{
  "context": "Tests whether the response identifies both the singleton race condition and the shared mutable state bug.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "Identifies shared mutable state as primary bug",
      "description": "Explains that storing per-user data in a singleton field means all threads share the same currentUserId — one thread's setUser overwrites another's",
      "max_score": 20
    },
    {
      "name": "Recommends ThreadLocal",
      "description": "Suggests using ThreadLocal<String> for per-thread user context isolation",
      "max_score": 15
    },
    {
      "name": "Identifies double-checked locking issue",
      "description": "Notes the singleton getInstance() has a race condition — two threads could create separate instances (or suggests fixing with synchronized, enum, or holder pattern)",
      "max_score": 10
    },
    {
      "name": "No incorrect information",
      "description": "Response does not contain factually wrong statements about Java concurrency, ThreadLocal, or singleton patterns",
      "max_score": 12
    }
  ]
}