{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "qb-1.1 question bank record",
  "description": "题库记录。qb-1.0 向后兼容升级：新增 source.source_id（必填）与 source.source_item_id（可选）。",
  "type": "object",
  "required": ["schema", "id", "exam", "cefr", "paper", "part", "type", "items", "source", "license"],
  "properties": {
    "schema": { "const": "qb-1.1" },
    "id": { "type": "string" },
    "exam": { "type": "string", "enum": ["A2 Key", "A2 Key for Schools", "B1 Preliminary", "B1 Preliminary for Schools"] },
    "cefr": { "type": "string", "enum": ["A2", "B1"] },
    "paper": { "type": "string", "enum": ["reading_writing", "reading", "writing", "listening", "speaking", "vocabulary"] },
    "part": { "type": ["integer", "null"] },
    "type": { "type": "string", "enum": ["mcq", "matching", "open_cloze", "gap_fill", "word_formation", "writing_task", "speaking_prompt", "word_entry", "other"] },
    "task_prompt": { "type": ["string", "null"] },
    "title": { "type": ["string", "null"] },
    "passage": { "type": ["string", "null"] },
    "blank_token": { "type": "string" },
    "items": { "type": "array", "items": { "type": "object" } },
    "source": {
      "type": "object",
      "required": ["source_id"],
      "properties": {
        "source_id": { "type": "string", "pattern": "^[a-z0-9][a-z0-9-]*$" },
        "source_item_id": { "type": ["string", "null"] },
        "origin": { "type": "string" },
        "file": { "type": ["string", "null"] },
        "url": { "type": ["string", "null"] },
        "retrieved": { "type": ["string", "null"] }
      }
    },
    "license": { "type": "string", "enum": ["official-free", "cc-by", "cc-by-sa", "cc-nc-education", "restricted", "internal-only", "llm-generated", "unknown"] },
    "tags": { "type": "array", "items": { "type": "string" } },
    "note": { "type": ["string", "null"] },
    "meta": { "type": ["object", "null"] }
  }
}