{
  "version": "SIU-2026a",
  "print_id": "2026-09-26-frontier",
  "date": "2026-09-26",
  "status": "provisional",
  "basket_costs": [
    {
      "model_id": "claude-sonnet-5",
      "cost_usd": "0.023450"
    },
    {
      "model_id": "gpt-5.1",
      "cost_usd": "0.009110"
    },
    {
      "model_id": "gemini-3.1-pro-preview",
      "excluded_reason": "undefined class: T1 (no run records for this class); T2 (no run records for this class); T3 (no run records for this class)"
    },
    {
      "model_id": "grok-4.6",
      "cost_usd": "0.017376"
    },
    {
      "model_id": "claude-haiku-4-5",
      "cost_usd": "0.007684"
    },
    {
      "model_id": "gpt-5.4-mini",
      "cost_usd": "0.005303"
    }
  ],
  "weights": {
    "source": "equal",
    "values": [
      {
        "model_id": "claude-sonnet-5",
        "weight": "0.200000"
      },
      {
        "model_id": "gpt-5.1",
        "weight": "0.200000"
      },
      {
        "model_id": "grok-4.6",
        "weight": "0.200000"
      },
      {
        "model_id": "claude-haiku-4-5",
        "weight": "0.200000"
      },
      {
        "model_id": "gpt-5.4-mini",
        "weight": "0.200000"
      }
    ]
  },
  "dated_siu": "0.01258",
  "exchange_rate_table": [
    {
      "model_id": "claude-sonnet-5",
      "usd_per_siu": "0.0234",
      "spread_to_index": "0.8633",
      "siu_per_usd": "42.6"
    },
    {
      "model_id": "gpt-5.1",
      "usd_per_siu": "0.0091",
      "spread_to_index": "-0.2761",
      "siu_per_usd": "109.7"
    },
    {
      "model_id": "gemini-3.1-pro-preview",
      "excluded_reason": "undefined class: T1 (no run records for this class); T2 (no run records for this class); T3 (no run records for this class)"
    },
    {
      "model_id": "grok-4.6",
      "usd_per_siu": "0.0174",
      "spread_to_index": "0.3808",
      "siu_per_usd": "57.5"
    },
    {
      "model_id": "claude-haiku-4-5",
      "usd_per_siu": "0.0077",
      "spread_to_index": "-0.3894",
      "siu_per_usd": "130.1"
    },
    {
      "model_id": "gpt-5.4-mini",
      "usd_per_siu": "0.0053",
      "spread_to_index": "-0.5786",
      "siu_per_usd": "188.5"
    }
  ],
  "sensitivity_block": [
    {
      "policy_variant": "cache-enabled: 40% of T2 input at 10% of input price",
      "dated_siu": "0.008709",
      "delta": "-0.3080",
      "applies_to": [
        "claude-sonnet-5",
        "gpt-5.1",
        "gemini-3.1-pro-preview",
        "grok-4.6",
        "claude-haiku-4-5",
        "gpt-5.4-mini"
      ]
    },
    {
      "policy_variant": "batch-discount: 50% off input and output",
      "dated_siu": "0.006311",
      "delta": "-0.4985",
      "applies_to": [
        "claude-sonnet-5",
        "gpt-5.1",
        "gemini-3.1-pro-preview",
        "grok-4.6",
        "claude-haiku-4-5",
        "gpt-5.4-mini"
      ]
    }
  ],
  "rounding": {
    "dated_siu_sig_figs": 4,
    "basket_cost_dp": 6,
    "usd_per_siu_dp": 4,
    "spread_dp": 4,
    "siu_per_usd_dp": 1,
    "mode": "ROUND_HALF_UP",
    "siu_per_usd_mode": "ROUND_DOWN",
    "notes": "Applied at publication only; all intermediate arithmetic is full-precision decimal. dated_siu rounds to significant figures, not a fixed decimal-place count, so its precision scales with the price rather than being lost as it falls (found live, 2026-09-25 — see docs/methodology.md's Rounding section). basket_cost carries more decimal places than dated_siu needs at any price level so the published print stays reproducible from its own published figures. siu_per_usd truncates so it never overstates the work a dollar buys."
  },
  "cost_of_production_usd": "1.0158",
  "price_snapshot_ref": "price-snapshot-merged-2026-09-25T00-59-34.865Z.json",
  "methodology_version": "v0-draft",
  "methodology_revision": "rules-2026-09-25",
  "series": "frontier",
  "signature": "0xe69066b180b4b16215665816e5dc9de6c4f9d42d5dcedd5028f72b309204d5e50d4ba776e32ff1972a53d3dd890da9173e17739e587e2c1c18302c7b869ed352",
  "public_key": "0x030c598ee35bd24b6942e9155bd36c1dbbe77936c700f859e75b0168b0e25cb299",
  "anchor": {
    "chain": "base-sepolia",
    "status": "anchored",
    "tx_hash": "0xab31ab1fbca98643ccdefabe53f729310e1e69b794f59282c93ecd8da27c9a17",
    "posted_at": "2026-09-26T11:12:50.000Z"
  }
}