Describe the bug
OpenClaw returns 400 when using Xiaomi MiMo models (mimo-v2.5, mimo-v2.5-pro) with thinking mode enabled and multi-turn tool calls. The model requires reasoning_content field on assistant messages that contain tool_calls, but OpenClaw does not include it.

To Reproduce

1. Set agent model to xiaomi-coding/mimo-v2.5 with thinking enabled.
2. Have a multi-turn conversation where the assistant makes tool calls.
3. Subsequent user turns will fail with 400 Param Incorrect.

Expected behavior
All assistant messages with tool_calls should include the reasoning_content field (even if empty) when sending request to MiMo API.

Root cause
In @earendil-works/pi-ai detectCompat(), requiresReasoningContentOnAssistantMessages is only true for DeepSeek. MiMo uses the same protocol (thinking format deepseek) but is not recognized.

Possible solution
Add MiMo detection in detectCompat (match provider xiaomi / xiaomi-coding or baseUrl xiaomimimo.com) and set requiresReasoningContentOnAssistantMessages and thinkingFormat accordingly.

Environment

• OpenClaw version: 2026.5.12-beta.4
• Model: mimo-v2.5, mimo-v2.5-pro
• Platform: Windows / Node 24+

References:

• Xiaomi MiMo announcement: https://platform.xiaomimimo.com/docs/zh-CN/usage-guide/passing-back-reasoning_content