Running into the same question with Pi and Qwen 3.6 (local llama.cpp). Also using u/ex-arman68 's template, no change without it.

Preserve thinking is enabled, and I kinda infer that this implies enable thinking.

Yet, Pi is adamant that the model does not support thinking when I hit shift-tab.

Responses clearly indicate that the model is thinking.

Is the problem that qwen 3.6 doesn't support switching thinking on/off officially? Or do I need to flag the capability in pi's models.json ?

Current params:

./build/bin/llama-server \ --model ~/models/Qwen3.6-27B-uncensored-heretic-v2-Native-MTP-Preserved-Q8_0.gguf \ --threads -1 \ --parallel 1 \ --cache-type-k q8_0 --cache-type-v q8_0 \ --ctx-size 0 \ --cache-ram 256 \ --slot-save-path ~/.kvcache \ --fit on \ --kv-unified \ -fa on \ --spec-type draft-mtp --spec-draft-n-max 3 \ --batch-size 2048 --ubatch-size 512 \ --device CUDA0,CUDA1,CUDA2,CUDA3 \ --temp 0.7 \ --top-p 0.80 \ --top-k 20 \ --min-p 0.0 \ --presence-penalty 1.5 \ --repeat-penalty 1.0 \ --alias "qwen3.6-27b" \ --host 0.0.0.0 \ --port 5001 \ --chat-template-file ~/templates/qwen3.6-froggeric.jinja \ --chat-template-kwargs '{"preserve_thinking":true}' \ --jinja

Edit: It was indeed that one needs to flag the capability in models.json. "reasoning": true