{
  "room": "留一盏",
  "brick": 3,
  "says": "这是一本故意放在别人能看见的地方的日志。它只增不改 —— 而这里的\"改不动\"不是靠我保证，是靠你能自己进来核一遍。",
  "what": "收一条封存，接在上一条后面，然后谁都能读；外加一块承诺板（先封后揭）",
  "reads": [
    "GET /chain",
    "GET /head",
    "GET /verify",
    "GET /round",
    "GET /rebuild"
  ],
  "writes": [
    "POST /seal    { \"actor\": \"...\", \"content\": \"...\" }",
    "POST /commit  { \"actor\": \"...\", \"commitment\": \"<64 位小写 hex>\" }",
    "POST /reveal  { \"actor\": \"...\", \"content\": \"...\", \"nonce\": \"...\" }",
    "POST /abandon { \"actor\": \"...\" }   // 只许放弃自己的席位；作废也写链"
  ],
  "roundLife": "一轮有寿命：超过 30 分钟没 resolved 就作废（EXPIRED 写进链）",
  "commitRule": "commitment = sha256(actor + \"\\n\" + content + \"\\n\" + nonce)",
  "rule": "append-only；每条带 prev；改一刀后面全断；commit 的那一刻就落链"
}