Sync Responses API streaming never closes the reasoning item

Finding: In an external report against LiteLLM v1.106.0 (https://github.com/BerriAI/litellm/issues/45561), sync Responses API streaming via litellm.responses(..., stream=True) in a plain for loop reportedly never closes the reasoning output item for bridged reasoning models. The reporter says the reasoning item receives response.output_item.added and its deltas, but no reasoning_summary_text.done, reasoning_summary_part.done or output_item.done event. Clients therefore see it as still in_progress when the response completes. Reported reproduction: the reporter ran the same prompt with reasoning effort high against two models (anthropic/claude-sonnet-5-5 and deepseek/deepseek-v4-pro) and printed non-delta event types. The reported sequence was response.created, response.in_progress, output_item.added 0, output_item.added 1, content_part.added 1, output_text.done 1, content_part.done 1, output_item.done 1, response.completed. There is no done event for output_index 0 before the message item at index 1 starts. The expected behavior, per the reporter, is that the reasoning item is closed before the message item begins, as it is with litellm.aresponses and async for (https://github.com/BerriAI/litellm/issues/45561). Suspected location (reporter's reading, not maintainer-confirmed): the async __anext__ in litellm/responses/litellm_completion_transformation/streaming_iterator.py emits the closing events when reasoning ends, while the sync __next__ does not. This is a hypothesis about cause, not a confirmed root cause. Status: the only comment is from a non-maintainer who says they plan to reproduce the problem, compare sync and async behavior, and add regression tests (https://github.com/BerriAI/litellm/issues/45561#issuecomment-6079799947). No maintainer response, fix commit, pull request or released fix appears in the supplied sources, so fix status is unknown. Possible mitigation (source-backed, not verified by KFA): per the reporter, the async path closes the item correctly. Consumers who depend on the reasoning item's completion events may try litellm.aresponses with async for instead of the sync iterator. Alternatively, they could avoid relying on explicit done events for reasoning items on the sync path until a fix is confirmed. Limitations: this is a single external report. The event sequence is reporter output and was not re-run, so there is no KFA reproduction. Other versions are unknown, and comment coverage is partial.