{"abstract":"A new reservation may end right as the next one starts, leaving no turnover time.","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":"Adding the buffer to the existing start shrinks the protected window instead of extending it.","family":"w2-ev_charging_session_scheduling-connector-reservation-conflicts-leading-buffer","id":"FA-92981","implementations":{"attempt":{"sha256":"cb83f26a2ecb654f8994bb9ee12082f83efc84d59113c91e7ff003c4aed565b6","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 + buffer < e:\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: leading buffer',\n   [[[3, 167, 214], [1, 185, 245], [1, 49, 98], [3, 101, 158], [2, 29, 77], [4, 51, 78]],\n    [11, 41, None], 10, 4],\n   3],\n  ['regression: leading buffer (partial repair)',\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  ['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: leading buffer',\n   [[[3, 167, 214], [1, 185, 245], [1, 49, 98], [3, 101, 158], [2, 29, 77], [4, 51, 78]],\n    [11, 41, None], 10, 4],\n   3],\n  ['regression: leading buffer (partial repair)',\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  ['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: leading buffer', [[[1, 136, 191], [1, 16, 74]], [120, 135, None], 15, 1], None],\n  ['regression: leading buffer (partial repair)',\n   [[[1, 73, 113], [1, 68, 107], [1, 36, 89], [3, 200, 258], [1, 22, 79], [3, 72, 84]],\n    [4, 34, None], 15, 3],\n   2],\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: leading buffer', [[[1, 136, 191], [1, 16, 74]], [120, 135, None], 15, 1], None],\n  ['regression: leading buffer (partial repair)',\n   [[[1, 73, 113], [1, 68, 107], [1, 36, 89], [3, 200, 258], [1, 22, 79], [3, 72, 84]],\n    [4, 34, None], 15, 3],\n   2],\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: leading buffer', [[[1, 136, 191], [1, 16, 74]], [120, 135, None], 15, 1], None],\n  ['regression: leading buffer (partial repair)',\n   [[[1, 73, 113], [1, 68, 107], [1, 36, 89], [3, 200, 258], [1, 22, 79], [3, 72, 84]],\n    [4, 34, None], 15, 3],\n   2],\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":"941bff112ad5e236a1f7d3da7a13ea88a731b61e21f2ae0893bd310f5f27eb89","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:\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: leading buffer',\n   [[[3, 167, 214], [1, 185, 245], [1, 49, 98], [3, 101, 158], [2, 29, 77], [4, 51, 78]],\n    [11, 41, None], 10, 4],\n   3],\n  ['regression: leading buffer (partial repair)',\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  ['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: leading buffer',\n   [[[3, 167, 214], [1, 185, 245], [1, 49, 98], [3, 101, 158], [2, 29, 77], [4, 51, 78]],\n    [11, 41, None], 10, 4],\n   3],\n  ['regression: leading buffer (partial repair)',\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  ['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: leading buffer', [[[1, 136, 191], [1, 16, 74]], [120, 135, None], 15, 1], None],\n  ['regression: leading buffer (partial repair)',\n   [[[1, 73, 113], [1, 68, 107], [1, 36, 89], [3, 200, 258], [1, 22, 79], [3, 72, 84]],\n    [4, 34, None], 15, 3],\n   2],\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: leading buffer', [[[1, 136, 191], [1, 16, 74]], [120, 135, None], 15, 1], None],\n  ['regression: leading buffer (partial repair)',\n   [[[1, 73, 113], [1, 68, 107], [1, 36, 89], [3, 200, 258], [1, 22, 79], [3, 72, 84]],\n    [4, 34, None], 15, 3],\n   2],\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: leading buffer', [[[1, 136, 191], [1, 16, 74]], [120, 135, None], 15, 1], None],\n  ['regression: leading buffer (partial repair)',\n   [[[1, 73, 113], [1, 68, 107], [1, 36, 89], [3, 200, 258], [1, 22, 79], [3, 72, 84]],\n    [4, 34, None], 15, 3],\n   2],\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-leading-buffer","generated_at":"2026-09-29T14:51:51.030220+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":"The buffer is applied only after existing reservations, not before them.","sha256":"2613ae9a1869ee88b50d3233f9a2c5fc664d23c83ba4950fa3ac41932113e939","title":"Connector reservation conflict check: leading buffer · 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":41.175,"exit_code":1,"observations":[{"actual":1,"check":"boundary: back-to-back with buffer","expected":1,"passed":true},{"actual":"invalid","check":"boundary: zero-length request","expected":"invalid","passed":true},{"actual":3,"check":"boundary: last connector requested","expected":3,"passed":true},{"actual":1,"check":"regression: leading buffer","expected":3,"passed":false},{"actual":1,"check":"regression: leading buffer (partial repair)","expected":null,"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\": \"invalid\", \"expected\": \"invalid\", \"passed\": true}, {\"check\": \"boundary: last connector requested\", \"actual\": 3, \"expected\": 3, \"passed\": true}, {\"check\": \"regression: leading buffer\", \"actual\": 1, \"expected\": 3, \"passed\": false}, {\"check\": \"regression: leading buffer (partial repair)\", \"actual\": 1, \"expected\": null, \"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":39.99,"exit_code":1,"observations":[{"actual":1,"check":"boundary: back-to-back with buffer","expected":1,"passed":true},{"actual":"invalid","check":"boundary: zero-length request","expected":"invalid","passed":true},{"actual":3,"check":"boundary: last connector requested","expected":3,"passed":true},{"actual":1,"check":"regression: leading buffer","expected":3,"passed":false},{"actual":1,"check":"regression: leading buffer (partial repair)","expected":null,"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\": \"invalid\", \"expected\": \"invalid\", \"passed\": true}, {\"check\": \"boundary: last connector requested\", \"actual\": 3, \"expected\": 3, \"passed\": true}, {\"check\": \"regression: leading buffer\", \"actual\": 1, \"expected\": 3, \"passed\": false}, {\"check\": \"regression: leading buffer (partial repair)\", \"actual\": 1, \"expected\": null, \"passed\": false}, {\"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."}}