fix: use prompt token length for advantage group extraction#2176
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fix: use prompt token length for advantage group extraction#2176
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The previous role-based extraction (`_extract_prompt_only_messages`) broke on multi-turn prompts containing assistant messages in the conversation history — it would strip them, corrupting the prompt IDs used for advantage estimation. Replace with `extract_initial_prompt_messages()` which uses the `length` field to identify the original prompt boundary. Applied to both sync and async GRPO paths. Closes #1960 Co-Authored-By: Jiaqi Zeng <[email protected]> Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]> Signed-off-by: Yi-Fu Wu <[email protected]>
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/ok to test 628a248 |
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The previous role-based extraction (
_extract_prompt_only_messages) broke on multi-turn prompts containing assistant messages in the conversation history — it would strip them, corrupting the prompt IDs used for advantage estimation.Replace with
extract_initial_prompt_messages()which uses thelengthfield to identify the original prompt boundary. Applied to both sync and async GRPO paths.Closes #1960
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