Qwen 3.5 ironic meta-reasoning thwarts /no_think tag

The persistence of reasoning despite explicit instructions signals a shift in LLM architecture where "thinking" is becoming an immutable default rather than a toggleable feature.

• –The `/no_think` tag is an official community-supported prompt marker, but its failure in this case suggests that the model's internal evaluation of the system prompt happens within the very reasoning loop it's trying to disable.
• –This "meta-awareness" in models like Qwen 3.5 and DeepSeek-R1 creates ironic failure modes where the model spends compute explaining why it shouldn't be spending compute.
• –For developers requiring strict non-reasoning outputs, local deployment flags like `--enable_thinking false` (llama.cpp) or custom Jinja templates remain more reliable than prompt-level instructions.
• –The incident underscores the move toward "agentic-first" models where planning and internal verification are core to the inference pipeline, making true "zero-thought" responses increasingly difficult to force.