OpenCode Go complex routing strips reasoning_content on Kimi K2.6 tool calls, causing 400 error

[moshment]

Title: OpenCode Go complex routing strips reasoning_content on Kimi K2.6 tool calls, causing 400 error

Provider: OpenCode Go (via Manifest)
Model: opencode-go/kimi-k2.6
Routing: complex
Date: Apr 29, 2026
Client: Hermes Agent v0.11.0 (OpenAI SDK 2.30.0)

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Problem Summary

When routing through Manifest to opencode-go/kimi-k2.6 with complex routing, all requests that involve tool calls fail with a 400 error from upstream. The same configuration works correctly when hitting OpenCode Go directly (bypassing Manifest).

Error Details

Error code: 400
{
"error": {
"message": "Error from provider: Provider returned error",
"code": 400,
"metadata": {
"raw": "{"error":{"message":"thinking is enabled but reasoning_content is missing in assistant tool call message at index 7","type":"invalid_request_error"}}",
"provider_name": "Moonshot AI",
"is_byok": true
}
}
}

Key Observation

Direct OpenCode Go to Moonshot works fine with thinking enabled and tool calls.
Manifest (complex) to OpenCode Go to Moonshot fails consistently on any tool call with reasoning enabled.
This suggests the complex routing layer strips or fails to preserve reasoning_content in assistant messages that contain tool_calls, causing Moonshot to reject the request.

Reproduction Steps

1. Configure client with thinking enabled or reasoning_effort medium
2. Send request to with model opencode-go/kimi-k2.6
3. Include tools in the request
4. After initial reasoning and tool_calls response, submit tool results
5. Moonshot returns 400 with message: thinking is enabled but reasoning_content is missing in assistant tool call message at index 7

Suggested Fix

The complex routing pipeline should preserve the reasoning_content field in assistant messages that contain tool_calls, or properly handle the thinking/reasoning state across the routing layer when proxying to Moonshot.

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