{
  "entity": "gpt-5-6-terra",
  "entity_type": "model",
  "category": "Coding",
  "suite": "suite-2026-08-skills/coding",
  "model": "openai/gpt-5.6-terra",
  "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": 93,
  "caps": 0,
  "cost_usd": 0.2789,
  "started_at": "2026-08-16T06:30:05.630Z",
  "finished_at": "2026-08-16T06:31:12.736Z",
  "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\n_DURATION_RE = re.compile(r\"(?:(\\d+)h)?(?:(\\d+)m)?(?:(\\d+)s)?\")\n\ndef parse_duration(s):\n    \"\"\"Convert a duration like '1h30m' into total seconds.\"\"\"\n    if not isinstance(s, str):\n        raise ValueError(\"Duration must be a string\")\n\n    match = _DURATION_RE.fullmatch(s)\n    if not match or not any(match.groups()):\n        raise ValueError(f\"Malformed duration: {s!r}\")\n\n    hours, minutes, seconds = (\n        int(value) if value is not None else 0\n        for value in match.groups()\n    )\n\n    return hours * 3600 + minutes * 60 + seconds\n\n\n# Tests\nassert parse_duration(\"1h30m\") == 5400\nassert parse_duration(\"1h2m3s\") == 3723\n\ntry:\n    parse_duration(\"1m2h\")  # Units must appear in h, m, s order.\n    assert False, \"Expected ValueError\"\nexcept ValueError:\n    pass\n```",
      "latency_ms": 4297,
      "cost": 0.002409,
      "task_score": 8,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct implementation and tests, handles malformed input via order/format check. Minor: matches empty string improperly rejected? Actually empty string raises ValueError since groups all None - correct. Good quality overall."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly fulfills all instructions, providing a robust regex-based parsing function and exactly three tests, including one for malformed input."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct robust parser with regex and ValueError. Three assert tests present (two valid, one malformed via try/assert). Minor: non-idiomatic malformed test style."
        }
      ],
      "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": "The bug is that `n` is incremented for every element, including non-positive values, instead of only for positive values.\n\n```js\nfunction avgPositive(xs) {\n  let sum = 0, n = 0;\n  for (const x of xs) {\n    if (x > 0) {\n      sum += x;\n      n++;\n    }\n  }\n  return n === 0 ? 0 : sum / n;\n}\n```",
      "latency_ms": 1197,
      "cost": 0.000672,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Correctly identifies bug, provides accurate fix, adds sensible zero-division guard, clear and concise."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly identifies the bug, explains it in exactly one sentence, and provides a corrected function that also smartly handles the division-by-zero edge case."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Correctly identifies bug in one sentence and supplies proper fix plus safe zero-division handling."
        }
      ],
      "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": 1306,
      "cost": 0.000543,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct, efficient Postgres SQL, no window functions, meets all requirements: filters last 30 days, groups by user, having >3, orders descending. Clear and concise."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The SQL query perfectly matches all requirements, uses valid PostgreSQL syntax, correctly filters by date and order count, and avoids window functions as instructed."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Correct Postgres SQL meeting all requirements exactly; clear, concise, and immediately useful."
        }
      ],
      "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": "`items` is both:\n\n1. A dependency of the effect: `}, [items])`\n2. Updated by the effect: `.then(setItems)`\n\nThat creates this cycle:\n\n1. Component renders with `items = []`.\n2. The effect runs because it runs after the initial render.\n3. `fetch` resolves and `r.json()` produces a new array/object value.\n4. `setItems(newItems)` updates state.\n5. React re-renders.\n6. The `items` dependency is now a different reference than before (`Object.is(oldItems, newItems)` is false).\n7. React runs the effect again.\n8. It fetches again, creates another new array, calls `setItems` again, and repeats.\n\nEven if the API returns identical JSON each time, parsing JSON creates a new array/object reference, so React sees `items` as changed.\n\nIf the request should happen once when the component mounts, remove `items` from the dependency list:\n\n```jsx\nconst [items, setItems] = useState([]);\n\nuseEffect(() => {\n  fetch('/api/items')\n    .then((r) => {\n      if (!r.ok) throw new Error('Failed to fetch items');\n      return r.json();\n    })\n    .then(setItems)\n    .catch(console.error);\n}, []);\n```\n\nA more robust version cancels/ignores the result if the component unmounts before the request finishes:\n\n```jsx\nconst [items, setItems] = useState([]);\n\nuseEffect(() => {\n  const controller = new AbortController();\n\n  async function loadItems() {\n    try {\n      const response = await fetch('/api/items', {\n        signal: controller.signal,\n      });\n\n      if (!response.ok) {\n        throw new Error(`Failed to fetch items: ${response.status}`);\n      }\n\n      const data = await response.json();\n      setItems(data);\n    } catch (error) {\n      if (error.name !== 'AbortError') {\n        console.error(error);\n      }\n    }\n  }\n\n  loadItems();\n\n  return () => controller.abort();\n}, []);\n```\n\nIn React development Strict Mode, the mount effect may intentionally run twice to help detect unsafe effects. That can mean two initial requests in development, but it is separate from the infinite loop caused by `[items]`.",
      "latency_ms": 6886,
      "cost": 0.003249,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate, thorough explanation with correct fix and bonus robust version; clear and useful, slightly verbose but well organized."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly explains the infinite loop caused by updating a dependency inside the effect, including the detail about reference equality. It provides a clear fix and an excellent robust alternative with AbortController."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Accurate loop explanation via dependency/update cycle and reference inequality; correct empty-deps fix plus robust abort version; clear and complete."
        }
      ],
      "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<Args extends unknown[]> = {\n  (...args: Args): void;\n  cancel(): void;\n};\n\nexport function debounce<Args extends unknown[]>(\n  callback: (...args: Args) => unknown,\n  delayMs: number,\n): Debounced<Args> {\n  let timer: ReturnType<typeof setTimeout> | undefined;\n\n  const debounced = (...args: Args): void => {\n    if (timer !== undefined) {\n      clearTimeout(timer);\n    }\n\n    timer = setTimeout(() => {\n      timer = undefined;\n      void callback(...args);\n    }, delayMs);\n  };\n\n  debounced.cancel = (): void => {\n    if (timer !== undefined) {\n      clearTimeout(timer);\n      timer = undefined;\n    }\n  };\n\n  return debounced;\n}\n```\n\n```ts\nconst saveUser = debounce((id: string, active: boolean) => {\n  console.log(id, active);\n}, 300);\n\nsaveUser(\"user-1\", true); // typed correctly\nsaveUser.cancel();\n```\n\nA naive signature using a broad rest-parameter type loses information because it replaces the original parameter tuple with an unconstrained list rather than preserving each argument’s position and type.",
      "latency_ms": 8206,
      "cost": 0.004679,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct, no 'any', has cancel(), preserves types, explanation given though slightly vague—doesn't mention Parameters<T> or 'any[]' naive signature explicitly."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly implements the debounce function in TypeScript, strictly avoiding 'any', preserving argument types, including a cancel method, and providing a clear, one-sentence explanation as requested."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Correct typed debounce with cancel, no any; one-sentence explanation accurate; fully meets all requirements clearly."
        }
      ],
      "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 first_occurrence(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          # Record match\n            right = mid - 1       # Keep searching left half\n        elif arr[mid] < target:\n            left = mid + 1\n        else:\n            right = mid - 1\n\n    return result\n```\n\nExample test case that distinguishes this from ordinary binary search:\n\n```python\narr = [1, 2, 2, 2, 3, 4]\ntarget = 2\n\nprint(first_occurrence(arr, target))  # 1\n```\n\nAn ordinary binary search might return index `2` or `3` after finding any `2`, but this version continues searching left and returns the first occurrence, index `1`.\n\n- Time complexity: `O(log n)`\n- Space complexity: `O(1)`",
      "latency_ms": 2159,
      "cost": 0.00142,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct implementation, proper complexity, clear distinguishing test case, concise and well-explained."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly fulfills all requirements: it provides the correct algorithm, states both time and space complexity, and includes 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, proper complexities, 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": "1. **Path traversal / arbitrary file read — critical**\n\n   `p` is appended directly to a filesystem path:\n\n   ```js\n   __dirname + '/uploads/' + p\n   ```\n\n   An attacker can request values such as:\n\n   ```text\n   ?name=../../../../etc/passwd\n   ?name=../config/secrets.json\n   ```\n\n   Depending on the resolved path and process permissions, this can expose arbitrary files readable by the Node process.\n\n   **Fix:** Do not use a client-provided path. Prefer an opaque file ID and look up a server-controlled stored filename/path. Also use `sendFile`’s `root` option and validate that the filename is a simple basename, not a path.\n\n   ```js\n   const uploadRoot = path.join(__dirname, 'uploads');\n\n   res.sendFile(storedFilename, {\n     root: uploadRoot,\n     dotfiles: 'deny'\n   }, next);\n   ```\n\n   Validate `storedFilename` with a strict allowlist, for example UUIDs or generated IDs, and reject values containing `/`, `\\`, `..`, or unexpected characters.\n\n---\n\n2. **SQL injection — critical**\n\n   User input is interpolated directly into SQL:\n\n   ```js\n   `SELECT * FROM files WHERE name = '${p}'`\n   ```\n\n   A request such as:\n\n   ```text\n   ?name=' OR '1'='1\n   ```\n\n   changes the query. Impact depends on the database driver and configuration, but can include data disclosure, authentication/authorization bypass if the query is later used for access control, denial of service, and possibly data modification if multi-statement execution is enabled.\n\n   **Fix:** Use parameterized queries/prepared statements.\n\n   ```js\n   db.query(\n     'SELECT id, stored_name FROM files WHERE name = ?',\n     [p],\n     callback\n   );\n   ```\n\n   Better: query by a server-issued opaque file ID rather than a user-controlled filename.\n\n---\n\n3. **The database lookup does not protect anything — high**\n\n   The query result is ignored:\n\n   ```js\n   db.query(..., (e, rows) => {\n     res.sendFile(...);\n   });\n   ```\n\n   Even if no database row exists, or the query fails, the server still attempts to send the requested file. Therefore the query provides no existence check, authorization check, or path validation.\n\n   This is especially dangerous if the author intended the database query to control file access.\n\n   **Fix:** Fail closed. Send a file only after a successful query returns exactly an authorized record.\n\n   ```js\n   if (err) return next(err);\n   if (rows.length !== 1) return res.sendStatus(404);\n   ```\n\n   Use the database result’s server-controlled stored filename, not `req.query.name`.\n\n---\n\n4. **Missing authentication and authorization check — high if files are not meant to be public**\n\n   Nothing verifies who is requesting the file or whether that user may access it. Any caller who knows or guesses a filename can request it.\n\n   **Fix:** Authenticate the requester and include authorization in the database lookup. For example, scope the lookup to the current user, tenant, or access policy:\n\n   ```sql\n   SELECT stored_name\n   FROM files\n   WHERE id = ? AND owner_id = ?\n   ```\n\n   Do not reveal whether another user’s file exists; return a generic `404` or `403` according to the application’s policy.\n\n---\n\n5. **Database errors are ignored — medium**\n\n   The callback ignores `e`:\n\n   ```js\n   (e, rows) => {\n     res.sendFile(...);\n   }\n   ```\n\n   If the database is unavailable or the SQL fails, the handler still tries to serve a local file. This can bypass intended database-based access control and creates inconsistent behavior.\n\n   **Fix:** Handle errors before proceeding:\n\n   ```js\n   if (err) return next(err);\n   ```\n\n   Use centralized production error handling that does not expose SQL details, stack traces, or filesystem paths to users.\n\n---\n\n6. **Unrestricted filename input / weak input validation — medium**\n\n   `req.query.name` is accepted with no type, length, or character validation. Besides enabling traversal and SQL injection, extremely long or malformed values can cause unnecessary database and application work.\n\n   **Fix:** Prefer a file ID with a strict format. For example:\n\n   ```js\n   const fileId = String(req.query.id || '');\n\n   if (!/^[0-9a-f-]{36}$/i.test(fileId)) {\n     return res.status(400).json({ error: 'Invalid file id' });\n   }\n   ```\n\n   Do not accept arbitrary paths or arbitrary user-selected filenames as the access mechanism.\n\n---\n\n7. **Potential exposure through uploaded-file symlinks — medium, depending on upload behavior**\n\n   Even with a safe upload root, if attackers can create or influence symlinks inside `uploads`, a seemingly harmless filename can resolve outside that directory and expose other files.\n\n   **Fix:** Store uploads outside attacker-controlled filesystem structures, prevent symlink creation, and ensure the upload process writes regular files with safe permissions. Ideally store files under generated names and maintain metadata in the database.\n\n---\n\nA safer version would look like this:\n\n```js\nconst path = require('path');\n\nconst uploadRoot = path.join(__dirname, 'uploads');\n\napp.get('/file', requireAuth, (req, res, next) => {\n  const fileId = String(req.query.id || '');\n\n  // Example: UUID validation. Use the format your application issues.\n  if (!/^[0-9a-f-]{36}$/i.test(fileId)) {\n    return res.status(400).json({ error: 'Invalid file id' });\n  }\n\n  db.query(\n    `SELECT stored_name\n     FROM files\n     WHERE id = ? AND owner_id = ?`,\n    [fileId, req.user.id],\n    (err, rows) => {\n      if (err) return next(err);\n      if (rows.length !== 1) return res.sendStatus(404);\n\n      const storedName = rows[0].stored_name;\n\n      // Defense in depth: stored names should be generated basenames only.\n      if (!/^[A-Za-z0-9_-]+(?:\\.[A-Za-z0-9]+)?$/.test(storedName)) {\n        return next(new Error('Invalid stored file name'));\n      }\n\n      res.sendFile(storedName, {\n        root: uploadRoot,\n        dotfiles: 'deny'\n      }, next);\n    }\n  );\n});\n```\n\nThe most important design change is: **clients should request an opaque file ID, while the server maps that ID to a server-controlled stored filename after authorization.**",
      "latency_ms": 17819,
      "cost": 0.011593,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Thorough, accurate, correctly ranked by severity, with clear fixes and safer code example. Covers SQLi, path traversal, missing auth, error handling. Well organized and useful, though lengthy for non-technical reader."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response accurately identifies all security vulnerabilities, orders them by severity, and provides clear, practical fixes. It is highly useful, well-structured, and includes a comprehensive refactored code example."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Accurate severity-ordered findings with correct fixes; fully matches task; clear and professional."
        }
      ],
      "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": "For PostgreSQL **11+**, adding a column with a constant default is metadata-only: existing rows are treated as having the default without physically updating 40 million rows.\n\n```sql\nBEGIN;\n\n-- Do not wait indefinitely for an ACCESS EXCLUSIVE lock.\nSET LOCAL lock_timeout = '5s';\n\nALTER TABLE orders\n  ADD COLUMN status text NOT NULL DEFAULT 'pending';\n\nCOMMIT;\n```\n\n### Steps, in order\n\n1. **Ensure PostgreSQL is version 11 or newer.**\n   ```sql\n   SHOW server_version;\n   ```\n\n2. **Run the `ALTER TABLE` with a short `lock_timeout`.**\n   ```sql\n   BEGIN;\n   SET LOCAL lock_timeout = '5s';\n\n   ALTER TABLE orders\n     ADD COLUMN status text NOT NULL DEFAULT 'pending';\n\n   COMMIT;\n   ```\n\n3. **If it times out, retry later.**  \n   Do not remove the lock timeout and let it wait behind long-running transactions.\n\n### Why this is safe on PostgreSQL 11+\n\nBecause `'pending'` is a constant, PostgreSQL stores the default in table metadata rather than rewriting every existing row. The command still needs an `ACCESS EXCLUSIVE` lock, but it is held only briefly once acquired.\n\nNew inserts automatically receive `'pending'`, and existing rows read as `'pending'`.\n\n### Dangerous step\n\nThe dangerous step is:\n\n```sql\nALTER TABLE orders\n  ADD COLUMN status text NOT NULL DEFAULT 'pending';\n```\n\non **PostgreSQL 10 or earlier**.\n\nOn those versions, adding a column with a non-NULL default rewrites the entire table, which can take a very long time for 40 million rows and holds an `ACCESS EXCLUSIVE` lock for the duration. That blocks reads and writes.\n\nAlso, even on PostgreSQL 11+, the command can be delayed waiting to acquire its short exclusive lock if there are long-running queries or transactions. That is why `lock_timeout` is important.\n\n---\n\nIf the server is PostgreSQL 10 or older, use a staged migration instead:\n\n```sql\n-- 1. Brief metadata lock: add nullable column without a default.\nALTER TABLE orders ADD COLUMN status text;\n\n-- 2. Brief metadata lock: make future inserts get the default.\nALTER TABLE orders ALTER COLUMN status SET DEFAULT 'pending';\n\n-- 3. Backfill in small committed batches from application/job code.\n-- Example pattern; repeat until zero rows are updated:\nUPDATE orders\nSET status = 'pending'\nWHERE id IN (\n  SELECT id\n  FROM orders\n  WHERE status IS NULL\n  ORDER BY id\n  LIMIT 10000\n);\n\n-- 4. Add and validate a NOT NULL-equivalent check without blocking writes.\nALTER TABLE orders\n  ADD CONSTRAINT orders_status_not_null\n  CHECK (status IS NOT NULL) NOT VALID;\n\nALTER TABLE orders\n  VALIDATE CONSTRAINT orders_status_not_null;\n\n-- 5. Final short lock to make it a true NOT NULL column.\nALTER TABLE orders\n  ALTER COLUMN status SET NOT NULL;\n\n-- Optional: remove the temporary/check constraint afterward.\nALTER TABLE orders\n  DROP CONSTRAINT orders_status_not_null;\n```\n\nFor the old-version approach, the most dangerous operation is the backfill if done as one giant `UPDATE`: it creates large WAL volume, table bloat, long-running transactions, replication lag, and contention. Backfill in small batches instead.",
      "latency_ms": 12079,
      "cost": 0.007348,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Accurate, correctly notes PG11+ fast path, gives safe staged migration for older versions, identifies dangerous steps clearly. Slightly verbose but well-organized and correct."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 9,
          "violates": false,
          "reasoning": "Excellent, accurate response. It correctly identifies the PG 11+ optimization, provides the safe approach with lock_timeout, and explains the dangers for older versions. Highly useful and clear."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate PG11+ fast-path and staged fallback; clear ordered steps; correctly flags lock/rewrite risks. 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(/[^\\p{L}\\p{N}]+/gu, '-')\n    .replace(/^-+|-+$/g, '');\n```\n\nThis trims leading/trailing whitespace, collapses spaces and punctuation into a single hyphen, and removes any leftover edge hyphens.\n\n```js\nslugify('  Hello   World!  '); // 'hello-world'\n```",
      "latency_ms": 4400,
      "cost": 0.002036,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct fix, produces expected output, concise explanation, addresses task properly without modifying test."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The provided implementation correctly fixes the function to pass the test, handling multiple spaces, punctuation, and trimming effectively. It is concise and accurate."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct fix passes the test; clear, concise, follows task. Minor overkill with Unicode classes but solid."
        }
      ],
      "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 a **check-then-act** race:\n\n```js\nif (cache) return cache;\n```\n\nTwo callers can both observe `cache === null` before either fetch completes.\n\nExample interleaving:\n\n1. Call A enters `getConfig`, sees `cache` is `null`.\n2. A starts `fetch('/config')` and pauses at `await`.\n3. Call B enters, also sees `cache` is `null`.\n4. B starts a second fetch and pauses.\n5. B finishes first and stores one result in `cache`.\n6. A finishes later and overwrites `cache` with its result.\n\nThis causes duplicate requests and can leave the cache containing an older response if the server response changed between requests.\n\nStore the in-flight promise so all concurrent callers share one request:\n\n```js\nlet cache = null;\nlet hasCache = false;\nlet configRequest = null;\n\nfunction getConfig() {\n  if (hasCache) {\n    return Promise.resolve(cache);\n  }\n\n  if (configRequest) {\n    return configRequest;\n  }\n\n  configRequest = fetch('/config')\n    .then(r => {\n      if (!r.ok) {\n        throw new Error(`Failed to load config: ${r.status}`);\n      }\n      return r.json();\n    })\n    .then(config => {\n      cache = config;\n      hasCache = true;\n      return config;\n    })\n    .finally(() => {\n      configRequest = null;\n    });\n\n  return configRequest;\n}\n```\n\nNow:\n\n- The first caller creates `configRequest`.\n- Concurrent callers return that same promise instead of starting additional fetches.\n- If the request fails, `configRequest` is cleared so a later call can retry.\n- `hasCache` avoids relying on truthiness in case the parsed config could be a falsy value.",
      "latency_ms": 9529,
      "cost": 0.005436,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Correctly identifies check-then-act race, gives clear interleaving example, and provides a robust fix using an in-flight promise. Minor: could mention resetting cache on error, but overall accurate and useful."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "Accurately identifies the check-then-act race condition, clearly explains the interleaving, and provides a robust fix that handles concurrent requests, falsy cache values, and errors perfectly."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate race ID, clear interleaving, solid shared-promise fix with extras. Minor polish only; fully meets task."
        }
      ],
      "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 = {\n  maxAttempts?: number;\n  baseDelayMs?: number;\n  maxDelayMs?: number;\n};\n\nexport async function retry<T>(\n  fn: () => Promise<T>,\n  { maxAttempts = 5, baseDelayMs = 100, maxDelayMs = 10_000 }: RetryOptions = {}\n): Promise<T> {\n  if (maxAttempts < 1) throw new RangeError(\"maxAttempts must be >= 1\");\n\n  for (let attempt = 1; attempt <= maxAttempts; attempt++) {\n    try {\n      return await fn();\n    } catch (error) {\n      const e = error as { status?: number; response?: { status?: number } };\n      const status = e.response?.status ?? e.status;\n      const nonRetryable4xx = status != null && status >= 400 && status < 500 && status !== 429;\n\n      if (nonRetryable4xx || attempt === maxAttempts) throw error;\n\n      const cap = Math.min(maxDelayMs, baseDelayMs * 2 ** (attempt - 1));\n      await new Promise(resolve => setTimeout(resolve, Math.random() * cap));\n    }\n  }\n  throw new Error(\"unreachable\");\n}\n```\n\nOn the final failed attempt, it immediately rethrows the last error; no additional delay or retry occurs.",
      "latency_ms": 7513,
      "cost": 0.004776,
      "task_score": 8,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct logic, meets constraints, concise (~25 lines), states final-failure behavior clearly. Minor: jitter is full-range random rather than added jitter, slight style nuance."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 5,
          "violates": true,
          "reasoning": "The response provides a correct and well-implemented TypeScript retry wrapper meeting all functional requirements. However, it violates the constraint of a maximum of 30 lines (the response is 32 lines long)."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct TS retry with exp backoff+jitter, max attempts, skips non-429 4xx; states final rethrow. 28-line code. Minor polish only."
        }
      ],
      "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 readonly (infer U)[]\n    ? T extends (infer _MutableU)[]\n      ? DeepPartial<U>[]\n      : readonly DeepPartial<U>[]\n    : T extends object\n      ? { [K in keyof T]?: DeepPartial<T[K]> }\n      : T;\n```\n\nArrays must preserve their array/readonly-array shape while recursively applying `DeepPartial` to their element type, rather than treating numeric indices and array methods as ordinary optional object properties.",
      "latency_ms": 1732,
      "cost": 0.000703,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct, robust implementation handling readonly arrays too; explanation sentence satisfies requirement; concise and clear, minor edge cases (functions) unaddressed but not required."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response provides a highly accurate and robust DeepPartial type, correctly handling arrays and readonly arrays. The explanation is exactly one sentence and perfectly describes the distinction."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct, robust DeepPartial handling arrays/readonly; one clear 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 -nr | head -z -n 10 | numfmt -z --field=1 --to=iec-i --suffix=B --delimiter=$'\\t' | tr '\\0' '\\n'\n```\n\nBriefly:\n\n- `find . -type f` — recursively finds regular files below the current directory.\n- `-printf '%s\\t%p\\0'` — prints each file’s size, a tab, its path, and a NUL terminator. NUL separation safely handles spaces in filenames.\n- `sort -z -nr` — sorts NUL-terminated records numerically (`-n`) in reverse/largest-first order (`-r`).\n- `head -z -n 10` — keeps the first ten NUL-terminated records.\n- `numfmt ... --to=iec-i` — converts the size field to readable units such as `12MiB`.\n- `tr '\\0' '\\n'` — converts the final NUL separators into displayable newlines.\n\nThis uses GNU versions of `find`, `sort`, `head`, and `numfmt`.",
      "latency_ms": 7529,
      "cost": 0.00467,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Correct, robust GNU command handling spaces via NUL, clear per-part explanation; slightly complex for non-technical user but accurate and functional."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response provides a flawless, highly robust shell command using NUL-termination to safely handle spaces. The explanation is clear, concise, and perfectly addresses all requirements."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct NUL-safe GNU pipeline; clear brief explanations; notes portability. Minor: numfmt options slightly verbose but accurate."
        }
      ],
      "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": "`has_dup(xs)` checks whether a list contains any duplicate value.\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\n### How it works\n\n- The outer loop selects each element at index `i`.\n- The inner loop compares that element to every later element (`j = i + 1` onward).\n- If two values are equal, it immediately returns `True`.\n- If all pairs are checked without finding a match, it returns `False`.\n\nFor example:\n\n```python\nhas_dup([1, 2, 3, 2])  # True\nhas_dup([1, 2, 3])     # False\n```\n\n### Complexity\n\nLet `n` be the length of `xs`.\n\n- **Time:** `O(n²)` in the worst case, because it may compare roughly every pair of elements.\n- **Space:** `O(1)` extra space, since it only uses loop variables.\n\n### O(n) rewrite\n\nUse a `set` to track values already seen:\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\nThis version:\n\n- Checks whether each item has appeared before.\n- Returns `True` as soon as it finds a repeated item.\n\nComplexity:\n\n- **Time:** `O(n)` on average, since set membership and insertion are average `O(1)`.\n- **Space:** `O(n)` in the worst case for the `seen` set.",
      "latency_ms": 3208,
      "cost": 0.002221,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate explanation, correct complexities, correct O(n) rewrite with proper tradeoff noted (space O(n)). Clear and well-structured, minor note average-case O(1) set ops is a slight nuance but standard."
        },
        {
          "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 a flawless O(n) rewrite using a set with accurate complexity analysis."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Perfect explanation, accurate O(n^{2})/O(1) analysis, correct O(n) set-based rewrite with proper average-case notes. Clear and complete."
        }
      ],
      "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)\\A(?:GIR|[A-PR-UWYZ][0-9]{1,2}|[A-PR-UWYZ][A-HK-Y][0-9]{1,2}|[A-PR-UWYZ][0-9][ABEHMNPRVWXY]|[A-PR-UWYZ][A-HK-Y][0-9][ABEHMNPRVWXY])[ ]?[0-9][ABDEFGHJLNPQRSTUWXYZ]{2}\\z\n```\n\n- `(?i)` — makes matching case-insensitive; remove it if uppercase-only input is required.  \n- `\\A` and `\\z` — require the entire input to be a postcode (PCRE-style anchors).  \n- `GIR` — permits the special outward code used by `GIR 0AA`.  \n- `[A-PR-UWYZ][0-9]{1,2}` — matches outward codes such as `M1` or `B33`.  \n- `[A-PR-UWYZ][A-HK-Y][0-9]{1,2}` — matches outward codes such as `EC1` or `SW19`.  \n- `[A-PR-UWYZ][0-9][ABEHMNPRVWXY]` — matches forms such as `W1A`.  \n- `[A-PR-UWYZ][A-HK-Y][0-9][ABEHMNPRVWXY]` — matches forms such as `EC1A`.  \n- `[ ]?` — allows an optional ordinary space between outward and inward parts.  \n- `[0-9]` — matches the first digit of the inward code.  \n- `[ABDEFGHJLNPQRSTUWXYZ]{2}` — matches the two permitted final inward-code letters.  \n\nThis is a format validator, not a perfect postcode database check: it would accept invalid/unallocated examples such as `A1 1AA` and `AA1A 1AA`, because neither `A` nor `AA` is an allocated UK postcode area.",
      "latency_ms": 32280,
      "cost": 0.018237,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Solid regex with explanations and two accepted-invalid examples; doesn't claim perfection. Minor: examples plausibility unverified, slight redundancy in explanation."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly follows all instructions, providing a robust regex, clear one-line explanations, and correctly identifying two invalid postcodes the regex would accept, while explicitly stating it is not perfect."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Accurate regex with clear one-line part explanations; correctly notes two invalid accepts and avoids perfection claim. Minor polish only."
        }
      ],
      "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\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\nIf the existing functions are callback-based, promisify them first:\n\n```js\nconst { promisify } = require('node: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 getTotalsAsync(orders);\n}\n```\n\nErrors from any operation automatically reject the returned promise and propagate to the caller:\n\n```js\ntry {\n  const totals = await getUserTotals(id);\n  // use totals\n} catch (err) {\n  // handle error\n}\n```",
      "latency_ms": 1960,
      "cost": 0.001255,
      "task_score": 9,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 7,
          "violates": false,
          "reasoning": "Correct promisify approach, proper error propagation via async/await and try/catch. Minor inconsistency: second snippet drops 'await' before return, harmless but slightly less clear."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly refactors the callback hell into async/await, correctly explains how to promisify the original functions, and accurately describes how errors propagate without swallowing them."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 9,
          "violates": false,
          "reasoning": "Correct async/await refactor via promisify; errors propagate properly. Clear, concise, useful. Minor first-snippet redundancy."
        }
      ],
      "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 calling `.map()` on a value that is `undefined` during the initial production render—likely an async-loaded prop/state value such as `rows`, `data`, or `items`. Development timing may hide it because data arrives before the problematic render or because dev behavior differs.\n\n**First thing to check:** Open `/app/src/table.js` at **line 42** and identify the expression before `.map`, e.g.:\n\n```js\nrows.map(...)\n```\n\nThen verify why `rows` is undefined on the first render in production. Check the parent’s initial state/props and API-loading path. Typical fix:\n\n```js\nconst [rows, setRows] = useState([]);\n```\n\nor guard the render:\n\n```js\n(rows ?? []).map(...)\n```\n\nAlso confirm any production-only API/config/environment variable isn’t causing the data request to fail or return an unexpected shape.",
      "latency_ms": 3839,
      "cost": 0.001882,
      "task_score": 8,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Accurate, actionable diagnosis and check steps; concise with helpful code snippets; minor lack of specific prod-vs-dev timing/bundling nuance."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response accurately identifies the root cause and provides the exact first step to check, tailored perfectly to the provided stack trace and context. It is clear, concise, and highly useful."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 8,
          "violates": false,
          "reasoning": "Accurate root cause and check for the React prod-only undefined map error; clear and useful though slightly code-heavy for non-tech users."
        }
      ],
      "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": "`POST /payments` requires an `Idempotency-Key` header: a client-generated UUID unique per logical payment.\n\nStore it durably in a database table keyed by `(merchant_id, idempotency_key)` with:\n\n- request payload hash\n- status: `processing`, `succeeded`, `failed`\n- payment/provider reference\n- original HTTP status and response body\n\nCreate the row using a unique constraint/transaction. If the key already exists:\n\n- If the payload hash differs, return `422 Idempotency key reused with different request`.\n- If status is `processing`, either wait briefly for completion or return `409/202` indicating the request is in progress.\n- If completed, return the exact originally stored status code and response body; do not create another charge.\n\nUse the same idempotency key (or derived stable key) when calling the payment provider, so provider retries are also deduplicated.\n\nRemaining failure mode: the **external side-effect atomicity gap**—the service can crash after the provider charges the card but before the local database records success. Provider-side idempotency and later reconciliation reduce this, but true exactly-once charging across separate systems is not guaranteed.",
      "latency_ms": 5020,
      "cost": 0.002587,
      "task_score": 10,
      "judges": [
        {
          "judge": "anthropic/claude-sonnet-5",
          "score": 8,
          "violates": false,
          "reasoning": "Accurate, well-structured design covering key, storage, concurrency handling, and returned response; names a valid failure mode. Slightly over concise ideal but within 200 words, clear and useful."
        },
        {
          "judge": "google/gemini-3.1-pro-preview",
          "score": 10,
          "violates": false,
          "reasoning": "The response perfectly addresses all prompts: describes the key, storage, concurrent duplicate handling, second response, and names the remaining failure mode. It is highly accurate, concise, and well under the 200-word limit."
        },
        {
          "judge": "x-ai/grok-4.5",
          "score": 10,
          "violates": false,
          "reasoning": "Complete, accurate idempotency design covering key, storage, concurrency, replay, and residual failure; under 200 words; clear and useful."
        }
      ],
      "machine_checks": {
        "max_words": 200
      },
      "machine_violation": false,
      "machine_reasons": []
    }
  ],
  "recapped_at": "2026-08-16T08:16:35.370Z",
  "recap_note": "Machine constraint caps applied retroactively under protocol judge-2026-08b; judge verdicts unchanged, task scores capped where a deterministic check failed."
}