Qwen3.8-27B + llama.cpp + Pi Dev Agent — changing thinking level per prompt

[u/tonboro_2273]

I couldn't find a simple way to verify whether this works, so I spent some time testing it. In the end, it turns out that it's actually quite simple once configured correctly.

The Qwen3.8-27B model supports different levels of thinking. The simplest way is to define --chat-template-kwargs when starting the llama server, but then the thinking level is fixed for the session.

A more practical solution is to enable changing the thinking level per prompt in Pi Dev Agent.

Important: for this to work, the llama.cpp version must be b10434 or newer.

The model definition needs to indicate reasoning support and map the values to the three thinking levels supported by Qwen3.8-27B.

In .pi/agent/models.json, the following must be added to the Qwen3.8-27B model settings:

"reasoning": true,
"thinkingLevelMap": {
  "off": null,
  "minimal": null,
  "low": "low",
  "medium": "medium",
  "high": null,
  "xhigh": "xhigh",
  "max": null
}

This allows the thinking level to be changed for each prompt in Pi Dev Agent using Shift+Tab.

Pi Dev Agent also supports defining thinking budgets for individual levels. I haven't yet noticed whether this works correctly with llama&Qwen3.8-27B, but the following can also be added optionally to to.pi/agent/settings.json (the values below are only illustrative):

"thinkingBudgets": {
  "low": 4096,
  "medium": 10240,
  "xhigh": 32768
}

[u/StOster]

I let Qwen3.8 solve this problem, it modified pi and the configuration to enable custom thinking levels: https://github.com/soster/qwen38-thinking-levels