{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://raw.githubusercontent.com/api-evangelist/pubmed/main/json-schema/esearch-response.json",
  "title": "ESearch Response",
  "description": "Schema for the JSON response from the NCBI E-utilities ESearch endpoint.",
  "type": "object",
  "properties": {
    "header": {
      "type": "object",
      "description": "Response header metadata.",
      "properties": {
        "type": { "type": "string", "description": "Response type identifier.", "example": "esearch" },
        "version": { "type": "string", "description": "ESearch version.", "example": "0.3" }
      }
    },
    "esearchresult": {
      "type": "object",
      "description": "Main search result container.",
      "properties": {
        "count": {
          "type": "string",
          "description": "Total number of records matching the query.",
          "example": "42317"
        },
        "retmax": {
          "type": "string",
          "description": "Number of UIDs returned in this response.",
          "example": "20"
        },
        "retstart": {
          "type": "string",
          "description": "Index of the first UID returned.",
          "example": "0"
        },
        "querykey": {
          "type": "string",
          "description": "Integer query key assigned on the History server (only present when usehistory=y).",
          "example": "1"
        },
        "webenv": {
          "type": "string",
          "description": "Web environment string for use with History server (only present when usehistory=y)."
        },
        "idlist": {
          "type": "array",
          "description": "List of UIDs matching the search query.",
          "items": { "type": "string" },
          "example": ["36328499", "36328500", "36328501"]
        },
        "translationset": {
          "type": "array",
          "description": "Details of any query translation performed by Entrez.",
          "items": {
            "type": "object",
            "properties": {
              "from": { "type": "string", "description": "Original search term." },
              "to": { "type": "string", "description": "Translated Entrez query term." }
            }
          }
        },
        "translationstack": {
          "type": "array",
          "description": "Stack representation of the query translation.",
          "items": {
            "oneOf": [
              {
                "type": "object",
                "properties": {
                  "term": { "type": "string" },
                  "field": { "type": "string" },
                  "count": { "type": "string" },
                  "explode": { "type": "string" }
                }
              },
              { "type": "string", "enum": ["AND", "OR", "NOT", "GROUP"] }
            ]
          }
        },
        "querytranslation": {
          "type": "string",
          "description": "Full Entrez query translation used for the search.",
          "example": "\"neoplasms\"[MeSH Terms] OR \"cancer\"[All Fields]"
        },
        "errorlist": {
          "type": "object",
          "description": "Lists any errors encountered during the search.",
          "properties": {
            "phrasesnotfound": {
              "type": "array",
              "items": { "type": "string" },
              "description": "Search phrases that produced no results."
            },
            "fieldsnotfound": {
              "type": "array",
              "items": { "type": "string" },
              "description": "Specified fields that were not recognized."
            }
          }
        },
        "warninglist": {
          "type": "object",
          "description": "Lists any warnings generated during the search.",
          "properties": {
            "phrasesignored": {
              "type": "array",
              "items": { "type": "string" }
            },
            "quotedphrasesnotfound": {
              "type": "array",
              "items": { "type": "string" }
            },
            "outputmessages": {
              "type": "array",
              "items": { "type": "string" }
            }
          }
        }
      },
      "required": ["count", "retmax", "retstart", "idlist"]
    }
  },
  "required": ["esearchresult"]
}