Problem
The Responses API distinguishes between:
response.reasoning_text.delta: raw reasoning textresponse.reasoning_summary_text.delta: human-readable reasoning summary
However, the SDK currently maps both events to ReasoningDeltaPart.
Other providers also expose different concepts:
- Chat Completions:
reasoning_content
- Anthropic:
thinking_delta
- Gemini:
thought
- Responses API: reasoning summary and encrypted reasoning state
Current Compatibility Behavior
For now, both Responses events are intentionally mapped to ReasoningDeltaPart, with reasoning_text.delta preferred when both are available.
Proposed Future Change
Introduce separate SDK types, for example:
ReasoningDeltaPartReasoningSummaryDeltaPart
This should be treated as a breaking API change because existing consumers currently receive reasoning summaries as ReasoningDeltaPart.
Problem
The Responses API distinguishes between:
response.reasoning_text.delta: raw reasoning textresponse.reasoning_summary_text.delta: human-readable reasoning summaryHowever, the SDK currently maps both events to
ReasoningDeltaPart.Other providers also expose different concepts:
reasoning_contentthinking_deltathoughtCurrent Compatibility Behavior
For now, both Responses events are intentionally mapped to
ReasoningDeltaPart, withreasoning_text.deltapreferred when both are available.Proposed Future Change
Introduce separate SDK types, for example:
ReasoningDeltaPartReasoningSummaryDeltaPartThis should be treated as a breaking API change because existing consumers currently receive reasoning summaries as
ReasoningDeltaPart.