GPT-6.1 Sol (effort default (no reasoning-effort override) · thinking on) on Fix keyset pagination of a SQLite feed (ties, filters before paging, exact next-cursor, rows changing between pages, cursor validation)

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{"type": "turn.started"}
{"type": "item.completed", "item": {"id": "item_0", "type": "agent_message", "text": "I\u2019ll read the pagination contract and current code, then rewrite `list_items` and check it locally without network access.\n"}}
{"type": "item.started", "item": {"id": "item_1", "type": "command_execution", "command": "/bin/bash -lc \"pwd && rg --files -g 'AGENTS.md' -g 'PAGINATION.md' -g 'feed.py' -g 'schema.sql' -g '*test*'\"", "aggregated_output": "", "exit_code": null, "status": "in_progress"}}
{"type": "item.completed", "item": {"id": "item_1", "type": "command_execution", "command": "/bin/bash -lc \"pwd && rg --files -g 'AGENTS.md' -g 'PAGINATION.md' -g 'feed.py' -g 'schema.sql' -g '*test*'\"", "aggregated_output": "/home/bob/usecase-runs/batch/out/gpt-6.1-sol/184_g05/work\nPAGINATION.md\nfeed.py\nschema.sql\n", "exit_code": 0, "status": "completed"}}
{"type": "item.started", "item": {"id": "item_2", "type": "command_execution", "command": "/bin/bash -lc 'cat PAGINATION.md feed.py schema.sql'", "aggregated_output": "", "exit_code": null, "status": "in_progress"}}
{"type": "item.completed", "item": {"id": "item_2", "type": "command_execution", "command": "/bin/bash -lc 'cat PAGINATION.md feed.py schema.sql'", "aggregated_output": "# list_items(conn, limit=20, cursor=None, status=None, order=\"desc\")\n\n`conn` is an open `sqlite3.Connection` to a database created with `schema.sql`. Returns `{\"items\": [...], \"next_cursor\": <str or None>}`; each item is a dict with exactly the keys `id`, `created_at`, `status`, `title` (values as stored).\n\n1. Order. `order=\"desc\"`: newest first, i.e. `created_at` descending, ties broken by `id` descending. `order=\"asc\"`: `created_at` ascending, ties by `id` ascending. Any other value raises `ValueError`.\n2. Limit. `limit` must be an `int` from 1 to 100 inclusive; anything else (0, 101, negative, a string) raises `ValueError`.\n3. Filter. `status=None` means all items; otherwise only items whose `status` equals the given string exactly. The filter is applied before paging: every page contains exactly `limit` items, except the last page, which contains the remaining ones. The status value is data, never SQL (a status such as `x' OR '1'='1` just matches nothing).\n4. Next cursor. `next_cursor` is an opaque string, or `None` exactly when no matching item comes after the last returned item at the time of the call. So a final page that is exactly full has `next_cursor=None`, and an empty result is `{\"items\": [], \"next_cursor\": None}`.\n5. Continuation. Calling again with `cursor=<next_cursor>` and the same `status` and `order` (limit may change) returns the following page. Walking all pages returns every matching item exactly once, in the order of rule 1, even when rows change between calls: items inserted with a `created_at` newer than every existing item never appear in a later page of a `desc` walk (and appear at the end of an `asc` walk); a deleted item that was not yet returned is simply absent; deleting items that were already returned never causes skips or repeats. Ties on `created_at` across page boundaries must not cause skips or repeats.\n6. Bad cursors. `cursor=None` means the first page. Any other value must be a cursor returned by a previous call; anything else (empty string, random text, corrupted data) raises `ValueError` (not any other exception type). A cursor used with a different `status` or `order` than the call that produced it raises `ValueError`.\n\"\"\"Item feed pagination.\"\"\"\nimport base64\n\n\ndef list_items(conn, limit=20, cursor=None, status=None, order=\"desc\"):\n    cmp = \"<\" if order == \"desc\" else \">\"\n    sql = \"SELECT id, created_at, status, title FROM items\"\n    args = []\n    if cursor:\n        last = base64.b64decode(cursor).decode()\n        sql += f\" WHERE created_at {cmp} ?\"\n        args.append(last)\n    sql += f\" ORDER BY created_at {order} LIMIT ?\"\n    args.append(limit)\n    rows = conn.execute(sql, args).fetchall()\n    items = [dict(zip((\"id\", \"created_at\", \"status\", \"title\"), r)) for r in rows]\n    if status is not None:\n        items = [i for i in items if i[\"status\"] == status]\n    nxt = None\n    if len(rows) == limit:\n        nxt = base64.b64encode(rows[-1][1].encode()).decode()\n    return {\"items\": items, \"next_cursor\": nxt}\nCREATE TABLE items (\n  id INTEGER PRIMARY KEY,\n  created_at TEXT NOT NULL,   -- 'YYYY-MM-DDTHH:MM:SSZ', many rows share a value\n  status TEXT NOT NULL,\n  title TEXT NOT NULL\n);\nCREATE INDEX items_created ON items(created_at, id);\n", "exit_code": 0, "status": "completed"}}
{"type": "item.completed", "item": {"id": "item_3", "type": "agent_message", "text": "The code pages before filtering and uses only `created_at` as the cursor, which explains the short pages and skipped ties. I\u2019ll filter in SQL, paginate by `(created_at, id)`, and fetch one extra row to determine whether a next page exists. Cursors will also carry the filter and order, with integrity checks to reject altered data.\n"}}
{"type": "item.started", "item": {"id": "item_4", "type": "command_execution", "command": "/bin/bash -lc \"cat > feed.py <<'PY'\n\\\"\\\"\\\"Item feed pagination using authenticated keyset cursors.\\\"\\\"\\\"\nimport base64\nimport binascii\nimport hashlib\nimport hmac\nimport json\nimport secrets\n\n\n_CURSOR_KEY = secrets.token_bytes(32)\n_COLUMNS = (\\\"id\\\", \\\"created_at\\\", \\\"status\\\", \\\"title\\\")\n\n\ndef _encode_cursor(created_at, item_id, status, order):\n    payload = json.dumps(\n        [1, created_at, item_id, status, order],\n        ensure_ascii=True, separators=(\\\",\\\", \\\":\\\"),\n    ).encode(\\\"ascii\\\")\n    signature = hmac.digest(_CURSOR_KEY, payload, hashlib.sha256)\n    return base64.urlsafe_b64encode(signature + payload).decode(\\\"ascii\\\")\n\n\ndef _decode_cursor(cursor, status, order):\n    try:\n        if not isinstance(cursor, str) or not cursor:\n            raise ValueError(\\\"Invalid cursor\\\")\n        raw = base64.b64decode(cursor.encode(\\\"ascii\\\"), altchars=b\\\"-_\\\", validate=True)\n        if base64.urlsafe_b64encode(raw).decode(\\\"ascii\\\") \"'!= cursor:\n            raise ValueError(\"Invalid cursor\")\n        signature, payload = raw[:32], raw[32:]\n        if not hmac.compare_digest(\n            signature, hmac.digest(_CURSOR_KEY, payload, hashlib.sha256)\n        ):\n            raise ValueError(\"Invalid cursor\")\n        data = json.loads(payload)\n        if not isinstance(data, list) or len(data) != 5:\n            raise ValueError(\"Invalid cursor\")\n        version, created_at, item_id, saved_status, saved_order = data\n        if (type(version) is not int or version != 1\n                or not isinstance(created_at, str) or type(item_id) is not int\n                or saved_status != status or saved_order != order):\n            raise ValueError(\"Invalid cursor or mismatched filter/order\")\n        return created_at, item_id\n    except (ValueError, TypeError, UnicodeError, binascii.Error) as exc:\n        raise ValueError(\"Invalid cursor or mismatched filter/order\") from exc\n\n\ndef list_items(conn, limit=20, cursor=None, status=None, order=\"desc\"):\n    if type(limit) is not int or not 1 <= limit <= 100:\n        raise ValueError(\"limit must be an integer from 1 to 100\")\n    if not isinstance(order, str) or order not in (\"asc\", \"desc\"):\n        raise ValueError(\"order must be '\"'asc' or 'desc'\\\")\n    if status is not None and not isinstance(status, str):\n        raise ValueError(\\\"status must be a string or None\\\")\n\n    clauses = []\n    args = []\n    if status is not None:\n        clauses.append(\\\"status = ?\\\")\n        args.append(status)\n    if cursor is not None:\n        created_at, item_id = _decode_cursor(cursor, status, order)\n        comparison = \\\"<\\\" if order == \\\"desc\\\" else \\\">\\\"\n        clauses.append(f\\\"(created_at, id) {comparison} (?, ?)\\\")\n        args.extend((created_at, item_id))\n\n    sql = \\\"SELECT id, created_at, status, title FROM items\\\"\n    if clauses:\n        sql += \\\" WHERE \\\" + \\\" AND \\\".join(clauses)\n    sql += f\\\" ORDER BY created_at {order}, id {order} LIMIT ?\\\"\n    args.append(limit + 1)\n    # A single SELECT supplies both the page and its lookahead in one snapshot.\n    rows = conn.execute(sql, args).fetchall()\n    page = rows[:limit]\n    items = [dict(zip(_COLUMNS, row)) for row in page]\n    next_cursor = None\n    if len(rows) > limit:\n        last = items[-1]\n        next_cursor = _encode_cursor(last[\\\"created_at\\\"], last[\\\"id\\\"], status, order)\n    return {\\\"items\\\": items, \\\"next_cursor\\\": next_cursor}\nPY\"", "aggregated_output": "", "exit_code": null, "status": "in_progress"}}
{"type": "item.completed", "item": {"id": "item_4", "type": "command_execution", "command": "/bin/bash -lc \"cat > feed.py <<'PY'\n\\\"\\\"\\\"Item feed pagination using authenticated keyset cursors.\\\"\\\"\\\"\nimport base64\nimport binascii\nimport hashlib\nimport hmac\nimport json\nimport secrets\n\n\n_CURSOR_KEY = secrets.token_bytes(32)\n_COLUMNS = (\\\"id\\\", \\\"created_at\\\", \\\"status\\\", \\\"title\\\")\n\n\ndef _encode_cursor(created_at, item_id, status, order):\n    payload = json.dumps(\n        [1, created_at, item_id, status, order],\n        ensure_ascii=True, separators=(\\\",\\\", \\\":\\\"),\n    ).encode(\\\"ascii\\\")\n    signature = hmac.digest(_CURSOR_KEY, payload, hashlib.sha256)\n    return base64.urlsafe_b64encode(signature + payload).decode(\\\"ascii\\\")\n\n\ndef _decode_cursor(cursor, status, order):\n    try:\n        if not isinstance(cursor, str) or not cursor:\n            raise ValueError(\\\"Invalid cursor\\\")\n        raw = base64.b64decode(cursor.encode(\\\"ascii\\\"), altchars=b\\\"-_\\\", validate=True)\n        if base64.urlsafe_b64encode(raw).decode(\\\"ascii\\\") \"'!= cursor:\n            raise ValueError(\"Invalid cursor\")\n        signature, payload = raw[:32], raw[32:]\n        if not hmac.compare_digest(\n            signature, hmac.digest(_CURSOR_KEY, payload, hashlib.sha256)\n        ):\n            raise ValueError(\"Invalid cursor\")\n        data = json.loads(payload)\n        if not isinstance(data, list) or len(data) != 5:\n            raise ValueError(\"Invalid cursor\")\n        version, created_at, item_id, saved_status, saved_order = data\n        if (type(version) is not int or version != 1\n                or not isinstance(created_at, str) or type(item_id) is not int\n                or saved_status != status or saved_order != order):\n            raise ValueError(\"Invalid cursor or mismatched filter/order\")\n        return created_at, item_id\n    except (ValueError, TypeError, UnicodeError, binascii.Error) as exc:\n        raise ValueError(\"Invalid cursor or mismatched filter/order\") from exc\n\n\ndef list_items(conn, limit=20, cursor=None, status=None, order=\"desc\"):\n    if type(limit) is not int or not 1 <= limit <= 100:\n        raise ValueError(\"limit must be an integer from 1 to 100\")\n    if not isinstance(order, str) or order not in (\"asc\", \"desc\"):\n        raise ValueError(\"order must be '\"'asc' or 'desc'\\\")\n    if status is not None and not isinstance(status, str):\n        raise ValueError(\\\"status must be a string or None\\\")\n\n    clauses = []\n    args = []\n    if status is not None:\n        clauses.append(\\\"status = ?\\\")\n        args.append(status)\n    if cursor is not None:\n        created_at, item_id = _decode_cursor(cursor, status, order)\n        comparison = \\\"<\\\" if order == \\\"desc\\\" else \\\">\\\"\n        clauses.append(f\\\"(created_at, id) {comparison} (?, ?)\\\")\n        args.extend((created_at, item_id))\n\n    sql = \\\"SELECT id, created_at, status, title FROM items\\\"\n    if clauses:\n        sql += \\\" WHERE \\\" + \\\" AND \\\".join(clauses)\n    sql += f\\\" ORDER BY created_at {order}, id {order} LIMIT ?\\\"\n    args.append(limit + 1)\n    # A single SELECT supplies both the page and its lookahead in one snapshot.\n    rows = conn.execute(sql, args).fetchall()\n    page = rows[:limit]\n    items = [dict(zip(_COLUMNS, row)) for row in page]\n    next_cursor = None\n    if len(rows) > limit:\n        last = items[-1]\n        next_cursor = _encode_cursor(last[\\\"created_at\\\"], last[\\\"id\\\"], status, order)\n    return {\\\"items\\\": items, \\\"next_cursor\\\": next_cursor}\nPY\"", "aggregated_output": "", "exit_code": 0, "status": "completed"}}
{"type": "item.started", "item": {"id": "item_5", "type": "command_execution", "command": "/bin/bash -lc \"cat > test_feed.py <<'PY'\nimport sqlite3\nimport unittest\nfrom pathlib import Path\n\nfrom feed import list_items\n\n\nclass FeedTests(unittest.TestCase):\n    def setUp(self):\n        self.conn = sqlite3.connect(':memory:')\n        self.conn.executescript(Path(__file__).with_name('schema.sql').read_text())\n        self.conn.executemany('INSERT INTO items VALUES (?, ?, ?, ?)', [\n            (i, f'2026-01-{1 + i // 19:02}T00:00:00Z',\n             'published' if i % 3 else 'draft', str(i)) for i in range(1, 241)\n        ])\n\n    def tearDown(self):\n        self.conn.close()\n\n    def test_walks(self):\n        for order in ('asc', 'desc'):\n            for status in (None, 'published', 'draft', \\\"x' OR '1'='1\\\", ''):\n                for limit in (1, 7, 20, 80, 100):\n                    with self.subTest(order=order, status=status, limit=limit):\n                        expected = self.conn.execute(\n                            'SELECT id FROM items' + ('' if status is None else ' WHERE status=?')\n                            + f' ORDER BY created_at {order}, id {order}',\n                            () if status is None else (status,),\n                        ).fetchall()\n                        seen, cursor = [], None\n                        while True:\n                            result = list_items(self.conn, limit, cursor, status, order)\n                            seen.extend((item['id'],) for item in result['items'])\n                            for item in result['items']:\n                                self.assertEqual(set(item), {'id', 'created_at', 'status', 'title'})\n                            cursor = result['next_cursor']\n                            if cursor is None:\n                                break\n                            self.assertEqual(len(result['items']), limit)\n                            self.assertLess(len(seen), len(expected))\n                        self.assertEqual(seen, expected)\n\n    def test_changes_between_pages(self):\n        for order in ('asc', 'desc'):\n            with self.subTest(order=order):\n                self.setUp()\n                first = list_items(self.conn, 23, order=order)\n                original = [r[0] for r in self.conn.execute(\n                    f'SELECT id FROM items ORDER BY created_at {order}, id {order}')]\n                returned = [item['id'] for item in first['items']]\n                deleted = original[30]\n                self.conn.execute('DELETE FROM items WHERE id IN (?, ?)', (returned[-1], deleted))\n                self.conn.execute(\\\"INSERT INTO items VALUES (999, '2099-01-01T00:00:00Z', 'published', 'new')\\\")\n                cursor = first['next_cursor']\n                while cursor is not None:\n                    page = list_items(self.conn, 17, cursor, order=order)\n                    returned.extend(item['id'] for item in page['items'])\n                    cursor = page['next_cursor']\n                expected = [i for i in original if i \"'!= deleted]\n                if order == '\"'asc':\n                    expected.append(999)\n                self.assertEqual(returned, expected)\n                self.conn.close()\n\n    def test_invalid_arguments(self):\n        for limit in (True, False, 0, -1, 101, '20', 1.5, None):\n            with self.assertRaises(ValueError):\n                list_items(self.conn, limit=limit)\n        for order in ('ASC', '', None, [], 1):\n            with self.assertRaises(ValueError):\n                list_items(self.conn, order=order)\n        valid = list_items(self.conn, 1)['next_cursor']\n        for cursor in ('', 'random', '\u2603', 123, b'abc', [], valid[:-2],\n                       ('A' if valid[0] \"'!= '\"'A' else 'B') + valid[1:]):\n            with self.assertRaises(ValueError):\n                list_items(self.conn, cursor=cursor)\n        for kwargs in ({'status': ''}, {'status': 'draft'}, {'order': 'asc'}):\n            with self.assertRaises(ValueError):\n                list_items(self.conn, cursor=valid, **kwargs)\n\n\nif __name__ == '__main__':\n    unittest.main()\nPY\npython -m unittest -v\"", "aggregated_output": "", "exit_code": null, "status": "in_progress"}}
{"type": "item.completed", "item": {"id": "item_5", "type": "command_execution", "command": "/bin/bash -lc \"cat > test_feed.py <<'PY'\nimport sqlite3\nimport unittest\nfrom pathlib import Path\n\nfrom feed import list_items\n\n\nclass FeedTests(unittest.TestCase):\n    def setUp(self):\n        self.conn = sqlite3.connect(':memory:')\n        self.conn.executescript(Path(__file__).with_name('schema.sql').read_text())\n        self.conn.executemany('INSERT INTO items VALUES (?, ?, ?, ?)', [\n            (i, f'2026-01-{1 + i // 19:02}T00:00:00Z',\n             'published' if i % 3 else 'draft', str(i)) for i in range(1, 241)\n        ])\n\n    def tearDown(self):\n        self.conn.close()\n\n    def test_walks(self):\n        for order in ('asc', 'desc'):\n            for status in (None, 'published', 'draft', \\\"x' OR '1'='1\\\", ''):\n                for limit in (1, 7, 20, 80, 100):\n                    with self.subTest(order=order, status=status, limit=limit):\n                        expected = self.conn.execute(\n                            'SELECT id FROM items' + ('' if status is None else ' WHERE status=?')\n                            + f' ORDER BY created_at {order}, id {order}',\n                            () if status is None else (status,),\n                        ).fetchall()\n                        seen, cursor = [], None\n                        while True:\n                            result = list_items(self.conn, limit, cursor, status, order)\n                            seen.extend((item['id'],) for item in result['items'])\n                            for item in result['items']:\n                                self.assertEqual(set(item), {'id', 'created_at', 'status', 'title'})\n                            cursor = result['next_cursor']\n                            if cursor is None:\n                                break\n                            self.assertEqual(len(result['items']), limit)\n                            self.assertLess(len(seen), len(expected))\n                        self.assertEqual(seen, expected)\n\n    def test_changes_between_pages(self):\n        for order in ('asc', 'desc'):\n            with self.subTest(order=order):\n                self.setUp()\n                first = list_items(self.conn, 23, order=order)\n                original = [r[0] for r in self.conn.execute(\n                    f'SELECT id FROM items ORDER BY created_at {order}, id {order}')]\n                returned = [item['id'] for item in first['items']]\n                deleted = original[30]\n                self.conn.execute('DELETE FROM items WHERE id IN (?, ?)', (returned[-1], deleted))\n                self.conn.execute(\\\"INSERT INTO items VALUES (999, '2099-01-01T00:00:00Z', 'published', 'new')\\\")\n                cursor = first['next_cursor']\n                while cursor is not None:\n                    page = list_items(self.conn, 17, cursor, order=order)\n                    returned.extend(item['id'] for item in page['items'])\n                    cursor = page['next_cursor']\n                expected = [i for i in original if i \"'!= deleted]\n                if order == '\"'asc':\n                    expected.append(999)\n                self.assertEqual(returned, expected)\n                self.conn.close()\n\n    def test_invalid_arguments(self):\n        for limit in (True, False, 0, -1, 101, '20', 1.5, None):\n            with self.assertRaises(ValueError):\n                list_items(self.conn, limit=limit)\n        for order in ('ASC', '', None, [], 1):\n            with self.assertRaises(ValueError):\n                list_items(self.conn, order=order)\n        valid = list_items(self.conn, 1)['next_cursor']\n        for cursor in ('', 'random', '\u2603', 123, b'abc', [], valid[:-2],\n                       ('A' if valid[0] \"'!= '\"'A' else 'B') + valid[1:]):\n            with self.assertRaises(ValueError):\n                list_items(self.conn, cursor=cursor)\n        for kwargs in ({'status': ''}, {'status': 'draft'}, {'order': 'asc'}):\n            with self.assertRaises(ValueError):\n                list_items(self.conn, cursor=valid, **kwargs)\n\n\nif __name__ == '__main__':\n    unittest.main()\nPY\npython -m unittest -v\"", "aggregated_output": "/bin/bash: line 86: python: command not found\n", "exit_code": 127, "status": "failed"}}
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{"type": "item.completed", "item": {"id": "item_6", "type": "command_execution", "command": "/bin/bash -lc 'python3 -m unittest -v'", "aggregated_output": "test_changes_between_pages (test_feed.FeedTests.test_changes_between_pages) ... ok\ntest_invalid_arguments (test_feed.FeedTests.test_invalid_arguments) ... ok\ntest_walks (test_feed.FeedTests.test_walks) ... /usr/lib/python3.13/unittest/case.py:1147: ResourceWarning: unclosed database in <sqlite3.Connection object at 0x7b53890bff10>\n  difference2 = set2.difference(set1)\nResourceWarning: Enable tracemalloc to get the object allocation traceback\nok\n\n----------------------------------------------------------------------\nRan 3 tests in 0.043s\n\nOK\n", "exit_code": 0, "status": "completed"}}
{"type": "item.started", "item": {"id": "item_7", "type": "command_execution", "command": "/bin/bash -lc \"python3 - <<'PY'\nfrom pathlib import Path\np = Path('test_feed.py')\ns = p.read_text().replace(\\\"            with self.subTest(order=order):\\\\n                self.setUp()\\\", \\\"            with self.subTest(order=order):\\\\n                self.conn.close()\\\\n                self.setUp()\\\")\np.write_text(s)\nPY\npython3 -W error::ResourceWarning -m unittest -v\"", "aggregated_output": "", "exit_code": null, "status": "in_progress"}}
{"type": "item.completed", "item": {"id": "item_7", "type": "command_execution", "command": "/bin/bash -lc \"python3 - <<'PY'\nfrom pathlib import Path\np = Path('test_feed.py')\ns = p.read_text().replace(\\\"            with self.subTest(order=order):\\\\n                self.setUp()\\\", \\\"            with self.subTest(order=order):\\\\n                self.conn.close()\\\\n                self.setUp()\\\")\np.write_text(s)\nPY\npython3 -W error::ResourceWarning -m unittest -v\"", "aggregated_output": "test_changes_between_pages (test_feed.FeedTests.test_changes_between_pages) ... ok\ntest_invalid_arguments (test_feed.FeedTests.test_invalid_arguments) ... ok\ntest_walks (test_feed.FeedTests.test_walks) ... ok\n\n----------------------------------------------------------------------\nRan 3 tests in 0.040s\n\nOK\n", "exit_code": 0, "status": "completed"}}
{"type": "item.completed", "item": {"id": "item_8", "type": "agent_message", "text": "Fixed `list_items` in [feed.py](feed.py) with stable `(created_at, id)` pagination, SQL filtering, lookahead for accurate next cursors, and argument/cursor validation. Schema unchanged; standard library only.\n\nAdded regression tests for ties, filters, changing limits, inserts/deletes, and invalid inputs. All pass with `python3 -W error::ResourceWarning -m unittest -v`."}}
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