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[gpt-oss] Add model_identity to system message retrieval for harmony chat template #30247

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[gpt-oss] Add model_identity to system message retrieval for harmony chat template #30247

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Add model_identity to system message retrieval
lyuwen Dec 8, 2025
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Update vllm/entrypoints/openai/serving_chat.py
lyuwen Dec 8, 2025
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1 change: 1 addition & 0 deletions vllm/entrypoints/openai/serving_chat.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1761,6 +1761,7 @@ def _make_request_with_harmony(
assert not self.supports_browsing
assert not self.supports_code_interpreter
sys_msg = get_system_message(
model_identity=(request.chat_template_kwargs or {}).get("model_identity"),
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@chaunceyjiang chaunceyjiang Dec 15, 2025

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Suggested change
model_identity=(request.chat_template_kwargs or {}).get("model_identity"),
model_identity=(request.chat_template_kwargs or {}).get("harmony_model_identity"),

WDYT? @yeqcharlotte @lyuwen

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@lyuwen lyuwen Dec 22, 2025 •
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"model_identity" seems more straightforward since it aligns with the GPT-OSS's original chat template. Using "harmony_model_identity" would need a bit more explanation in the vllm docs.
Pasted from the chat template:

{#-
--
In addition to the normal inputs of `messages` and `tools`, this template also accepts the
following kwargs:
- "builtin_tools": A list, can contain "browser" and/or "python".
- "model_identity": A string that optionally describes the model identity.
- "reasoning_effort": A string that describes the reasoning effort, defaults to "medium".
#}

Maybe the additional ones suggested in #30873 could use a prefix since it could be harmony specific?
Anyway, either works for me.

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@seunggil1 seunggil1 Jan 1, 2026

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It appears that apart from reasoning_effort, the remaining fields are specific to the Harmony format.

I think it might be beneficial to add a harmony_ prefix to these keys (e.g., harmony_model_identity). My concern is that even users familiar with the Harmony format might easily overlook this feature unless they carefully read the vLLM documentation.

reasoning_effort=request.reasoning_effort,
browser_description=None,
python_description=None,
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