{
  "schema": "fc-lang-arena-board/v1",
  "product": "lang.ugrad.ai",
  "title": "Lang Arena · Translation Accuracy Leaderboard",
  "style": "arena.ai/leaderboard/agent multi-signal ranking",
  "updated": "2026-08-10T12:00:00Z",
  "source": {
    "pack": "Alice R1 · 18-lang complete fanout",
    "persona": "poet",
    "prompt": "Alice's Adventures in Wonderland (Carroll) — public domain opening",
    "source_en_chars": 302,
    "urls": {
      "charts": "https://lang.ugrad.ai/charts/",
      "board_json": "https://lang.ugrad.ai/data/language/arena-lang-board.json",
      "alice": "https://lang.ugrad.ai/data/language/alice-mt-analysis/",
      "analysis": "https://lang.ugrad.ai/data/language/alice-mt-analysis/ANALYSIS.md",
      "semantic": "https://lang.ugrad.ai/data/language/alice-mt-analysis/semantic_ppl_metrics.json",
      "bundle": "https://lang.ugrad.ai/data/language/alice-mt-analysis/alice_mt_bundle.json",
      "scorecard": "https://lang.ugrad.ai/data/language/scorecard.json",
      "arena_reference": "https://arena.ai/leaderboard/agent"
    }
  },
  "formula": {
    "arena_pct": "0.50 * complete_understanding + 0.30 * live_slip + 0.20 * emit_completeness",
    "complete_understanding": "semantic anchor coverage on complete MT (tired/sister/bank/book/pictures/conversations/use)",
    "live_slip": "same anchors under live char-budget truncation (what smoke actually emitted)",
    "emit_completeness": "trunc_ratio = emitted_chars / complete_chars for that language",
    "bands": {
      "T3_complete": ">= 90%",
      "T2_near": "70–89%",
      "T1_partial": "40–69%",
      "T0_critical": "< 40%"
    },
    "note": "Not sacreBLEU / COMET. Complete Understanding ≈ meaning slip; Live Slip is budget-truncated understanding. Ops product score is separate (scorecard ~96%)."
  },
  "system": {
    "semantic_fidelity": 88,
    "fluency": 86,
    "completeness_live_trunc": 62,
    "overall_usable_trunc": 78,
    "ops_scorecard": 96.4,
    "literary_note": "Ops score ≠ T3 literary quality. Train positives = pairs_complete.jsonl only."
  },
  "langs": 18,
  "rows": [
    {
      "rank": 1,
      "lang": "JA",
      "name": "Japanese",
      "script": "Japanese",
      "family": "CJK",
      "arena_pct": 100.0,
      "complete_understanding": 100.0,
      "live_slip": 100.0,
      "emit_completeness": 100.0,
      "live_band": "T3",
      "density_vs_en": 0.3344,
      "proxy_drop_points": 0.0,
      "was_fully_emitted": true,
      "slip_note": "Fully emitted · all 7 anchors"
    },
    {
      "rank": 1,
      "lang": "KO",
      "name": "Korean",
      "script": "Hangul",
      "family": "CJK",
      "arena_pct": 100.0,
      "complete_understanding": 100.0,
      "live_slip": 100.0,
      "emit_completeness": 100.0,
      "live_band": "T3",
      "density_vs_en": 0.3576,
      "proxy_drop_points": 0.0,
      "was_fully_emitted": true,
      "slip_note": "Fully emitted · all 7 anchors"
    },
    {
      "rank": 1,
      "lang": "ZH",
      "name": "Chinese",
      "script": "Han",
      "family": "CJK",
      "arena_pct": 100.0,
      "complete_understanding": 100.0,
      "live_slip": 100.0,
      "emit_completeness": 100.0,
      "live_band": "T3",
      "density_vs_en": 0.2649,
      "proxy_drop_points": 0.0,
      "was_fully_emitted": true,
      "slip_note": "Fully emitted · all 7 anchors"
    },
    {
      "rank": 4,
      "lang": "EN",
      "name": "English",
      "script": "Latin",
      "family": "Source",
      "arena_pct": 98.54,
      "complete_understanding": 100.0,
      "live_slip": 100.0,
      "emit_completeness": 92.72,
      "live_band": "T3",
      "density_vs_en": 1.0,
      "proxy_drop_points": 0.0,
      "was_fully_emitted": false,
      "slip_note": "Mid-word pictu clip only"
    },
    {
      "rank": 5,
      "lang": "HI",
      "name": "Hindi",
      "script": "Devanagari",
      "family": "Indic",
      "arena_pct": 90.32,
      "complete_understanding": 100.0,
      "live_slip": 85.7,
      "emit_completeness": 73.06,
      "live_band": "T2",
      "density_vs_en": 0.7252,
      "proxy_drop_points": 14.53,
      "was_fully_emitted": false,
      "slip_note": "Setup OK · tail cut"
    },
    {
      "rank": 6,
      "lang": "UK",
      "name": "Ukrainian",
      "script": "Cyrillic",
      "family": "Cyrillic",
      "arena_pct": 85.27,
      "complete_understanding": 100.0,
      "live_slip": 71.4,
      "emit_completeness": 69.26,
      "live_band": "T2",
      "density_vs_en": 0.7649,
      "proxy_drop_points": 16.77,
      "was_fully_emitted": false,
      "slip_note": "Punchline often gone live"
    },
    {
      "rank": 7,
      "lang": "RU",
      "name": "Russian",
      "script": "Cyrillic",
      "family": "Cyrillic",
      "arena_pct": 84.92,
      "complete_understanding": 100.0,
      "live_slip": 71.4,
      "emit_completeness": 67.51,
      "live_band": "T2",
      "density_vs_en": 0.7848,
      "proxy_drop_points": 17.84,
      "was_fully_emitted": false,
      "slip_note": "Same class as UK"
    },
    {
      "rank": 8,
      "lang": "TR",
      "name": "Turkish",
      "script": "Latin",
      "family": "Turkic",
      "arena_pct": 84.7,
      "complete_understanding": 100.0,
      "live_slip": 71.4,
      "emit_completeness": 66.39,
      "live_band": "T2",
      "density_vs_en": 0.798,
      "proxy_drop_points": 18.52,
      "was_fully_emitted": false,
      "slip_note": "Agglutinative tail risk"
    },
    {
      "rank": 9,
      "lang": "AR",
      "name": "Arabic",
      "script": "Arabic",
      "family": "Semitic",
      "arena_pct": 83.65,
      "complete_understanding": 85.7,
      "live_slip": 85.7,
      "emit_completeness": 75.47,
      "live_band": "T2",
      "density_vs_en": 0.702,
      "proxy_drop_points": 18.52,
      "was_fully_emitted": false,
      "slip_note": "Missing punchline use in complete + trunc"
    },
    {
      "rank": 10,
      "lang": "PL",
      "name": "Polish",
      "script": "Latin",
      "family": "Slavic Latin",
      "arena_pct": 82.66,
      "complete_understanding": 100.0,
      "live_slip": 66.7,
      "emit_completeness": 63.24,
      "live_band": "T1",
      "density_vs_en": 0.8377,
      "proxy_drop_points": 20.48,
      "was_fully_emitted": false,
      "slip_note": "Scene without punchline"
    },
    {
      "rank": 11,
      "lang": "SV",
      "name": "Swedish",
      "script": "Latin",
      "family": "Germanic",
      "arena_pct": 81.73,
      "complete_understanding": 100.0,
      "live_slip": 66.7,
      "emit_completeness": 58.61,
      "live_band": "T1",
      "density_vs_en": 0.904,
      "proxy_drop_points": 23.44,
      "was_fully_emitted": false,
      "slip_note": "Live slip mid-clause"
    },
    {
      "rank": 12,
      "lang": "PT",
      "name": "Portuguese",
      "script": "Latin",
      "family": "Romance",
      "arena_pct": 79.49,
      "complete_understanding": 100.0,
      "live_slip": 57.1,
      "emit_completeness": 61.78,
      "live_band": "T1",
      "density_vs_en": 0.8576,
      "proxy_drop_points": 21.4,
      "was_fully_emitted": false,
      "slip_note": "Setup only under budget"
    },
    {
      "rank": 13,
      "lang": "IT",
      "name": "Italian",
      "script": "Latin",
      "family": "Romance",
      "arena_pct": 79.39,
      "complete_understanding": 100.0,
      "live_slip": 57.1,
      "emit_completeness": 61.3,
      "live_band": "T1",
      "density_vs_en": 0.8642,
      "proxy_drop_points": 21.7,
      "was_fully_emitted": false,
      "slip_note": "Setup only under budget"
    },
    {
      "rank": 14,
      "lang": "ES",
      "name": "Spanish",
      "script": "Latin",
      "family": "Romance",
      "arena_pct": 78.89,
      "complete_understanding": 100.0,
      "live_slip": 57.1,
      "emit_completeness": 58.82,
      "live_band": "T1",
      "density_vs_en": 0.9007,
      "proxy_drop_points": 23.3,
      "was_fully_emitted": false,
      "slip_note": "Setup only under budget"
    },
    {
      "rank": 15,
      "lang": "NL",
      "name": "Dutch",
      "script": "Latin",
      "family": "Germanic",
      "arena_pct": 78.81,
      "complete_understanding": 100.0,
      "live_slip": 57.1,
      "emit_completeness": 58.39,
      "live_band": "T1",
      "density_vs_en": 0.9073,
      "proxy_drop_points": 23.58,
      "was_fully_emitted": false,
      "slip_note": "Setup only under budget"
    },
    {
      "rank": 16,
      "lang": "EL",
      "name": "Greek",
      "script": "Greek",
      "family": "Hellenic",
      "arena_pct": 78.28,
      "complete_understanding": 100.0,
      "live_slip": 57.1,
      "emit_completeness": 55.75,
      "live_band": "T1",
      "density_vs_en": 0.9503,
      "proxy_drop_points": 25.33,
      "was_fully_emitted": false,
      "slip_note": "Dense · budget-starved"
    },
    {
      "rank": 17,
      "lang": "FR",
      "name": "French",
      "script": "Latin",
      "family": "Romance",
      "arena_pct": 78.1,
      "complete_understanding": 100.0,
      "live_slip": 57.1,
      "emit_completeness": 54.83,
      "live_band": "T1",
      "density_vs_en": 0.9603,
      "proxy_drop_points": 25.95,
      "was_fully_emitted": false,
      "slip_note": "High density · worst Latin cut class"
    },
    {
      "rank": 18,
      "lang": "DE",
      "name": "German",
      "script": "Latin",
      "family": "Germanic",
      "arena_pct": 77.49,
      "complete_understanding": 100.0,
      "live_slip": 57.1,
      "emit_completeness": 51.79,
      "live_band": "T1",
      "density_vs_en": 1.0166,
      "proxy_drop_points": 28.03,
      "was_fully_emitted": false,
      "slip_note": "Longest densest · worst live slip"
    }
  ],
  "families": [
    { "family": "CJK", "langs": ["JA", "KO", "ZH"], "mean_arena_pct": 100.0, "live_band": "T3" },
    { "family": "Source", "langs": ["EN"], "mean_arena_pct": 98.54, "live_band": "T3" },
    { "family": "Indic", "langs": ["HI"], "mean_arena_pct": 90.32, "live_band": "T2" },
    { "family": "Cyrillic", "langs": ["RU", "UK"], "mean_arena_pct": 85.1, "live_band": "T2" },
    { "family": "Turkic", "langs": ["TR"], "mean_arena_pct": 84.7, "live_band": "T2" },
    { "family": "Semitic", "langs": ["AR"], "mean_arena_pct": 83.65, "live_band": "T2" },
    { "family": "Slavic Latin", "langs": ["PL"], "mean_arena_pct": 82.66, "live_band": "T1" },
    { "family": "Romance / Germanic / Hellenic", "langs": ["PT", "IT", "ES", "NL", "SV", "EL", "FR", "DE"], "mean_arena_pct": 79.02, "live_band": "T1" }
  ],
  "signal_leaders": {
    "complete_understanding": { "best": ["JA", "KO", "ZH", "EN", "DE", "FR", "ES", "IT", "PT", "NL", "SV", "PL", "TR", "RU", "UK", "HI", "EL"], "weakest": { "lang": "AR", "pct": 85.7 } },
    "live_slip": { "best": ["JA", "KO", "ZH", "EN"], "mid": ["AR", "HI"], "weakest_class": "Romance/Germanic ~57.1%" },
    "emit_completeness": { "best": ["JA", "KO", "ZH"], "worst": { "lang": "DE", "pct": 51.79 } },
    "truncation_damage_worst_first": ["DE", "FR", "EL", "NL", "SV", "ES", "IT", "PT", "PL", "AR", "TR", "RU", "UK", "HI", "JA", "KO", "ZH"]
  },
  "engines": [
    { "rank": 1, "id": "qwen3:8b", "where": "Ollama offline", "role": "Best local multi-lang" },
    { "rank": 2, "id": "m2m100", "where": "Workers AI edge", "role": "Bulk fanout" },
    { "rank": 3, "id": "mistral", "where": "Ollama offline", "role": "EU alt" },
    { "rank": null, "id": "kimi-k2.x", "where": "CF cloud only", "role": "Not in this smoke" }
  ]
}