Response terminates prematurely when using Gemini 3 via LiteLLM

[themw123]

Description

When using gemini-3-flash-preview through a LiteLLM proxy, OpenCode stops processing the response as soon as the model triggers a tool call. The model provides a reasoning block and a tool call, but OpenCode does not seem to execute the requested tool (e.g., read) and the interaction hangs or terminates without output.

The model response from LiteLLM looks like this (shortened for clarity):

{
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": null,
        "tool_calls": [
          {
            "id": "call_023b94f976e14e3a8711dd9c9864",
            "type": "function",
            "function": {
              "name": "read",
              "arguments": "{\"filePath\": \"/path/to/file/test.txt\"}"
            },
            "provider_specific_fields": {
              "thought_signature": "..." 
            }
          }
        ],
        "reasoning_content": "**Synthesizing Knowledge Bases**\n\nI've been analyzing..."
      },
      "finish_reason": "stop"
    }
  ]
}

The issue does NOT occur when connecting Gemini 3 directly to OpenCode (without LiteLLM)

OpenCode version

1.0.203

LiteLLM Version

1.80.11

Steps to reproduce

1. Set up LiteLLM with a Gemini 3 model - for example here is my litellm config:

model_list:
  - model_name: gemini/gemini-3-flash-preview
    litellm_params:
      model: gemini/gemini-3-flash-preview
      api_key: xxx
      drop_params: true

2. Configure OpenCode to use the LiteLLM endpoint:

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "litellm": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "litellm",
      "options": {
        "baseURL": "https://localhost:4000/v1",
        "apiKey": "sk-xxx"
      },
      "models": {
        "gemini/gemini-3-flash-preview": {
          "name": "gemini/gemini-3-flash-preview",
          "options": {
            "reasoningEffort": "high"
          }
        }
      }
    }
  }
}

3. Ask a question that requires reading a file or using a tool.

Observe that the process stops and no file is read, despite the model requesting it in the JSON.

Screenshot and/or share link

No response

Operating System

Windows 11 with WSL 2

Terminal

No response