Reconcile Thread Tail

Safely replace the tail of a thread without changing append semantics.

Optional request fields:

• matched_count (required int): Number of leading messages that still match
• messages (required array): Replacement tail messages
• expected_tail_ids (optional string[]): Current remote tail message IDs for optimistic concurrency

curl -X POST "http://127.0.0.1:14242/threads/string/reconcile-tail" \  -H "Content-Type: application/json" \  -d '{}'

{
  "success": true,
  "thread_id": "string",
  "messages_replaced": 0,
  "messages_added": 0,
  "total_messages": 0
}

{
  "detail": [
    {
      "loc": [
        "string"
      ],
      "msg": "string",
      "type": "string",
      "input": null,
      "ctx": {}
    }
  ]
}