{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "gno://schemas/document-diff@1.0",
  "title": "GNO Document Structural Diff",
  "type": "object",
  "required": [
    "schemaVersion",
    "status",
    "document",
    "change",
    "content",
    "history",
    "warnings"
  ],
  "properties": {
    "schemaVersion": { "type": "string", "const": "1.0" },
    "status": {
      "type": "string",
      "enum": ["available", "expired", "unavailable"]
    },
    "document": {
      "type": "object",
      "required": ["id", "uri", "title", "collection", "relPath", "active"],
      "properties": {
        "id": { "type": "string", "pattern": "^#[a-f0-9]{6,}$" },
        "uri": { "type": "string", "pattern": "^gno://.+" },
        "title": { "type": ["string", "null"] },
        "collection": { "type": "string" },
        "relPath": { "type": "string" },
        "active": { "type": "boolean" }
      },
      "additionalProperties": false
    },
    "change": {
      "anyOf": [
        { "$ref": "gno://schemas/changes@1.0#/definitions/change" },
        { "type": "null" }
      ]
    },
    "content": {
      "type": "object",
      "required": ["status", "reason"],
      "properties": {
        "status": { "type": "string", "const": "not_retained" },
        "reason": { "type": "string", "const": "journal_metadata_only" }
      },
      "additionalProperties": false
    },
    "history": {
      "type": "object",
      "required": ["status", "reason"],
      "properties": {
        "status": {
          "type": "string",
          "enum": ["available", "partial", "unavailable"]
        },
        "reason": {
          "type": ["string", "null"],
          "enum": [
            null,
            "structure_delta_truncated",
            "change_expired",
            "no_retained_change",
            "change_not_found"
          ]
        }
      },
      "additionalProperties": false
    },
    "warnings": { "type": "array", "items": { "type": "string" } }
  },
  "additionalProperties": false,
  "allOf": [
    {
      "if": {
        "properties": { "status": { "const": "available" } },
        "required": ["status"]
      },
      "then": {
        "properties": {
          "change": {
            "$ref": "gno://schemas/changes@1.0#/definitions/change"
          },
          "history": {
            "type": "object",
            "properties": {
              "status": { "enum": ["available", "partial"] }
            }
          }
        }
      }
    },
    {
      "if": {
        "properties": { "status": { "const": "expired" } },
        "required": ["status"]
      },
      "then": {
        "properties": {
          "change": { "type": "null" },
          "history": {
            "type": "object",
            "properties": {
              "status": { "const": "unavailable" },
              "reason": { "const": "change_expired" }
            }
          }
        }
      }
    },
    {
      "if": {
        "properties": { "status": { "const": "unavailable" } },
        "required": ["status"]
      },
      "then": {
        "properties": {
          "change": { "type": "null" },
          "history": {
            "type": "object",
            "properties": {
              "status": { "const": "unavailable" },
              "reason": {
                "enum": ["no_retained_change", "change_not_found"]
              }
            }
          }
        }
      }
    },
    {
      "if": {
        "properties": {
          "history": {
            "type": "object",
            "properties": { "status": { "const": "available" } },
            "required": ["status"]
          }
        },
        "required": ["history"]
      },
      "then": {
        "properties": {
          "history": {
            "type": "object",
            "properties": { "reason": { "type": "null" } }
          }
        }
      }
    },
    {
      "if": {
        "properties": {
          "history": {
            "type": "object",
            "properties": { "status": { "const": "partial" } },
            "required": ["status"]
          }
        },
        "required": ["history"]
      },
      "then": {
        "properties": {
          "change": {
            "type": "object",
            "properties": {
              "structureDelta": {
                "type": "object",
                "properties": { "truncated": { "const": true } },
                "required": ["truncated"]
              }
            },
            "required": ["structureDelta"]
          },
          "history": {
            "type": "object",
            "properties": {
              "reason": { "const": "structure_delta_truncated" }
            }
          }
        }
      }
    }
  ]
}