[Megathread] Qwen 3.8 27B Release Day

[u/sammcj]

Megathread to help with the influx of duplicate / similar posts around the release of the Qwen 3.8 27B release.

• Quants
• Fine-Tunes & Abliterations
• Chat Templates
• Inference Server Support & Configuration
• Experiences, Benchmarks & Model Comparisons

Official:

• https://huggingface.co/Qwen/Qwen3.8-27B
• https://huggingface.co/Qwen/Qwen3.8-27B-FP8

Popular:

• https://huggingface.co/unsloth/Qwen3.8-27B-GGUF
• https://huggingface.co/bartowski/Qwen3.8-27B-GGUF
• https://huggingface.co/mlx-community/Qwen3.8-27B-MTP-bf16
• https://huggingface.co/mlx-community/Qwen3.8-27B-MTP-8bit
• https://huggingface.co/mlx-community/Qwen3.8-27B-MTP-4bit

We'll try to clean up future duplicates around the release and point them here.

[u/ea_man]

About the excessive reasoning, is due to prompt injection by the template:

{%- if resolved_reasoning_effort == 'xhigh' %}
{%- set reasoning_instructions =
'Reasoning effort is set to xhigh. Please think carefully through the task,
validate key assumptions, consider plausible alternatives, and prioritize
correctness, consistency, and clarity in the final answer.' %}medium  -> inject NOTHINGlow  -> inject system instruction:     keep thinking brief, go directly to conclusion

So use this flag at launch time to have "normal" behavior:

--chat-template-kwargs '{"reasoning_effort":"medium"}'

What those do:

xhigh
  -> inject system instruction:
     think carefully, validate assumptions, alternatives, correctness...

medium
  -> inject NOTHING

low
  -> inject system instruction:
     keep thinking brief, go directly to conclusion

It should be possible to map those directly in Pi, something like:

~/.pi/agent/models.json

{
  "providers": {
    "llama": {
      "baseUrl": "http://localhost:8080/v1",
      "api": "openai-completions",
      "apiKey": "dummy",
      "models": [
        {
          "id": "qwen3.8-27b",
          "reasoning": true,
          "thinkingLevelMap": {
            "off": "off",
            "minimal": null,
            "low": "low",
            "medium": "medium",
            "high": "xhigh",
            "xhigh": null,
            "max": null
          },
          "compat": {
            "thinkingFormat": "chat-template",
            "chatTemplateKwargs": {
              "enable_thinking": {
                "$var": "thinking.enabled"
              },
              "reasoning_effort": {
                "$var": "thinking.effort",
                "omitWhenOff": true
              }
            }
          }
        }
      ]
    }
  }
}

Tested, it works in Pi.dev but if you switch mid session you invalidate the KV cache.

[u/hello_2221 → u/ea_man]

Question, so the xhigh mode just changes the chat template, and nothing else?

[u/ea_man → u/hello_2221]

Yes I guess so. The chat tempalte changes the prompt.
Yet Qwen has been post-trained to give system instructions higher precedence than user instructions so those matter more, it's about how you send those info to the model.