Are <|inner_prefix|>...<|inner_suffix|> thoughts generated by released Instruct checkpoints?

#18
by pd95 - opened

Hi, I am experimenting with running Apertus Instruct through Ollama's MLX runner and have a question about thinking/deliberation output.

The official chat template supports:

  • enable_thinking=True
  • Deliberation: enabled
  • assistant thoughts blocks rendered as <|inner_prefix|>...<|inner_suffix|>

I wired this locally so that think: true enables Deliberation: enabled, and the parser extracts <|inner_prefix|>...<|inner_suffix|> into a thinking field.

However, in smoke tests with Apertus-8B-Instruct-2509 and Apertus-70B-Instruct-2509, the models answer normally but do not emit any <|inner_prefix|>...<|inner_suffix|> spans. The API path appears to work, but
thinking remains empty.

Is this expected behavior for the released Instruct checkpoints?

Concretely:

  1. Are Apertus Instruct models expected to generate visible/parseable thoughts blocks when enable_thinking=True?
  2. Are there recommended prompts or decoding settings that induce this behavior?
  3. Is Deliberation: enabled intended only as an internal instruction, with the model usually returning only the final response?
  4. Should downstream integrations advertise this as a thinking-capable model, or only as supporting the Apertus thinking format for replay/history?

Thanks!

Swiss AI Initiative org

This is a known issue of our limited support for instruction following in the first release. For now, I would not label the current version of Apertus as a thinking model. Our team is working on making sure the next version of Apertus improves support here, and uses thinking special tokens more frequently. Thanks for your interest, and please stay tuned!

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