{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://marxh.cn/schemas/transaction-rule.schema.json",
  "title": "TransactionDecisionRule",
  "type": "object",
  "additionalProperties": false,
  "required": ["rule_id", "jurisdiction", "decision_type", "priority", "required_inputs", "when", "result", "effective_from", "evidence_ids", "version", "review_status"],
  "properties": {
    "rule_id": { "type": "string", "pattern": "^[A-Z0-9-]+$" },
    "jurisdiction": { "type": "string" },
    "decision_type": { "enum": ["purchase_eligibility", "tax", "holding_tax", "scope_route"] },
    "description": { "type": "string" },
    "priority": { "type": "integer" },
    "required_inputs": { "type": "array", "items": { "type": "string" }, "uniqueItems": true },
    "when": { "$ref": "#/$defs/expression" },
    "result": {
      "type": "object",
      "additionalProperties": true,
      "required": ["status"],
      "properties": {
        "status": { "enum": ["eligible", "ineligible", "conditional", "unknown", "out_of_scope", "applies", "exempt"] },
        "reason": { "type": "string" },
        "tax_item": { "type": "string" },
        "legal_taxpayer": { "type": "string" },
        "formula": { "type": "string" },
        "rate": { "type": ["number", "null"] }
      }
    },
    "effective_from": { "type": "string", "format": "date" },
    "effective_to": { "type": ["string", "null"], "format": "date" },
    "evidence_ids": { "type": "array", "items": { "type": "string" }, "minItems": 1, "uniqueItems": true },
    "version": { "type": "string" },
    "supersedes": { "type": "array", "items": { "type": "string" }, "uniqueItems": true },
    "review_status": { "enum": ["verified", "needs_review", "conflict", "expired"] }
  },
  "$defs": {
    "condition": {
      "type": "object",
      "additionalProperties": false,
      "required": ["field", "op"],
      "properties": {
        "field": { "type": "string" },
        "op": { "enum": ["eq", "neq", "in", "not_in", "gt", "gte", "lt", "lte", "exists"] },
        "value": {}
      }
    },
    "expression": {
      "oneOf": [
        { "$ref": "#/$defs/condition" },
        {
          "type": "object",
          "additionalProperties": false,
          "required": ["all"],
          "properties": { "all": { "type": "array", "items": { "$ref": "#/$defs/expression" }, "minItems": 1 } }
        },
        {
          "type": "object",
          "additionalProperties": false,
          "required": ["any"],
          "properties": { "any": { "type": "array", "items": { "$ref": "#/$defs/expression" }, "minItems": 1 } }
        },
        {
          "type": "object",
          "additionalProperties": false,
          "required": ["not"],
          "properties": { "not": { "$ref": "#/$defs/expression" } }
        }
      ]
    }
  }
}