{"abstract":"A zero-length reservation is accepted and blocks a connector.","category":"EV charging session scheduling","checks":7,"contract":"Connectors are numbered 1..n_conn. existing holds [connector, start, end) reservations. req is [start, end, connector or None]. end <= start or an out-of-range connector returns 'invalid'. Two reservations on the same connector conflict unless separated by at least buffer minutes on both sides. Return the requested connector if free, or the lowest free connector when None was requested, else None.","contract_signature":"existing, req, buffer, n_conn","evaluation_group":"w2-ev_charging_session_scheduling-connector-reservation-conflicts","failed_approach":"Rejecting requests shorter than the buffer refuses legitimate short sessions.","family":"w2-ev_charging_session_scheduling-connector-reservation-conflicts-empty-request-window","id":"FA-92991","implementations":{"attempt":{"sha256":"35c92125d24b445861d2e0e0a71e0674a5687fa56141a2d51042514e8646950f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(existing, req, buffer, n_conn):\n    s, e, want = req\n    if e - s < buffer:\n        return 'invalid'\n    if want is not None and not 1 <= want <= n_conn:\n        return 'invalid'\n    conns = [want] if want is not None else list(range(1, n_conn + 1))\n    for c in conns:\n        clash = False\n        for c2, s2, e2 in existing:\n            if c2 == c and s < e2 + buffer and s2 < e + buffer:\n                clash = True\n                break\n        if not clash:\n            return c\n    return None\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window',\n   [[[1, 70, 116], [2, 43, 88], [1, 109, 153]], [45, 45, None], 0, 2], 'invalid'],\n  ['regression: empty request window (partial repair)', [[], [159, 164, 1], 10, 3], 1],\n  ['control 1', [[[2, 157, 203], [1, 191, 236]], [179, 224, None], 5, 2], None],\n  ['control 2',\n   [[[3, 190, 210], [4, 11, 28], [2, 54, 68], [4, 54, 104], [3, 134, 162]], [79, 139, 4], 5, 4],\n   None]],\n [['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window', [[[1, 191, 246], [2, 105, 128]], [128, 128, None], 15, 2],\n   'invalid'],\n  ['regression: empty request window (partial repair)', [[], [171, 171, None], 0, 1], 'invalid'],\n  ['control 1',\n   [[[2, 130, 150], [3, 5, 36], [3, 174, 193], [2, 18, 78], [1, 61, 115], [4, 68, 95]],\n    [171, 201, 2], 10, 4],\n   2],\n  ['control 2',\n   [[[3, 116, 135], [1, 178, 208], [1, 83, 123], [1, 136, 157], [3, 111, 126], [1, 97, 137]],\n    [217, 222, 2], 0, 3],\n   2]],\n [['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window',\n   [[[1, 61, 98], [2, 89, 148], [1, 159, 190], [2, 124, 167], [1, 197, 219]], [29, 29, None], 15,\n    2],\n   'invalid'],\n  ['regression: empty request window (partial repair)',\n   [[[1, 125, 139], [4, 142, 161], [2, 3, 17]], [206, 211, None], 15, 4], 1],\n  ['control 1', [[[3, 198, 211], [1, 147, 191], [4, 137, 178]], [148, 208, None], 10, 4], 2],\n  ['control 2',\n   [[[1, 75, 109], [1, 5, 46], [3, 128, 161], [3, 171, 198], [2, 190, 240], [1, 13, 36]],\n    [58, 73, 1], 10, 3],\n   None]],\n [['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window',\n   [[[1, 144, 201], [1, 99, 140], [1, 187, 246], [1, 92, 150], [1, 120, 150]], [55, 55, 1], 0, 2],\n   'invalid'],\n  ['regression: empty request window (partial repair)',\n   [[[1, 1, 57], [2, 28, 64]], [70, 75, 2], 15, 2], None],\n  ['control 1', [[[3, 69, 129], [1, 134, 154], [4, 142, 167]], [67, 72, 0], 15, 4], 'invalid'],\n  ['control 2', [[[2, 188, 212]], [190, 180, 2], 15, 2], 'invalid']],\n [['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window',\n   [[[2, 141, 198], [2, 146, 161], [3, 91, 117], [2, 43, 82]], [0, 0, 1], 5, 4], 'invalid'],\n  ['regression: empty request window (partial repair)', [[], [64, 69, None], 15, 4], 1],\n  ['control 1', [[[4, 7, 51], [4, 60, 108], [1, 80, 129]], [8, 68, None], 0, 4], 1],\n  ['control 2',\n   [[[1, 169, 199], [1, 193, 217], [1, 118, 149], [1, 4, 58], [1, 125, 169], [1, 1, 52]],\n    [156, 146, None], 10, 1],\n   'invalid']]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"1e89ab417de4b6a666160c9b0cbbb00cbfa3bcf045573f79debcc805eb7560ae","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(existing, req, buffer, n_conn):\n    s, e, want = req\n    if e < s:\n        return 'invalid'\n    if want is not None and not 1 <= want <= n_conn:\n        return 'invalid'\n    conns = [want] if want is not None else list(range(1, n_conn + 1))\n    for c in conns:\n        clash = False\n        for c2, s2, e2 in existing:\n            if c2 == c and s < e2 + buffer and s2 < e + buffer:\n                clash = True\n                break\n        if not clash:\n            return c\n    return None\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window',\n   [[[1, 70, 116], [2, 43, 88], [1, 109, 153]], [45, 45, None], 0, 2], 'invalid'],\n  ['regression: empty request window (partial repair)', [[], [159, 164, 1], 10, 3], 1],\n  ['control 1', [[[2, 157, 203], [1, 191, 236]], [179, 224, None], 5, 2], None],\n  ['control 2',\n   [[[3, 190, 210], [4, 11, 28], [2, 54, 68], [4, 54, 104], [3, 134, 162]], [79, 139, 4], 5, 4],\n   None]],\n [['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window', [[[1, 191, 246], [2, 105, 128]], [128, 128, None], 15, 2],\n   'invalid'],\n  ['regression: empty request window (partial repair)', [[], [171, 171, None], 0, 1], 'invalid'],\n  ['control 1',\n   [[[2, 130, 150], [3, 5, 36], [3, 174, 193], [2, 18, 78], [1, 61, 115], [4, 68, 95]],\n    [171, 201, 2], 10, 4],\n   2],\n  ['control 2',\n   [[[3, 116, 135], [1, 178, 208], [1, 83, 123], [1, 136, 157], [3, 111, 126], [1, 97, 137]],\n    [217, 222, 2], 0, 3],\n   2]],\n [['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window',\n   [[[1, 61, 98], [2, 89, 148], [1, 159, 190], [2, 124, 167], [1, 197, 219]], [29, 29, None], 15,\n    2],\n   'invalid'],\n  ['regression: empty request window (partial repair)',\n   [[[1, 125, 139], [4, 142, 161], [2, 3, 17]], [206, 211, None], 15, 4], 1],\n  ['control 1', [[[3, 198, 211], [1, 147, 191], [4, 137, 178]], [148, 208, None], 10, 4], 2],\n  ['control 2',\n   [[[1, 75, 109], [1, 5, 46], [3, 128, 161], [3, 171, 198], [2, 190, 240], [1, 13, 36]],\n    [58, 73, 1], 10, 3],\n   None]],\n [['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window',\n   [[[1, 144, 201], [1, 99, 140], [1, 187, 246], [1, 92, 150], [1, 120, 150]], [55, 55, 1], 0, 2],\n   'invalid'],\n  ['regression: empty request window (partial repair)',\n   [[[1, 1, 57], [2, 28, 64]], [70, 75, 2], 15, 2], None],\n  ['control 1', [[[3, 69, 129], [1, 134, 154], [4, 142, 167]], [67, 72, 0], 15, 4], 'invalid'],\n  ['control 2', [[[2, 188, 212]], [190, 180, 2], 15, 2], 'invalid']],\n [['boundary: back-to-back with buffer', [[[1, 0, 30]], [40, 60, 1], 10, 1], 1],\n  ['boundary: zero-length request', [[], [10, 10, None], 0, 2], 'invalid'],\n  ['boundary: last connector requested', [[[1, 0, 30]], [0, 30, 3], 0, 3], 3],\n  ['regression: empty request window',\n   [[[2, 141, 198], [2, 146, 161], [3, 91, 117], [2, 43, 82]], [0, 0, 1], 5, 4], 'invalid'],\n  ['regression: empty request window (partial repair)', [[], [64, 69, None], 15, 4], 1],\n  ['control 1', [[[4, 7, 51], [4, 60, 108], [1, 80, 129]], [8, 68, None], 0, 4], 1],\n  ['control 2',\n   [[[1, 169, 199], [1, 193, 217], [1, 118, 149], [1, 4, 58], [1, 125, 169], [1, 1, 52]],\n    [156, 146, None], 10, 1],\n   'invalid']]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Deterministic stipulated toy contract for teaching; no claim of conformance with any standard, vendor protocol or production controller. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-ev_charging_session_scheduling-connector-reservation-conflicts-empty-request-window","generated_at":"2026-09-29T14:51:51.031483+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Depot, workplace and public EV chargers schedule sessions against prices, circuit limits and departure deadlines; a wrong decision silently strands a driver or overloads a feeder.","root_cause":"Only negative-length requests are treated as invalid.","sha256":"8e7d5e5884e80cf1dd92ec8f54000a1d059c0f33445fa7134e6a310ec1455eb4","title":"Connector reservation conflict check: empty request window · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":40.881,"exit_code":1,"observations":[{"actual":1,"check":"boundary: back-to-back with buffer","expected":1,"passed":true},{"actual":1,"check":"boundary: zero-length request","expected":"invalid","passed":false},{"actual":3,"check":"boundary: last connector requested","expected":3,"passed":true},{"actual":1,"check":"regression: empty request window","expected":"invalid","passed":false},{"actual":"invalid","check":"regression: empty request window (partial repair)","expected":1,"passed":false},{"actual":null,"check":"control 1","expected":null,"passed":true},{"actual":null,"check":"control 2","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: back-to-back with buffer\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"boundary: zero-length request\", \"actual\": 1, \"expected\": \"invalid\", \"passed\": false}, {\"check\": \"boundary: last connector requested\", \"actual\": 3, \"expected\": 3, \"passed\": true}, {\"check\": \"regression: empty request window\", \"actual\": 1, \"expected\": \"invalid\", \"passed\": false}, {\"check\": \"regression: empty request window (partial repair)\", \"actual\": \"invalid\", \"expected\": 1, \"passed\": false}, {\"check\": \"control 1\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"control 2\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.695,"exit_code":1,"observations":[{"actual":1,"check":"boundary: back-to-back with buffer","expected":1,"passed":true},{"actual":1,"check":"boundary: zero-length request","expected":"invalid","passed":false},{"actual":3,"check":"boundary: last connector requested","expected":3,"passed":true},{"actual":1,"check":"regression: empty request window","expected":"invalid","passed":false},{"actual":1,"check":"regression: empty request window (partial repair)","expected":1,"passed":true},{"actual":null,"check":"control 1","expected":null,"passed":true},{"actual":null,"check":"control 2","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: back-to-back with buffer\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"boundary: zero-length request\", \"actual\": 1, \"expected\": \"invalid\", \"passed\": false}, {\"check\": \"boundary: last connector requested\", \"actual\": 3, \"expected\": 3, \"passed\": true}, {\"check\": \"regression: empty request window\", \"actual\": 1, \"expected\": \"invalid\", \"passed\": false}, {\"check\": \"regression: empty request window (partial repair)\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"control 1\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"control 2\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}