curl --request GET \
  --url https://api.example.com/api/v1/runs/{id}/billing \
  --header 'Authorization: Bearer <token>'

{
  "stages": [
    {
      "stage": {
        "id": "propose-changes",
        "name": "Propose Changes"
      },
      "model": {
        "id": "claude-opus-4-6"
      },
      "billing": {
        "input_tokens": 28640,
        "output_tokens": 8750,
        "total_tokens": 37390,
        "reasoning_tokens": 1200,
        "cache_read_tokens": 4800,
        "cache_write_tokens": 1500,
        "total_usd_micros": 720000
      },
      "runtime_secs": 154
    }
  ],
  "totals": {
    "runtime_secs": 389,
    "input_tokens": 71540,
    "output_tokens": 21080,
    "total_tokens": 92620,
    "reasoning_tokens": 3400,
    "cache_read_tokens": 22000,
    "cache_write_tokens": 4500,
    "total_usd_micros": 2260000
  },
  "by_model": [
    {
      "model": {
        "id": "claude-opus-4-6"
      },
      "stages": 2,
      "billing": {
        "input_tokens": 28640,
        "output_tokens": 8750,
        "total_tokens": 37390,
        "reasoning_tokens": 1200,
        "cache_read_tokens": 4800,
        "cache_write_tokens": 1500,
        "total_usd_micros": 720000
      }
    }
  ]
}