For those trying to get it to work in OpenCode with a Qwen Cloud Token Plan, this is what worked for me. Note that I've just matched Qwen 3.7 Max for the limits as I don't know exactly what they are.

  "provider": {
    "alibaba-token-plan": {
      "models": {
        "qwen3.8-max-preview": {
          "limit": {
            "context": 1048576,
            "output": 65536
          },
          "modalities": {
            "input": [
              "text"
            ],
            "output": [
              "text"
            ]
          },
          "name": "Qwen3.8 Max Preview"
        }
      }
    }
  }