Bug Description

When using kimi-for-coding with Hermes Agent, any session that triggers tool calls becomes permanently broken after several rounds. The Moonshot API returns HTTP 400 because assistant messages containing tool_calls are missing the required reasoning_content field, and this corrupted message stays in conversation history and gets replayed every subsequent turn.

Actual Error Log

Error: Error code: 400 - {'error': {'type': 'invalid_request_error', 'message': 'thinking is enabled but reasoning_content is missing in assistant tool call message at index 2'}, 'type': 'error'}

Steps to Reproduce

1、configure Hermes Agent with kimi-for-coding or kimi-k2.6
2、start a new session and trigger a tool call(ex. can you use lark cli? if you can, create a file)
.

Expected Behavior

expected to call the tool

Actual Behavior

returned api error
API call failed (attempt 1/3): BadRequestError [HTTP 400]
🔌 Provider: kimi-coding Model: kimi-k2.6
🌐 Endpoint: https://api.kimi.com/coding
📝 Error: HTTP 400: thinking is enabled but reasoning_content is missing in assistant tool call message at index 2
📋 Details: {'error': {'type': 'invalid_request_error', 'message': 'thinking is enabled but reasoning_content is missing in assistant tool call message at index 2'}, 'type': 'error'}
⚠️ Non-retryable error (HTTP 400) — trying fallback...
❌ Non-retryable error (HTTP 400): HTTP 400: thinking is enabled but reasoning_content is missing in assistant tool call message at index 2
❌ Non-retryable client error (HTTP 400). Aborting.
🔌 Provider: kimi-coding Model: kimi-k2.6
🌐 Endpoint: https://api.kimi.com/coding
💡 This type of error won't be fixed by retrying.

Affected Component

CLI (interactive chat), Tools (terminal, file ops, web, code execution, etc.), Skills (skill loading, skill hub, skill guard), Gateway (Telegram/Discord/Slack/WhatsApp)

Messaging Platform (if gateway-related)

No response

Debug Report

Report     https://paste.rs/6V2iw
agent.log  https://paste.rs/MfgGO

Operating System

Ubuntu24.04

Python Version

3.11.15

Hermes Version

2.1.0

Additional Logs / Traceback (optional)

Root Cause Analysis (optional)

No response

Proposed Fix (optional)

No response

Are you willing to submit a PR for this?

• I'd like to fix this myself and submit a PR