{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://github.com/BichengWang/ai-decision-system/schema/expgate/decision.v3.json",
  "title": "experiment-gate decision.json, schema 3",
  "$comment": "Canonicalization: RFC 8785 (JCS). input_sha256 is the lowercase hex SHA-256 of the canonical bytes of /input; no other field is digested. Integers and floats are one number type under JCS, so the integer constraints below cannot distinguish 100 from 100.0; the verifier additionally requires Python integers for counts. The verifier rejects duplicate object keys and non-finite numbers in schema 3 documents, which a schema cannot express. Replay compares computed statistics (p_value, diff, se, improvement, improvement_bounds, z, mde, adjustment numbers) within a relative 1e-9 (1e-12 absolute where the replayed value is 0) and everything else exactly; the verifier also rejects any member anywhere in the document that RFC 8785 cannot encode (integers beyond 2^53-1, overflowed floats, lone surrogates). Rules that relate several fields (exactly one primary metric, successes <= units, arm metrics matching the declared metrics, every derived field equal to a replay of /input) belong to the replay and are not repeated here. Unknown top-level members are ignored by the verifier and therefore allowed; every other object is closed.",
  "type": "object",
  "required": ["schema_version", "produced_by", "input", "input_sha256", "experiment", "decision", "reasons", "policy", "sample_ratio", "metrics"],
  "properties": {
    "schema_version": {"const": 3},
    "expgate_version": {"type": "string"},
    "produced_by": {
      "type": "object",
      "required": ["name", "version"],
      "properties": {"name": {"const": "expgate"}, "version": {"type": "string"}}
    },
    "input": {"$ref": "#/$defs/input"},
    "input_sha256": {"type": "string", "pattern": "^[0-9a-f]{64}$"},
    "experiment": {"type": "string"},
    "decision": {"enum": ["SHIP", "HOLD", "ROLLBACK", "INVALID"]},
    "reasons": {"type": "array", "items": {"type": "string"}},
    "policy": {
      "type": "object",
      "required": ["alpha", "srm_alpha", "power"],
      "properties": {
        "alpha": {"$ref": "#/$defs/open_unit_interval"},
        "srm_alpha": {"$ref": "#/$defs/open_unit_interval"},
        "power": {"$ref": "#/$defs/open_unit_interval"},
        "sequential": {"$ref": "#/$defs/sequential_policy"}
      },
      "additionalProperties": false
    },
    "sample_ratio": {
      "type": "object",
      "required": ["control_units", "treatment_units", "expected_treatment_share", "p_value", "pass"],
      "properties": {
        "control_units": {"type": "integer", "minimum": 1},
        "treatment_units": {"type": "integer", "minimum": 1},
        "expected_treatment_share": {"$ref": "#/$defs/open_unit_interval"},
        "p_value": {"type": "number", "minimum": 0, "maximum": 1},
        "pass": {"type": "boolean"}
      },
      "additionalProperties": false
    },
    "sequential": {
      "type": "object",
      "required": ["planned_units", "units", "information_fraction"],
      "properties": {
        "planned_units": {"type": "integer", "minimum": 2},
        "units": {"type": "integer", "minimum": 2},
        "information_fraction": {"type": "number", "exclusiveMinimum": 0}
      },
      "additionalProperties": false
    },
    "metrics": {"type": "array", "items": {"$ref": "#/$defs/metric_row"}}
  },
  "$defs": {
    "open_unit_interval": {"type": "number", "exclusiveMinimum": 0, "exclusiveMaximum": 1},
    "correlation": {"type": "number", "minimum": -1, "maximum": 1},
    "non_negative": {"type": "number", "minimum": 0},
    "sequential_policy": {
      "type": "object",
      "required": ["planned_units"],
      "properties": {"planned_units": {"type": "integer", "minimum": 2}},
      "additionalProperties": false
    },
    "input": {
      "type": "object",
      "required": ["metrics", "arms"],
      "properties": {
        "experiment": {"type": "string", "minLength": 1},
        "description": {},
        "seed": {},
        "source": {"$ref": "#/$defs/source"},
        "metrics": {
          "type": "object",
          "minProperties": 1,
          "additionalProperties": {"$ref": "#/$defs/metric_spec"}
        },
        "policy": {
          "type": "object",
          "properties": {
            "alpha": {"$ref": "#/$defs/open_unit_interval"},
            "srm_alpha": {"$ref": "#/$defs/open_unit_interval"},
            "power": {"$ref": "#/$defs/open_unit_interval"},
            "sequential": {"$ref": "#/$defs/sequential_policy"}
          },
          "additionalProperties": false
        },
        "assignment": {
          "type": "object",
          "properties": {"expected_treatment_share": {"$ref": "#/$defs/open_unit_interval"}},
          "additionalProperties": false
        },
        "arms": {
          "type": "object",
          "required": ["control", "treatment"],
          "properties": {
            "control": {"$ref": "#/$defs/arm"},
            "treatment": {"$ref": "#/$defs/arm"}
          }
        }
      },
      "additionalProperties": false
    },
    "source": {
      "$comment": "Provenance of an imported summary. Never an input to the decision; its reading.differences become reasons only when reading.decision differs from the replayed decision.",
      "type": "object",
      "required": ["format", "export_sha256"],
      "properties": {
        "format": {"enum": ["growthbook"]},
        "export_sha256": {"type": "string", "pattern": "^[0-9a-f]{64}$"},
        "experiment_id": {"type": "string", "minLength": 1},
        "snapshot_id": {"type": "string", "minLength": 1},
        "snapshot_updated": {"type": "string", "minLength": 1},
        "stats_engine": {"enum": ["bayesian", "frequentist"]},
        "asserted": {
          "$comment": "Facts about the snapshot that the export cannot establish, asserted by the operator in the mapping file and checked only against the export's current settings.",
          "type": "object",
          "required": ["expected_treatment_share", "regression_adjustment"],
          "properties": {
            "expected_treatment_share": {"$ref": "#/$defs/open_unit_interval"},
            "regression_adjustment": {"const": false}
          },
          "additionalProperties": false
        },
        "reading": {
          "type": "object",
          "required": ["decision", "basis", "differences"],
          "properties": {
            "decision": {"enum": ["SHIP", "HOLD", "ROLLBACK", "INVALID"]},
            "alpha": {"$ref": "#/$defs/open_unit_interval"},
            "srm_alpha": {"$ref": "#/$defs/open_unit_interval"},
            "basis": {"type": "array", "items": {"type": "string", "minLength": 1}},
            "differences": {"type": "array", "items": {"type": "string", "minLength": 1}}
          },
          "additionalProperties": false
        }
      },
      "additionalProperties": false
    },
    "metric_spec": {
      "type": "object",
      "required": ["type", "role", "direction"],
      "properties": {
        "type": {"enum": ["proportion", "mean", "ratio"]},
        "role": {"enum": ["primary", "guardrail"]},
        "direction": {"enum": ["increase", "decrease"]},
        "margin": {"$ref": "#/$defs/non_negative"}
      },
      "if": {"type": "object", "properties": {"role": {"const": "guardrail"}}, "required": ["role"]},
      "then": {"type": "object", "required": ["margin"]},
      "additionalProperties": false
    },
    "arm": {
      "type": "object",
      "required": ["units", "metrics"],
      "properties": {
        "units": {"type": "integer", "minimum": 1},
        "metrics": {
          "type": "object",
          "additionalProperties": {
            "oneOf": [
              {"$ref": "#/$defs/proportion_stat"},
              {"$ref": "#/$defs/mean_stat"},
              {"$ref": "#/$defs/ratio_stat"}
            ]
          }
        }
      }
    },
    "covariate": {
      "type": "object",
      "required": ["mean", "sd", "corr"],
      "properties": {
        "mean": {"type": "number"},
        "sd": {"type": "number", "exclusiveMinimum": 0},
        "corr": {"$ref": "#/$defs/correlation"}
      },
      "additionalProperties": false
    },
    "proportion_stat": {
      "type": "object",
      "required": ["successes"],
      "properties": {
        "successes": {"type": "integer", "minimum": 0},
        "covariate": {"$ref": "#/$defs/covariate"}
      },
      "additionalProperties": false
    },
    "mean_stat": {
      "type": "object",
      "required": ["mean", "sd"],
      "properties": {
        "mean": {"type": "number"},
        "sd": {"$ref": "#/$defs/non_negative"},
        "covariate": {"$ref": "#/$defs/covariate"}
      },
      "additionalProperties": false
    },
    "ratio_stat": {
      "type": "object",
      "required": ["numerator", "denominator", "corr"],
      "properties": {
        "numerator": {
          "type": "object",
          "required": ["mean", "sd"],
          "properties": {"mean": {"type": "number"}, "sd": {"$ref": "#/$defs/non_negative"}},
          "additionalProperties": false
        },
        "denominator": {
          "type": "object",
          "required": ["mean", "sd"],
          "properties": {"mean": {"type": "number", "exclusiveMinimum": 0}, "sd": {"$ref": "#/$defs/non_negative"}},
          "additionalProperties": false
        },
        "corr": {"$ref": "#/$defs/correlation"}
      },
      "additionalProperties": false
    },
    "metric_row": {
      "type": "object",
      "required": ["metric", "role", "type", "direction", "control", "treatment", "diff", "se", "improvement", "improvement_bounds", "z", "mde", "mde_basis", "status"],
      "properties": {
        "metric": {"type": "string"},
        "role": {"enum": ["primary", "guardrail"]},
        "type": {"enum": ["proportion", "mean", "ratio"]},
        "direction": {"enum": ["increase", "decrease"]},
        "control": {"type": "number"},
        "treatment": {"type": "number"},
        "diff": {"type": "number"},
        "se": {"type": "number"},
        "improvement": {"type": "number"},
        "improvement_bounds": {"type": "array", "items": {"type": "number"}, "minItems": 2, "maxItems": 2},
        "z": {"type": "number"},
        "mde": {"type": "number"},
        "mde_basis": {"enum": ["fixed_horizon_normal_approximation", "current_look_normal_approximation"]},
        "margin": {"$ref": "#/$defs/non_negative"},
        "status": {"enum": ["IMPROVED", "DEGRADED", "INCONCLUSIVE", "BREACH", "NON_INFERIOR"]},
        "adjustment": {
          "type": "object",
          "required": ["method", "theta", "raw_diff", "raw_se", "variance_reduction"],
          "properties": {
            "method": {"const": "cuped"},
            "theta": {"type": "number"},
            "raw_diff": {"type": "number"},
            "raw_se": {"type": "number"},
            "variance_reduction": {"type": "number"}
          },
          "additionalProperties": false
        }
      },
      "additionalProperties": false
    }
  }
}