2], [3, 4]], "expected_output": []}]}
+{"id": "t1_036", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "intersection_of_arrays", "buggy_code": "def intersection_of_arrays(nums1, nums2):\n    return list(set(nums1) - set(nums2))", "original_code": "def intersection_of_arrays(nums1, nums2):\n    return list(set(nums1) & set(nums2))", "initial_error": "AssertionError: intersection_of_arrays([1,2,2,1], [2,2]) expected [2], got [1]", "bug_location": {"function": "intersection_of_arrays", "line_start": 2}, "test_cases": [{"input": [[1, 2, 2, 1], [2, 2]], "expected_output": [2]}, {"input": [[4, 9, 5], [9, 4, 9, 8, 4]], "expected_output": [9, 4]}, {"input": [[], [1]], "expected_output": []}, {"input": [[1, 2], [3, 4]], "expected_output": []}]}
+{"id": "t1_037", "difficulty": 1, "bug_type": "wrong_comparison", "function_name": "group_anagrams", "buggy_code": "def group_anagrams(strs):\n    from collections import defaultdict\n    ans = defaultdict(list)\n    for s in strs:\n        ans[tuple(s)].append(s)\n    return list(ans.values())", "original_code": "def group_anagrams(strs):\n    from collections import defaultdict\n    ans = defaultdict(list)\n    for s in strs:\n        ans[tuple(sorted(s))].append(s)\n    return list(ans.values())", "initial_error": "AssertionError: expected [['eat','tea','ate'],['tan','nat'],['bat']]", "bug_location": {"function": "group_anagrams", "line_start": 5}, "test_cases": [{"input": [["eat", "tea", "tan", "ate", "nat", "bat"]], "expected_output": [["eat", "tea", "ate"], ["tan", "nat"], ["bat"]]}, {"input": [[""]], "expected_output": [[""]]}, {"input": [["a"]], "expected_output": [["a"]]}, {"input": [["ab", "ba"]], "expected_output": [["ab", "ba"]]}]}
+{"id": "t1_038", "difficulty": 1, "bug_type": "logic_inversion", "function_name": "group_anagrams", "buggy_code": "def group_anagrams(strs):\n    from collections import defaultdict\n    ans = defaultdict(list)\n    for s in strs:\n        ans[tuple(sorted(s))].append(s[::-1])\n    return list(ans.values())", "original_code": "def group_anagrams(strs):\n    from collections import defaultdict\n    ans = defaultdict(list)\n    for s in strs:\n        ans[tuple(sorted(s))].append(s)\n    return list(ans.values())", "initial_error": "AssertionError: expected [['eat','tea','ate'],['tan','nat'],['bat']]", "bug_location": {"function": "group_anagrams", "line_start": 5}, "test_cases": [{"input": [["eat", "tea", "tan", "ate", "nat", "bat"]], "expected_output": [["eat", "tea", "ate"], ["tan", "nat"], ["bat"]]}, {"input": [[""]], "expected_output": [[""]]}, {"input": [["a"]], "expected_output": [["a"]]}, {"input": [["ab", "ba"]], "expected_output": [["ab", "ba"]]}]}
+{"id": "t1_039", "difficulty": 1, "bug_type": "wrong_operator", "function_name": "sum_digits", "buggy_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total *= n % 10\n        n //= 10\n    return total", "original_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total += n % 10\n        n //= 10\n    return total", "initial_error": "AssertionError: sum_digits(123) expected 6, got 0", "bug_location": {"function": "sum_digits", "line_start": 4}, "test_cases": [{"input": 123, "expected_output": 6}, {"input": 0, "expected_output": 0}, {"input": 999, "expected_output": 27}, {"input": 10, "expected_output": 1}]}
+{"id": "t1_040", "difficulty": 1, "bug_type": "off_by_one", "function_name": "factorial", "buggy_code": "def factorial(n):\n    if n <= 0:\n        return 0\n    return n * factorial(n - 1)", "original_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n * factorial(n - 1)", "initial_error": "AssertionError: factorial(3) expected 6, got 0", "bug_location": {"function": "factorial", "line_start": 3}, "test_cases": [{"input": 0, "expected_output": 1}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 120}, {"input": 3, "expected_output": 6}]}

data/bugs_tier2.jsonl

@@ -1,3 +1,30 @@
 {"id": "t2_001", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "two_sum", "buggy_code": "def two_sum(nums, target):\n    seen = {}\n    for i, num in enumerate(nums):\n        complement = target - num\n        if complement in seen:\n            return [seen[complement], i]\n        seen[num] = num\n    return []", "original_code": "def two_sum(nums, target):\n    seen = {}\n    for i, num in enumerate(nums):\n        complement = target - num\n        if complement in seen:\n            return [seen[complement], i]\n        seen[num] = i\n    return []", "initial_error": "AssertionError: two_sum([2,7,11,15], 9) expected [0,1], got [2,1]", "bug_location": {"function": "two_sum", "line_start": 7}, "test_cases": [{"input": [[2, 7, 11, 15], 9], "expected_output": [0, 1]}, {"input": [[3, 2, 4], 6], "expected_output": [1, 2]}, {"input": [[3, 3], 6], "expected_output": [0, 1]}]}
 {"id": "t2_002", "difficulty": 2, "bug_type": "missing_base_case", "function_name": "fibonacci", "buggy_code": "def fibonacci(n):\n    if n == 0:\n        return 0\n    return fibonacci(n - 1) + fibonacci(n - 2)", "original_code": "def fibonacci(n):\n    if n == 0:\n        return 0\n    if n == 1:\n        return 1\n    return fibonacci(n - 1) + fibonacci(n - 2)", "initial_error": "RecursionError: maximum recursion depth exceeded", "bug_location": {"function": "fibonacci", "line_start": 4}, "test_cases": [{"input": 0, "expected_output": 0}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 5}, {"input": 7, "expected_output": 13}]}
-{"id": "t2_003", "difficulty": 2, "bug_type": "wrong_accumulator", "function_name": "flatten", "buggy_code": "def flatten(lst):\n    result = []\n    for item in lst:\n        if isinstance(item, list):\n            result.append(flatten(item))\n        else:\n            result.append(item)\n    return result", "original_code": "def flatten(lst):\n    result = []\n    for item in lst:\n        if isinstance(item, list):\n            result.extend(flatten(item))\n        else:\n            result.append(item)\n    return result", "initial_error": "AssertionError: flatten([[1,[2]],3]) expected [1,2,3], got [1,[2],3]", "bug_location": {"function": "flatten", "line_start": 5}, "test_cases": [{"input": [[1, [2]], 3], "expected_output": [1, 2, 3]}, {"input": [1, 2, 3], "expected_output": [1, 2, 3]}, {"input": [[1, 2], [3, [4, 5]]], "expected_output": [1, 2, 3, 4, 5]}]}
+{"id": "t2_003", "difficulty": 2, "bug_type": "wrong_accumulator", "function_name": "flatten", "buggy_code": "def flatten(lst):\n    result = []\n    for item in lst:\n        if isinstance(item, list):\n            result.append(flatten(item))\n        else:\n            result.append(item)\n    return result", "original_code": "def flatten(lst):\n    result = []\n    for item in lst:\n        if isinstance(item, list):\n            result.extend(flatten(item))\n        else:\n            result.append(item)\n    return result", "initial_error": "AssertionError: flatten([[1,[2]],3]) expected [1,2,3], got [1,[2],3]", "bug_location": {"function": "flatten", "line_start": 5}, "test_cases": [{"input": [[[1, [2]], 3]], "expected_output": [1, 2, 3]}, {"input": [[1, 2, 3]], "expected_output": [1, 2, 3]}, {"input": [[[1, 2], [3, [4, 5]]]], "expected_output": [1, 2, 3, 4, 5]}]}
+{"id": "t2_004", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "find_first_positive", "buggy_code": "def find_first_positive(nums):\n    i = 0\n    while i < len(nums) - 1:\n        if nums[i] > 0:\n            return nums[i]\n        i += 1\n    return -1", "original_code": "def find_first_positive(nums):\n    i = 0\n    while i < len(nums):\n        if nums[i] > 0:\n            return nums[i]\n        i += 1\n    return -1", "initial_error": "AssertionError: expected 5, got -1", "bug_location": {"function": "find_first_positive", "line_start": 3}, "test_cases": [{"input": [[-1, -2, 5]], "expected_output": 5}, {"input": [[1, 2, 3]], "expected_output": 1}, {"input": [[-1]], "expected_output": -1}, {"input": [[-5, -3, -1, 10]], "expected_output": 10}]}
+{"id": "t2_005", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "binary_search_insert", "buggy_code": "def binary_search_insert(arr, target):\n    left, right = 0, len(arr) - 1\n    while left < right:\n        mid = (left + right) // 2\n        if arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid\n    return left", "original_code": "def binary_search_insert(arr, target):\n    left, right = 0, len(arr)\n    while left < right:\n        mid = (left + right) // 2\n        if arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid\n    return left", "initial_error": "AssertionError: expected 3, got 2", "bug_location": {"function": "binary_search_insert", "line_start": 2}, "test_cases": [{"input": [[1, 3, 5], 6], "expected_output": 3}, {"input": [[1, 3, 5], 4], "expected_output": 2}, {"input": [[1, 3, 5], 0], "expected_output": 0}, {"input": [[], 1], "expected_output": 0}]}
+{"id": "t2_006", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "countdown_to_zero", "buggy_code": "def countdown_to_zero(n):\n    res = []\n    while n > 0:\n        res.append(n)\n        n -= 1\n    return res", "original_code": "def countdown_to_zero(n):\n    res = []\n    while n >= 0:\n        res.append(n)\n        n -= 1\n    return res", "initial_error": "AssertionError: expected [3, 2, 1, 0], got [3, 2, 1]", "bug_location": {"function": "countdown_to_zero", "line_start": 3}, "test_cases": [{"input": 3, "expected_output": [3, 2, 1, 0]}, {"input": 0, "expected_output": [0]}, {"input": 1, "expected_output": [1, 0]}, {"input": -1, "expected_output": []}]}
+{"id": "t2_007", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "collect_until_negative", "buggy_code": "def collect_until_negative(nums):\n    res = []\n    i = 0\n    while i <= len(nums) and nums[i] >= 0:\n        res.append(nums[i])\n        i += 1\n    return res", "original_code": "def collect_until_negative(nums):\n    res = []\n    i = 0\n    while i < len(nums) and nums[i] >= 0:\n        res.append(nums[i])\n        i += 1\n    return res", "initial_error": "IndexError: list index out of range", "bug_location": {"function": "collect_until_negative", "line_start": 4}, "test_cases": [{"input": [[1, 2, -1, 3]], "expected_output": [1, 2]}, {"input": [[1, 2, 3]], "expected_output": [1, 2, 3]}, {"input": [[-1]], "expected_output": []}, {"input": [[]], "expected_output": []}]}
+{"id": "t2_008", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "skip_spaces", "buggy_code": "def skip_spaces(s):\n    i = 0\n    while s[i] == ' ':\n        i += 1\n    return s[i:]", "original_code": "def skip_spaces(s):\n    i = 0\n    while i < len(s) and s[i] == ' ':\n        i += 1\n    return s[i:]", "initial_error": "IndexError: string index out of range", "bug_location": {"function": "skip_spaces", "line_start": 3}, "test_cases": [{"input": "  hello", "expected_output": "hello"}, {"input": "   ", "expected_output": ""}, {"input": "world", "expected_output": "world"}, {"input": "", "expected_output": ""}]}
+{"id": "t2_009", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "find_last_even", "buggy_code": "def find_last_even(nums):\n    i = len(nums) - 1\n    while i > 0:\n        if nums[i] % 2 == 0:\n            return nums[i]\n        i -= 1\n    return -1", "original_code": "def find_last_even(nums):\n    i = len(nums) - 1\n    while i >= 0:\n        if nums[i] % 2 == 0:\n            return nums[i]\n        i -= 1\n    return -1", "initial_error": "AssertionError: expected 2, got -1", "bug_location": {"function": "find_last_even", "line_start": 3}, "test_cases": [{"input": [[2, 3, 5]], "expected_output": 2}, {"input": [[1, 3, 4]], "expected_output": 4}, {"input": [[1, 3, 5]], "expected_output": -1}, {"input": [[6]], "expected_output": 6}]}
+{"id": "t2_010", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "get_chunks", "buggy_code": "def get_chunks(lst, size):\n    chunks = []\n    i = 0\n    while i < len(lst) - size:\n        chunks.append(lst[i:i+size])\n        i += size\n    return chunks", "original_code": "def get_chunks(lst, size):\n    chunks = []\n    i = 0\n    while i < len(lst):\n        chunks.append(lst[i:i+size])\n        i += size\n    return chunks", "initial_error": "AssertionError: expected [[1,2],[3]], got [[1,2]]", "bug_location": {"function": "get_chunks", "line_start": 4}, "test_cases": [{"input": [[1, 2, 3], 2], "expected_output": [[1, 2], [3]]}, {"input": [[1, 2], 2], "expected_output": [[1, 2]]}, {"input": [[1, 2, 3, 4], 2], "expected_output": [[1, 2], [3, 4]]}, {"input": [[], 2], "expected_output": []}]}
+{"id": "t2_011", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "sum_even_numbers", "buggy_code": "def sum_even_numbers(nums):\n    total = 1\n    for n in nums:\n        if n % 2 == 0:\n            total += n\n    return total", "original_code": "def sum_even_numbers(nums):\n    total = 0\n    for n in nums:\n        if n % 2 == 0:\n            total += n\n    return total", "initial_error": "AssertionError: expected 6, got 7", "bug_location": {"function": "sum_even_numbers", "line_start": 2}, "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": 6}, {"input": [[1, 3, 5]], "expected_output": 0}, {"input": [[2, 2]], "expected_output": 4}, {"input": [[]], "expected_output": 0}]}
+{"id": "t2_012", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "multiply_all", "buggy_code": "def multiply_all(nums):\n    total = 0\n    for n in nums:\n        total *= n\n    return total", "original_code": "def multiply_all(nums):\n    total = 1\n    for n in nums:\n        total *= n\n    return total", "initial_error": "AssertionError: expected 24, got 0", "bug_location": {"function": "multiply_all", "line_start": 2}, "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": 24}, {"input": [[5]], "expected_output": 5}, {"input": [[1, -1]], "expected_output": -1}, {"input": [[0, 5]], "expected_output": 0}]}
+{"id": "t2_013", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "concatenate_strings", "buggy_code": "def concatenate_strings(strs):\n    res = strs[0]\n    for s in strs:\n        res += s\n    return res", "original_code": "def concatenate_strings(strs):\n    res = ''\n    for s in strs:\n        res += s\n    return res", "initial_error": "AssertionError: expected 'abc', got 'aabc'", "bug_location": {"function": "concatenate_strings", "line_start": 2}, "test_cases": [{"input": [["a", "b", "c"]], "expected_output": "abc"}, {"input": [["hello", "world"]], "expected_output": "helloworld"}, {"input": [["a"]], "expected_output": "a"}, {"input": [["x", "y"]], "expected_output": "xy"}]}
+{"id": "t2_014", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "max_profit", "buggy_code": "def max_profit(prices):\n    min_price = 0\n    max_prof = 0\n    for price in prices:\n        min_price = min(min_price, price)\n        max_prof = max(max_prof, price - min_price)\n    return max_prof", "original_code": "def max_profit(prices):\n    min_price = float('inf')\n    max_prof = 0\n    for price in prices:\n        min_price = min(min_price, price)\n        max_prof = max(max_prof, price - min_price)\n    return max_prof", "initial_error": "AssertionError: expected 5, got 6", "bug_location": {"function": "max_profit", "line_start": 2}, "test_cases": [{"input": [[7, 1, 5, 3, 6, 4]], "expected_output": 5}, {"input": [[7, 6, 4, 3, 1]], "expected_output": 0}, {"input": [[1, 2]], "expected_output": 1}, {"input": [[2, 4, 1]], "expected_output": 2}]}
+{"id": "t2_015", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "find_longest_word", "buggy_code": "def find_longest_word(words):\n    longest = words[0]\n    for word in words:\n        if len(word) > len(longest):\n            longest = longest\n    return longest", "original_code": "def find_longest_word(words):\n    longest = ''\n    for word in words:\n        if len(word) > len(longest):\n            longest = word\n    return longest", "initial_error": "AssertionError: expected 'banana', got 'apple'", "bug_location": {"function": "find_longest_word", "line_start": 5}, "test_cases": [{"input": [["apple", "banana", "kiwi"]], "expected_output": "banana"}, {"input": [["a", "ab", "abc"]], "expected_output": "abc"}, {"input": [["dog"]], "expected_output": "dog"}, {"input": [["x", "yz"]], "expected_output": "yz"}]}
+{"id": "t2_016", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "running_sum", "buggy_code": "def running_sum(nums):\n    res = []\n    current = nums[0]\n    for n in nums:\n        current += n\n        res.append(current)\n    return res", "original_code": "def running_sum(nums):\n    res = []\n    current = 0\n    for n in nums:\n        current += n\n        res.append(current)\n    return res", "initial_error": "AssertionError: expected [1, 3, 6], got [2, 4, 7]", "bug_location": {"function": "running_sum", "line_start": 3}, "test_cases": [{"input": [[1, 2, 3]], "expected_output": [1, 3, 6]}, {"input": [[1, 1, 1]], "expected_output": [1, 2, 3]}, {"input": [[5]], "expected_output": [5]}, {"input": [[0, 0, 0]], "expected_output": [0, 0, 0]}]}
+{"id": "t2_017", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "count_negatives", "buggy_code": "def count_negatives(nums):\n    count = -1\n    for n in nums:\n        if n < 0:\n            count += 1\n    return count", "original_code": "def count_negatives(nums):\n    count = 0\n    for n in nums:\n        if n < 0:\n            count += 1\n    return count", "initial_error": "AssertionError: expected 2, got 1", "bug_location": {"function": "count_negatives", "line_start": 2}, "test_cases": [{"input": [[1, -1, 2, -2]], "expected_output": 2}, {"input": [[1, 2, 3]], "expected_output": 0}, {"input": [[-1, -2, -3]], "expected_output": 3}, {"input": [[]], "expected_output": 0}]}
+{"id": "t2_018", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "classify_number", "buggy_code": "def classify_number(n):\n    if n > 0:\n        return 'positive'\n    elif n < 0:\n        return 'negative'\n    elif n == 0:\n        return 'negative'", "original_code": "def classify_number(n):\n    if n > 0:\n        return 'positive'\n    elif n < 0:\n        return 'negative'\n    else:\n        return 'zero'", "initial_error": "AssertionError: expected 'zero', got 'negative'", "bug_location": {"function": "classify_number", "line_start": 6}, "test_cases": [{"input": 5, "expected_output": "positive"}, {"input": -3, "expected_output": "negative"}, {"input": 0, "expected_output": "zero"}, {"input": 1, "expected_output": "positive"}]}
+{"id": "t2_019", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "get_discount", "buggy_code": "def get_discount(price):\n    if price > 100:\n        return 20\n    if price > 50:\n        return 50\n    return 0", "original_code": "def get_discount(price):\n    if price > 100:\n        return 20\n    elif price > 50:\n        return 10\n    return 0", "initial_error": "AssertionError: expected 10, got 50", "bug_location": {"function": "get_discount", "line_start": 5}, "test_cases": [{"input": 150, "expected_output": 20}, {"input": 75, "expected_output": 10}, {"input": 50, "expected_output": 0}, {"input": 20, "expected_output": 0}]}
+{"id": "t2_020", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "fizz_buzz", "buggy_code": "def fizz_buzz(n):\n    if n % 3 == 0:\n        return 'Fizz'\n    if n % 5 == 0:\n        return 'Buzz'\n    if n % 15 == 0:\n        return 'FizzBuzz'\n    return str(n)", "original_code": "def fizz_buzz(n):\n    if n % 15 == 0:\n        return 'FizzBuzz'\n    if n % 3 == 0:\n        return 'Fizz'\n    if n % 5 == 0:\n        return 'Buzz'\n    return str(n)", "initial_error": "AssertionError: expected 'FizzBuzz', got 'Fizz'", "bug_location": {"function": "fizz_buzz", "line_start": 2}, "test_cases": [{"input": 3, "expected_output": "Fizz"}, {"input": 5, "expected_output": "Buzz"}, {"input": 15, "expected_output": "FizzBuzz"}, {"input": 2, "expected_output": "2"}]}
+{"id": "t2_021", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "is_leap_year", "buggy_code": "def is_leap_year(year):\n    if year % 4 == 0:\n        if year % 100 == 0:\n            if year % 400 == 0:\n                return False\n            return True\n        return True\n    return False", "original_code": "def is_leap_year(year):\n    if year % 4 == 0:\n        if year % 100 == 0:\n            if year % 400 == 0:\n                return True\n            return False\n        return True\n    return False", "initial_error": "AssertionError: expected False, got True", "bug_location": {"function": "is_leap_year", "line_start": 5}, "test_cases": [{"input": 2000, "expected_output": true}, {"input": 1900, "expected_output": false}, {"input": 2004, "expected_output": true}, {"input": 2001, "expected_output": false}]}
+{"id": "t2_022", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "grade_score", "buggy_code": "def grade_score(score):\n    if score >= 90:\n        return 'A'\n    elif score >= 80:\n        return 'B'\n    elif score > 70:\n        return 'C'\n    else:\n        return 'F'", "original_code": "def grade_score(score):\n    if score >= 90:\n        return 'A'\n    elif score >= 80:\n        return 'B'\n    elif score >= 70:\n        return 'C'\n    else:\n        return 'F'", "initial_error": "AssertionError: expected 'C', got 'F'", "bug_location": {"function": "grade_score", "line_start": 6}, "test_cases": [{"input": 95, "expected_output": "A"}, {"input": 80, "expected_output": "B"}, {"input": 70, "expected_output": "C"}, {"input": 60, "expected_output": "F"}]}
+{"id": "t2_023", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "can_drink_alcohol", "buggy_code": "def can_drink_alcohol(age, country):\n    if country == 'US':\n        if age > 21:\n            return True\n        return False\n    return age >= 18", "original_code": "def can_drink_alcohol(age, country):\n    if country == 'US':\n        if age >= 21:\n            return True\n        return False\n    return age >= 18", "initial_error": "AssertionError: expected True, got False", "bug_location": {"function": "can_drink_alcohol", "line_start": 3}, "test_cases": [{"input": [21, "US"], "expected_output": true}, {"input": [20, "US"], "expected_output": false}, {"input": [18, "UK"], "expected_output": true}, {"input": [17, "UK"], "expected_output": false}]}
+{"id": "t2_024", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "get_quadrant", "buggy_code": "def get_quadrant(x, y):\n    if x > 0 and y > 0:\n        return 1\n    elif x < 0 and y > 0:\n        return 2\n    elif x > 0 and y < 0:\n        return 3\n    elif x < 0 and y < 0:\n        return 4\n    return 0", "original_code": "def get_quadrant(x, y):\n    if x > 0 and y > 0:\n        return 1\n    elif x < 0 and y > 0:\n        return 2\n    elif x < 0 and y < 0:\n        return 3\n    elif x > 0 and y < 0:\n        return 4\n    return 0", "initial_error": "AssertionError: expected 4, got 3", "bug_location": {"function": "get_quadrant", "line_start": 6}, "test_cases": [{"input": [1, 1], "expected_output": 1}, {"input": [-1, 1], "expected_output": 2}, {"input": [-1, -1], "expected_output": 3}, {"input": [1, -1], "expected_output": 4}]}
+{"id": "t2_025", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "merge_arrays", "buggy_code": "def merge_arrays(a, b):\n    res = a + b\n    res.sort()\n    return a", "original_code": "def merge_arrays(a, b):\n    res = a + b\n    res.sort()\n    return res", "initial_error": "AssertionError: expected [1, 2, 3, 4], got [1, 3]", "bug_location": {"function": "merge_arrays", "line_start": 4}, "test_cases": [{"input": [[1, 3], [2, 4]], "expected_output": [1, 2, 3, 4]}, {"input": [[], [1]], "expected_output": [1]}, {"input": [[2], [1]], "expected_output": [1, 2]}, {"input": [[], []], "expected_output": []}]}
+{"id": "t2_026", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "find_min_max", "buggy_code": "def find_min_max(nums):\n    if not nums:\n        return None\n    mn = min(nums)\n    mx = max(nums)\n    return [mn, mn]", "original_code": "def find_min_max(nums):\n    if not nums:\n        return None\n    mn = min(nums)\n    mx = max(nums)\n    return [mn, mx]", "initial_error": "AssertionError: expected (1, 5), got (1, 1)", "bug_location": {"function": "find_min_max", "line_start": 6}, "test_cases": [{"input": [[1, 2, 5]], "expected_output": [1, 5]}, {"input": [[3, 3]], "expected_output": [3, 3]}, {"input": [[-1, 0, 1]], "expected_output": [-1, 1]}, {"input": [[]], "expected_output": null}]}
+{"id": "t2_027", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "remove_evens", "buggy_code": "def remove_evens(nums):\n    res = []\n    for n in nums:\n        if n % 2 != 0:\n            res.append(n)\n    return nums", "original_code": "def remove_evens(nums):\n    res = []\n    for n in nums:\n        if n % 2 != 0:\n            res.append(n)\n    return res", "initial_error": "AssertionError: expected [1, 3], got [1, 2, 3]", "bug_location": {"function": "remove_evens", "line_start": 6}, "test_cases": [{"input": [[1, 2, 3]], "expected_output": [1, 3]}, {"input": [[2, 4]], "expected_output": []}, {"input": [[1, 3]], "expected_output": [1, 3]}, {"input": [[]], "expected_output": []}]}
+{"id": "t2_028", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "duplicate_list", "buggy_code": "def duplicate_list(lst):\n    res = lst[:]\n    res.extend(lst)\n    return lst", "original_code": "def duplicate_list(lst):\n    res = lst[:]\n    res.extend(lst)\n    return res", "initial_error": "AssertionError: expected [1, 1], got [1]", "bug_location": {"function": "duplicate_list", "line_start": 4}, "test_cases": [{"input": [[1]], "expected_output": [1, 1]}, {"input": [[1, 2]], "expected_output": [1, 2, 1, 2]}, {"input": [[]], "expected_output": []}, {"input": [[0]], "expected_output": [0, 0]}]}
+{"id": "t2_029", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "swap_halves", "buggy_code": "def swap_halves(lst):\n    mid = len(lst) // 2\n    left = lst[:mid]\n    right = lst[mid:]\n    return left + left", "original_code": "def swap_halves(lst):\n    mid = len(lst) // 2\n    left = lst[:mid]\n    right = lst[mid:]\n    return right + left", "initial_error": "AssertionError: expected [3, 4, 1, 2], got [1, 2, 1, 2]", "bug_location": {"function": "swap_halves", "line_start": 5}, "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": [3, 4, 1, 2]}, {"input": [[1, 2, 3]], "expected_output": [2, 3, 1]}, {"input": [[1]], "expected_output": [1]}, {"input": [[]], "expected_output": []}]}
+{"id": "t2_030", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "get_initials", "buggy_code": "def get_initials(name):\n    words = name.split()\n    initials = [w[0].upper() for w in words]\n    return ''.join(words)", "original_code": "def get_initials(name):\n    words = name.split()\n    initials = [w[0].upper() for w in words]\n    return ''.join(initials)", "initial_error": "AssertionError: expected 'JD', got 'JohnDoe'", "bug_location": {"function": "get_initials", "line_start": 4}, "test_cases": [{"input": "John Doe", "expected_output": "JD"}, {"input": "Alice", "expected_output": "A"}, {"input": "bob smith junior", "expected_output": "BSJ"}, {"input": "", "expected_output": ""}]}

data/bugs_tier3.jsonl

@@ -1,2 +1,20 @@
 {"id": "t3_001", "difficulty": 3, "bug_type": "edge_case_only", "function_name": "merge_sorted", "buggy_code": "def merge_sorted(a, b):\n    result = []\n    i = j = 0\n    while i < len(a) and j < len(b):\n        if a[i] <= b[j]:\n            result.append(a[i])\n            i += 1\n        else:\n            result.append(b[j])\n            j += 1\n    return result", "original_code": "def merge_sorted(a, b):\n    result = []\n    i = j = 0\n    while i < len(a) and j < len(b):\n        if a[i] <= b[j]:\n            result.append(a[i])\n            i += 1\n        else:\n            result.append(b[j])\n            j += 1\n    result.extend(a[i:])\n    result.extend(b[j:])\n    return result", "initial_error": "AssertionError: merge_sorted([1,3],[2,4,5]) expected [1,2,3,4,5], got [1,2,3]", "bug_location": {"function": "merge_sorted", "line_start": 11}, "test_cases": [{"input": [[1, 3], [2, 4, 5]], "expected_output": [1, 2, 3, 4, 5]}, {"input": [[], [1, 2]], "expected_output": [1, 2]}, {"input": [[1, 2], []], "expected_output": [1, 2]}, {"input": [[1], [2]], "expected_output": [1, 2]}]}
-{"id": "t3_002", "difficulty": 3, "bug_type": "subtle_logic", "function_name": "rotate_matrix", "buggy_code": "def rotate_matrix(matrix):\n    n = len(matrix)\n    for i in range(n):\n        for j in range(i, n):\n            matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]\n    return matrix", "original_code": "def rotate_matrix(matrix):\n    n = len(matrix)\n    for i in range(n):\n        for j in range(i, n):\n            matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]\n    for row in matrix:\n        row.reverse()\n    return matrix", "initial_error": "AssertionError: rotate_matrix([[1,2],[3,4]]) expected [[3,1],[4,2]], got [[1,3],[2,4]]", "bug_location": {"function": "rotate_matrix", "line_start": 6}, "test_cases": [{"input": [[1, 2], [3, 4]], "expected_output": [[3, 1], [4, 2]]}, {"input": [[1, 2, 3], [4, 5, 6], [7, 8, 9]], "expected_output": [[7, 4, 1], [8, 5, 2], [9, 6, 3]]}]}
+{"id": "t3_002", "difficulty": 3, "bug_type": "subtle_logic", "function_name": "rotate_matrix", "buggy_code": "def rotate_matrix(matrix):\n    n = len(matrix)\n    for i in range(n):\n        for j in range(i, n):\n            matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]\n    return matrix", "original_code": "def rotate_matrix(matrix):\n    n = len(matrix)\n    for i in range(n):\n        for j in range(i, n):\n            matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]\n    for row in matrix:\n        row.reverse()\n    return matrix", "initial_error": "AssertionError: rotate_matrix([[1,2],[3,4]]) expected [[3,1],[4,2]], got [[1,3],[2,4]]", "bug_location": {"function": "rotate_matrix", "line_start": 6}, "test_cases": [{"input": [[[1, 2], [3, 4]]], "expected_output": [[3, 1], [4, 2]]}, {"input": [[[1, 2, 3], [4, 5, 6], [7, 8, 9]]], "expected_output": [[7, 4, 1], [8, 5, 2], [9, 6, 3]]}]}
+{"id": "t3_003", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "process_user", "buggy_code": "def format_name(first, last):\n    return f'{last}, {first}'\n\ndef process_user(first_name, last_name):\n    return format_name(last_name, first_name)", "original_code": "def format_name(first, last):\n    return f'{last}, {first}'\n\ndef process_user(first_name, last_name):\n    return format_name(first_name, last_name)", "initial_error": "AssertionError: expected 'Doe, John', got 'John, Doe'", "bug_location": {"function": "process_user", "line_start": 5}, "test_cases": [{"input": ["John", "Doe"], "expected_output": "Doe, John"}, {"input": ["Alice", "Smith"], "expected_output": "Smith, Alice"}, {"input": ["A", "B"], "expected_output": "B, A"}, {"input": ["X", "Y"], "expected_output": "Y, X"}]}
+{"id": "t3_004", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "calculate_total", "buggy_code": "def apply_discount(price, discount):\n    return price - (price * discount)\n\ndef calculate_total(price, discount_rate):\n    return apply_discount(discount_rate, price)", "original_code": "def apply_discount(price, discount):\n    return price - (price * discount)\n\ndef calculate_total(price, discount_rate):\n    return apply_discount(price, discount_rate)", "initial_error": "AssertionError: expected 80.0, got -19.8", "bug_location": {"function": "calculate_total", "line_start": 5}, "test_cases": [{"input": [100, 0.2], "expected_output": 80.0}, {"input": [50, 0.1], "expected_output": 45.0}, {"input": [200, 0.5], "expected_output": 100.0}, {"input": [10, 0.0], "expected_output": 10.0}]}
+{"id": "t3_005", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "build_url", "buggy_code": "def join_parts(domain, path):\n    return f'https://{domain}/{path}'\n\ndef build_url(domain, path):\n    return join_parts(path, domain)", "original_code": "def join_parts(domain, path):\n    return f'https://{domain}/{path}'\n\ndef build_url(domain, path):\n    return join_parts(domain, path)", "initial_error": "AssertionError: expected 'https://example.com/api', got 'https://api/example.com'", "bug_location": {"function": "build_url", "line_start": 5}, "test_cases": [{"input": ["example.com", "api"], "expected_output": "https://example.com/api"}, {"input": ["google.com", "search"], "expected_output": "https://google.com/search"}, {"input": ["a.com", "b"], "expected_output": "https://a.com/b"}, {"input": ["x.org", "y"], "expected_output": "https://x.org/y"}]}
+{"id": "t3_006", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "divide_numbers", "buggy_code": "def safe_divide(num, den):\n    if den == 0:\n        return 0\n    return num / den\n\ndef divide_numbers(a, b):\n    return safe_divide(b, a)", "original_code": "def safe_divide(num, den):\n    if den == 0:\n        return 0\n    return num / den\n\ndef divide_numbers(a, b):\n    return safe_divide(a, b)", "initial_error": "AssertionError: expected 2.0, got 0.5", "bug_location": {"function": "divide_numbers", "line_start": 7}, "test_cases": [{"input": [10, 5], "expected_output": 2.0}, {"input": [5, 0], "expected_output": 0}, {"input": [100, 10], "expected_output": 10.0}, {"input": [0, 5], "expected_output": 0.0}]}
+{"id": "t3_007", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "create_rectangle", "buggy_code": "def calc_area(w, h):\n    return w * h\n\ndef create_rectangle(width, height):\n    return {'w': width, 'h': height, 'area': calc_area(height, height)}", "original_code": "def calc_area(w, h):\n    return w * h\n\ndef create_rectangle(width, height):\n    return {'w': width, 'h': height, 'area': calc_area(width, height)}", "initial_error": "AssertionError: doesn't strictly fail math but conceptually wrong", "bug_location": {"function": "create_rectangle", "line_start": 5}, "test_cases": [{"input": [5, 10], "expected_output": {"w": 5, "h": 10, "area": 50}}, {"input": [2, 3], "expected_output": {"w": 2, "h": 3, "area": 6}}, {"input": [1, 1], "expected_output": {"w": 1, "h": 1, "area": 1}}, {"input": [0, 5], "expected_output": {"w": 0, "h": 5, "area": 0}}]}
+{"id": "t3_008", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "power_wrapper", "buggy_code": "def compute_pow(base, exp):\n    return base ** exp\n\ndef power_wrapper(base, exp):\n    return compute_pow(exp, base)", "original_code": "def compute_pow(base, exp):\n    return base ** exp\n\ndef power_wrapper(base, exp):\n    return compute_pow(base, exp)", "initial_error": "AssertionError: expected 8, got 9", "bug_location": {"function": "power_wrapper", "line_start": 5}, "test_cases": [{"input": [2, 3], "expected_output": 8}, {"input": [3, 2], "expected_output": 9}, {"input": [5, 2], "expected_output": 25}, {"input": [2, 4], "expected_output": 16}]}
+{"id": "t3_009", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "get_unique_items", "buggy_code": "seen = {1}\ndef filter_unique(items):\n    res = []\n    for item in items:\n        if item not in seen:\n            seen.add(item)\n            res.append(item)\n    return res\n\ndef get_unique_items(items):\n    return filter_unique(items)", "original_code": "def filter_unique(items, seen):\n    res = []\n    for item in items:\n        if item not in seen:\n            seen.add(item)\n            res.append(item)\n    return res\n\ndef get_unique_items(items):\n    return filter_unique(items, set())", "initial_error": "AssertionError: test fails on second call", "bug_location": {"function": "filter_unique", "line_start": 4}, "test_cases": [{"input": [[1, 2, 2, 3]], "expected_output": [1, 2, 3]}, {"input": [[1, 2, 2, 3]], "expected_output": [1, 2, 3]}, {"input": [[4, 4, 5]], "expected_output": [4, 5]}, {"input": [[4, 4, 5]], "expected_output": [4, 5]}]}
+{"id": "t3_010", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "accumulate_values", "buggy_code": "total = 10\ndef add_to_total(val):\n    global total\n    total += val\n    return total\n\ndef accumulate_values(vals):\n    return [add_to_total(v) for v in vals]", "original_code": "def accumulate_values(vals):\n    total = 0\n    res = []\n    for v in vals:\n        total += v\n        res.append(total)\n    return res", "initial_error": "AssertionError: expected [1, 3], got [1, 3] then [4, 6] on next call", "bug_location": {"function": "add_to_total", "line_start": 4}, "test_cases": [{"input": [[1, 2]], "expected_output": [1, 3]}, {"input": [[1, 2]], "expected_output": [1, 3]}, {"input": [[5, 5]], "expected_output": [5, 10]}, {"input": [[5, 5]], "expected_output": [5, 10]}]}
+{"id": "t3_011", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "append_to_default", "buggy_code": "def helper(val, lst=[1]):\n    lst.append(val)\n    return lst\n\ndef append_to_default(val):\n    return helper(val)", "original_code": "def helper(val, lst=None):\n    if lst is None:\n        lst = []\n    lst.append(val)\n    return lst\n\ndef append_to_default(val):\n    return helper(val)", "initial_error": "AssertionError: expected [2], got [1, 2]", "bug_location": {"function": "helper", "line_start": 1}, "test_cases": [{"input": 1, "expected_output": [1]}, {"input": 2, "expected_output": [2]}, {"input": 3, "expected_output": [3]}, {"input": 4, "expected_output": [4]}]}
+{"id": "t3_012", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "count_calls", "buggy_code": "calls = 5\ndef tracker():\n    global calls\n    calls += 1\n    return calls\n\ndef count_calls(n):\n    res = []\n    for _ in range(n):\n        res.append(tracker())\n    return res", "original_code": "def count_calls(n):\n    calls = 0\n    res = []\n    for _ in range(n):\n        calls += 1\n        res.append(calls)\n    return res", "initial_error": "AssertionError: expected [1, 2], got [3, 4] on second run", "bug_location": {"function": "tracker", "line_start": 4}, "test_cases": [{"input": 2, "expected_output": [1, 2]}, {"input": 2, "expected_output": [1, 2]}, {"input": 3, "expected_output": [1, 2, 3]}, {"input": 3, "expected_output": [1, 2, 3]}]}
+{"id": "t3_013", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "build_sentence", "buggy_code": "words_cache = ['ERROR']\ndef add_word(w):\n    words_cache.append(w)\n    return ' '.join(words_cache)\n\ndef build_sentence(words):\n    res = ''\n    for w in words:\n        res = add_word(w)\n    return res", "original_code": "def build_sentence(words):\n    words_cache = []\n    def add_word(w):\n        words_cache.append(w)\n        return ' '.join(words_cache)\n    res = ''\n    for w in words:\n        res = add_word(w)\n    return res", "initial_error": "AssertionError: expected 'hello world', got '... hello world'", "bug_location": {"function": "add_word", "line_start": 3}, "test_cases": [{"input": [["hello", "world"]], "expected_output": "hello world"}, {"input": [["foo", "bar"]], "expected_output": "foo bar"}, {"input": [["a", "b", "c"]], "expected_output": "a b c"}, {"input": [["x"]], "expected_output": "x"}]}
+{"id": "t3_014", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "collect_errors", "buggy_code": "errors = ['fatal']\ndef log_error(err):\n    errors.append(err)\n    return errors\n\ndef collect_errors(err_list):\n    for e in err_list:\n        res = log_error(e)\n    return res if err_list else []", "original_code": "def collect_errors(err_list):\n    errors = []\n    def log_error(err):\n        errors.append(err)\n        return errors\n    res = []\n    for e in err_list:\n        res = log_error(e)\n    return res", "initial_error": "AssertionError: state leak between calls", "bug_location": {"function": "log_error", "line_start": 3}, "test_cases": [{"input": [["e1"]], "expected_output": ["e1"]}, {"input": [["e2"]], "expected_output": ["e2"]}, {"input": [["e3", "e4"]], "expected_output": ["e3", "e4"]}, {"input": [["e5"]], "expected_output": ["e5"]}]}
+{"id": "t3_015", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "process_data", "buggy_code": "def get_first(lst):\n    return lst[0]\n\ndef process_data(data):\n    if not data:\n        return None\n    return [get_first(d) for d in data]", "original_code": "def get_first(lst):\n    if not lst:\n        return None\n    return lst[0]\n\ndef process_data(data):\n    if not data:\n        return []\n    return [get_first(d) for d in data]", "initial_error": "IndexError: list index out of range", "bug_location": {"function": "get_first", "line_start": 2}, "test_cases": [{"input": [[[1, 2], [3, 4]]], "expected_output": [1, 3]}, {"input": [[[1], []]], "expected_output": [1, null]}, {"input": [[[], [2]]], "expected_output": [null, 2]}, {"input": [[]], "expected_output": []}]}
+{"id": "t3_016", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "average_scores", "buggy_code": "def calc_avg(scores):\n    return sum(scores) / len(scores)\n\ndef average_scores(students):\n    return {k: calc_avg(v) for k, v in students.items()}", "original_code": "def calc_avg(scores):\n    if not scores:\n        return 0\n    return sum(scores) / len(scores)\n\ndef average_scores(students):\n    return {k: calc_avg(v) for k, v in students.items()}", "initial_error": "ZeroDivisionError: division by zero", "bug_location": {"function": "calc_avg", "line_start": 2}, "test_cases": [{"input": [{"Alice": [10, 20], "Bob": []}], "expected_output": {"Alice": 15.0, "Bob": 0}}, {"input": [{"A": [5]}], "expected_output": {"A": 5.0}}, {"input": [{}], "expected_output": {}}, {"input": [{"B": []}], "expected_output": {"B": 0}}]}
+{"id": "t3_017", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "find_max_nested", "buggy_code": "def find_max(lst):\n    return max(lst)\n\ndef find_max_nested(nested_lists):\n    return [find_max(l) for l in nested_lists]", "original_code": "def find_max(lst):\n    if not lst:\n        return None\n    return max(lst)\n\ndef find_max_nested(nested_lists):\n    return [find_max(l) for l in nested_lists]", "initial_error": "ValueError: max() arg is an empty sequence", "bug_location": {"function": "find_max", "line_start": 2}, "test_cases": [{"input": [[[1, 2], []]], "expected_output": [2, null]}, {"input": [[[1], [2, 3]]], "expected_output": [1, 3]}, {"input": [[[], []]], "expected_output": [null, null]}, {"input": [[]], "expected_output": []}]}
+{"id": "t3_018", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "get_extensions", "buggy_code": "def extract_ext(filename):\n    return filename.split('.')[1]\n\ndef get_extensions(files):\n    return [extract_ext(f) for f in files]", "original_code": "def extract_ext(filename):\n    parts = filename.split('.')\n    if len(parts) < 2:\n        return ''\n    return parts[-1]\n\ndef get_extensions(files):\n    return [extract_ext(f) for f in files]", "initial_error": "IndexError: list index out of range", "bug_location": {"function": "extract_ext", "line_start": 2}, "test_cases": [{"input": [["a.txt", "b"]], "expected_output": ["txt", ""]}, {"input": [["a.txt", "b.pdf"]], "expected_output": ["txt", "pdf"]}, {"input": [["noext"]], "expected_output": [""]}, {"input": [[]], "expected_output": []}]}
+{"id": "t3_019", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "get_lengths", "buggy_code": "def get_len(item):\n    return len(item)\n\ndef get_lengths(items):\n    return [get_len(i) for i in items]", "original_code": "def get_len(item):\n    if item is None:\n        return 0\n    return len(item)\n\ndef get_lengths(items):\n    return [get_len(i) for i in items]", "initial_error": "TypeError: object of type 'NoneType' has no len()", "bug_location": {"function": "get_len", "line_start": 2}, "test_cases": [{"input": [["abc", null]], "expected_output": [3, 0]}, {"input": [["a", "b"]], "expected_output": [1, 1]}, {"input": [[null, null]], "expected_output": [0, 0]}, {"input": [[]], "expected_output": []}]}
+{"id": "t3_020", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "parse_integers", "buggy_code": "def to_int(s):\n    return int(s)\n\ndef parse_integers(strings):\n    return [to_int(s) for s in strings]", "original_code": "def to_int(s):\n    try:\n        return int(s)\n    except ValueError:\n        return 0\n\ndef parse_integers(strings):\n    return [to_int(s) for s in strings]", "initial_error": "ValueError: invalid literal for int() with base 10", "bug_location": {"function": "to_int", "line_start": 2}, "test_cases": [{"input": [["1", "abc"]], "expected_output": [1, 0]}, {"input": [["1", "2"]], "expected_output": [1, 2]}, {"input": [["foo", "bar"]], "expected_output": [0, 0]}, {"input": [[]], "expected_output": []}]}

scratch/data_tier1.py

@@ -0,0 +1,354 @@
+t1_bugs = [
+    {
+        "id": "t1_009",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "factorial",
+        "buggy_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n * factorial(n)",
+        "original_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n * factorial(n - 1)",
+        "initial_error": "RecursionError: maximum recursion depth exceeded",
+        "bug_location": {"function": "factorial", "line_start": 4},
+        "test_cases": [{"input": 0, "expected_output": 1}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 120}, {"input": 3, "expected_output": 6}]
+    },
+    {
+        "id": "t1_010",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "factorial",
+        "buggy_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n + factorial(n - 1)",
+        "original_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n * factorial(n - 1)",
+        "initial_error": "AssertionError: factorial(3) expected 6, got 6 - wait got 7",
+        "bug_location": {"function": "factorial", "line_start": 4},
+        "test_cases": [{"input": 0, "expected_output": 1}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 120}, {"input": 3, "expected_output": 6}]
+    },
+    {
+        "id": "t1_011",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "fibonacci",
+        "buggy_code": "def fibonacci(n):\n    if n < 1:\n        return n\n    return fibonacci(n-1) + fibonacci(n-2)",
+        "original_code": "def fibonacci(n):\n    if n <= 1:\n        return n\n    return fibonacci(n-1) + fibonacci(n-2)",
+        "initial_error": "RecursionError: maximum recursion depth exceeded",
+        "bug_location": {"function": "fibonacci", "line_start": 2},
+        "test_cases": [{"input": 0, "expected_output": 0}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 5}, {"input": 7, "expected_output": 13}]
+    },
+    {
+        "id": "t1_012",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "fibonacci",
+        "buggy_code": "def fibonacci(n):\n    if n <= 1:\n        return n\n    return fibonacci(n-1) * fibonacci(n-2)",
+        "original_code": "def fibonacci(n):\n    if n <= 1:\n        return n\n    return fibonacci(n-1) + fibonacci(n-2)",
+        "initial_error": "AssertionError: fibonacci(5) expected 5, got 0",
+        "bug_location": {"function": "fibonacci", "line_start": 4},
+        "test_cases": [{"input": 0, "expected_output": 0}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 5}, {"input": 7, "expected_output": 13}]
+    },
+    {
+        "id": "t1_013",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "string_reverse",
+        "buggy_code": "def string_reverse(s):\n    return s[:-1]",
+        "original_code": "def string_reverse(s):\n    return s[::-1]",
+        "initial_error": "AssertionError: string_reverse('hello') expected 'olleh', got 'hell'",
+        "bug_location": {"function": "string_reverse", "line_start": 2},
+        "test_cases": [{"input": "hello", "expected_output": "olleh"}, {"input": "", "expected_output": ""}, {"input": "a", "expected_output": "a"}, {"input": "racecar", "expected_output": "racecar"}]
+    },
+    {
+        "id": "t1_014",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "string_reverse",
+        "buggy_code": "def string_reverse(s):\n    return s[1:]",
+        "original_code": "def string_reverse(s):\n    return s[::-1]",
+        "initial_error": "AssertionError: string_reverse('hello') expected 'olleh', got 'ello'",
+        "bug_location": {"function": "string_reverse", "line_start": 2},
+        "test_cases": [{"input": "hello", "expected_output": "olleh"}, {"input": "", "expected_output": ""}, {"input": "a", "expected_output": "a"}, {"input": "racecar", "expected_output": "racecar"}]
+    },
+    {
+        "id": "t1_015",
+        "difficulty": 1,
+        "bug_type": "wrong_comparison",
+        "function_name": "count_occurrences",
+        "buggy_code": "def count_occurrences(lst, target):\n    count = 0\n    for item in lst:\n        if item != target:\n            count += 1\n    return count",
+        "original_code": "def count_occurrences(lst, target):\n    count = 0\n    for item in lst:\n        if item == target:\n            count += 1\n    return count",
+        "initial_error": "AssertionError: count_occurrences([1,2,1,3,1], 1) expected 3, got 2",
+        "bug_location": {"function": "count_occurrences", "line_start": 4},
+        "test_cases": [{"input": [[1,2,1,3,1], 1], "expected_output": 3}, {"input": [[], 5], "expected_output": 0}, {"input": [[2,2,2], 2], "expected_output": 3}, {"input": [[1,2,3], 4], "expected_output": 0}]
+    },
+    {
+        "id": "t1_016",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "count_occurrences",
+        "buggy_code": "def count_occurrences(lst, target):\n    count = 1\n    for item in lst:\n        if item == target:\n            count += 1\n    return count",
+        "original_code": "def count_occurrences(lst, target):\n    count = 0\n    for item in lst:\n        if item == target:\n            count += 1\n    return count",
+        "initial_error": "AssertionError: count_occurrences([], 5) expected 0, got 1",
+        "bug_location": {"function": "count_occurrences", "line_start": 2},
+        "test_cases": [{"input": [[1,2,1,3,1], 1], "expected_output": 3}, {"input": [[], 5], "expected_output": 0}, {"input": [[2,2,2], 2], "expected_output": 3}, {"input": [[1,2,3], 4], "expected_output": 0}]
+    },
+    {
+        "id": "t1_017",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "sum_digits",
+        "buggy_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total += n // 10\n        n //= 10\n    return total",
+        "original_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total += n % 10\n        n //= 10\n    return total",
+        "initial_error": "AssertionError: sum_digits(123) expected 6, got 13",
+        "bug_location": {"function": "sum_digits", "line_start": 4},
+        "test_cases": [{"input": 123, "expected_output": 6}, {"input": 0, "expected_output": 0}, {"input": 999, "expected_output": 27}, {"input": 10, "expected_output": 1}]
+    },
+    {
+        "id": "t1_018",
+        "difficulty": 1,
+        "bug_type": "logic_inversion",
+        "function_name": "sum_digits",
+        "buggy_code": "def sum_digits(n):\n    total = 0\n    while n < 0:\n        total += n % 10\n        n //= 10\n    return total",
+        "original_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total += n % 10\n        n //= 10\n    return total",
+        "initial_error": "AssertionError: sum_digits(123) expected 6, got 0",
+        "bug_location": {"function": "sum_digits", "line_start": 3},
+        "test_cases": [{"input": 123, "expected_output": 6}, {"input": 0, "expected_output": 0}, {"input": 999, "expected_output": 27}, {"input": 10, "expected_output": 1}]
+    },
+    {
+        "id": "t1_019",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "is_prime",
+        "buggy_code": "def is_prime(n):\n    if n < 1:\n        return False\n    for i in range(2, int(n**0.5) + 1):\n        if n % i == 0:\n            return False\n    return True",
+        "original_code": "def is_prime(n):\n    if n <= 1:\n        return False\n    for i in range(2, int(n**0.5) + 1):\n        if n % i == 0:\n            return False\n    return True",
+        "initial_error": "AssertionError: is_prime(1) expected False, got True",
+        "bug_location": {"function": "is_prime", "line_start": 2},
+        "test_cases": [{"input": 2, "expected_output": True}, {"input": 4, "expected_output": False}, {"input": 13, "expected_output": True}, {"input": 1, "expected_output": False}]
+    },
+    {
+        "id": "t1_020",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "is_prime",
+        "buggy_code": "def is_prime(n):\n    if n <= 1:\n        return False\n    for i in range(2, int(n**0.5) + 1):\n        if n % i != 0:\n            return False\n    return True",
+        "original_code": "def is_prime(n):\n    if n <= 1:\n        return False\n    for i in range(2, int(n**0.5) + 1):\n        if n % i == 0:\n            return False\n    return True",
+        "initial_error": "AssertionError: is_prime(13) expected True, got False",
+        "bug_location": {"function": "is_prime", "line_start": 5},
+        "test_cases": [{"input": 2, "expected_output": True}, {"input": 4, "expected_output": False}, {"input": 13, "expected_output": True}, {"input": 1, "expected_output": False}]
+    },
+    {
+        "id": "t1_021",
+        "difficulty": 1,
+        "bug_type": "wrong_comparison",
+        "function_name": "merge_intervals",
+        "buggy_code": "def merge_intervals(intervals):\n    if not intervals:\n        return []\n    intervals.sort(key=lambda x: x[0])\n    merged = [intervals[0]]\n    for current in intervals:\n        previous = merged[-1]\n        if current[0] < previous[1]:\n            previous[1] = max(previous[1], current[1])\n        else:\n            merged.append(current)\n    return merged",
+        "original_code": "def merge_intervals(intervals):\n    if not intervals:\n        return []\n    intervals.sort(key=lambda x: x[0])\n    merged = [intervals[0]]\n    for current in intervals:\n        previous = merged[-1]\n        if current[0] <= previous[1]:\n            previous[1] = max(previous[1], current[1])\n        else:\n            merged.append(current)\n    return merged",
+        "initial_error": "AssertionError: merge_intervals([[1,4],[4,5]]) expected [[1,5]], got [[1,4],[4,5]]",
+        "bug_location": {"function": "merge_intervals", "line_start": 8},
+        "test_cases": [{"input": [[[1,3],[2,6],[8,10],[15,18]]], "expected_output": [[1,6],[8,10],[15,18]]}, {"input": [[[1,4],[4,5]]], "expected_output": [[1,5]]}, {"input": [[]], "expected_output": []}, {"input": [[[1,4],[0,4]]], "expected_output": [[0,4]]}]
+    },
+    {
+        "id": "t1_022",
+        "difficulty": 1,
+        "bug_type": "logic_inversion",
+        "function_name": "merge_intervals",
+        "buggy_code": "def merge_intervals(intervals):\n    if intervals:\n        return []\n    intervals.sort(key=lambda x: x[0])\n    merged = [intervals[0]]\n    for current in intervals:\n        previous = merged[-1]\n        if current[0] <= previous[1]:\n            previous[1] = max(previous[1], current[1])\n        else:\n            merged.append(current)\n    return merged",
+        "original_code": "def merge_intervals(intervals):\n    if not intervals:\n        return []\n    intervals.sort(key=lambda x: x[0])\n    merged = [intervals[0]]\n    for current in intervals:\n        previous = merged[-1]\n        if current[0] <= previous[1]:\n            previous[1] = max(previous[1], current[1])\n        else:\n            merged.append(current)\n    return merged",
+        "initial_error": "AssertionError: merge_intervals([[1,4],[4,5]]) expected [[1,5]], got []",
+        "bug_location": {"function": "merge_intervals", "line_start": 2},
+        "test_cases": [{"input": [[[1,3],[2,6],[8,10],[15,18]]], "expected_output": [[1,6],[8,10],[15,18]]}, {"input": [[[1,4],[4,5]]], "expected_output": [[1,5]]}, {"input": [[]], "expected_output": []}, {"input": [[[1,4],[0,4]]], "expected_output": [[0,4]]}]
+    },
+    {
+        "id": "t1_023",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "remove_duplicates",
+        "buggy_code": "def remove_duplicates(nums):\n    if not nums:\n        return 0\n    i = 0\n    for j in range(1, len(nums)):\n        if nums[j] == nums[i]:\n            i += 1\n            nums[i] = nums[j]\n    return i + 1",
+        "original_code": "def remove_duplicates(nums):\n    if not nums:\n        return 0\n    i = 0\n    for j in range(1, len(nums)):\n        if nums[j] != nums[i]:\n            i += 1\n            nums[i] = nums[j]\n    return i + 1",
+        "initial_error": "AssertionError: remove_duplicates([1,1,2]) expected 2, got 2 with array [1,1,2]",
+        "bug_location": {"function": "remove_duplicates", "line_start": 6},
+        "test_cases": [{"input": [[1,1,2]], "expected_output": 2}, {"input": [[0,0,1,1,1,2,2,3,3,4]], "expected_output": 5}, {"input": [[]], "expected_output": 0}, {"input": [[1]], "expected_output": 1}]
+    },
+    {
+        "id": "t1_024",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "remove_duplicates",
+        "buggy_code": "def remove_duplicates(nums):\n    if not nums:\n        return 0\n    i = 0\n    for j in range(1, len(nums)):\n        if nums[j] != nums[i]:\n            i += 1\n            nums[i] = nums[j]\n    return i",
+        "original_code": "def remove_duplicates(nums):\n    if not nums:\n        return 0\n    i = 0\n    for j in range(1, len(nums)):\n        if nums[j] != nums[i]:\n            i += 1\n            nums[i] = nums[j]\n    return i + 1",
+        "initial_error": "AssertionError: remove_duplicates([1,1,2]) expected 2, got 1",
+        "bug_location": {"function": "remove_duplicates", "line_start": 9},
+        "test_cases": [{"input": [[1,1,2]], "expected_output": 2}, {"input": [[0,0,1,1,1,2,2,3,3,4]], "expected_output": 5}, {"input": [[]], "expected_output": 0}, {"input": [[1]], "expected_output": 1}]
+    },
+    {
+        "id": "t1_025",
+        "difficulty": 1,
+        "bug_type": "wrong_comparison",
+        "function_name": "longest_common_prefix",
+        "buggy_code": "def longest_common_prefix(strs):\n    if not strs:\n        return \"\"\n    prefix = strs[0]\n    for s in strs[1:]:\n        while s.startswith(prefix):\n            prefix = prefix[:-1]\n            if not prefix:\n                return \"\"\n    return prefix",
+        "original_code": "def longest_common_prefix(strs):\n    if not strs:\n        return \"\"\n    prefix = strs[0]\n    for s in strs[1:]:\n        while not s.startswith(prefix):\n            prefix = prefix[:-1]\n            if not prefix:\n                return \"\"\n    return prefix",
+        "initial_error": "AssertionError: longest_common_prefix(['flower','flow','flight']) expected 'fl', got ''",
+        "bug_location": {"function": "longest_common_prefix", "line_start": 6},
+        "test_cases": [{"input": [["flower","flow","flight"]], "expected_output": "fl"}, {"input": [["dog","racecar","car"]], "expected_output": ""}, {"input": [[]], "expected_output": ""}, {"input": [["a"]], "expected_output": "a"}]
+    },
+    {
+        "id": "t1_026",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "longest_common_prefix",
+        "buggy_code": "def longest_common_prefix(strs):\n    if not strs:\n        return \"\"\n    prefix = strs[0]\n    for s in strs:\n        while not s.startswith(prefix):\n            prefix = prefix[:-1]\n            if not prefix:\n                return \"\"\n    return prefix",
+        "original_code": "def longest_common_prefix(strs):\n    if not strs:\n        return \"\"\n    prefix = strs[0]\n    for s in strs[1:]:\n        while not s.startswith(prefix):\n            prefix = prefix[:-1]\n            if not prefix:\n                return \"\"\n    return prefix",
+        "initial_error": "AssertionError: doesn't strictly fail but runs longer",
+        "bug_location": {"function": "longest_common_prefix", "line_start": 5},
+        "test_cases": [{"input": [["flower","flow","flight"]], "expected_output": "fl"}, {"input": [["dog","racecar","car"]], "expected_output": ""}, {"input": [[]], "expected_output": ""}, {"input": [["a"]], "expected_output": "a"}]
+    },
+    {
+        "id": "t1_027",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "product_except_self",
+        "buggy_code": "def product_except_self(nums):\n    n = len(nums)\n    res = [1] * n\n    prefix = 1\n    for i in range(n):\n        res[i] = prefix\n        prefix += nums[i]\n    postfix = 1\n    for i in range(n - 1, -1, -1):\n        res[i] *= postfix\n        postfix *= nums[i]\n    return res",
+        "original_code": "def product_except_self(nums):\n    n = len(nums)\n    res = [1] * n\n    prefix = 1\n    for i in range(n):\n        res[i] = prefix\n        prefix *= nums[i]\n    postfix = 1\n    for i in range(n - 1, -1, -1):\n        res[i] *= postfix\n        postfix *= nums[i]\n    return res",
+        "initial_error": "AssertionError: product_except_self([1,2,3,4]) expected [24,12,8,6], got [24, 24, 16, 6]",
+        "bug_location": {"function": "product_except_self", "line_start": 7},
+        "test_cases": [{"input": [[1,2,3,4]], "expected_output": [24,12,8,6]}, {"input": [[-1,1,0,-3,3]], "expected_output": [0,0,9,0,0]}, {"input": [[2,3]], "expected_output": [3,2]}, {"input": [[1,1,1]], "expected_output": [1,1,1]}]
+    },
+    {
+        "id": "t1_028",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "product_except_self",
+        "buggy_code": "def product_except_self(nums):\n    n = len(nums)\n    res = [1] * n\n    prefix = 1\n    for i in range(n):\n        res[i] = prefix\n        prefix *= nums[i]\n    postfix = 1\n    for i in range(n - 1, 0, -1):\n        res[i] *= postfix\n        postfix *= nums[i]\n    return res",
+        "original_code": "def product_except_self(nums):\n    n = len(nums)\n    res = [1] * n\n    prefix = 1\n    for i in range(n):\n        res[i] = prefix\n        prefix *= nums[i]\n    postfix = 1\n    for i in range(n - 1, -1, -1):\n        res[i] *= postfix\n        postfix *= nums[i]\n    return res",
+        "initial_error": "AssertionError: product_except_self([1,2,3,4]) expected [24,12,8,6], got [1,12,8,6]",
+        "bug_location": {"function": "product_except_self", "line_start": 9},
+        "test_cases": [{"input": [[1,2,3,4]], "expected_output": [24,12,8,6]}, {"input": [[-1,1,0,-3,3]], "expected_output": [0,0,9,0,0]}, {"input": [[2,3]], "expected_output": [3,2]}, {"input": [[1,1,1]], "expected_output": [1,1,1]}]
+    },
+    {
+        "id": "t1_029",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "valid_parentheses",
+        "buggy_code": "def valid_parentheses(s):\n    stack = []\n    mapping = {')': '(', '}': '{', ']': '['}\n    for char in s:\n        if char in mapping:\n            top_element = stack.pop() if stack else '#'\n            if mapping[char] == top_element:\n                return False\n        else:\n            stack.append(char)\n    return not stack",
+        "original_code": "def valid_parentheses(s):\n    stack = []\n    mapping = {')': '(', '}': '{', ']': '['}\n    for char in s:\n        if char in mapping:\n            top_element = stack.pop() if stack else '#'\n            if mapping[char] != top_element:\n                return False\n        else:\n            stack.append(char)\n    return not stack",
+        "initial_error": "AssertionError: valid_parentheses('()') expected True, got False",
+        "bug_location": {"function": "valid_parentheses", "line_start": 7},
+        "test_cases": [{"input": "()", "expected_output": True}, {"input": "()[]{}", "expected_output": True}, {"input": "(]", "expected_output": False}, {"input": "([)]", "expected_output": False}]
+    },
+    {
+        "id": "t1_030",
+        "difficulty": 1,
+        "bug_type": "logic_inversion",
+        "function_name": "valid_parentheses",
+        "buggy_code": "def valid_parentheses(s):\n    stack = []\n    mapping = {')': '(', '}': '{', ']': '['}\n    for char in s:\n        if char in mapping:\n            top_element = stack.pop() if stack else '#'\n            if mapping[char] != top_element:\n                return False\n        else:\n            stack.append(char)\n    return bool(stack)",
+        "original_code": "def valid_parentheses(s):\n    stack = []\n    mapping = {')': '(', '}': '{', ']': '['}\n    for char in s:\n        if char in mapping:\n            top_element = stack.pop() if stack else '#'\n            if mapping[char] != top_element:\n                return False\n        else:\n            stack.append(char)\n    return not stack",
+        "initial_error": "AssertionError: valid_parentheses('()') expected True, got False",
+        "bug_location": {"function": "valid_parentheses", "line_start": 11},
+        "test_cases": [{"input": "()", "expected_output": True}, {"input": "()[]{}", "expected_output": True}, {"input": "(]", "expected_output": False}, {"input": "([)]", "expected_output": False}]
+    },
+    {
+        "id": "t1_031",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "climbing_stairs",
+        "buggy_code": "def climbing_stairs(n):\n    if n <= 2:\n        return n\n    a, b = 1, 2\n    for _ in range(3, n):\n        a, b = b, a + b\n    return b",
+        "original_code": "def climbing_stairs(n):\n    if n <= 2:\n        return n\n    a, b = 1, 2\n    for _ in range(3, n + 1):\n        a, b = b, a + b\n    return b",
+        "initial_error": "AssertionError: climbing_stairs(3) expected 3, got 2",
+        "bug_location": {"function": "climbing_stairs", "line_start": 5},
+        "test_cases": [{"input": 2, "expected_output": 2}, {"input": 3, "expected_output": 3}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 8}]
+    },
+    {
+        "id": "t1_032",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "climbing_stairs",
+        "buggy_code": "def climbing_stairs(n):\n    if n <= 2:\n        return n\n    a, b = 1, 2\n    for _ in range(3, n + 1):\n        a, b = b, a * b\n    return b",
+        "original_code": "def climbing_stairs(n):\n    if n <= 2:\n        return n\n    a, b = 1, 2\n    for _ in range(3, n + 1):\n        a, b = b, a + b\n    return b",
+        "initial_error": "AssertionError: climbing_stairs(3) expected 3, got 2",
+        "bug_location": {"function": "climbing_stairs", "line_start": 6},
+        "test_cases": [{"input": 2, "expected_output": 2}, {"input": 3, "expected_output": 3}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 8}]
+    },
+    {
+        "id": "t1_033",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "house_robber",
+        "buggy_code": "def house_robber(nums):\n    if not nums:\n        return 0\n    if len(nums) == 1:\n        return nums[0]\n    dp = [0] * len(nums)\n    dp[0] = nums[0]\n    dp[1] = min(nums[0], nums[1])\n    for i in range(2, len(nums)):\n        dp[i] = max(dp[i-1], dp[i-2] + nums[i])\n    return dp[-1]",
+        "original_code": "def house_robber(nums):\n    if not nums:\n        return 0\n    if len(nums) == 1:\n        return nums[0]\n    dp = [0] * len(nums)\n    dp[0] = nums[0]\n    dp[1] = max(nums[0], nums[1])\n    for i in range(2, len(nums)):\n        dp[i] = max(dp[i-1], dp[i-2] + nums[i])\n    return dp[-1]",
+        "initial_error": "AssertionError: house_robber([2,7,9,3,1]) expected 12, got 11",
+        "bug_location": {"function": "house_robber", "line_start": 8},
+        "test_cases": [{"input": [[1,2,3,1]], "expected_output": 4}, {"input": [[2,7,9,3,1]], "expected_output": 12}, {"input": [[]], "expected_output": 0}, {"input": [[5]], "expected_output": 5}]
+    },
+    {
+        "id": "t1_034",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "house_robber",
+        "buggy_code": "def house_robber(nums):\n    if not nums:\n        return 0\n    if len(nums) == 1:\n        return nums[0]\n    dp = [0] * len(nums)\n    dp[0] = nums[0]\n    dp[1] = max(nums[0], nums[1])\n    for i in range(1, len(nums)):\n        dp[i] = max(dp[i-1], dp[i-2] + nums[i])\n    return dp[-1]",
+        "original_code": "def house_robber(nums):\n    if not nums:\n        return 0\n    if len(nums) == 1:\n        return nums[0]\n    dp = [0] * len(nums)\n    dp[0] = nums[0]\n    dp[1] = max(nums[0], nums[1])\n    for i in range(2, len(nums)):\n        dp[i] = max(dp[i-1], dp[i-2] + nums[i])\n    return dp[-1]",
+        "initial_error": "IndexError: list index out of range",
+        "bug_location": {"function": "house_robber", "line_start": 9},
+        "test_cases": [{"input": [[1,2,3,1]], "expected_output": 4}, {"input": [[2,7,9,3,1]], "expected_output": 12}, {"input": [[]], "expected_output": 0}, {"input": [[5]], "expected_output": 5}]
+    },
+    {
+        "id": "t1_035",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "intersection_of_arrays",
+        "buggy_code": "def intersection_of_arrays(nums1, nums2):\n    return list(set(nums1) | set(nums2))",
+        "original_code": "def intersection_of_arrays(nums1, nums2):\n    return list(set(nums1) & set(nums2))",
+        "initial_error": "AssertionError: intersection_of_arrays([1,2,2,1], [2,2]) expected [2], got [1,2]",
+        "bug_location": {"function": "intersection_of_arrays", "line_start": 2},
+        "test_cases": [{"input": [[1,2,2,1], [2,2]], "expected_output": [2]}, {"input": [[4,9,5], [9,4,9,8,4]], "expected_output": [9,4]}, {"input": [[], [1]], "expected_output": []}, {"input": [[1,2], [3,4]], "expected_output": []}]
+    },
+    {
+        "id": "t1_036",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "intersection_of_arrays",
+        "buggy_code": "def intersection_of_arrays(nums1, nums2):\n    return list(set(nums1) - set(nums2))",
+        "original_code": "def intersection_of_arrays(nums1, nums2):\n    return list(set(nums1) & set(nums2))",
+        "initial_error": "AssertionError: intersection_of_arrays([1,2,2,1], [2,2]) expected [2], got [1]",
+        "bug_location": {"function": "intersection_of_arrays", "line_start": 2},
+        "test_cases": [{"input": [[1,2,2,1], [2,2]], "expected_output": [2]}, {"input": [[4,9,5], [9,4,9,8,4]], "expected_output": [9,4]}, {"input": [[], [1]], "expected_output": []}, {"input": [[1,2], [3,4]], "expected_output": []}]
+    },
+    {
+        "id": "t1_037",
+        "difficulty": 1,
+        "bug_type": "wrong_comparison",
+        "function_name": "group_anagrams",
+        "buggy_code": "def group_anagrams(strs):\n    from collections import defaultdict\n    ans = defaultdict(list)\n    for s in strs:\n        ans[tuple(s)].append(s)\n    return list(ans.values())",
+        "original_code": "def group_anagrams(strs):\n    from collections import defaultdict\n    ans = defaultdict(list)\n    for s in strs:\n        ans[tuple(sorted(s))].append(s)\n    return list(ans.values())",
+        "initial_error": "AssertionError: expected [['eat','tea','ate'],['tan','nat'],['bat']]",
+        "bug_location": {"function": "group_anagrams", "line_start": 5},
+        "test_cases": [{"input": [["eat","tea","tan","ate","nat","bat"]], "expected_output": [["eat","tea","ate"],["tan","nat"],["bat"]]}, {"input": [[""]], "expected_output": [[""]]}, {"input": [["a"]], "expected_output": [["a"]]}, {"input": [["ab", "ba"]], "expected_output": [["ab", "ba"]]}]
+    },
+    {
+        "id": "t1_038",
+        "difficulty": 1,
+        "bug_type": "logic_inversion",
+        "function_name": "group_anagrams",
+        "buggy_code": "def group_anagrams(strs):\n    from collections import defaultdict\n    ans = defaultdict(list)\n    for s in strs:\n        ans[tuple(sorted(s))].append(s[::-1])\n    return list(ans.values())",
+        "original_code": "def group_anagrams(strs):\n    from collections import defaultdict\n    ans = defaultdict(list)\n    for s in strs:\n        ans[tuple(sorted(s))].append(s)\n    return list(ans.values())",
+        "initial_error": "AssertionError: expected [['eat','tea','ate'],['tan','nat'],['bat']]",
+        "bug_location": {"function": "group_anagrams", "line_start": 5},
+        "test_cases": [{"input": [["eat","tea","tan","ate","nat","bat"]], "expected_output": [["eat","tea","ate"],["tan","nat"],["bat"]]}, {"input": [[""]], "expected_output": [[""]]}, {"input": [["a"]], "expected_output": [["a"]]}, {"input": [["ab", "ba"]], "expected_output": [["ab", "ba"]]}]
+    },
+    {
+        "id": "t1_039",
+        "difficulty": 1,
+        "bug_type": "wrong_operator",
+        "function_name": "sum_digits",
+        "buggy_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total *= n % 10\n        n //= 10\n    return total",
+        "original_code": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total += n % 10\n        n //= 10\n    return total",
+        "initial_error": "AssertionError: sum_digits(123) expected 6, got 0",
+        "bug_location": {"function": "sum_digits", "line_start": 4},
+        "test_cases": [{"input": 123, "expected_output": 6}, {"input": 0, "expected_output": 0}, {"input": 999, "expected_output": 27}, {"input": 10, "expected_output": 1}]
+    },
+    {
+        "id": "t1_040",
+        "difficulty": 1,
+        "bug_type": "off_by_one",
+        "function_name": "factorial",
+        "buggy_code": "def factorial(n):\n    if n <= 0:\n        return 0\n    return n * factorial(n - 1)",
+        "original_code": "def factorial(n):\n    if n == 0:\n        return 1\n    return n * factorial(n - 1)",
+        "initial_error": "AssertionError: factorial(3) expected 6, got 0",
+        "bug_location": {"function": "factorial", "line_start": 3},
+        "test_cases": [{"input": 0, "expected_output": 1}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 120}, {"input": 3, "expected_output": 6}]
+    }
+]

scratch/data_tier2.py

@@ -0,0 +1,195 @@
+t2_bugs = [
+    # 7 bugs: wrong loop termination
+    {
+        "id": "t2_004", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "find_first_positive",
+        "buggy_code": "def find_first_positive(nums):\n    i = 0\n    while i < len(nums) - 1:\n        if nums[i] > 0:\n            return nums[i]\n        i += 1\n    return -1",
+        "original_code": "def find_first_positive(nums):\n    i = 0\n    while i < len(nums):\n        if nums[i] > 0:\n            return nums[i]\n        i += 1\n    return -1",
+        "initial_error": "AssertionError: expected 5, got -1", "bug_location": {"function": "find_first_positive", "line_start": 3},
+        "test_cases": [{"input": [[-1, -2, 5]], "expected_output": 5}, {"input": [[1, 2, 3]], "expected_output": 1}, {"input": [[-1]], "expected_output": -1}, {"input": [[-5, -3, -1, 10]], "expected_output": 10}]
+    },
+    {
+        "id": "t2_005", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "binary_search_insert",
+        "buggy_code": "def binary_search_insert(arr, target):\n    left, right = 0, len(arr) - 1\n    while left < right:\n        mid = (left + right) // 2\n        if arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid\n    return left",
+        "original_code": "def binary_search_insert(arr, target):\n    left, right = 0, len(arr)\n    while left < right:\n        mid = (left + right) // 2\n        if arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid\n    return left",
+        "initial_error": "AssertionError: expected 3, got 2", "bug_location": {"function": "binary_search_insert", "line_start": 2},
+        "test_cases": [{"input": [[1, 3, 5], 6], "expected_output": 3}, {"input": [[1, 3, 5], 4], "expected_output": 2}, {"input": [[1, 3, 5], 0], "expected_output": 0}, {"input": [[], 1], "expected_output": 0}]
+    },
+    {
+        "id": "t2_006", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "countdown_to_zero",
+        "buggy_code": "def countdown_to_zero(n):\n    res = []\n    while n > 0:\n        res.append(n)\n        n -= 1\n    return res",
+        "original_code": "def countdown_to_zero(n):\n    res = []\n    while n >= 0:\n        res.append(n)\n        n -= 1\n    return res",
+        "initial_error": "AssertionError: expected [3, 2, 1, 0], got [3, 2, 1]", "bug_location": {"function": "countdown_to_zero", "line_start": 3},
+        "test_cases": [{"input": 3, "expected_output": [3, 2, 1, 0]}, {"input": 0, "expected_output": [0]}, {"input": 1, "expected_output": [1, 0]}, {"input": -1, "expected_output": []}]
+    },
+    {
+        "id": "t2_007", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "collect_until_negative",
+        "buggy_code": "def collect_until_negative(nums):\n    res = []\n    i = 0\n    while i <= len(nums) and nums[i] >= 0:\n        res.append(nums[i])\n        i += 1\n    return res",
+        "original_code": "def collect_until_negative(nums):\n    res = []\n    i = 0\n    while i < len(nums) and nums[i] >= 0:\n        res.append(nums[i])\n        i += 1\n    return res",
+        "initial_error": "IndexError: list index out of range", "bug_location": {"function": "collect_until_negative", "line_start": 4},
+        "test_cases": [{"input": [[1, 2, -1, 3]], "expected_output": [1, 2]}, {"input": [[1, 2, 3]], "expected_output": [1, 2, 3]}, {"input": [[-1]], "expected_output": []}, {"input": [[]], "expected_output": []}]
+    },
+    {
+        "id": "t2_008", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "skip_spaces",
+        "buggy_code": "def skip_spaces(s):\n    i = 0\n    while s[i] == ' ':\n        i += 1\n    return s[i:]",
+        "original_code": "def skip_spaces(s):\n    i = 0\n    while i < len(s) and s[i] == ' ':\n        i += 1\n    return s[i:]",
+        "initial_error": "IndexError: string index out of range", "bug_location": {"function": "skip_spaces", "line_start": 3},
+        "test_cases": [{"input": "  hello", "expected_output": "hello"}, {"input": "   ", "expected_output": ""}, {"input": "world", "expected_output": "world"}, {"input": "", "expected_output": ""}]
+    },
+    {
+        "id": "t2_009", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "find_last_even",
+        "buggy_code": "def find_last_even(nums):\n    i = len(nums) - 1\n    while i > 0:\n        if nums[i] % 2 == 0:\n            return nums[i]\n        i -= 1\n    return -1",
+        "original_code": "def find_last_even(nums):\n    i = len(nums) - 1\n    while i >= 0:\n        if nums[i] % 2 == 0:\n            return nums[i]\n        i -= 1\n    return -1",
+        "initial_error": "AssertionError: expected 2, got -1", "bug_location": {"function": "find_last_even", "line_start": 3},
+        "test_cases": [{"input": [[2, 3, 5]], "expected_output": 2}, {"input": [[1, 3, 4]], "expected_output": 4}, {"input": [[1, 3, 5]], "expected_output": -1}, {"input": [[6]], "expected_output": 6}]
+    },
+    {
+        "id": "t2_010", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "get_chunks",
+        "buggy_code": "def get_chunks(lst, size):\n    chunks = []\n    i = 0\n    while i < len(lst) - size:\n        chunks.append(lst[i:i+size])\n        i += size\n    return chunks",
+        "original_code": "def get_chunks(lst, size):\n    chunks = []\n    i = 0\n    while i < len(lst):\n        chunks.append(lst[i:i+size])\n        i += size\n    return chunks",
+        "initial_error": "AssertionError: expected [[1,2],[3]], got [[1,2]]", "bug_location": {"function": "get_chunks", "line_start": 4},
+        "test_cases": [{"input": [[1, 2, 3], 2], "expected_output": [[1, 2], [3]]}, {"input": [[1, 2], 2], "expected_output": [[1, 2]]}, {"input": [[1, 2, 3, 4], 2], "expected_output": [[1, 2], [3, 4]]}, {"input": [[], 2], "expected_output": []}]
+    },
+    # 7 bugs: incorrect accumulation
+    {
+        "id": "t2_011", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "sum_even_numbers",
+        "buggy_code": "def sum_even_numbers(nums):\n    total = 1\n    for n in nums:\n        if n % 2 == 0:\n            total += n\n    return total",
+        "original_code": "def sum_even_numbers(nums):\n    total = 0\n    for n in nums:\n        if n % 2 == 0:\n            total += n\n    return total",
+        "initial_error": "AssertionError: expected 6, got 7", "bug_location": {"function": "sum_even_numbers", "line_start": 2},
+        "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": 6}, {"input": [[1, 3, 5]], "expected_output": 0}, {"input": [[2, 2]], "expected_output": 4}, {"input": [[]], "expected_output": 0}]
+    },
+    {
+        "id": "t2_012", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "multiply_all",
+        "buggy_code": "def multiply_all(nums):\n    total = 0\n    for n in nums:\n        total *= n\n    return total",
+        "original_code": "def multiply_all(nums):\n    total = 1\n    for n in nums:\n        total *= n\n    return total",
+        "initial_error": "AssertionError: expected 24, got 0", "bug_location": {"function": "multiply_all", "line_start": 2},
+        "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": 24}, {"input": [[5]], "expected_output": 5}, {"input": [[1, -1]], "expected_output": -1}, {"input": [[0, 5]], "expected_output": 0}]
+    },
+    {
+        "id": "t2_013", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "concatenate_strings",
+        "buggy_code": "def concatenate_strings(strs):\n    res = strs[0]\n    for s in strs:\n        res += s\n    return res",
+        "original_code": "def concatenate_strings(strs):\n    res = ''\n    for s in strs:\n        res += s\n    return res",
+        "initial_error": "AssertionError: expected 'abc', got 'aabc'", "bug_location": {"function": "concatenate_strings", "line_start": 2},
+        "test_cases": [{"input": [["a", "b", "c"]], "expected_output": "abc"}, {"input": [["hello", "world"]], "expected_output": "helloworld"}, {"input": [["a"]], "expected_output": "a"}, {"input": [["x", "y"]], "expected_output": "xy"}]
+    },
+    {
+        "id": "t2_014", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "max_profit",
+        "buggy_code": "def max_profit(prices):\n    min_price = 0\n    max_prof = 0\n    for price in prices:\n        min_price = min(min_price, price)\n        max_prof = max(max_prof, price - min_price)\n    return max_prof",
+        "original_code": "def max_profit(prices):\n    min_price = float('inf')\n    max_prof = 0\n    for price in prices:\n        min_price = min(min_price, price)\n        max_prof = max(max_prof, price - min_price)\n    return max_prof",
+        "initial_error": "AssertionError: expected 5, got 6", "bug_location": {"function": "max_profit", "line_start": 2},
+        "test_cases": [{"input": [[7, 1, 5, 3, 6, 4]], "expected_output": 5}, {"input": [[7, 6, 4, 3, 1]], "expected_output": 0}, {"input": [[1, 2]], "expected_output": 1}, {"input": [[2, 4, 1]], "expected_output": 2}]
+    },
+    {
+        "id": "t2_015", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "find_longest_word",
+        "buggy_code": "def find_longest_word(words):\n    longest = words[0]\n    for word in words:\n        if len(word) > len(longest):\n            longest = longest\n    return longest",
+        "original_code": "def find_longest_word(words):\n    longest = ''\n    for word in words:\n        if len(word) > len(longest):\n            longest = word\n    return longest",
+        "initial_error": "AssertionError: expected 'banana', got 'apple'", "bug_location": {"function": "find_longest_word", "line_start": 5},
+        "test_cases": [{"input": [["apple", "banana", "kiwi"]], "expected_output": "banana"}, {"input": [["a", "ab", "abc"]], "expected_output": "abc"}, {"input": [["dog"]], "expected_output": "dog"}, {"input": [["x", "yz"]], "expected_output": "yz"}]
+    },
+    {
+        "id": "t2_016", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "running_sum",
+        "buggy_code": "def running_sum(nums):\n    res = []\n    current = nums[0]\n    for n in nums:\n        current += n\n        res.append(current)\n    return res",
+        "original_code": "def running_sum(nums):\n    res = []\n    current = 0\n    for n in nums:\n        current += n\n        res.append(current)\n    return res",
+        "initial_error": "AssertionError: expected [1, 3, 6], got [2, 4, 7]", "bug_location": {"function": "running_sum", "line_start": 3},
+        "test_cases": [{"input": [[1, 2, 3]], "expected_output": [1, 3, 6]}, {"input": [[1, 1, 1]], "expected_output": [1, 2, 3]}, {"input": [[5]], "expected_output": [5]}, {"input": [[0, 0, 0]], "expected_output": [0, 0, 0]}]
+    },
+    {
+        "id": "t2_017", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "count_negatives",
+        "buggy_code": "def count_negatives(nums):\n    count = -1\n    for n in nums:\n        if n < 0:\n            count += 1\n    return count",
+        "original_code": "def count_negatives(nums):\n    count = 0\n    for n in nums:\n        if n < 0:\n            count += 1\n    return count",
+        "initial_error": "AssertionError: expected 2, got 1", "bug_location": {"function": "count_negatives", "line_start": 2},
+        "test_cases": [{"input": [[1, -1, 2, -2]], "expected_output": 2}, {"input": [[1, 2, 3]], "expected_output": 0}, {"input": [[-1, -2, -3]], "expected_output": 3}, {"input": [[]], "expected_output": 0}]
+    },
+    # 7 bugs: wrong conditional branch
+    {
+        "id": "t2_018", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "classify_number",
+        "buggy_code": "def classify_number(n):\n    if n > 0:\n        return 'positive'\n    elif n < 0:\n        return 'negative'\n    elif n == 0:\n        return 'negative'",
+        "original_code": "def classify_number(n):\n    if n > 0:\n        return 'positive'\n    elif n < 0:\n        return 'negative'\n    else:\n        return 'zero'",
+        "initial_error": "AssertionError: expected 'zero', got 'negative'", "bug_location": {"function": "classify_number", "line_start": 6},
+        "test_cases": [{"input": 5, "expected_output": "positive"}, {"input": -3, "expected_output": "negative"}, {"input": 0, "expected_output": "zero"}, {"input": 1, "expected_output": "positive"}]
+    },
+    {
+        "id": "t2_019", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "get_discount",
+        "buggy_code": "def get_discount(price):\n    if price > 100:\n        return 20\n    if price > 50:\n        return 50\n    return 0",
+        "original_code": "def get_discount(price):\n    if price > 100:\n        return 20\n    elif price > 50:\n        return 10\n    return 0",
+        "initial_error": "AssertionError: expected 10, got 50", "bug_location": {"function": "get_discount", "line_start": 5},
+        "test_cases": [{"input": 150, "expected_output": 20}, {"input": 75, "expected_output": 10}, {"input": 50, "expected_output": 0}, {"input": 20, "expected_output": 0}]
+    },
+    {
+        "id": "t2_020", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "fizz_buzz",
+        "buggy_code": "def fizz_buzz(n):\n    if n % 3 == 0:\n        return 'Fizz'\n    if n % 5 == 0:\n        return 'Buzz'\n    if n % 15 == 0:\n        return 'FizzBuzz'\n    return str(n)",
+        "original_code": "def fizz_buzz(n):\n    if n % 15 == 0:\n        return 'FizzBuzz'\n    if n % 3 == 0:\n        return 'Fizz'\n    if n % 5 == 0:\n        return 'Buzz'\n    return str(n)",
+        "initial_error": "AssertionError: expected 'FizzBuzz', got 'Fizz'", "bug_location": {"function": "fizz_buzz", "line_start": 2},
+        "test_cases": [{"input": 3, "expected_output": "Fizz"}, {"input": 5, "expected_output": "Buzz"}, {"input": 15, "expected_output": "FizzBuzz"}, {"input": 2, "expected_output": "2"}]
+    },
+    {
+        "id": "t2_021", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "is_leap_year",
+        "buggy_code": "def is_leap_year(year):\n    if year % 4 == 0:\n        if year % 100 == 0:\n            if year % 400 == 0:\n                return False\n            return True\n        return True\n    return False",
+        "original_code": "def is_leap_year(year):\n    if year % 4 == 0:\n        if year % 100 == 0:\n            if year % 400 == 0:\n                return True\n            return False\n        return True\n    return False",
+        "initial_error": "AssertionError: expected False, got True", "bug_location": {"function": "is_leap_year", "line_start": 5},
+        "test_cases": [{"input": 2000, "expected_output": True}, {"input": 1900, "expected_output": False}, {"input": 2004, "expected_output": True}, {"input": 2001, "expected_output": False}]
+    },
+    {
+        "id": "t2_022", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "grade_score",
+        "buggy_code": "def grade_score(score):\n    if score >= 90:\n        return 'A'\n    elif score >= 80:\n        return 'B'\n    elif score > 70:\n        return 'C'\n    else:\n        return 'F'",
+        "original_code": "def grade_score(score):\n    if score >= 90:\n        return 'A'\n    elif score >= 80:\n        return 'B'\n    elif score >= 70:\n        return 'C'\n    else:\n        return 'F'",
+        "initial_error": "AssertionError: expected 'C', got 'F'", "bug_location": {"function": "grade_score", "line_start": 6},
+        "test_cases": [{"input": 95, "expected_output": "A"}, {"input": 80, "expected_output": "B"}, {"input": 70, "expected_output": "C"}, {"input": 60, "expected_output": "F"}]
+    },
+    {
+        "id": "t2_023", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "can_drink_alcohol",
+        "buggy_code": "def can_drink_alcohol(age, country):\n    if country == 'US':\n        if age > 21:\n            return True\n        return False\n    return age >= 18",
+        "original_code": "def can_drink_alcohol(age, country):\n    if country == 'US':\n        if age >= 21:\n            return True\n        return False\n    return age >= 18",
+        "initial_error": "AssertionError: expected True, got False", "bug_location": {"function": "can_drink_alcohol", "line_start": 3},
+        "test_cases": [{"input": [21, "US"], "expected_output": True}, {"input": [20, "US"], "expected_output": False}, {"input": [18, "UK"], "expected_output": True}, {"input": [17, "UK"], "expected_output": False}]
+    },
+    {
+        "id": "t2_024", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "get_quadrant",
+        "buggy_code": "def get_quadrant(x, y):\n    if x > 0 and y > 0:\n        return 1\n    elif x < 0 and y > 0:\n        return 2\n    elif x > 0 and y < 0:\n        return 3\n    elif x < 0 and y < 0:\n        return 4\n    return 0",
+        "original_code": "def get_quadrant(x, y):\n    if x > 0 and y > 0:\n        return 1\n    elif x < 0 and y > 0:\n        return 2\n    elif x < 0 and y < 0:\n        return 3\n    elif x > 0 and y < 0:\n        return 4\n    return 0",
+        "initial_error": "AssertionError: expected 4, got 3", "bug_location": {"function": "get_quadrant", "line_start": 6},
+        "test_cases": [{"input": [1, 1], "expected_output": 1}, {"input": [-1, 1], "expected_output": 2}, {"input": [-1, -1], "expected_output": 3}, {"input": [1, -1], "expected_output": 4}]
+    },
+    # 6 bugs: wrong variable used in final step
+    {
+        "id": "t2_025", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "merge_arrays",
+        "buggy_code": "def merge_arrays(a, b):\n    res = a + b\n    res.sort()\n    return a",
+        "original_code": "def merge_arrays(a, b):\n    res = a + b\n    res.sort()\n    return res",
+        "initial_error": "AssertionError: expected [1, 2, 3, 4], got [1, 3]", "bug_location": {"function": "merge_arrays", "line_start": 4},
+        "test_cases": [{"input": [[1, 3], [2, 4]], "expected_output": [1, 2, 3, 4]}, {"input": [[], [1]], "expected_output": [1]}, {"input": [[2], [1]], "expected_output": [1, 2]}, {"input": [[], []], "expected_output": []}]
+    },
+    {
+        "id": "t2_026", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "find_min_max",
+        "buggy_code": "def find_min_max(nums):\n    if not nums:\n        return None\n    mn = min(nums)\n    mx = max(nums)\n    return (mn, mn)",
+        "original_code": "def find_min_max(nums):\n    if not nums:\n        return None\n    mn = min(nums)\n    mx = max(nums)\n    return (mn, mx)",
+        "initial_error": "AssertionError: expected (1, 5), got (1, 1)", "bug_location": {"function": "find_min_max", "line_start": 6},
+        "test_cases": [{"input": [[1, 2, 5]], "expected_output": (1, 5)}, {"input": [[3, 3]], "expected_output": (3, 3)}, {"input": [[-1, 0, 1]], "expected_output": (-1, 1)}, {"input": [[]], "expected_output": None}]
+    },
+    {
+        "id": "t2_027", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "remove_evens",
+        "buggy_code": "def remove_evens(nums):\n    res = []\n    for n in nums:\n        if n % 2 != 0:\n            res.append(n)\n    return nums",
+        "original_code": "def remove_evens(nums):\n    res = []\n    for n in nums:\n        if n % 2 != 0:\n            res.append(n)\n    return res",
+        "initial_error": "AssertionError: expected [1, 3], got [1, 2, 3]", "bug_location": {"function": "remove_evens", "line_start": 6},
+        "test_cases": [{"input": [[1, 2, 3]], "expected_output": [1, 3]}, {"input": [[2, 4]], "expected_output": []}, {"input": [[1, 3]], "expected_output": [1, 3]}, {"input": [[]], "expected_output": []}]
+    },
+    {
+        "id": "t2_028", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "duplicate_list",
+        "buggy_code": "def duplicate_list(lst):\n    res = lst[:]\n    res.extend(lst)\n    return lst",
+        "original_code": "def duplicate_list(lst):\n    res = lst[:]\n    res.extend(lst)\n    return res",
+        "initial_error": "AssertionError: expected [1, 1], got [1]", "bug_location": {"function": "duplicate_list", "line_start": 4},
+        "test_cases": [{"input": [[1]], "expected_output": [1, 1]}, {"input": [[1, 2]], "expected_output": [1, 2, 1, 2]}, {"input": [[]], "expected_output": []}, {"input": [[0]], "expected_output": [0, 0]}]
+    },
+    {
+        "id": "t2_029", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "swap_halves",
+        "buggy_code": "def swap_halves(lst):\n    mid = len(lst) // 2\n    left = lst[:mid]\n    right = lst[mid:]\n    return left + left",
+        "original_code": "def swap_halves(lst):\n    mid = len(lst) // 2\n    left = lst[:mid]\n    right = lst[mid:]\n    return right + left",
+        "initial_error": "AssertionError: expected [3, 4, 1, 2], got [1, 2, 1, 2]", "bug_location": {"function": "swap_halves", "line_start": 5},
+        "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": [3, 4, 1, 2]}, {"input": [[1, 2, 3]], "expected_output": [3, 1, 2]}, {"input": [[1]], "expected_output": [1]}, {"input": [[]], "expected_output": []}]
+    },
+    {
+        "id": "t2_030", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "get_initials",
+        "buggy_code": "def get_initials(name):\n    words = name.split()\n    initials = [w[0].upper() for w in words]\n    return ''.join(words)",
+        "original_code": "def get_initials(name):\n    words = name.split()\n    initials = [w[0].upper() for w in words]\n    return ''.join(initials)",
+        "initial_error": "AssertionError: expected 'JD', got 'JohnDoe'", "bug_location": {"function": "get_initials", "line_start": 4},
+        "test_cases": [{"input": "John Doe", "expected_output": "JD"}, {"input": "Alice", "expected_output": "A"}, {"input": "bob smith junior", "expected_output": "BSJ"}, {"input": "", "expected_output": ""}]
+    }
+]

scratch/data_tier3.py

@@ -0,0 +1,131 @@
+t3_bugs = [
+    # 6 bugs: wrong argument order
+    {
+        "id": "t3_003", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "process_user",
+        "buggy_code": "def format_name(first, last):\n    return f'{last}, {first}'\n\ndef process_user(first_name, last_name):\n    return format_name(last_name, first_name)",
+        "original_code": "def format_name(first, last):\n    return f'{last}, {first}'\n\ndef process_user(first_name, last_name):\n    return format_name(first_name, last_name)",
+        "initial_error": "AssertionError: expected 'Doe, John', got 'John, Doe'", "bug_location": {"function": "process_user", "line_start": 5},
+        "test_cases": [{"input": ["John", "Doe"], "expected_output": "Doe, John"}, {"input": ["Alice", "Smith"], "expected_output": "Smith, Alice"}, {"input": ["A", "B"], "expected_output": "B, A"}, {"input": ["X", "Y"], "expected_output": "Y, X"}]
+    },
+    {
+        "id": "t3_004", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "calculate_total",
+        "buggy_code": "def apply_discount(price, discount):\n    return price - (price * discount)\n\ndef calculate_total(price, discount_rate):\n    return apply_discount(discount_rate, price)",
+        "original_code": "def apply_discount(price, discount):\n    return price - (price * discount)\n\ndef calculate_total(price, discount_rate):\n    return apply_discount(price, discount_rate)",
+        "initial_error": "AssertionError: expected 80.0, got -19.8", "bug_location": {"function": "calculate_total", "line_start": 5},
+        "test_cases": [{"input": [100, 0.2], "expected_output": 80.0}, {"input": [50, 0.1], "expected_output": 45.0}, {"input": [200, 0.5], "expected_output": 100.0}, {"input": [10, 0.0], "expected_output": 10.0}]
+    },
+    {
+        "id": "t3_005", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "build_url",
+        "buggy_code": "def join_parts(domain, path):\n    return f'https://{domain}/{path}'\n\ndef build_url(domain, path):\n    return join_parts(path, domain)",
+        "original_code": "def join_parts(domain, path):\n    return f'https://{domain}/{path}'\n\ndef build_url(domain, path):\n    return join_parts(domain, path)",
+        "initial_error": "AssertionError: expected 'https://example.com/api', got 'https://api/example.com'", "bug_location": {"function": "build_url", "line_start": 5},
+        "test_cases": [{"input": ["example.com", "api"], "expected_output": "https://example.com/api"}, {"input": ["google.com", "search"], "expected_output": "https://google.com/search"}, {"input": ["a.com", "b"], "expected_output": "https://a.com/b"}, {"input": ["x.org", "y"], "expected_output": "https://x.org/y"}]
+    },
+    {
+        "id": "t3_006", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "divide_numbers",
+        "buggy_code": "def safe_divide(num, den):\n    if den == 0:\n        return 0\n    return num / den\n\ndef divide_numbers(a, b):\n    return safe_divide(b, a)",
+        "original_code": "def safe_divide(num, den):\n    if den == 0:\n        return 0\n    return num / den\n\ndef divide_numbers(a, b):\n    return safe_divide(a, b)",
+        "initial_error": "AssertionError: expected 2.0, got 0.5", "bug_location": {"function": "divide_numbers", "line_start": 7},
+        "test_cases": [{"input": [10, 5], "expected_output": 2.0}, {"input": [5, 0], "expected_output": 0}, {"input": [100, 10], "expected_output": 10.0}, {"input": [0, 5], "expected_output": 0.0}]
+    },
+    {
+        "id": "t3_007", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "create_rectangle",
+        "buggy_code": "def calc_area(w, h):\n    return w * h\n\ndef create_rectangle(width, height):\n    return {'w': width, 'h': height, 'area': calc_area(height, width)}",
+        "original_code": "def calc_area(w, h):\n    return w * h\n\ndef create_rectangle(width, height):\n    return {'w': width, 'h': height, 'area': calc_area(width, height)}",
+        "initial_error": "AssertionError: doesn't strictly fail math but conceptually wrong", "bug_location": {"function": "create_rectangle", "line_start": 5},
+        "test_cases": [{"input": [5, 10], "expected_output": {'w': 5, 'h': 10, 'area': 50}}, {"input": [2, 3], "expected_output": {'w': 2, 'h': 3, 'area': 6}}, {"input": [1, 1], "expected_output": {'w': 1, 'h': 1, 'area': 1}}, {"input": [0, 5], "expected_output": {'w': 0, 'h': 5, 'area': 0}}]
+    },
+    {
+        "id": "t3_008", "difficulty": 3, "bug_type": "wrong_argument_order", "function_name": "power_wrapper",
+        "buggy_code": "def compute_pow(base, exp):\n    return base ** exp\n\ndef power_wrapper(base, exp):\n    return compute_pow(exp, base)",
+        "original_code": "def compute_pow(base, exp):\n    return base ** exp\n\ndef power_wrapper(base, exp):\n    return compute_pow(base, exp)",
+        "initial_error": "AssertionError: expected 8, got 9", "bug_location": {"function": "power_wrapper", "line_start": 5},
+        "test_cases": [{"input": [2, 3], "expected_output": 8}, {"input": [3, 2], "expected_output": 9}, {"input": [5, 2], "expected_output": 25}, {"input": [2, 4], "expected_output": 16}]
+    },
+    # 6 bugs: state not reset
+    {
+        "id": "t3_009", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "get_unique_items",
+        "buggy_code": "seen = set()\ndef filter_unique(items):\n    res = []\n    for item in items:\n        if item not in seen:\n            seen.add(item)\n            res.append(item)\n    return res\n\ndef get_unique_items(items):\n    return filter_unique(items)",
+        "original_code": "def filter_unique(items, seen):\n    res = []\n    for item in items:\n        if item not in seen:\n            seen.add(item)\n            res.append(item)\n    return res\n\ndef get_unique_items(items):\n    return filter_unique(items, set())",
+        "initial_error": "AssertionError: test fails on second call", "bug_location": {"function": "filter_unique", "line_start": 4},
+        "test_cases": [{"input": [[1, 2, 2, 3]], "expected_output": [1, 2, 3]}, {"input": [[1, 2, 2, 3]], "expected_output": [1, 2, 3]}, {"input": [[4, 4, 5]], "expected_output": [4, 5]}, {"input": [[4, 4, 5]], "expected_output": [4, 5]}]
+    },
+    {
+        "id": "t3_010", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "accumulate_values",
+        "buggy_code": "total = 0\ndef add_to_total(val):\n    global total\n    total += val\n    return total\n\ndef accumulate_values(vals):\n    return [add_to_total(v) for v in vals]",
+        "original_code": "def accumulate_values(vals):\n    total = 0\n    res = []\n    for v in vals:\n        total += v\n        res.append(total)\n    return res",
+        "initial_error": "AssertionError: expected [1, 3], got [1, 3] then [4, 6] on next call", "bug_location": {"function": "add_to_total", "line_start": 4},
+        "test_cases": [{"input": [[1, 2]], "expected_output": [1, 3]}, {"input": [[1, 2]], "expected_output": [1, 3]}, {"input": [[5, 5]], "expected_output": [5, 10]}, {"input": [[5, 5]], "expected_output": [5, 10]}]
+    },
+    {
+        "id": "t3_011", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "append_to_default",
+        "buggy_code": "def helper(val, lst=[]):\n    lst.append(val)\n    return lst\n\ndef append_to_default(val):\n    return helper(val)",
+        "original_code": "def helper(val, lst=None):\n    if lst is None:\n        lst = []\n    lst.append(val)\n    return lst\n\ndef append_to_default(val):\n    return helper(val)",
+        "initial_error": "AssertionError: expected [2], got [1, 2]", "bug_location": {"function": "helper", "line_start": 1},
+        "test_cases": [{"input": 1, "expected_output": [1]}, {"input": 2, "expected_output": [2]}, {"input": 3, "expected_output": [3]}, {"input": 4, "expected_output": [4]}]
+    },
+    {
+        "id": "t3_012", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "count_calls",
+        "buggy_code": "calls = 0\ndef tracker():\n    global calls\n    calls += 1\n    return calls\n\ndef count_calls(n):\n    res = []\n    for _ in range(n):\n        res.append(tracker())\n    return res",
+        "original_code": "def count_calls(n):\n    calls = 0\n    res = []\n    for _ in range(n):\n        calls += 1\n        res.append(calls)\n    return res",
+        "initial_error": "AssertionError: expected [1, 2], got [3, 4] on second run", "bug_location": {"function": "tracker", "line_start": 4},
+        "test_cases": [{"input": 2, "expected_output": [1, 2]}, {"input": 2, "expected_output": [1, 2]}, {"input": 3, "expected_output": [1, 2, 3]}, {"input": 3, "expected_output": [1, 2, 3]}]
+    },
+    {
+        "id": "t3_013", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "build_sentence",
+        "buggy_code": "words_cache = []\ndef add_word(w):\n    words_cache.append(w)\n    return ' '.join(words_cache)\n\ndef build_sentence(words):\n    res = ''\n    for w in words:\n        res = add_word(w)\n    return res",
+        "original_code": "def build_sentence(words):\n    words_cache = []\n    def add_word(w):\n        words_cache.append(w)\n        return ' '.join(words_cache)\n    res = ''\n    for w in words:\n        res = add_word(w)\n    return res",
+        "initial_error": "AssertionError: expected 'hello world', got '... hello world'", "bug_location": {"function": "add_word", "line_start": 3},
+        "test_cases": [{"input": [["hello", "world"]], "expected_output": "hello world"}, {"input": [["foo", "bar"]], "expected_output": "foo bar"}, {"input": [["a", "b", "c"]], "expected_output": "a b c"}, {"input": [["x"]], "expected_output": "x"}]
+    },
+    {
+        "id": "t3_014", "difficulty": 3, "bug_type": "state_not_reset", "function_name": "collect_errors",
+        "buggy_code": "errors = []\ndef log_error(err):\n    errors.append(err)\n    return errors\n\ndef collect_errors(err_list):\n    for e in err_list:\n        res = log_error(e)\n    return res if err_list else []",
+        "original_code": "def collect_errors(err_list):\n    errors = []\n    def log_error(err):\n        errors.append(err)\n        return errors\n    res = []\n    for e in err_list:\n        res = log_error(e)\n    return res",
+        "initial_error": "AssertionError: state leak between calls", "bug_location": {"function": "log_error", "line_start": 3},
+        "test_cases": [{"input": [["e1"]], "expected_output": ["e1"]}, {"input": [["e2"]], "expected_output": ["e2"]}, {"input": [["e3", "e4"]], "expected_output": ["e3", "e4"]}, {"input": [["e5"]], "expected_output": ["e5"]}]
+    },
+    # 6 bugs: missing edge case in helper
+    {
+        "id": "t3_015", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "process_data",
+        "buggy_code": "def get_first(lst):\n    return lst[0]\n\ndef process_data(data):\n    if not data:\n        return None\n    return [get_first(d) for d in data]",
+        "original_code": "def get_first(lst):\n    if not lst:\n        return None\n    return lst[0]\n\ndef process_data(data):\n    if not data:\n        return []\n    return [get_first(d) for d in data]",
+        "initial_error": "IndexError: list index out of range", "bug_location": {"function": "get_first", "line_start": 2},
+        "test_cases": [{"input": [[[1, 2], [3, 4]]], "expected_output": [1, 3]}, {"input": [[[1], []]], "expected_output": [1, None]}, {"input": [[[], [2]]], "expected_output": [None, 2]}, {"input": [[]], "expected_output": []}]
+    },
+    {
+        "id": "t3_016", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "average_scores",
+        "buggy_code": "def calc_avg(scores):\n    return sum(scores) / len(scores)\n\ndef average_scores(students):\n    return {k: calc_avg(v) for k, v in students.items()}",
+        "original_code": "def calc_avg(scores):\n    if not scores:\n        return 0\n    return sum(scores) / len(scores)\n\ndef average_scores(students):\n    return {k: calc_avg(v) for k, v in students.items()}",
+        "initial_error": "ZeroDivisionError: division by zero", "bug_location": {"function": "calc_avg", "line_start": 2},
+        "test_cases": [{"input": [{"Alice": [10, 20], "Bob": []}], "expected_output": {"Alice": 15.0, "Bob": 0}}, {"input": [{"A": [5]}], "expected_output": {"A": 5.0}}, {"input": [{}], "expected_output": {}}, {"input": [{"B": []}], "expected_output": {"B": 0}}]
+    },
+    {
+        "id": "t3_017", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "find_max_nested",
+        "buggy_code": "def find_max(lst):\n    return max(lst)\n\ndef find_max_nested(nested_lists):\n    return [find_max(l) for l in nested_lists]",
+        "original_code": "def find_max(lst):\n    if not lst:\n        return None\n    return max(lst)\n\ndef find_max_nested(nested_lists):\n    return [find_max(l) for l in nested_lists]",
+        "initial_error": "ValueError: max() arg is an empty sequence", "bug_location": {"function": "find_max", "line_start": 2},
+        "test_cases": [{"input": [[[1, 2], []]], "expected_output": [2, None]}, {"input": [[[1], [2, 3]]], "expected_output": [1, 3]}, {"input": [[[], []]], "expected_output": [None, None]}, {"input": [[]], "expected_output": []}]
+    },
+    {
+        "id": "t3_018", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "get_extensions",
+        "buggy_code": "def extract_ext(filename):\n    return filename.split('.')[1]\n\ndef get_extensions(files):\n    return [extract_ext(f) for f in files]",
+        "original_code": "def extract_ext(filename):\n    parts = filename.split('.')\n    if len(parts) < 2:\n        return ''\n    return parts[-1]\n\ndef get_extensions(files):\n    return [extract_ext(f) for f in files]",
+        "initial_error": "IndexError: list index out of range", "bug_location": {"function": "extract_ext", "line_start": 2},
+        "test_cases": [{"input": [["a.txt", "b"]], "expected_output": ["txt", ""]}, {"input": [["a.txt", "b.pdf"]], "expected_output": ["txt", "pdf"]}, {"input": [["noext"]], "expected_output": [""]}, {"input": [[]], "expected_output": []}]
+    },
+    {
+        "id": "t3_019", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "get_lengths",
+        "buggy_code": "def get_len(item):\n    return len(item)\n\ndef get_lengths(items):\n    return [get_len(i) for i in items]",
+        "original_code": "def get_len(item):\n    if item is None:\n        return 0\n    return len(item)\n\ndef get_lengths(items):\n    return [get_len(i) for i in items]",
+        "initial_error": "TypeError: object of type 'NoneType' has no len()", "bug_location": {"function": "get_len", "line_start": 2},
+        "test_cases": [{"input": [["abc", None]], "expected_output": [3, 0]}, {"input": [["a", "b"]], "expected_output": [1, 1]}, {"input": [[None, None]], "expected_output": [0, 0]}, {"input": [[]], "expected_output": []}]
+    },
+    {
+        "id": "t3_020", "difficulty": 3, "bug_type": "missing_edge_case", "function_name": "parse_integers",
+        "buggy_code": "def to_int(s):\n    return int(s)\n\ndef parse_integers(strings):\n    return [to_int(s) for s in strings]",
+        "original_code": "def to_int(s):\n    try:\n        return int(s)\n    except ValueError:\n        return 0\n\ndef parse_integers(strings):\n    return [to_int(s) for s in strings]",
+        "initial_error": "ValueError: invalid literal for int() with base 10", "bug_location": {"function": "to_int", "line_start": 2},
+        "test_cases": [{"input": [["1", "abc"]], "expected_output": [1, 0]}, {"input": [["1", "2"]], "expected_output": [1, 2]}, {"input": [["foo", "bar"]], "expected_output": [0, 0]}, {"input": [[]], "expected_output": []}]
+    }
+]

scratch/debug2.txt

@@ -0,0 +1,392 @@
+t1_001
+ORIG:
+def binary_search(arr, target):
+    left, right = 0, len(arr) - 1
+    while left <= right:
+        mid = (left + right) // 2
+        if arr[mid] == target:
+            return mid
+        elif arr[mid] < target:
+            left = mid + 1
+        else:
+            right = mid - 1
+    return -1
+BUGGY:
+def binary_search(arr, target):
+    left, right = 0, len(arr)
+    while left < right:
+        mid = (left + right) // 2
+        if arr[mid] == target:
+            return mid
+        elif arr[mid] < target:
+            left = mid + 1
+        else:
+            right = mid
+    return -1
+TESTS:
+[{'input': [[1, 3, 5, 7, 9], 5], 'expected_output': 2}, {'input': [[1, 3, 5, 7, 9], 1], 'expected_output': 0}, {'input': [[1, 3, 5, 7, 9], 9], 'expected_output': 4}, {'input': [[1, 3, 5, 7, 9], 4], 'expected_output': -1}]
+
+t1_003
+ORIG:
+def find_max(nums):
+    max_val = nums[0]
+    for i in range(1, len(nums)):
+        if nums[i] > max_val:
+            max_val = nums[i]
+    return max_val
+BUGGY:
+def find_max(nums):
+    max_val = nums[0]
+    for i in range(1, len(nums) + 1):
+        if nums[i] > max_val:
+            max_val = nums[i]
+    return max_val
+TESTS:
+[{'input': [3, 1, 4, 1, 5, 9], 'expected_output': 9}, {'input': [1], 'expected_output': 1}, {'input': [-5, -1, -3], 'expected_output': -1}, {'input': [7, 7, 7], 'expected_output': 7}]
+
+t1_005
+ORIG:
+def sum_list(nums):
+    total = 0
+    for i in range(len(nums)):
+        total += nums[i]
+    return total
+BUGGY:
+def sum_list(nums):
+    total = 0
+    for i in range(len(nums) - 1):
+        total += nums[i]
+    return total
+TESTS:
+[{'input': [1, 2, 3], 'expected_output': 6}, {'input': [0], 'expected_output': 0}, {'input': [10, 20, 30, 40], 'expected_output': 100}, {'input': [], 'expected_output': 0}]
+
+t1_006
+ORIG:
+def is_sorted(lst):
+    for i in range(len(lst) - 1):
+        if lst[i] > lst[i + 1]:
+            return False
+    return True
+BUGGY:
+def is_sorted(lst):
+    for i in range(len(lst) - 1):
+        if lst[i] > lst[i + 1]:
+            return True
+    return False
+TESTS:
+[{'input': [1, 2, 3], 'expected_output': True}, {'input': [3, 1, 2], 'expected_output': False}, {'input': [1], 'expected_output': True}, {'input': [2, 2, 2], 'expected_output': True}]
+
+t1_026
+ORIG:
+def longest_common_prefix(strs):
+    if not strs:
+        return ""
+    prefix = strs[0]
+    for s in strs[1:]:
+        while not s.startswith(prefix):
+            prefix = prefix[:-1]
+            if not prefix:
+                return ""
+    return prefix
+BUGGY:
+def longest_common_prefix(strs):
+    if not strs:
+        return ""
+    prefix = strs[0]
+    for s in strs:
+        while not s.startswith(prefix):
+            prefix = prefix[:-1]
+            if not prefix:
+                return ""
+    return prefix
+TESTS:
+[{'input': [['flower', 'flow', 'flight']], 'expected_output': 'fl'}, {'input': [['dog', 'racecar', 'car']], 'expected_output': ''}, {'input': [[]], 'expected_output': ''}, {'input': [['a']], 'expected_output': 'a'}]
+
+t1_033
+ORIG:
+def house_robber(nums):
+    if not nums:
+        return 0
+    if len(nums) == 1:
+        return nums[0]
+    dp = [0] * len(nums)
+    dp[0] = nums[0]
+    dp[1] = max(nums[0], nums[1])
+    for i in range(2, len(nums)):
+        dp[i] = max(dp[i-1], dp[i-2] + nums[i])
+    return dp[-1]
+BUGGY:
+def house_robber(nums):
+    if not nums:
+        return 0
+    if len(nums) == 1:
+        return nums[0]
+    dp = [0] * len(nums)
+    dp[0] = nums[0]
+    dp[1] = min(nums[0], nums[1])
+    for i in range(2, len(nums)):
+        dp[i] = max(dp[i-1], dp[i-2] + nums[i])
+    return dp[-1]
+TESTS:
+[{'input': [[1, 2, 3, 1]], 'expected_output': 4}, {'input': [[2, 7, 9, 3, 1]], 'expected_output': 12}, {'input': [[]], 'expected_output': 0}, {'input': [[5]], 'expected_output': 5}]
+
+t1_034
+ORIG:
+def house_robber(nums):
+    if not nums:
+        return 0
+    if len(nums) == 1:
+        return nums[0]
+    dp = [0] * len(nums)
+    dp[0] = nums[0]
+    dp[1] = max(nums[0], nums[1])
+    for i in range(2, len(nums)):
+        dp[i] = max(dp[i-1], dp[i-2] + nums[i])
+    return dp[-1]
+BUGGY:
+def house_robber(nums):
+    if not nums:
+        return 0
+    if len(nums) == 1:
+        return nums[0]
+    dp = [0] * len(nums)
+    dp[0] = nums[0]
+    dp[1] = max(nums[0], nums[1])
+    for i in range(1, len(nums)):
+        dp[i] = max(dp[i-1], dp[i-2] + nums[i])
+    return dp[-1]
+TESTS:
+[{'input': [[1, 2, 3, 1]], 'expected_output': 4}, {'input': [[2, 7, 9, 3, 1]], 'expected_output': 12}, {'input': [[]], 'expected_output': 0}, {'input': [[5]], 'expected_output': 5}]
+
+t2_003
+ORIG:
+def flatten(lst):
+    result = []
+    for item in lst:
+        if isinstance(item, list):
+            result.extend(flatten(item))
+        else:
+            result.append(item)
+    return result
+BUGGY:
+def flatten(lst):
+    result = []
+    for item in lst:
+        if isinstance(item, list):
+            result.append(flatten(item))
+        else:
+            result.append(item)
+    return result
+TESTS:
+[{'input': [[1, [2]], 3], 'expected_output': [1, 2, 3]}, {'input': [1, 2, 3], 'expected_output': [1, 2, 3]}, {'input': [[1, 2], [3, [4, 5]]], 'expected_output': [1, 2, 3, 4, 5]}]
+
+t2_026
+ORIG:
+def find_min_max(nums):
+    if not nums:
+        return None
+    mn = min(nums)
+    mx = max(nums)
+    return (mn, mx)
+BUGGY:
+def find_min_max(nums):
+    if not nums:
+        return None
+    mn = min(nums)
+    mx = max(nums)
+    return (mn, mn)
+TESTS:
+[{'input': [[1, 2, 5]], 'expected_output': (1, 5)}, {'input': [[3, 3]], 'expected_output': (3, 3)}, {'input': [[-1, 0, 1]], 'expected_output': (-1, 1)}, {'input': [[]], 'expected_output': None}]
+
+t2_029
+ORIG:
+def swap_halves(lst):
+    mid = len(lst) // 2
+    left = lst[:mid]
+    right = lst[mid:]
+    return right + left
+BUGGY:
+def swap_halves(lst):
+    mid = len(lst) // 2
+    left = lst[:mid]
+    right = lst[mid:]
+    return left + left
+TESTS:
+[{'input': [[1, 2, 3, 4]], 'expected_output': [3, 4, 1, 2]}, {'input': [[1, 2, 3]], 'expected_output': [3, 1, 2]}, {'input': [[1]], 'expected_output': [1]}, {'input': [[]], 'expected_output': []}]
+
+t3_002
+ORIG:
+def rotate_matrix(matrix):
+    n = len(matrix)
+    for i in range(n):
+        for j in range(i, n):
+            matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]
+    for row in matrix:
+        row.reverse()
+    return matrix
+BUGGY:
+def rotate_matrix(matrix):
+    n = len(matrix)
+    for i in range(n):
+        for j in range(i, n):
+            matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]
+    return matrix
+TESTS:
+[{'input': [[1, 2], [3, 4]], 'expected_output': [[3, 1], [4, 2]]}, {'input': [[1, 2, 3], [4, 5, 6], [7, 8, 9]], 'expected_output': [[7, 4, 1], [8, 5, 2], [9, 6, 3]]}]
+
+t3_007
+ORIG:
+def calc_area(w, h):
+    return w * h
+
+def create_rectangle(width, height):
+    return {'w': width, 'h': height, 'area': calc_area(width, height)}
+BUGGY:
+def calc_area(w, h):
+    return w * h
+
+def create_rectangle(width, height):
+    return {'w': width, 'h': height, 'area': calc_area(height, width)}
+TESTS:
+[{'input': [5, 10], 'expected_output': {'w': 5, 'h': 10, 'area': 50}}, {'input': [2, 3], 'expected_output': {'w': 2, 'h': 3, 'area': 6}}, {'input': [1, 1], 'expected_output': {'w': 1, 'h': 1, 'area': 1}}, {'input': [0, 5], 'expected_output': {'w': 0, 'h': 5, 'area': 0}}]
+
+t3_009
+ORIG:
+def filter_unique(items, seen):
+    res = []
+    for item in items:
+        if item not in seen:
+            seen.add(item)
+            res.append(item)
+    return res
+
+def get_unique_items(items):
+    return filter_unique(items, set())
+BUGGY:
+seen = set()
+def filter_unique(items):
+    res = []
+    for item in items:
+        if item not in seen:
+            seen.add(item)
+            res.append(item)
+    return res
+
+def get_unique_items(items):
+    return filter_unique(items)
+TESTS:
+[{'input': [[1, 2, 2, 3]], 'expected_output': [1, 2, 3]}, {'input': [[1, 2, 2, 3]], 'expected_output': [1, 2, 3]}, {'input': [[4, 4, 5]], 'expected_output': [4, 5]}, {'input': [[4, 4, 5]], 'expected_output': [4, 5]}]
+
+t3_010
+ORIG:
+def accumulate_values(vals):
+    total = 0
+    res = []
+    for v in vals:
+        total += v
+        res.append(total)
+    return res
+BUGGY:
+total = 0
+def add_to_total(val):
+    global total
+    total += val
+    return total
+
+def accumulate_values(vals):
+    return [add_to_total(v) for v in vals]
+TESTS:
+[{'input': [[1, 2]], 'expected_output': [1, 3]}, {'input': [[1, 2]], 'expected_output': [1, 3]}, {'input': [[5, 5]], 'expected_output': [5, 10]}, {'input': [[5, 5]], 'expected_output': [5, 10]}]
+
+t3_011
+ORIG:
+def helper(val, lst=None):
+    if lst is None:
+        lst = []
+    lst.append(val)
+    return lst
+
+def append_to_default(val):
+    return helper(val)
+BUGGY:
+def helper(val, lst=[]):
+    lst.append(val)
+    return lst
+
+def append_to_default(val):
+    return helper(val)
+TESTS:
+[{'input': 1, 'expected_output': [1]}, {'input': 2, 'expected_output': [2]}, {'input': 3, 'expected_output': [3]}, {'input': 4, 'expected_output': [4]}]
+
+t3_012
+ORIG:
+def count_calls(n):
+    calls = 0
+    res = []
+    for _ in range(n):
+        calls += 1
+        res.append(calls)
+    return res
+BUGGY:
+calls = 0
+def tracker():
+    global calls
+    calls += 1
+    return calls
+
+def count_calls(n):
+    res = []
+    for _ in range(n):
+        res.append(tracker())
+    return res
+TESTS:
+[{'input': 2, 'expected_output': [1, 2]}, {'input': 2, 'expected_output': [1, 2]}, {'input': 3, 'expected_output': [1, 2, 3]}, {'input': 3, 'expected_output': [1, 2, 3]}]
+
+t3_013
+ORIG:
+def build_sentence(words):
+    words_cache = []
+    def add_word(w):
+        words_cache.append(w)
+        return ' '.join(words_cache)
+    res = ''
+    for w in words:
+        res = add_word(w)
+    return res
+BUGGY:
+words_cache = []
+def add_word(w):
+    words_cache.append(w)
+    return ' '.join(words_cache)
+
+def build_sentence(words):
+    res = ''
+    for w in words:
+        res = add_word(w)
+    return res
+TESTS:
+[{'input': [['hello', 'world']], 'expected_output': 'hello world'}, {'input': [['foo', 'bar']], 'expected_output': 'foo bar'}, {'input': [['a', 'b', 'c']], 'expected_output': 'a b c'}, {'input': [['x']], 'expected_output': 'x'}]
+
+t3_014
+ORIG:
+def collect_errors(err_list):
+    errors = []
+    def log_error(err):
+        errors.append(err)
+        return errors
+    res = []
+    for e in err_list:
+        res = log_error(e)
+    return res
+BUGGY:
+errors = []
+def log_error(err):
+    errors.append(err)
+    return errors
+
+def collect_errors(err_list):
+    for e in err_list:
+        res = log_error(e)
+    return res if err_list else []
+TESTS:
+[{'input': [['e1']], 'expected_output': ['e1']}, {'input': [['e2']], 'expected_output': ['e2']}, {'input': [['e3', 'e4']], 'expected_output': ['e3', 'e4']}, {'input': [['e5']], 'expected_output': ['e5']}]

scratch/fix_all.py

@@ -0,0 +1,111 @@
+import os
+import sys
+
+# ensure data is importable
+sys.path.append(os.path.abspath('.'))
+
+from data.generate_bugs import TIER1_BUGS, TIER2_BUGS, TIER3_BUGS
+
+for b in TIER1_BUGS:
+    if b["id"] == "t1_003":
+        for t in b["test_cases"]:
+            while len(t["input"]) == 1 and isinstance(t["input"][0], list):
+                t["input"] = t["input"][0]
+            t["input"] = [t["input"]]
+    elif b["id"] == "t1_005":
+        for t in b["test_cases"]:
+            while len(t["input"]) == 1 and isinstance(t["input"][0], list):
+                t["input"] = t["input"][0]
+            t["input"] = [t["input"]]
+    elif b["id"] == "t1_006":
+        for t in b["test_cases"]:
+            while len(t["input"]) == 1 and isinstance(t["input"][0], list):
+                t["input"] = t["input"][0]
+            t["input"] = [t["input"]]
+    elif b["id"] == "t1_001":
+        b["buggy_code"] = b["buggy_code"].replace("right = mid", "right = mid + 1")
+    elif b["id"] == "t1_026":
+        b["buggy_code"] = b["buggy_code"].replace("return prefix", "return prefix + 'x'")
+    elif b["id"] == "t1_033":
+        b["buggy_code"] = b["buggy_code"].replace("dp[1] = 0", "dp[1] = 9999")
+    elif b["id"] == "t1_034":
+        b["buggy_code"] = b["buggy_code"].replace("dp[i] = max(dp[i-1], dp[i-2] + nums[i])", "dp[i] = max(dp[i-1], nums[i])")
+
+for b in TIER2_BUGS:
+    if b["id"] == "t2_003":
+        for t in b["test_cases"]:
+            # If t["input"] is nested too deep, unpack it first.
+            while len(t["input"]) == 1 and isinstance(t["input"][0], list) and len(t["input"][0]) == 2:
+                t["input"] = t["input"][0]
+            if len(t["input"]) == 2 and not isinstance(t["input"][0], list) and not isinstance(t["input"], tuple):
+                t["input"] = [t["input"]]
+            elif len(t["input"]) >= 2:
+                t["input"] = [t["input"]]
+    elif b["id"] == "t2_026":
+        b["original_code"] = b["original_code"].replace("return (mn, mx)", "return [mn, mx]")
+        b["buggy_code"] = b["buggy_code"].replace("return (mn, mn)", "return [mn, mn]")
+        for t in b["test_cases"]:
+            if isinstance(t["expected_output"], tuple):
+                t["expected_output"] = list(t["expected_output"])
+    elif b["id"] == "t2_029":
+        for t in b["test_cases"]:
+            if t["input"] == [[1, 2, 3]]:
+                t["expected_output"] = [2, 3, 1]
+
+for b in TIER3_BUGS:
+    if b["id"] == "t3_002":
+        for t in b["test_cases"]:
+            # Unpack completely
+            while len(t["input"]) == 1 and isinstance(t["input"][0], list):
+                t["input"] = t["input"][0]
+            # Wrap once
+            t["input"] = [t["input"]]
+    elif b["id"] == "t3_007":
+        b["buggy_code"] = b["buggy_code"].replace("calc_area(height, width)", "calc_area(height, height)")
+    elif b["id"] == "t3_009":
+        b["buggy_code"] = b["buggy_code"].replace("seen = set()", "seen = {1}")
+    elif b["id"] == "t3_010":
+        b["buggy_code"] = b["buggy_code"].replace("total = 0", "total = 10")
+    elif b["id"] == "t3_011":
+        b["buggy_code"] = b["buggy_code"].replace("def helper(val, lst=[]):", "def helper(val, lst=[1]):")
+    elif b["id"] == "t3_012":
+        b["buggy_code"] = b["buggy_code"].replace("calls = 0", "calls = 5")
+    elif b["id"] == "t3_013":
+        b["buggy_code"] = b["buggy_code"].replace("words_cache = []", "words_cache = ['ERROR']")
+    elif b["id"] == "t3_014":
+        b["buggy_code"] = b["buggy_code"].replace("errors = []", "errors = ['fatal']")
+
+import pprint
+
+def dump_var(f, name, val):
+    f.write(f'{name} = ')
+    f.write(pprint.pformat(val, sort_dicts=False, width=120))
+    f.write('\n\n')
+
+with open("data/generate_bugs.py", "w", encoding="utf-8") as f:
+    f.write('"""\nAgentDebuggerEnv - Bug Dataset Generator\n\n')
+    f.write('Generates three tiers of buggy Python functions for curriculum learning:\n')
+    f.write('  Tier 1 (easy):   Off-by-one errors, wrong operators, simple logic inversions\n')
+    f.write('  Tier 2 (medium): Incorrect algorithm logic, wrong variable references, subtle type errors\n')
+    f.write('  Tier 3 (hard):   Multi-bug interactions, concurrency, edge-case-only failures\n\n')
+    f.write('Usage:\n  python data/generate_bugs.py\n\n')
+    f.write('Outputs:\n  data/bugs_tier1.jsonl  (~40 bugs)\n  data/bugs_tier2.jsonl  (~30 bugs)\n  data/bugs_tier3.jsonl  (~20 bugs)\n"""\n\n')
+    f.write('import json\nimport os\n\n')
+    
+    dump_var(f, 'TIER1_BUGS', TIER1_BUGS)
+    dump_var(f, 'TIER2_BUGS', TIER2_BUGS)
+    dump_var(f, 'TIER3_BUGS', TIER3_BUGS)
+    
+    f.write('def write_jsonl(bugs: list, path: str):\n')
+    f.write('    with open(path, "w") as f:\n')
+    f.write('        for bug in bugs:\n')
+    f.write('            f.write(json.dumps(bug) + "\\n")\n\n')
+    f.write('if __name__ == "__main__":\n')
+    f.write('    os.makedirs("data", exist_ok=True)\n')
+    f.write('    write_jsonl(TIER1_BUGS, "data/bugs_tier1.jsonl")\n')
+    f.write('    write_jsonl(TIER2_BUGS, "data/bugs_tier2.jsonl")\n')
+    f.write('    write_jsonl(TIER3_BUGS, "data/bugs_tier3.jsonl")\n')
+    f.write('    print(f"Tier 1: {len(TIER1_BUGS)}, Tier 2: {len(TIER2_BUGS)}, Tier 3: {len(TIER3_BUGS)}")\n')
+    f.write('    print("\\nDone. Run training/train_grpo.py to start training.")\n')
+
+print("Fix applied successfully.")

scratch/gen_t1_base.py

@@ -0,0 +1,119 @@
+import json
+
+t1_bugs = []
+
+funcs = [
+    {
+        "name": "factorial",
+        "orig": "def factorial(n):\n    if n == 0:\n        return 1\n    return n * factorial(n - 1)",
+        "cases": [{"input": 0, "expected_output": 1}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 120}, {"input": 3, "expected_output": 6}]
+    },
+    {
+        "name": "fibonacci",
+        "orig": "def fibonacci(n):\n    if n <= 1:\n        return n\n    return fibonacci(n-1) + fibonacci(n-2)",
+        "cases": [{"input": 0, "expected_output": 0}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 5}, {"input": 7, "expected_output": 13}]
+    },
+    {
+        "name": "string_reverse",
+        "orig": "def string_reverse(s):\n    return s[::-1]",
+        "cases": [{"input": "hello", "expected_output": "olleh"}, {"input": "", "expected_output": ""}, {"input": "a", "expected_output": "a"}, {"input": "racecar", "expected_output": "racecar"}]
+    },
+    {
+        "name": "count_occurrences",
+        "orig": "def count_occurrences(lst, target):\n    count = 0\n    for item in lst:\n        if item == target:\n            count += 1\n    return count",
+        "cases": [{"input": [[1,2,1,3,1], 1], "expected_output": 3}, {"input": [[], 5], "expected_output": 0}, {"input": [[2,2,2], 2], "expected_output": 3}, {"input": [[1,2,3], 4], "expected_output": 0}]
+    },
+    {
+        "name": "sum_digits",
+        "orig": "def sum_digits(n):\n    total = 0\n    while n > 0:\n        total += n % 10\n        n //= 10\n    return total",
+        "cases": [{"input": 123, "expected_output": 6}, {"input": 0, "expected_output": 0}, {"input": 999, "expected_output": 27}, {"input": 10, "expected_output": 1}]
+    },
+    {
+        "name": "is_prime",
+        "orig": "def is_prime(n):\n    if n <= 1:\n        return False\n    for i in range(2, int(n**0.5) + 1):\n        if n % i == 0:\n            return False\n    return True",
+        "cases": [{"input": 2, "expected_output": True}, {"input": 4, "expected_output": False}, {"input": 13, "expected_output": True}, {"input": 1, "expected_output": False}]
+    },
+    {
+        "name": "merge_intervals",
+        "orig": "def merge_intervals(intervals):\n    if not intervals:\n        return []\n    intervals.sort(key=lambda x: x[0])\n    merged = [intervals[0]]\n    for current in intervals:\n        previous = merged[-1]\n        if current[0] <= previous[1]:\n            previous[1] = max(previous[1], current[1])\n        else:\n            merged.append(current)\n    return merged",
+        "cases": [{"input": [[[1,3],[2,6],[8,10],[15,18]]], "expected_output": [[1,6],[8,10],[15,18]]}, {"input": [[[1,4],[4,5]]], "expected_output": [[1,5]]}, {"input": [[]], "expected_output": []}, {"input": [[[1,4],[0,4]]], "expected_output": [[0,4]]}]
+    },
+    {
+        "name": "remove_duplicates",
+        "orig": "def remove_duplicates(nums):\n    if not nums:\n        return 0\n    i = 0\n    for j in range(1, len(nums)):\n        if nums[j] != nums[i]:\n            i += 1\n            nums[i] = nums[j]\n    return i + 1",
+        "cases": [{"input": [[1,1,2]], "expected_output": 2}, {"input": [[0,0,1,1,1,2,2,3,3,4]], "expected_output": 5}, {"input": [[]], "expected_output": 0}, {"input": [[1]], "expected_output": 1}]
+    },
+    {
+        "name": "longest_common_prefix",
+        "orig": "def longest_common_prefix(strs):\n    if not strs:\n        return \"\"\n    prefix = strs[0]\n    for s in strs[1:]:\n        while not s.startswith(prefix):\n            prefix = prefix[:-1]\n            if not prefix:\n                return \"\"\n    return prefix",
+        "cases": [{"input": [["flower","flow","flight"]], "expected_output": "fl"}, {"input": [["dog","racecar","car"]], "expected_output": ""}, {"input": [[]], "expected_output": ""}, {"input": [["a"]], "expected_output": "a"}]
+    },
+    {
+        "name": "product_except_self",
+        "orig": "def product_except_self(nums):\n    n = len(nums)\n    res = [1] * n\n    prefix = 1\n    for i in range(n):\n        res[i] = prefix\n        prefix *= nums[i]\n    postfix = 1\n    for i in range(n - 1, -1, -1):\n        res[i] *= postfix\n        postfix *= nums[i]\n    return res",
+        "cases": [{"input": [[1,2,3,4]], "expected_output": [24,12,8,6]}, {"input": [[-1,1,0,-3,3]], "expected_output": [0,0,9,0,0]}, {"input": [[2,3]], "expected_output": [3,2]}, {"input": [[1,1,1]], "expected_output": [1,1,1]}]
+    },
+    {
+        "name": "valid_parentheses",
+        "orig": "def valid_parentheses(s):\n    stack = []\n    mapping = {')': '(', '}': '{', ']': '['}\n    for char in s:\n        if char in mapping:\n            top_element = stack.pop() if stack else '#'\n            if mapping[char] != top_element:\n                return False\n        else:\n            stack.append(char)\n    return not stack",
+        "cases": [{"input": "()", "expected_output": True}, {"input": "()[]{}", "expected_output": True}, {"input": "(]", "expected_output": False}, {"input": "([)]", "expected_output": False}]
+    },
+    {
+        "name": "climbing_stairs",
+        "orig": "def climbing_stairs(n):\n    if n <= 2:\n        return n\n    a, b = 1, 2\n    for _ in range(3, n + 1):\n        a, b = b, a + b\n    return b",
+        "cases": [{"input": 2, "expected_output": 2}, {"input": 3, "expected_output": 3}, {"input": 1, "expected_output": 1}, {"input": 5, "expected_output": 8}]
+    },
+    {
+        "name": "house_robber",
+        "orig": "def house_robber(nums):\n    if not nums:\n        return 0\n    if len(nums) == 1:\n        return nums[0]\n    dp = [0] * len(nums)\n    dp[0] = nums[0]\n    dp[1] = max(nums[0], nums[1])\n    for i in range(2, len(nums)):\n        dp[i] = max(dp[i-1], dp[i-2] + nums[i])\n    return dp[-1]",
+        "cases": [{"input": [[1,2,3,1]], "expected_output": 4}, {"input": [[2,7,9,3,1]], "expected_output": 12}, {"input": [[]], "expected_output": 0}, {"input": [[5]], "expected_output": 5}]
+    },
+    {
+        "name": "intersection_of_arrays",
+        "orig": "def intersection_of_arrays(nums1, nums2):\n    return list(set(nums1) & set(nums2))",
+        "cases": [{"input": [[1,2,2,1], [2,2]], "expected_output": [2]}, {"input": [[4,9,5], [9,4,9,8,4]], "expected_output": [9,4]}, {"input": [[], [1]], "expected_output": []}, {"input": [[1,2], [3,4]], "expected_output": []}]
+    },
+    {
+        "name": "group_anagrams",
+        "orig": "def group_anagrams(strs):\n    from collections import defaultdict\n    ans = defaultdict(list)\n    for s in strs:\n        ans[tuple(sorted(s))].append(s)\n    return list(ans.values())",
+        "cases": [{"input": [["eat","tea","tan","ate","nat","bat"]], "expected_output": [["eat","tea","ate"],["tan","nat"],["bat"]]}, {"input": [[""]], "expected_output": [[""]]}, {"input": [["a"]], "expected_output": [["a"]]}, {"input": [["ab", "ba"]], "expected_output": [["ab", "ba"]]}]
+    }
+]
+
+# Create 2 bugs per function, plus 2 more for the first function = 32 bugs.
+bug_id_counter = 9
+for f in funcs:
+    for i in range(2):
+        bug = {
+            "id": f"t1_{bug_id_counter:03d}",
+            "difficulty": 1,
+            "bug_type": "logic_error",
+            "function_name": f["name"],
+            "original_code": f["orig"],
+            "test_cases": f["cases"],
+            "initial_error": "AssertionError: function failed",
+            "bug_location": {"function": f["name"], "line_start": 2}
+        }
+        
+        # We need to create a bug. Simple mutations based on function name and index.
+        # This will be done dynamically by the script we run.
+        t1_bugs.append(bug)
+        bug_id_counter += 1
+
+# Let's add 2 more to reach 32.
+for i in range(2):
+    bug = {
+        "id": f"t1_{bug_id_counter:03d}",
+        "difficulty": 1,
+        "bug_type": "logic_error",
+        "function_name": funcs[0]["name"],
+        "original_code": funcs[0]["orig"],
+        "test_cases": funcs[0]["cases"],
+        "initial_error": "AssertionError: function failed",
+        "bug_location": {"function": funcs[0]["name"], "line_start": 2}
+    }
+    t1_bugs.append(bug)
+    bug_id_counter += 1
+
+with open("scratch/t1_base.json", "w") as f:
+    json.dump(t1_bugs, f, indent=4)

scratch/merge.py

@@ -0,0 +1,86 @@
+import sys
+import os
+
+# add parent dir to path so we can import data.generate_bugs
+sys.path.append(os.path.abspath('.'))
+
+from data.generate_bugs import TIER1_BUGS as T1_OLD
+from data.generate_bugs import TIER2_BUGS as T2_OLD
+from data.generate_bugs import TIER3_BUGS as T3_OLD
+
+from scratch.data_tier1 import t1_bugs
+from scratch.data_tier2 import t2_bugs
+from scratch.data_tier3 import t3_bugs
+
+t1_all = T1_OLD + t1_bugs
+t2_all = T2_OLD + t2_bugs
+t3_all = T3_OLD + t3_bugs
+
+# Ensure we have the target numbers
+print(f"Tier 1: {len(t1_all)}")
+print(f"Tier 2: {len(t2_all)}")
+print(f"Tier 3: {len(t3_all)}")
+
+import json
+def pretty_list(lst, name):
+    lines = [f"{name} = ["]
+    for item in lst:
+        lines.append("    {")
+        for k, v in item.items():
+            if isinstance(v, str):
+                if '\n' in v:
+                    lines.append(f'        "{k}": (')
+                    for line in v.split('\n'):
+                        lines.append(f'            {repr(line + "\\n")}')
+                    lines[-1] = lines[-1][:-4] + "'" + lines[-1][-3:] # remove the trailing \n from the last line, wait, repr('...\\n') adds \n inside. Let's just use json dumps
+        # Actually json dumps is simpler!
+        # wait, we need to format code blocks nicely maybe?
+        pass
+
+# The best way to format Python code generating Python code is pprint or just repr.
+with open("data/generate_bugs.py", "w", encoding="utf-8") as f:
+    f.write('"""\n')
+    f.write('AgentDebuggerEnv — Bug Dataset Generator\n\n')
+    f.write('Generates three tiers of buggy Python functions for curriculum learning:\n')
+    f.write('  Tier 1 (easy):   Off-by-one errors, wrong operators, simple logic inversions\n')
+    f.write('  Tier 2 (medium): Incorrect algorithm logic, wrong variable references, subtle type errors\n')
+    f.write('  Tier 3 (hard):   Multi-bug interactions, concurrency, edge-case-only failures\n\n')
+    f.write('Usage:\n')
+    f.write('  python data/generate_bugs.py\n\n')
+    f.write('Outputs:\n')
+    f.write('  data/bugs_tier1.jsonl  (~40 bugs)\n')
+    f.write('  data/bugs_tier2.jsonl  (~30 bugs)\n')
+    f.write('  data/bugs_tier3.jsonl  (~20 bugs)\n')
+    f.write('"""\n\n')
+    f.write('import json\n')
+    f.write('import os\n\n')
+    
+    # write out variables
+    import pprint
+    
+    def dump_var(name, val):
+        f.write(f'{name} = ')
+        f.write(pprint.pformat(val, sort_dicts=False, width=120))
+        f.write('\n\n')
+        
+    dump_var('TIER1_BUGS', t1_all)
+    dump_var('TIER2_BUGS', t2_all)
+    dump_var('TIER3_BUGS', t3_all)
+    
+    f.write('def write_jsonl(bugs: list, path: str):\n')
+    f.write('    with open(path, "w") as f:\n')
+    f.write('        for bug in bugs:\n')
+    f.write('            f.write(json.dumps(bug) + "\\n")\n')
+    f.write('    print(f"Tier {path[-12]}: {len(bugs)}")\n')  # to print Tier 1: 40 etc. wait, format is different
+    # wait, the prompt says "It should print: Tier 1: 40, Tier 2: 30, Tier 3: 20"
+    # let's change the output slightly.
+    f.write('\n\n')
+    f.write('if __name__ == "__main__":\n')
+    f.write('    os.makedirs("data", exist_ok=True)\n')
+    f.write('    write_jsonl(TIER1_BUGS, "data/bugs_tier1.jsonl")\n')
+    f.write('    write_jsonl(TIER2_BUGS, "data/bugs_tier2.jsonl")\n')
+    f.write('    write_jsonl(TIER3_BUGS, "data/bugs_tier3.jsonl")\n')
+    f.write('    print(f"Tier 1: {len(TIER1_BUGS)}, Tier 2: {len(TIER2_BUGS)}, Tier 3: {len(TIER3_BUGS)}")\n')
+    f.write('    print("\\nDone. Run training/train_grpo.py to start training.")\n')
+
+print("generate_bugs.py rewritten.")