{
  "entity": "gpt-5-5",
  "entity_type": "model",
  "category": "Coding",
  "suite": "suite-2026-08-skills/coding",
  "model": "openai/gpt-5.5",
  "judges": [
    "anthropic/claude-sonnet-5",
    "google/gemini-3.1-pro-preview",
    "x-ai/grok-4.5"
  ],
  "judge_protocol": "judge-2026-08",
  "anchors": "solo-2026-08-a",
  "score": 91,
  "caps": 0,
  "cost_usd": 0.6886,
  "started_at": "2026-08-16T06:26:35.634Z",
  "finished_at": "2026-08-16T06:27:46.950Z",
  "tasks": [
    {
      "id": "c1",
      "name": "Duration parser",
      "prompt": "Write a Python function parse_duration(s) that converts strings like '1h30m', '45s', '2h', '90m', '1h2m3s' into total seconds. Raise ValueError on anything malformed. Include three assert-based tests, one of which covers a malformed input.",
      "output": "```python\nimport re\n\ndef parse_duration(s):\n    \"\"\"\n    Convert a duration string like '1h30m', '45s', '2h', '90m',\n    or '1h2m3s' into total seconds.\n\n    Raises ValueError if the input is malformed.\n    \"\"\"\n    if not isinstance(s, str):\n        raise ValueError(\"duration must be a string\")\n\n    match = re.fullmatch(r\"(?:(\\d+)h)?(?:(\\d+)m)?(?:(\\d+)s)?\", s)\n\n    if not match or not any(match.groups()):\n        raise ValueError(f\"malformed duration: {s!r}\")\n\n    hours, minutes, seconds = match.groups()\n\n    return (\n        int(hours or 0) * 3600\n        + int(minutes or 0) * 60\n        + int(seconds or 0)\n    )\n\n\n# Tests\nassert parse_duration(\"1h30m\") == 5400\nassert parse_duration(\"1h2m3s\") == 3723\n\ntry:\n    parse_duration(\"1x30m\")\n    assert False, \"Expected ValueError\"\nexcept ValueError:\n    pass\n```",
      "latency_ms": 8480,
      "cost": 0.021645,
      "task_score": 8,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct, handles edge cases well, includes required tests with malformed input. Minor deduction: only two direct asserts plus try/except pattern, but functionally meets requirement of three tests."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The function correctly parses the duration strings into seconds using regex, raises ValueError on malformed inputs, and includes the three requested assert-based tests (including one for malformed input)."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct function and three tests (two positive asserts, one malformed via assert). Minor: only two success cases shown; try/except style slightly non-idiomatic."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c2",
      "name": "Find the bug",
      "prompt": "This is meant to return the average of the positive numbers but returns the wrong value. Identify the bug, explain it in one sentence, and give the corrected function.\n\nfunction avgPositive(xs) {\n  let sum = 0, n = 0;\n  for (const x of xs) {\n    if (x > 0) sum += x;\n    n++;\n  }\n  return sum / n;\n}",
      "output": "Bug: `n++` is outside the `if`, so the function divides by the total number of elements instead of the number of positive elements.\n\n```js\nfunction avgPositive(xs) {\n  let sum = 0, n = 0;\n\n  for (const x of xs) {\n    if (x > 0) {\n      sum += x;\n      n++;\n    }\n  }\n\n  return sum / n;\n}\n```",
      "latency_ms": 3252,
      "cost": 0.00627,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Correctly identifies bug, explains clearly in one sentence, provides correct fixed function. Concise and useful."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly identifies the bug, explains it in exactly one sentence as requested, and provides the correctly fixed function."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Correct bug ID, one-sentence explanation, and fixed code. Fully meets task."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c3",
      "name": "SQL without window functions",
      "prompt": "Given tables users(id, email) and orders(id, user_id, created_at, total), write SQL returning the email and order count of every user with more than 3 orders in the last 30 days, most orders first. Do not use window functions. Target Postgres.",
      "output": "```sql\nSELECT\n  u.email,\n  COUNT(o.id) AS order_count\nFROM users AS u\nJOIN orders AS o\n  ON o.user_id = u.id\nWHERE o.created_at >= NOW() - INTERVAL '30 days'\nGROUP BY u.id, u.email\nHAVING COUNT(o.id) > 3\nORDER BY order_count DESC;\n```",
      "latency_ms": 3151,
      "cost": 0.006285,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct, valid Postgres SQL, no window functions, meets all requirements, clear and concise."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The SQL query perfectly meets all requirements, uses correct Postgres syntax, avoids window functions, and accurately filters and sorts the data as requested."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Correct Postgres SQL meeting all requirements: joins, 30-day filter, HAVING >3, no windows, ordered by count desc."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c4",
      "name": "Infinite useEffect",
      "prompt": "Explain precisely why this React effect loops forever, then give the fixed version.\n\nconst [items, setItems] = useState([]);\nuseEffect(() => {\n  fetch('/api/items').then(r => r.json()).then(setItems);\n}, [items]);",
      "output": "It loops because `items` is both:\n\n1. A dependency of the effect:\n\n```js\nuseEffect(() => {\n  ...\n}, [items]);\n```\n\n2. Updated inside that same effect:\n\n```js\n.then(setItems);\n```\n\nThe sequence is:\n\n1. Component renders with `items = []`.\n2. The effect runs because it runs after the initial render.\n3. The effect fetches data and calls `setItems(newItems)`.\n4. Calling `setItems` updates state, causing a re-render.\n5. On the next render, React compares the previous `items` value with the new one using reference equality.\n6. The fetched JSON array is a new array object, so `items` has changed.\n7. Because `items` changed, the effect runs again.\n8. It fetches again, calls `setItems` again, creates another new array, and the cycle repeats forever.\n\nThe effect should not depend on `items` if the effect itself is responsible for loading `items`.\n\nFixed version:\n\n```jsx\nconst [items, setItems] = useState([]);\n\nuseEffect(() => {\n  fetch('/api/items')\n    .then(r => r.json())\n    .then(setItems);\n}, []);\n```\n\nThe empty dependency array means: run this effect once after the component mounts.\n\nA slightly safer version avoids setting state after unmount:\n\n```jsx\nconst [items, setItems] = useState([]);\n\nuseEffect(() => {\n  let cancelled = false;\n\n  fetch('/api/items')\n    .then(r => r.json())\n    .then(data => {\n      if (!cancelled) {\n        setItems(data);\n      }\n    });\n\n  return () => {\n    cancelled = true;\n  };\n}, []);\n```\n\nIf the URL depends on some prop or state, put that value in the dependency array instead:\n\n```jsx\nuseEffect(() => {\n  fetch(`/api/items?category=${category}`)\n    .then(r => r.json())\n    .then(setItems);\n}, [category]);\n```",
      "latency_ms": 5767,
      "cost": 0.015555,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate explanation of infinite loop cause, correct fix with empty deps, plus bonus safe versions. Clear, concise, well-structured, useful."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "Flawless explanation of the infinite loop caused by the dependency array and reference equality, followed by the correct fixed code. Clear, accurate, and highly useful."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Precise correct explanation of the loop via dependency and new array refs; clean fixed code with empty deps plus useful safer variants."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c5",
      "name": "Typed debounce",
      "prompt": "Write a debounce function in TypeScript that preserves the argument types of the wrapped function, returns a function with a .cancel() method, and does not use 'any'. Explain in one sentence why the naive generic signature loses type information.",
      "output": "```ts\ntype Debounced<This, Args extends unknown[]> = ((\n  this: This,\n  ...args: Args\n) => void) & {\n  cancel: () => void;\n};\n\nexport function debounce<This, Args extends unknown[]>(\n  fn: (this: This, ...args: Args) => unknown,\n  delayMs: number\n): Debounced<This, Args> {\n  let timer: ReturnType<typeof setTimeout> | undefined;\n\n  const debounced = function (this: This, ...args: Args) {\n    if (timer !== undefined) {\n      clearTimeout(timer);\n    }\n\n    timer = setTimeout(() => {\n      timer = undefined;\n      fn.apply(this, args);\n    }, delayMs);\n  } as Debounced<This, Args>;\n\n  debounced.cancel = () => {\n    if (timer !== undefined) {\n      clearTimeout(timer);\n      timer = undefined;\n    }\n  };\n\n  return debounced;\n}\n```\n\nExample:\n\n```ts\nconst save = (id: number, name: string) => {\n  console.log(id, name);\n};\n\nconst debouncedSave = debounce(save, 300);\n\ndebouncedSave(1, \"Alice\"); // OK\ndebouncedSave.cancel();\n\n// debouncedSave(\"1\", \"Alice\"); // Type error\n```\n\nA naive signature like `fn: (...args: unknown[]) => unknown` loses type information because it types the wrapper from the broad constraint instead of inferring and reusing the function’s specific parameter tuple.",
      "latency_ms": 18529,
      "cost": 0.040825,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct, avoids 'any', includes cancel(), preserves types, and gives concise explanation as required. Minor: 'this' capture inside setTimeout arrow could be slightly imprecise but functionally fine."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly fulfills all requirements, providing a robust TypeScript debounce function without using 'any', including a cancel method, and accurately explaining the type loss issue in a single sentence."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct typed debounce with cancel, no any; one-sentence explanation accurate. Minor: return type ignored (typical). Highly technical yet clear and complete."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c6",
      "name": "Leftmost binary search",
      "prompt": "Implement binary search that returns the index of the FIRST occurrence of a target in a sorted array with duplicates, or -1. Give the code and state the complexity. Include the test case that distinguishes it from an ordinary binary search.",
      "output": "```python\ndef binary_search_first(arr, target):\n    left, right = 0, len(arr) - 1\n    result = -1\n\n    while left <= right:\n        mid = left + (right - left) // 2\n\n        if arr[mid] == target:\n            result = mid          # possible first occurrence\n            right = mid - 1       # keep searching to the left\n        elif arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid - 1\n\n    return result\n```\n\n### Complexity\n\n- **Time:** `O(log n)`\n- **Space:** `O(1)`\n\n### Test case distinguishing it from ordinary binary search\n\n```python\narr = [1, 2, 2, 2, 3, 4]\ntarget = 2\n\nprint(binary_search_first(arr, target))  # Output: 1\n```\n\nAn ordinary binary search might return index `2` or `3`, depending on how the midpoint is chosen, but this version always returns the **first occurrence**, which is index `1`.",
      "latency_ms": 3757,
      "cost": 0.01004,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct implementation, correct complexity, clear distinguishing test case demonstrating first-occurrence behavior. Minor stylistic nitpicks only."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly implements the requested algorithm, correctly states the time and space complexity, and provides a clear test case demonstrating the difference from standard binary search."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Correct first-occurrence binary search, accurate O(log n) complexity, and clear distinguishing test case. Fully meets task."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c7",
      "name": "Security review",
      "prompt": "Review this Express handler and list every security problem you find, most severe first, each with the fix.\n\napp.get('/file', (req, res) => {\n  const p = req.query.name;\n  db.query(`SELECT * FROM files WHERE name = '${p}'`, (e, rows) => {\n    res.sendFile(__dirname + '/uploads/' + p);\n  });\n});",
      "output": "Security issues, most severe first:\n\n| Severity | Problem | Why it’s dangerous | Fix |\n|---|---|---|---|\n| Critical | SQL injection | `p` is interpolated directly into SQL: `WHERE name = '${p}'`. An attacker can pass `name=' OR 1=1 --` or worse, depending on DB settings. | Use parameterized queries/prepared statements. Example: `db.query('SELECT * FROM files WHERE name = ?', [p], cb)` |\n| Critical | Path traversal / arbitrary file read | `res.sendFile(__dirname + '/uploads/' + p)` lets attackers request `?name=../../../../etc/passwd` or other files outside `uploads`. | Never concatenate paths with user input. Use a fixed root, validate the filename, canonicalize the path, and ensure it stays inside the upload directory. |\n| High | Authorization bypass / IDOR | Anyone who knows or guesses a filename can retrieve it. The DB query does not check the current user or permissions. | Require authentication and check ownership/ACL in the DB query, e.g. `WHERE name = ? AND owner_id = ?`. |\n| High | DB result is ignored | The handler sends the file even if the DB query fails or returns no rows. Any intended “file must exist in DB” check is bypassed. | Check `e` and `rows` before sending the file. Return `500`, `404`, or `403` as appropriate. |\n| High | User input is used as the storage filename | Even with SQL fixed, using a user-controlled name directly as the filesystem path is risky. It enables traversal, weird encodings, absolute paths, hidden files, and symlink surprises. | Store files under server-generated random names/IDs. Keep the original filename only as metadata. |\n| Medium | Possible stored XSS/content sniffing when serving uploads | If users can upload HTML/SVG/JS and the app serves it inline, browsers may execute it in your origin. | Serve untrusted uploads from a separate domain, force download with `Content-Disposition: attachment`, set `X-Content-Type-Options: nosniff`, and restrict allowed MIME types. |\n| Medium | Symlink escape risk | If an attacker can place or influence symlinks inside `uploads`, `sendFile` may follow a symlink to a sensitive file outside the upload directory. | Do not allow symlinks in uploads. Use `realpath` checks, hardened upload handling, or object storage. |\n| Low/Medium | Missing input validation and limits | `req.query.name` may be missing, huge, contain null bytes/odd Unicode, path separators, etc. This can cause errors or abuse. | Require a string, enforce length limits, and allow only expected characters or use an opaque file ID. |\n| Low | No explicit error handling for `sendFile` | File send failures may produce inconsistent behavior or leak stack traces depending on global error handling. | Use the `sendFile` callback and pass errors to `next(err)` or return controlled errors. |\n\nA safer shape would be:\n\n```js\nconst path = require('path');\nconst uploadsDir = path.resolve(__dirname, 'uploads');\n\napp.get('/file', requireAuth, (req, res, next) => {\n  const name = String(req.query.name || '');\n\n  // Better: use an opaque file ID instead of a filename.\n  if (!/^[a-zA-Z0-9._-]{1,255}$/.test(name)) {\n    return res.status(400).send('Invalid filename');\n  }\n\n  db.query(\n    'SELECT stored_name, original_name FROM files WHERE name = ? AND owner_id = ?',\n    [name, req.user.id],\n    (err, rows) => {\n      if (err) return next(err);\n      if (rows.length !== 1) return res.sendStatus(404);\n\n      const storedName = rows[0].stored_name;\n\n      const filePath = path.resolve(uploadsDir, storedName);\n      if (!filePath.startsWith(uploadsDir + path.sep)) {\n        return res.sendStatus(403);\n      }\n\n      res.setHeader('X-Content-Type-Options', 'nosniff');\n      res.download(filePath, rows[0].original_name, err => {\n        if (err) next(err);\n      });\n    }\n  );\n});\n```\n\nEven better: query by a file ID, store files under random server-generated names, check the authenticated user’s permission, and use object storage or a hardened file-serving layer.",
      "latency_ms": 26700,
      "cost": 0.075365,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Thorough, accurate, well-prioritized list of vulnerabilities with correct fixes and a solid safer code example; slightly verbose but highly useful and correct."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response accurately identifies all security issues, orders them by severity, provides clear explanations and fixes, and includes a helpful code example. It is highly useful and well-structured."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Accurate severity-ordered issues with solid fixes; complete, clear, and highly useful. No constraint breached."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c8",
      "name": "Safe migration",
      "prompt": "Write the Postgres migration to add a NOT NULL column 'status' with default 'pending' to an orders table with 40 million rows, without taking a long exclusive lock. Give the steps in order and say which step is the dangerous one and why.",
      "output": "Assume `orders` has a primary key `id`, and `status` is `text`.\n\n```sql\n-- 1. Add the column as nullable. Do not add NOT NULL yet.\n-- Keep lock_timeout short so this fails instead of waiting behind/holding a bad lock.\nBEGIN;\nSET LOCAL lock_timeout = '5s';\n\nALTER TABLE orders\n  ADD COLUMN status text;\n\nALTER TABLE orders\n  ALTER COLUMN status SET DEFAULT 'pending';\n\nCOMMIT;\n```\n\nBackfill existing rows in small batches, outside one giant transaction:\n\n```sql\n-- 2. Repeat this until it updates 0 rows.\n-- Tune LIMIT based on write load, e.g. 5k-50k.\nWITH batch AS (\n  SELECT id\n  FROM orders\n  WHERE status IS NULL\n  ORDER BY id\n  LIMIT 10000\n  FOR UPDATE SKIP LOCKED\n)\nUPDATE orders o\nSET status = 'pending'\nFROM batch\nWHERE o.id = batch.id;\n```\n\nAfter the main backfill:\n\n```sql\n-- 3. Add a NOT VALID check constraint.\n-- This is fast and prevents future NULLs, but does not scan the 40M existing rows yet.\nBEGIN;\nSET LOCAL lock_timeout = '5s';\n\nALTER TABLE orders\n  ADD CONSTRAINT orders_status_not_null\n  CHECK (status IS NOT NULL) NOT VALID;\n\nCOMMIT;\n```\n\nCatch any rows that became `NULL` during the race before the constraint existed:\n\n```sql\n-- 4. Run until 0 rows again.\nWITH batch AS (\n  SELECT id\n  FROM orders\n  WHERE status IS NULL\n  ORDER BY id\n  LIMIT 10000\n  FOR UPDATE SKIP LOCKED\n)\nUPDATE orders o\nSET status = 'pending'\nFROM batch\nWHERE o.id = batch.id;\n```\n\nValidate the constraint:\n\n```sql\n-- 5. This scans the table, but does not take a long ACCESS EXCLUSIVE lock.\nALTER TABLE orders\n  VALIDATE CONSTRAINT orders_status_not_null;\n```\n\nNow set the real `NOT NULL`:\n\n```sql\n-- 6. This should be fast because Postgres can use the validated CHECK constraint.\nBEGIN;\nSET LOCAL lock_timeout = '5s';\n\nALTER TABLE orders\n  ALTER COLUMN status SET NOT NULL;\n\nCOMMIT;\n```\n\nOptionally drop the helper constraint:\n\n```sql\n-- 7. Optional cleanup.\nBEGIN;\nSET LOCAL lock_timeout = '5s';\n\nALTER TABLE orders\n  DROP CONSTRAINT orders_status_not_null;\n\nCOMMIT;\n```\n\nFinal schema state:\n\n```sql\nstatus text NOT NULL DEFAULT 'pending'\n```\n\nThe dangerous step is:\n\n```sql\nALTER TABLE orders ALTER COLUMN status SET NOT NULL;\n```\n\nif you run it directly.\n\nWhy: PostgreSQL must prove that no row has `status IS NULL`. Without a previously validated constraint, it does that by scanning the whole `orders` table while holding an `ACCESS EXCLUSIVE` lock. On 40 million rows, that can block reads and writes for a long time.\n\nThe `CHECK (status IS NOT NULL) NOT VALID` + `VALIDATE CONSTRAINT` pattern moves the expensive table scan to `VALIDATE CONSTRAINT`, which uses a weaker lock and allows normal reads/writes. Then the final `SET NOT NULL` is only a brief metadata change.",
      "latency_ms": 36662,
      "cost": 0.08309,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Technically accurate, correct Postgres pattern (NOT VALID + VALIDATE), steps in order, clearly identifies dangerous step and why. Well-structured and clear."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 8,
          "violates": false,
          "reasoning": "Provides a perfectly accurate pre-Postgres 11 zero-downtime migration pattern. However, it misses that in Postgres 11+ (released 2018), adding a column with a constant default is instantaneous and doesn't require this complex backfill."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate Postgres zero-downtime pattern with correct locks, batching, and danger callout. Minor verbosity only."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c9",
      "name": "Fix the code not the test",
      "prompt": "This test fails. Fix the implementation, not the test.\n\n// impl\nexport const slugify = (s) => s.toLowerCase().replace(/ /g, '-');\n// test\nexpect(slugify('  Hello   World!  ')).toBe('hello-world');",
      "output": "```js\nexport const slugify = (s) =>\n  s\n    .toLowerCase()\n    .trim()\n    .replace(/[^\\w\\s-]/g, '')\n    .replace(/\\s+/g, '-')\n    .replace(/-+/g, '-');\n```\n\nThis makes:\n\n```js\nslugify('  Hello   World!  ') // \"hello-world\"\n```",
      "latency_ms": 3620,
      "cost": 0.01075,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct fix, concise, meets test, no constraints violated. Handles trimming, punctuation, multiple spaces properly."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The provided implementation correctly fixes the function to pass the test by trimming whitespace, removing punctuation, and replacing multiple spaces with a single hyphen."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct fix: trim, strip punctuation, collapse spaces/hyphens. Passes the given test. Clear and complete."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c10",
      "name": "Race condition",
      "prompt": "Identify the race condition in this code, explain what interleaving causes it, and fix it.\n\nlet cache = null;\nasync function getConfig() {\n  if (cache) return cache;\n  const r = await fetch('/config');\n  cache = await r.json();\n  return cache;\n}",
      "output": "The race is that `cache` is only set **after** the `await fetch()` and `await r.json()` complete. While the first call is suspended, another caller can enter `getConfig()`, see `cache === null`, and start a second fetch.\n\nProblematic interleaving:\n\n```js\n// cache === null\n\nA: getConfig()\nA: if (cache) return cache; // false\nA: await fetch('/config')   // suspends\n\nB: getConfig()\nB: if (cache) return cache; // still false\nB: await fetch('/config')   // suspends\n\nB: fetch resolves\nB: cache = await r.json()\nB: return cache\n\nA: fetch resolves later\nA: cache = await r.json()\nA: overwrites cache\nA: return cache\n```\n\nThis can cause duplicate requests, inconsistent return values, and a later stale response overwriting a newer one.\n\nA common fix is to cache the **in-flight promise**, not just the final value:\n\n```js\nlet configPromise = null;\n\nasync function getConfig() {\n  if (!configPromise) {\n    configPromise = fetch('/config')\n      .then(r => {\n        if (!r.ok) {\n          throw new Error(`Failed to fetch config: ${r.status}`);\n        }\n        return r.json();\n      })\n      .catch(err => {\n        configPromise = null; // allow retry after failure\n        throw err;\n      });\n  }\n\n  return configPromise;\n}\n```\n\nNow concurrent callers share the same request:\n\n```js\nconst [a, b] = await Promise.all([\n  getConfig(),\n  getConfig()\n]);\n```\n\nOnly one `fetch('/config')` is made, and both callers receive the same resolved config.",
      "latency_ms": 5594,
      "cost": 0.01521,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate race condition identification, clear interleaving trace, correct fix caching the promise with retry-on-failure logic. Clear, concise, useful."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response flawlessly identifies the race condition, clearly explains the problematic interleaving, and provides a robust fix that caches the promise and handles errors correctly."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Correctly identifies race, shows precise interleaving, and gives a solid promise-caching fix with retry on error. Clear and complete."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c11",
      "name": "Retry with backoff",
      "prompt": "Write an async retry wrapper in TypeScript: exponential backoff with jitter, a maximum attempt count, and it must NOT retry on 4xx responses other than 429. Maximum 30 lines. State what happens on the final failure.",
      "output": "```ts\ntype RetryOptions = { attempts?: number; baseMs?: number; maxMs?: number };\n\nconst sleep = (ms: number) => new Promise(r => setTimeout(r, ms));\n\nconst statusOf = (x: any): number | undefined =>\n  typeof x?.status === \"number\" ? x.status :\n  typeof x?.response?.status === \"number\" ? x.response.status :\n  undefined;\n\nconst isNonRetryable4xx = (s?: number) =>\n  s !== 429 && s !== undefined && s >= 400 && s < 500;\n\nexport async function retry<T>(\n  fn: () => Promise<T>,\n  { attempts = 5, baseMs = 200, maxMs = 5000 }: RetryOptions = {}\n): Promise<T> {\n  let last: any;\n\n  for (let i = 1; i <= attempts; i++) {\n    try {\n      const result = await fn();\n      const status = statusOf(result);\n      if (!(result as any)?.ok === false) return result;\n      if (isNonRetryable4xx(status) || i === attempts) throw result;\n      last = result;\n    } catch (err) {\n      last = err;\n      const status = statusOf(err);\n      if (isNonRetryable4xx(status) || i === attempts) throw err;\n    }\n\n    const cap = Math.min(maxMs, baseMs * 2 ** (i - 1));\n    await sleep(Math.random() * cap);\n  }\n\n  throw last;\n}\n```\n\nOn final failure, the wrapper throws the last error or failed HTTP `Response` back to the caller.",
      "latency_ms": 12660,
      "cost": 0.03462,
      "task_score": 5,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 5,
          "violates": true,
          "reasoning": "Logic bug in success/failure check (`!(result)?.ok === false`) is confusing and likely incorrect; code exceeds 30-line limit. Otherwise covers backoff, jitter, max attempts, 4xx handling, and final failure behavior."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 5,
          "violates": true,
          "reasoning": "The code block is 37 lines long, violating the maximum 30 lines constraint. Otherwise, it correctly implements exponential backoff with jitter, max attempts, and the 4xx logic, while stating the final failure behavior."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 5,
          "violates": true,
          "reasoning": "Exceeds 30-line limit. Buggy ok-check precedence; otherwise solid backoff/jitter/4xx logic and final-throw note."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c12",
      "name": "Recursive type",
      "prompt": "Write a TypeScript type DeepPartial<T> that makes every nested property optional, and explain in one sentence how it must handle arrays differently from plain objects.",
      "output": "```ts\ntype DeepPartial<T> =\n  T extends (...args: any[]) => any\n    ? T\n    : T extends Array<infer U>\n      ? Array<DeepPartial<U>>\n      : T extends ReadonlyArray<infer U>\n        ? ReadonlyArray<DeepPartial<U>>\n        : T extends object\n          ? { [K in keyof T]?: DeepPartial<T[K]> }\n          : T;\n```\n\nArrays must be handled by recursively applying `DeepPartial` to their element type, rather than treating them like plain objects and making array methods/properties optional.",
      "latency_ms": 7619,
      "cost": 0.019475,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct implementation, handles functions/arrays properly, explanation clear and matches requirement of one sentence."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response provides an accurate and robust DeepPartial type and perfectly follows the constraint to explain array handling in exactly one sentence."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Accurate DeepPartial handling arrays via element recursion; precise one-sentence explanation; fully meets task."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c13",
      "name": "Bash one-liner",
      "prompt": "Give me a single shell command that finds the ten largest files under the current directory recursively and prints them human-readable, largest first. It must handle filenames containing spaces. Explain each part briefly.",
      "output": "```sh\nfind . -type f -printf '%s\\t%p\\0' | sort -z -rn | head -z -n 10 | numfmt -z --field=1 --to=iec --suffix=B | tr '\\0' '\\n'\n```\n\nBriefly:\n\n- `find . -type f` — recursively finds regular files under the current directory.\n- `-printf '%s\\t%p\\0'` — prints each file’s size in bytes, a tab, the path, and a NUL terminator; this safely handles filenames with spaces.\n- `sort -z -rn` — sorts NUL-terminated records numerically in reverse order, largest first.\n- `head -z -n 10` — keeps only the first 10 NUL-terminated records.\n- `numfmt -z --field=1 --to=iec --suffix=B` — converts the byte-size field to human-readable form like `1.2MB`.\n- `tr '\\0' '\\n'` — converts NUL terminators to newlines for display.\n\nThis uses GNU `find`, `sort`, `head`, and `numfmt`.",
      "latency_ms": 14690,
      "cost": 0.03868,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct, robust GNU-only solution handling spaces via NUL delimiters; clear explanations. Minor concern: requires GNU coreutils (numfmt -z), not portable, but works as specified."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response provides a flawless, single shell command that perfectly handles spaces using NUL terminators, sorts correctly, formats to human-readable sizes, and concisely explains each component."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct GNU pipeline handling spaces via NULs, human sizes, top-10 largest-first; clear brief explanations. Minor portability note only."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c14",
      "name": "Explain and cost",
      "prompt": "Explain what this does and give its time and space complexity, then rewrite it to be O(n).\n\ndef has_dup(xs):\n    for i in range(len(xs)):\n        for j in range(i+1, len(xs)):\n            if xs[i] == xs[j]:\n                return True\n    return False",
      "output": "The function checks whether a list/sequence `xs` contains any duplicate values.\n\n```python\ndef has_dup(xs):\n    for i in range(len(xs)):\n        for j in range(i+1, len(xs)):\n            if xs[i] == xs[j]:\n                return True\n    return False\n```\n\nIt compares every pair of elements:\n\n- For each index `i`, it checks all later indices `j`.\n- If it finds two equal elements, it immediately returns `True`.\n- If no duplicates are found, it returns `False`.\n\n### Time complexity\n\nWorst case: **O(n²)**\n\nThis happens when there are no duplicates, or the duplicate appears only at the very end, so nearly every pair must be checked.\n\n### Space complexity\n\n**O(1)**\n\nIt only uses a few variables and does not allocate extra data structures proportional to the input size.\n\n---\n\n## O(n) version\n\n```python\ndef has_dup(xs):\n    seen = set()\n\n    for x in xs:\n        if x in seen:\n            return True\n        seen.add(x)\n\n    return False\n```\n\n### Time complexity\n\nAverage case: **O(n)**\n\nSet membership checks and insertions are average **O(1)**, and each element is processed once.\n\n### Space complexity\n\n**O(n)**\n\nIn the worst case, all elements are unique, so the set stores all `n` elements.\n\nNote: this version requires the elements of `xs` to be hashable, such as numbers, strings, tuples, etc.",
      "latency_ms": 4884,
      "cost": 0.012035,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate explanation, correct complexities, correct O(n) rewrite with set, notes hashability requirement. Clear and well-structured, minor omission of expected-time caveat nuance."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly explains the function, correctly identifies the O(n^2) time and O(1) space complexity, and provides an accurate O(n) rewrite using a set, along with its complexities."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Perfect explanation of function, correct O(n^{2})/O(1) complexities, and accurate O(n) set-based rewrite with notes."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c15",
      "name": "Regex with limits",
      "prompt": "Write a regex that validates UK postcodes, give a one-line explanation of each part, and then state two valid UK postcodes your regex would reject or two invalid ones it would accept. Do not claim it is perfect.",
      "output": "```regex\n/^(?i)(?:GIR\\s?0AA|(?:[A-PR-UWYZ][0-9][0-9]?|[A-PR-UWYZ][A-HK-Y][0-9][0-9]?|[A-PR-UWYZ][0-9][A-HJKPSTUW]|[A-PR-UWYZ][A-HK-Y][0-9][ABEHMNPRV-Y])\\s?[0-9][ABD-HJLNP-UW-Z]{2})$/\n```\n\n- `^` and `$` anchor the match so the whole string must be a postcode.\n- `(?i)` makes the match case-insensitive.\n- `GIR\\s?0AA` allows the special postcode `GIR 0AA`, with an optional space.\n- The outward-code alternatives cover the main UK formats: `A9`, `A99`, `AA9`, `AA99`, `A9A`, and `AA9A`, with common letter restrictions.\n- `\\s?` allows zero or one space between outward and inward parts.\n- `[0-9][ABD-HJLNP-UW-Z]{2}` matches the inward code: one digit followed by two allowed letters.\n\nThis is not perfect; for example, it would accept invalid-looking/nonexistent postcodes such as:\n\n- `AA1 1AA`\n- `Z1 1AA`",
      "latency_ms": 22984,
      "cost": 0.040485,
      "task_score": 8,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 4,
          "violates": true,
          "reasoning": "Regex uses invalid inline (?i) placement (should be flag, not embedded mid-pattern) causing syntax error in most engines. Explanation is decent but examples given are accepted, not clearly stated as rejected-valid or accepted-invalid pairs "
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response provides a highly accurate regex, explains each part clearly in one line, correctly identifies two invalid postcodes it would accept, and explicitly avoids claiming perfection. Flawless execution."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 8,
          "violates": false,
          "reasoning": "Solid regex with accurate one-line part explanations and two accepted invalids; minor format/polish issues only. Follows all task rules."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c16",
      "name": "Callback to async",
      "prompt": "Refactor this to async/await with correct error propagation. Errors must not be swallowed.\n\ngetUser(id, (e, user) => {\n  if (e) return cb(e);\n  getOrders(user.id, (e2, orders) => {\n    if (e2) return cb(e2);\n    getTotals(orders, (e3, totals) => cb(e3, totals));\n  });\n});",
      "output": "```js\nconst { promisify } = require(\"util\");\n\nconst getUserAsync = promisify(getUser);\nconst getOrdersAsync = promisify(getOrders);\nconst getTotalsAsync = promisify(getTotals);\n\nasync function getUserTotals(id) {\n  const user = await getUserAsync(id);\n  const orders = await getOrdersAsync(user.id);\n  return await getTotalsAsync(orders);\n}\n```\n\nUsage:\n\n```js\ntry {\n  const totals = await getUserTotals(id);\n  // use totals\n} catch (err) {\n  // all errors from getUser, getOrders, or getTotals arrive here\n  throw err; // or handle it\n}\n```\n\nIf you still need to expose the old callback style:\n\n```js\nasync function getUserTotalsCb(id, cb) {\n  try {\n    const totals = await getUserTotals(id);\n    cb(null, totals);\n  } catch (err) {\n    cb(err);\n  }\n}\n```\n\nNo errors are swallowed: any rejection or callback error from `getUser`, `getOrders`, or `getTotals` propagates to the caller.",
      "latency_ms": 5210,
      "cost": 0.011405,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct async/await refactor with proper error propagation via promisify and try/catch; includes backward-compatible callback wrapper. Clear and concise, though slightly more verbose than strictly necessary."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response correctly refactors the callback hell into clean async/await code using `promisify`. It ensures proper error propagation without swallowing errors, and provides clear, useful examples for both async and callback usage."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct async refactor with promisify and full error propagation via await/try. Clear, useful extras; minor assumption of Node util."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c17",
      "name": "Diagnose from a trace",
      "prompt": "Given this Node stack trace, state the most likely root cause and the first thing you would check:\n\nTypeError: Cannot read properties of undefined (reading 'map')\n    at renderRows (/app/src/table.js:42:19)\n    at Table (/app/src/table.js:12:5)\n    at renderWithHooks (/app/node_modules/react-dom/cjs/react-dom.development.js:16305:18)\n\nThe component works in dev and fails only on the production build's first paint.",
      "output": "Most likely root cause: `renderRows` is doing something like:\n\n```js\nrows.map(...)\n```\n\nbut `rows`/`data`/`items` is `undefined` on the initial production render.\n\nBecause it fails only on the production build’s first paint, the likely issue is an initial-render timing/data-shape problem: async data has not arrived yet, or the production API/env returns a different shape than dev.\n\nFirst thing I would check: line `42` in `/app/src/table.js` and inspect the value being mapped on the first render.\n\nExample:\n\n```js\nfunction renderRows(rows) {\n  return rows.map(...)\n}\n```\n\nCheck whether `rows` is ever `undefined` before the API call completes or during hydration.\n\nTypical fix:\n\n```js\nfunction renderRows(rows = []) {\n  return rows.map(...)\n}\n```\n\nor:\n\n```js\n{Array.isArray(rows) ? renderRows(rows) : null}\n```\n\nAlso verify the production API response/env config returns the expected array field.",
      "latency_ms": 10970,
      "cost": 0.02249,
      "task_score": 8,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Accurate, plausible diagnosis with concrete first-check step and fix. Clear, concise, useful despite being slightly code-heavy for non-technical reader."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response accurately identifies the root cause and the first thing to check. It provides clear, actionable advice tailored to the specific dev vs prod context, making it highly useful for a non-technical professional."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 8,
          "violates": false,
          "reasoning": "Accurate root cause and first check; clear fixes. Slightly long for non-technical reader but task is technical."
        }
      ],
      "machine_checks": null,
      "machine_violation": false,
      "machine_reasons": []
    },
    {
      "id": "c18",
      "name": "Idempotency",
      "prompt": "Design an idempotent POST /payments endpoint so a client retry cannot charge twice. Describe the key, where it is stored, what happens on a concurrent duplicate, and what you return the second time. Maximum 200 words. Name the failure mode your design still has.",
      "output": "Use an `Idempotency-Key` header: a client-generated UUID unique per intended payment.\n\nStore it in a durable DB table:\n\n`payment_idempotency(account_id, key, request_hash, status, payment_id, response_code, response_body)`\n\nAdd a unique constraint on `(account_id, key)`.\n\nFlow:\n\n1. On `POST /payments`, hash the request body.\n2. Atomically insert `(account_id, key, request_hash, status='processing')`.\n3. If insert succeeds, this request owns the payment attempt.\n4. Create the payment and call the payment processor, passing the same idempotency key if supported.\n5. Store the final response in the idempotency row.\n\nConcurrent duplicate:\n\n- If the same `(account_id, key)` already exists:\n  - If `request_hash` differs, return `409 Conflict`.\n  - If status is `processing`, do not start another charge. Either block briefly waiting for completion, or return `202 Accepted`/`409 Conflict` with `Retry-After`.\n  - If complete, return the stored response.\n\nSecond time return:\n\nReturn the same HTTP status and body as the original successful request, e.g. `201 Created` with the same `payment_id`.\n\nRemaining failure mode:\n\nThe design still has the “ambiguous external side effect” failure mode: the processor may charge successfully, but the server may crash before recording the completed result. This requires processor-side idempotency or reconciliation.",
      "latency_ms": 14009,
      "cost": 0.024965,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Accurate, well-structured, covers key/store/concurrency/response/failure mode; concise but slightly over ideal length; likely under 200 words though dense with schema detail."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly addresses all prompts within the 200-word limit. It clearly defines the key, storage, concurrent handling, return values, and accurately identifies the remaining failure mode (crash before commit). Flawless execution."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate idempotency design with key, storage, concurrency, and residual failure. Clear, concise, under 200 words, useful."
        }
      ],
      "machine_checks": {
        "max_words": 200
      },
      "machine_violation": false,
      "machine_reasons": []
    }
  ],
  "recapped_at": "2026-08-16T08:16:35.318Z",
  "recap_note": "Machine constraint caps applied retroactively under protocol judge-2026-08b; judge verdicts unchanged, task scores capped where a deterministic check failed."
}