{
  "schema_version": "1.0",
  "case_id": "floater-005",
  "title": "Split discharge at two terminals",
  "difficulty": "hard",
  "task": "Update the synthetic European gas balance from the supplied LNG floater observations. Use only this case and return JSON matching schemas/answer.schema.json.",
  "as_of": "2026-01-14T12:00:00Z",
  "scope": {
    "market_area": "EU27+UK",
    "included_terminal_ids": [
      "FR-DKK",
      "BE-ZEE",
      "GB-SOU",
      "NL-GATE"
    ],
    "balance_gas_days": [
      "2026-01-15",
      "2026-01-16",
      "2026-01-17"
    ],
    "cargo_lookahead_end": "2026-01-20"
  },
  "conventions": {
    "unit": "GWh",
    "timezone": "Europe/Brussels",
    "gas_day_start_local": "06:00",
    "balance_representation": "signed_contribution",
    "balancing_component_id": "storage_net",
    "must_balance": true,
    "rounding_gwh": 0.001,
    "unknown_policy": "emit_null"
  },
  "rules": [
    {
      "rule_id": "R-CUTOFF",
      "description": "Use an observation only when received_at is at or before as_of and retracted is false."
    },
    {
      "rule_id": "R-SOURCE-PRECEDENCE",
      "description": "For destination and arrival, terminal_nomination outranks port_call, which outranks AIS. Equal-priority conflicts remain unresolved."
    },
    {
      "rule_id": "R-AIS-DESTINATION-STALENESS",
      "description": "An AIS destination older than 24 hours at as_of is stale and cannot override a non-stale higher-priority source.",
      "stale_after_hours": 24
    },
    {
      "rule_id": "R-STATE-LADEN",
      "description": "A recent AIS observation explicitly marked laden and underway supports the inferred state laden_underway."
    },
    {
      "rule_id": "R-GAS-DAY",
      "description": "Assign arrival to the gas day containing it in the case timezone. Gas days begin at 06:00 local time."
    },
    {
      "rule_id": "R-SENDOUT-STANDARD-3D",
      "description": "Allocate an in-scope discharge over three gas days from its start day using fractions 0.20, 0.50, and 0.30.",
      "fractions": [
        0.2,
        0.5,
        0.3
      ]
    },
    {
      "rule_id": "R-OUTAGE-PUSH",
      "description": "If sendout would start on a zero-capacity gas day, shift the whole three-day profile to the first open gas day."
    },
    {
      "rule_id": "R-DUPLICATE",
      "description": "Records for the same IMO, voyage_id, event, time, and value describe one cargo event, even when supplied by multiple feeds."
    },
    {
      "rule_id": "R-SPLIT",
      "description": "When explicit discharge fractions sum to one, keep one cargo identity and create one discharge leg per terminal."
    },
    {
      "rule_id": "R-SCOPE",
      "description": "An out-of-scope discharge contributes zero to European LNG sendout; retain its energy as unallocated_gwh for auditability."
    },
    {
      "rule_id": "R-UNKNOWN",
      "description": "Return null and an exception when the supplied evidence and rules cannot resolve a material value. Do not invent conversions or tie-breakers."
    },
    {
      "rule_id": "R-CARGO-DIFF",
      "description": "LNG balance delta equals updated in-scope cargo sendout minus the matched prior cargo sendout for each gas day."
    },
    {
      "rule_id": "R-BALANCE-ARITHMETIC",
      "description": "For every balance row, updated_contribution_gwh equals prior_contribution_gwh plus delta_contribution_gwh."
    },
    {
      "rule_id": "R-BALANCER",
      "description": "Offset the LNG sendout delta in storage_net with the opposite sign so the daily residual stays zero."
    }
  ],
  "reference_data": {
    "terminals": [
      {
        "terminal_id": "FR-DKK",
        "name": "Dunkerque LNG",
        "timezone": "Europe/Paris",
        "in_scope": true
      },
      {
        "terminal_id": "BE-ZEE",
        "name": "Zeebrugge LNG",
        "timezone": "Europe/Brussels",
        "in_scope": true
      },
      {
        "terminal_id": "GB-SOU",
        "name": "South Hook LNG",
        "timezone": "Europe/London",
        "in_scope": true
      },
      {
        "terminal_id": "NL-GATE",
        "name": "Gate LNG",
        "timezone": "Europe/Amsterdam",
        "in_scope": true
      },
      {
        "terminal_id": "TR-ALI",
        "name": "Aliaga LNG",
        "timezone": "Europe/Istanbul",
        "in_scope": false
      }
    ],
    "sendout_profiles": {
      "standard-3d": {
        "fractions": [
          0.2,
          0.5,
          0.3
        ]
      }
    },
    "capacity_schedule": [],
    "unit_conversions": []
  },
  "prior_balance": [
    {
      "record_id": "bal-2026-01-15-domestic_production",
      "gas_day": "2026-01-15",
      "component_id": "domestic_production",
      "contribution_gwh": 480.0
    },
    {
      "record_id": "bal-2026-01-15-pipeline_imports",
      "gas_day": "2026-01-15",
      "component_id": "pipeline_imports",
      "contribution_gwh": 2600.0
    },
    {
      "record_id": "bal-2026-01-15-lng_sendout",
      "gas_day": "2026-01-15",
      "component_id": "lng_sendout",
      "contribution_gwh": 1000.0
    },
    {
      "record_id": "bal-2026-01-15-demand",
      "gas_day": "2026-01-15",
      "component_id": "demand",
      "contribution_gwh": -3650.0
    },
    {
      "record_id": "bal-2026-01-15-exports",
      "gas_day": "2026-01-15",
      "component_id": "exports",
      "contribution_gwh": -120.0
    },
    {
      "record_id": "bal-2026-01-15-storage_net",
      "gas_day": "2026-01-15",
      "component_id": "storage_net",
      "contribution_gwh": -310.0
    },
    {
      "record_id": "bal-2026-01-16-domestic_production",
      "gas_day": "2026-01-16",
      "component_id": "domestic_production",
      "contribution_gwh": 475.0
    },
    {
      "record_id": "bal-2026-01-16-pipeline_imports",
      "gas_day": "2026-01-16",
      "component_id": "pipeline_imports",
      "contribution_gwh": 2580.0
    },
    {
      "record_id": "bal-2026-01-16-lng_sendout",
      "gas_day": "2026-01-16",
      "component_id": "lng_sendout",
      "contribution_gwh": 1020.0
    },
    {
      "record_id": "bal-2026-01-16-demand",
      "gas_day": "2026-01-16",
      "component_id": "demand",
      "contribution_gwh": -3620.0
    },
    {
      "record_id": "bal-2026-01-16-exports",
      "gas_day": "2026-01-16",
      "component_id": "exports",
      "contribution_gwh": -115.0
    },
    {
      "record_id": "bal-2026-01-16-storage_net",
      "gas_day": "2026-01-16",
      "component_id": "storage_net",
      "contribution_gwh": -340.0
    },
    {
      "record_id": "bal-2026-01-17-domestic_production",
      "gas_day": "2026-01-17",
      "component_id": "domestic_production",
      "contribution_gwh": 470.0
    },
    {
      "record_id": "bal-2026-01-17-pipeline_imports",
      "gas_day": "2026-01-17",
      "component_id": "pipeline_imports",
      "contribution_gwh": 2550.0
    },
    {
      "record_id": "bal-2026-01-17-lng_sendout",
      "gas_day": "2026-01-17",
      "component_id": "lng_sendout",
      "contribution_gwh": 980.0
    },
    {
      "record_id": "bal-2026-01-17-demand",
      "gas_day": "2026-01-17",
      "component_id": "demand",
      "contribution_gwh": -3600.0
    },
    {
      "record_id": "bal-2026-01-17-exports",
      "gas_day": "2026-01-17",
      "component_id": "exports",
      "contribution_gwh": -110.0
    },
    {
      "record_id": "bal-2026-01-17-storage_net",
      "gas_day": "2026-01-17",
      "component_id": "storage_net",
      "contribution_gwh": -290.0
    }
  ],
  "prior_cargo_book": [
    {
      "cargo_id": "cargo-501",
      "imo": "9100005",
      "voyage_id": "voyage-501",
      "quantity_gwh": 1000.0,
      "included_in_prior_balance": true,
      "discharge_legs": [
        {
          "leg_id": "prior-leg-501",
          "terminal_id": "FR-DKK",
          "included_in_scope": true,
          "arrival_time": "2026-01-15T08:00:00Z",
          "discharge_fraction": 1.0,
          "sendout_profile": [
            {
              "gas_day": "2026-01-15",
              "gwh": 200.0
            },
            {
              "gas_day": "2026-01-16",
              "gwh": 500.0
            },
            {
              "gas_day": "2026-01-17",
              "gwh": 300.0
            }
          ]
        }
      ]
    }
  ],
  "observations": [
    {
      "observation_id": "obs-501",
      "event_time": "2026-01-14T10:00:00Z",
      "received_at": "2026-01-14T10:01:00Z",
      "source": "terminal_nomination",
      "kind": "split_discharge",
      "subject": {
        "imo": "9100005",
        "voyage_id": "voyage-501"
      },
      "value": {
        "terminal_id": "FR-DKK",
        "arrival_time": "2026-01-15T08:00:00Z",
        "discharge_fraction": 0.4
      },
      "supersedes_observation_id": null,
      "retracted": false
    },
    {
      "observation_id": "obs-502",
      "event_time": "2026-01-14T10:05:00Z",
      "received_at": "2026-01-14T10:06:00Z",
      "source": "terminal_nomination",
      "kind": "split_discharge",
      "subject": {
        "imo": "9100005",
        "voyage_id": "voyage-501"
      },
      "value": {
        "terminal_id": "GB-SOU",
        "arrival_time": "2026-01-17T08:00:00Z",
        "discharge_fraction": 0.6
      },
      "supersedes_observation_id": null,
      "retracted": false
    },
    {
      "observation_id": "obs-503",
      "event_time": "2026-01-14T09:30:00Z",
      "received_at": "2026-01-14T09:31:00Z",
      "source": "ais",
      "kind": "position",
      "subject": {
        "imo": "9100005",
        "voyage_id": "voyage-501"
      },
      "value": {
        "navigation_state": "underway",
        "load_state": "laden"
      },
      "supersedes_observation_id": null,
      "retracted": false
    }
  ]
}