{"abstract":"A cornered black king that is not in check is declared mated.","category":"Chess move legality","checks":8,"contract":"Input: {\"wk\", \"wq\", \"bk\"} squares, black to move. Return \"checkmate\" if black has no legal king move and is attacked by the queen, \"stalemate\" if it has none and is not attacked, else \"ongoing\". The queen attacks along ranks, files and diagonals and is blocked only by the white king; the black king may capture the queen when it is not adjacent to the white king.","contract_signature":"x","evaluation_group":"w2-chess_move_legality-kqk-terminal-status","failed_approach":"Deciding check by queen adjacency calls long-range mates stalemate.","family":"w2-chess_move_legality-kqk-terminal-status-mate-versus-stalemate","id":"FA-82776","implementations":{"attempt":{"sha256":"4cfe0a6be0bc50fb7e55246090eb819e5471feab31ab9c6b3783df96109a9fd1","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    def c(q): return ord(q[0])-97,int(q[1])-1\n    wk,wq,bk=c(x['wk']),c(x['wq']),c(x['bk'])\n    def queen_hits(t, occupied):\n        if t==wq: return False\n        df,dr=t[0]-wq[0],t[1]-wq[1]\n        if not (df==0 or dr==0 or abs(df)==abs(dr)): return False\n        sf=(df>0)-(df<0); sr=(dr>0)-(dr<0)\n        f,r=wq[0]+sf,wq[1]+sr\n        while (f,r)!=t:\n            if (f,r) in occupied: return False\n            f+=sf; r+=sr\n        return True\n    def near(a,b2): return max(abs(a[0]-b2[0]),abs(a[1]-b2[1]))<=1\n    in_check=queen_hits(bk,{wk})\n    moves=0\n    for df in (-1,0,1):\n        for dr in (-1,0,1):\n            if not (df or dr): continue\n            t=(bk[0]+df,bk[1]+dr)\n            if not (0<=t[0]<8 and 0<=t[1]<8): continue\n            if near(t,wk): continue\n            if queen_hits(t,{wk}): continue\n            moves+=1\n    if moves: return 'ongoing'\n    return 'checkmate' if near(bk,wq) else 'stalemate'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('queen kiss mate', {'bk': 'a8', 'wk': 'b6', 'wq': 'b7'}, 'checkmate'),\n  ('back rank long mate', {'bk': 'h8', 'wk': 'g6', 'wq': 'a8'}, 'checkmate'),\n  ('capture free queen', {'bk': 'a8', 'wk': 'h1', 'wq': 'b7'}, 'ongoing'),\n  ('queen check escape', {'bk': 'e5', 'wk': 'a1', 'wq': 'e1'}, 'ongoing'),\n  ('shielded by king', {'bk': 'e5', 'wk': 'e3', 'wq': 'e1'}, 'ongoing'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate')],\n [('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('shielded by king', {'bk': 'e5', 'wk': 'e3', 'wq': 'e1'}, 'ongoing'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('queen behind white king', {'bk': 'a1', 'wk': 'b3', 'wq': 'b5'}, 'ongoing'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate'),\n  ('queen kiss far side', {'bk': 'b8', 'wk': 'a6', 'wq': 'd8'}, 'checkmate'),\n  ('edge mate', {'bk': 'e8', 'wk': 'e6', 'wq': 'e7'}, 'checkmate'),\n  ('orthogonal free capture', {'bk': 'a8', 'wk': 'h1', 'wq': 'a7'}, 'ongoing')],\n [('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('back rank long mate', {'bk': 'h8', 'wk': 'g6', 'wq': 'a8'}, 'checkmate'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate'),\n  ('queen kiss far side', {'bk': 'b8', 'wk': 'a6', 'wq': 'd8'}, 'checkmate'),\n  ('orthogonal free capture', {'bk': 'a8', 'wk': 'h1', 'wq': 'a7'}, 'ongoing'),\n  ('far queen ongoing', {'bk': 'd5', 'wk': 'a1', 'wq': 'h2'}, 'ongoing'),\n  ('king retreat along queen file', {'bk': 'd7', 'wk': 'a1', 'wq': 'd1'}, 'ongoing')],\n [('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('queen kiss mate', {'bk': 'a8', 'wk': 'b6', 'wq': 'b7'}, 'checkmate'),\n  ('back rank long mate', {'bk': 'h8', 'wk': 'g6', 'wq': 'a8'}, 'checkmate'),\n  ('capture free queen', {'bk': 'a8', 'wk': 'h1', 'wq': 'b7'}, 'ongoing'),\n  ('queen check escape', {'bk': 'e5', 'wk': 'a1', 'wq': 'e1'}, 'ongoing'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate'),\n  ('queen kiss far side', {'bk': 'b8', 'wk': 'a6', 'wq': 'd8'}, 'checkmate')],\n [('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('queen kiss mate', {'bk': 'a8', 'wk': 'b6', 'wq': 'b7'}, 'checkmate'),\n  ('capture free queen', {'bk': 'a8', 'wk': 'h1', 'wq': 'b7'}, 'ongoing'),\n  ('queen check escape', {'bk': 'e5', 'wk': 'a1', 'wq': 'e1'}, 'ongoing'),\n  ('shielded by king', {'bk': 'e5', 'wk': 'e3', 'wq': 'e1'}, 'ongoing'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate'),\n  ('queen kiss far side', {'bk': 'b8', 'wk': 'a6', 'wq': 'd8'}, 'checkmate')]]\nfor label, args, expected in fixtures[N-1]:\n    try:\n        actual = solve(args)\n    except Exception as exc:\n        actual = 'error:' + type(exc).__name__\n    check(label, actual, 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":"19d2cf27209379b6678ce858a6539b9f9b2ab115db81681a928590c0be51f51f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    def c(q): return ord(q[0])-97,int(q[1])-1\n    wk,wq,bk=c(x['wk']),c(x['wq']),c(x['bk'])\n    def queen_hits(t, occupied):\n        if t==wq: return False\n        df,dr=t[0]-wq[0],t[1]-wq[1]\n        if not (df==0 or dr==0 or abs(df)==abs(dr)): return False\n        sf=(df>0)-(df<0); sr=(dr>0)-(dr<0)\n        f,r=wq[0]+sf,wq[1]+sr\n        while (f,r)!=t:\n            if (f,r) in occupied: return False\n            f+=sf; r+=sr\n        return True\n    def near(a,b2): return max(abs(a[0]-b2[0]),abs(a[1]-b2[1]))<=1\n    in_check=queen_hits(bk,{wk})\n    moves=0\n    for df in (-1,0,1):\n        for dr in (-1,0,1):\n            if not (df or dr): continue\n            t=(bk[0]+df,bk[1]+dr)\n            if not (0<=t[0]<8 and 0<=t[1]<8): continue\n            if near(t,wk): continue\n            if queen_hits(t,{wk}): continue\n            moves+=1\n    if moves: return 'ongoing'\n    return 'checkmate'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('queen kiss mate', {'bk': 'a8', 'wk': 'b6', 'wq': 'b7'}, 'checkmate'),\n  ('back rank long mate', {'bk': 'h8', 'wk': 'g6', 'wq': 'a8'}, 'checkmate'),\n  ('capture free queen', {'bk': 'a8', 'wk': 'h1', 'wq': 'b7'}, 'ongoing'),\n  ('queen check escape', {'bk': 'e5', 'wk': 'a1', 'wq': 'e1'}, 'ongoing'),\n  ('shielded by king', {'bk': 'e5', 'wk': 'e3', 'wq': 'e1'}, 'ongoing'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate')],\n [('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('shielded by king', {'bk': 'e5', 'wk': 'e3', 'wq': 'e1'}, 'ongoing'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('queen behind white king', {'bk': 'a1', 'wk': 'b3', 'wq': 'b5'}, 'ongoing'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate'),\n  ('queen kiss far side', {'bk': 'b8', 'wk': 'a6', 'wq': 'd8'}, 'checkmate'),\n  ('edge mate', {'bk': 'e8', 'wk': 'e6', 'wq': 'e7'}, 'checkmate'),\n  ('orthogonal free capture', {'bk': 'a8', 'wk': 'h1', 'wq': 'a7'}, 'ongoing')],\n [('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('back rank long mate', {'bk': 'h8', 'wk': 'g6', 'wq': 'a8'}, 'checkmate'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate'),\n  ('queen kiss far side', {'bk': 'b8', 'wk': 'a6', 'wq': 'd8'}, 'checkmate'),\n  ('orthogonal free capture', {'bk': 'a8', 'wk': 'h1', 'wq': 'a7'}, 'ongoing'),\n  ('far queen ongoing', {'bk': 'd5', 'wk': 'a1', 'wq': 'h2'}, 'ongoing'),\n  ('king retreat along queen file', {'bk': 'd7', 'wk': 'a1', 'wq': 'd1'}, 'ongoing')],\n [('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('queen kiss mate', {'bk': 'a8', 'wk': 'b6', 'wq': 'b7'}, 'checkmate'),\n  ('back rank long mate', {'bk': 'h8', 'wk': 'g6', 'wq': 'a8'}, 'checkmate'),\n  ('capture free queen', {'bk': 'a8', 'wk': 'h1', 'wq': 'b7'}, 'ongoing'),\n  ('queen check escape', {'bk': 'e5', 'wk': 'a1', 'wq': 'e1'}, 'ongoing'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate'),\n  ('queen kiss far side', {'bk': 'b8', 'wk': 'a6', 'wq': 'd8'}, 'checkmate')],\n [('corner stalemate', {'bk': 'a8', 'wk': 'c6', 'wq': 'b6'}, 'stalemate'),\n  ('queen kiss mate', {'bk': 'a8', 'wk': 'b6', 'wq': 'b7'}, 'checkmate'),\n  ('capture free queen', {'bk': 'a8', 'wk': 'h1', 'wq': 'b7'}, 'ongoing'),\n  ('queen check escape', {'bk': 'e5', 'wk': 'a1', 'wq': 'e1'}, 'ongoing'),\n  ('shielded by king', {'bk': 'e5', 'wk': 'e3', 'wq': 'e1'}, 'ongoing'),\n  ('stalemate h-file', {'bk': 'h8', 'wk': 'f7', 'wq': 'g6'}, 'stalemate'),\n  ('mate with rank retreat', {'bk': 'b1', 'wk': 'a3', 'wq': 'd1'}, 'checkmate'),\n  ('queen kiss far side', {'bk': 'b8', 'wk': 'a6', 'wq': 'd8'}, 'checkmate')]]\nfor label, args, expected in fixtures[N-1]:\n    try:\n        actual = solve(args)\n    except Exception as exc:\n        actual = 'error:' + type(exc).__name__\n    check(label, actual, 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":"A deterministic toy model with an explicitly stated contract; boards are {square: piece} with white upper-case and black lower-case pieces; no claim of full FIDE Laws conformance. 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-chess_move_legality-kqk-terminal-status-mate-versus-stalemate","generated_at":"2026-09-29T14:50:15.292871+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Game-end detection must distinguish mate from stalemate exactly.","root_cause":"The final classification ignores whether the king is currently attacked.","sha256":"a511ca0572dcb4f34315863b8b8ef97de2c17cc9a2fb46d68fb096ad442844bc","title":"Every position without king moves called checkmate · 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":41.53,"exit_code":1,"observations":[{"actual":"stalemate","check":"corner stalemate","expected":"stalemate","passed":true},{"actual":"checkmate","check":"queen kiss mate","expected":"checkmate","passed":true},{"actual":"stalemate","check":"back rank long mate","expected":"checkmate","passed":false},{"actual":"ongoing","check":"capture free queen","expected":"ongoing","passed":true},{"actual":"ongoing","check":"queen check escape","expected":"ongoing","passed":true},{"actual":"ongoing","check":"shielded by king","expected":"ongoing","passed":true},{"actual":"stalemate","check":"stalemate h-file","expected":"stalemate","passed":true},{"actual":"stalemate","check":"mate with rank retreat","expected":"checkmate","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"corner stalemate\", \"actual\": \"stalemate\", \"expected\": \"stalemate\", \"passed\": true}, {\"check\": \"queen kiss mate\", \"actual\": \"checkmate\", \"expected\": \"checkmate\", \"passed\": true}, {\"check\": \"back rank long mate\", \"actual\": \"stalemate\", \"expected\": \"checkmate\", \"passed\": false}, {\"check\": \"capture free queen\", \"actual\": \"ongoing\", \"expected\": \"ongoing\", \"passed\": true}, {\"check\": \"queen check escape\", \"actual\": \"ongoing\", \"expected\": \"ongoing\", \"passed\": true}, {\"check\": \"shielded by king\", \"actual\": \"ongoing\", \"expected\": \"ongoing\", \"passed\": true}, {\"check\": \"stalemate h-file\", \"actual\": \"stalemate\", \"expected\": \"stalemate\", \"passed\": true}, {\"check\": \"mate with rank retreat\", \"actual\": \"stalemate\", \"expected\": \"checkmate\", \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":43.483,"exit_code":1,"observations":[{"actual":"checkmate","check":"corner stalemate","expected":"stalemate","passed":false},{"actual":"checkmate","check":"queen kiss mate","expected":"checkmate","passed":true},{"actual":"checkmate","check":"back rank long mate","expected":"checkmate","passed":true},{"actual":"ongoing","check":"capture free queen","expected":"ongoing","passed":true},{"actual":"ongoing","check":"queen check escape","expected":"ongoing","passed":true},{"actual":"ongoing","check":"shielded by king","expected":"ongoing","passed":true},{"actual":"checkmate","check":"stalemate h-file","expected":"stalemate","passed":false},{"actual":"checkmate","check":"mate with rank retreat","expected":"checkmate","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"corner stalemate\", \"actual\": \"checkmate\", \"expected\": \"stalemate\", \"passed\": false}, {\"check\": \"queen kiss mate\", \"actual\": \"checkmate\", \"expected\": \"checkmate\", \"passed\": true}, {\"check\": \"back rank long mate\", \"actual\": \"checkmate\", \"expected\": \"checkmate\", \"passed\": true}, {\"check\": \"capture free queen\", \"actual\": \"ongoing\", \"expected\": \"ongoing\", \"passed\": true}, {\"check\": \"queen check escape\", \"actual\": \"ongoing\", \"expected\": \"ongoing\", \"passed\": true}, {\"check\": \"shielded by king\", \"actual\": \"ongoing\", \"expected\": \"ongoing\", \"passed\": true}, {\"check\": \"stalemate h-file\", \"actual\": \"checkmate\", \"expected\": \"stalemate\", \"passed\": false}, {\"check\": \"mate with rank retreat\", \"actual\": \"checkmate\", \"expected\": \"checkmate\", \"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."}}