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[BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks #180

Closed
Feature
#215
Closed
[BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks#180
Feature
#215
Assignees
AbhiPrasad
Labels
bot-automationintegration: openai

Description

@braintrust-bot
braintrust-bot
bot
opened on Mar 31, 2026

Summary

When chat.completions.create(logprobs=True, stream=True) is used, the logprobs data present in each streaming chunk is discarded. The span output hardcodes "logprobs": None instead of accumulating the per-token log probabilities across chunks.

Non-streaming calls correctly capture logprobs because the full choices dict is logged directly (line 204 of oai.py). Streaming calls lose this data because _postprocess_streaming_results (lines 288–356) only accumulates content, tool_calls, role, and finish_reason from deltas, and then hardcodes logprobs to None at line 353.

What is missing

Each ChatCompletionChunk.choices[0].logprobs contains a ChoiceLogprobs object with:

  • content: list of per-token log probabilities and top alternatives
  • refusal: list of per-token log probabilities for refusal tokens

These are available in every streaming chunk but never read by the wrapper. The assembled span output sets:

"logprobs": None, # line 353 — hardcoded

Users who set logprobs=True for confidence scoring, model evaluation, or token-level analysis get correct data in non-streaming mode but silently lose it when switching to stream=True.

Braintrust docs status

not_found — The OpenAI integration docs document wrap_openai() and streaming token usage, but do not mention logprobs capture.

Upstream sources

  • OpenAI Python SDK type: ChatCompletionChunk.choices[0].logprobs → ChoiceLogprobs (source)
  • OpenAI API reference: logprobs parameter in chat completions

Local files inspected

  • py/src/braintrust/oai.py:
    • _postprocess_streaming_results (lines 288–356): accumulates content and tool_calls from deltas but ignores logprobs on each Choice; hardcodes output logprobs to None at line 353
    • Non-streaming path (line 204): logs log_response["choices"] which includes the full logprobs object — correct
  • py/src/braintrust/wrappers/test_openai.py: no test for logprobs=True with stream=True

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[BOT ISSUE] OpenAI: chat completions streaming discards `logprobs` from chunks · Issue #180 · braintrustdata/braintrust-sdk-python · GitHub
    Skip to content
    [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks #180
    Closed
    Feature
    #215
    Closed
    [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks#180
    Feature
    #215
    Assignees
    AbhiPrasad
    Labels
    bot-automationintegration: openai
    Description
    @braintrust-bot
    braintrust-bot
    bot
    opened on Mar 31, 2026
    Summary
    When chat.completions.create(logprobs=True, stream=True) is used, the logprobs data present in each streaming chunk is discarded. The span output hardcodes "logprobs": None instead of accumulating the per-token log probabilities across chunks.
    Non-streaming calls correctly capture logprobs because the full choices dict is logged directly (line 204 of oai.py). Streaming calls lose this data because _postprocess_streaming_results (lines 288–356) only accumulates content, tool_calls, role, and finish_reason from deltas, and then hardcodes logprobs to None at line 353.
    What is missing
    Each ChatCompletionChunk.choices[0].logprobs contains a ChoiceLogprobs object with:
    • content: list of per-token log probabilities and top alternatives
    • refusal: list of per-token log probabilities for refusal tokens
    These are available in every streaming chunk but never read by the wrapper. The assembled span output sets:
    "logprobs": None, # line 353 — hardcoded
    Users who set logprobs=True for confidence scoring, model evaluation, or token-level analysis get correct data in non-streaming mode but silently lose it when switching to stream=True.
    Braintrust docs status
    not_found — The OpenAI integration docs document wrap_openai() and streaming token usage, but do not mention logprobs capture.
    Upstream sources
    • OpenAI Python SDK type: ChatCompletionChunk.choices[0].logprobs → ChoiceLogprobs (source)
    • OpenAI API reference: logprobs parameter in chat completions
    Local files inspected
    • py/src/braintrust/oai.py:

      • _postprocess_streaming_results (lines 288–356): accumulates content and tool_calls from deltas but ignores logprobs on each Choice; hardcodes output logprobs to None at line 353
      • Non-streaming path (line 204): logs log_response["choices"] which includes the full logprobs object — correct
    • py/src/braintrust/wrappers/test_openai.py: no test for logprobs=True with stream=True
    Metadata
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[BOT ISSUE] OpenAI: chat completions streaming discards `logprobs` from chunks · Issue #180 · braintrustdata/braintrust-sdk-python · GitHub
      Skip to content
      [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks #180
      Closed
      Feature
      #215
      Closed
      [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks#180
      Feature
      #215
      Assignees
      AbhiPrasad
      Labels
      bot-automationintegration: openai
      Description
      @braintrust-bot
      braintrust-bot
      bot
      opened on Mar 31, 2026
      Summary
      When chat.completions.create(logprobs=True, stream=True) is used, the logprobs data present in each streaming chunk is discarded. The span output hardcodes "logprobs": None instead of accumulating the per-token log probabilities across chunks.
      Non-streaming calls correctly capture logprobs because the full choices dict is logged directly (line 204 of oai.py). Streaming calls lose this data because _postprocess_streaming_results (lines 288–356) only accumulates content, tool_calls, role, and finish_reason from deltas, and then hardcodes logprobs to None at line 353.
      What is missing
      Each ChatCompletionChunk.choices[0].logprobs contains a ChoiceLogprobs object with:
      • content: list of per-token log probabilities and top alternatives
      • refusal: list of per-token log probabilities for refusal tokens
      These are available in every streaming chunk but never read by the wrapper. The assembled span output sets:
      "logprobs": None, # line 353 — hardcoded
      Users who set logprobs=True for confidence scoring, model evaluation, or token-level analysis get correct data in non-streaming mode but silently lose it when switching to stream=True.
      Braintrust docs status
      not_found — The OpenAI integration docs document wrap_openai() and streaming token usage, but do not mention logprobs capture.
      Upstream sources
      • OpenAI Python SDK type: ChatCompletionChunk.choices[0].logprobs → ChoiceLogprobs (source)
      • OpenAI API reference: logprobs parameter in chat completions
      Local files inspected
      • py/src/braintrust/oai.py:

        • _postprocess_streaming_results (lines 288–356): accumulates content and tool_calls from deltas but ignores logprobs on each Choice; hardcodes output logprobs to None at line 353
        • Non-streaming path (line 204): logs log_response["choices"] which includes the full logprobs object — correct
      • py/src/braintrust/wrappers/test_openai.py: no test for logprobs=True with stream=True
      Metadata
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        No branches or pull requests
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var __m = "*";
var __re = new RegExp('^' + ".*" + '
[BOT ISSUE] OpenAI: chat completions streaming discards `logprobs` from chunks · Issue #180 · braintrustdata/braintrust-sdk-python · GitHub
        Skip to content
        [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks #180
        Closed
        Feature
        #215
        Closed
        [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks#180
        Feature
        #215
        Assignees
        AbhiPrasad
        Labels
        bot-automationintegration: openai
        Description
        @braintrust-bot
        braintrust-bot
        bot
        opened on Mar 31, 2026
        Summary
        When chat.completions.create(logprobs=True, stream=True) is used, the logprobs data present in each streaming chunk is discarded. The span output hardcodes "logprobs": None instead of accumulating the per-token log probabilities across chunks.
        Non-streaming calls correctly capture logprobs because the full choices dict is logged directly (line 204 of oai.py). Streaming calls lose this data because _postprocess_streaming_results (lines 288–356) only accumulates content, tool_calls, role, and finish_reason from deltas, and then hardcodes logprobs to None at line 353.
        What is missing
        Each ChatCompletionChunk.choices[0].logprobs contains a ChoiceLogprobs object with:
        • content: list of per-token log probabilities and top alternatives
        • refusal: list of per-token log probabilities for refusal tokens
        These are available in every streaming chunk but never read by the wrapper. The assembled span output sets:
        "logprobs": None, # line 353 — hardcoded
        Users who set logprobs=True for confidence scoring, model evaluation, or token-level analysis get correct data in non-streaming mode but silently lose it when switching to stream=True.
        Braintrust docs status
        not_found — The OpenAI integration docs document wrap_openai() and streaming token usage, but do not mention logprobs capture.
        Upstream sources
        • OpenAI Python SDK type: ChatCompletionChunk.choices[0].logprobs → ChoiceLogprobs (source)
        • OpenAI API reference: logprobs parameter in chat completions
        Local files inspected
        • py/src/braintrust/oai.py:

          • _postprocess_streaming_results (lines 288–356): accumulates content and tool_calls from deltas but ignores logprobs on each Choice; hardcodes output logprobs to None at line 353
          • Non-streaming path (line 204): logs log_response["choices"] which includes the full logprobs object — correct
        • py/src/braintrust/wrappers/test_openai.py: no test for logprobs=True with stream=True
        Metadata
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        bot-automationintegration: openai
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          No branches or pull requests
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var __re = new RegExp('^' + "youtube\\.com" + '
[BOT ISSUE] OpenAI: chat completions streaming discards `logprobs` from chunks · Issue #180 · braintrustdata/braintrust-sdk-python · GitHub
          Skip to content
          [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks #180
          Closed
          Feature
          #215
          Closed
          [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks#180
          Feature
          #215
          Assignees
          AbhiPrasad
          Labels
          bot-automationintegration: openai
          Description
          @braintrust-bot
          braintrust-bot
          bot
          opened on Mar 31, 2026
          Summary
          When chat.completions.create(logprobs=True, stream=True) is used, the logprobs data present in each streaming chunk is discarded. The span output hardcodes "logprobs": None instead of accumulating the per-token log probabilities across chunks.
          Non-streaming calls correctly capture logprobs because the full choices dict is logged directly (line 204 of oai.py). Streaming calls lose this data because _postprocess_streaming_results (lines 288–356) only accumulates content, tool_calls, role, and finish_reason from deltas, and then hardcodes logprobs to None at line 353.
          What is missing
          Each ChatCompletionChunk.choices[0].logprobs contains a ChoiceLogprobs object with:
          • content: list of per-token log probabilities and top alternatives
          • refusal: list of per-token log probabilities for refusal tokens
          These are available in every streaming chunk but never read by the wrapper. The assembled span output sets:
          "logprobs": None, # line 353 — hardcoded
          Users who set logprobs=True for confidence scoring, model evaluation, or token-level analysis get correct data in non-streaming mode but silently lose it when switching to stream=True.
          Braintrust docs status
          not_found — The OpenAI integration docs document wrap_openai() and streaming token usage, but do not mention logprobs capture.
          Upstream sources
          • OpenAI Python SDK type: ChatCompletionChunk.choices[0].logprobs → ChoiceLogprobs (source)
          • OpenAI API reference: logprobs parameter in chat completions
          Local files inspected
          • py/src/braintrust/oai.py:

            • _postprocess_streaming_results (lines 288–356): accumulates content and tool_calls from deltas but ignores logprobs on each Choice; hardcodes output logprobs to None at line 353
            • Non-streaming path (line 204): logs log_response["choices"] which includes the full logprobs object — correct
          • py/src/braintrust/wrappers/test_openai.py: no test for logprobs=True with stream=True
          Metadata
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            No branches or pull requests
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var __m = "*";
var __re = new RegExp('^' + ".*" + '
[BOT ISSUE] OpenAI: chat completions streaming discards `logprobs` from chunks · Issue #180 · braintrustdata/braintrust-sdk-python · GitHub
            Skip to content
            [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks #180
            Closed
            Feature
            #215
            Closed
            [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks#180
            Feature
            #215
            Assignees
            AbhiPrasad
            Labels
            bot-automationintegration: openai
            Description
            @braintrust-bot
            braintrust-bot
            bot
            opened on Mar 31, 2026
            Summary
            When chat.completions.create(logprobs=True, stream=True) is used, the logprobs data present in each streaming chunk is discarded. The span output hardcodes "logprobs": None instead of accumulating the per-token log probabilities across chunks.
            Non-streaming calls correctly capture logprobs because the full choices dict is logged directly (line 204 of oai.py). Streaming calls lose this data because _postprocess_streaming_results (lines 288–356) only accumulates content, tool_calls, role, and finish_reason from deltas, and then hardcodes logprobs to None at line 353.
            What is missing
            Each ChatCompletionChunk.choices[0].logprobs contains a ChoiceLogprobs object with:
            • content: list of per-token log probabilities and top alternatives
            • refusal: list of per-token log probabilities for refusal tokens
            These are available in every streaming chunk but never read by the wrapper. The assembled span output sets:
            "logprobs": None, # line 353 — hardcoded
            Users who set logprobs=True for confidence scoring, model evaluation, or token-level analysis get correct data in non-streaming mode but silently lose it when switching to stream=True.
            Braintrust docs status
            not_found — The OpenAI integration docs document wrap_openai() and streaming token usage, but do not mention logprobs capture.
            Upstream sources
            • OpenAI Python SDK type: ChatCompletionChunk.choices[0].logprobs → ChoiceLogprobs (source)
            • OpenAI API reference: logprobs parameter in chat completions
            Local files inspected
            • py/src/braintrust/oai.py:

              • _postprocess_streaming_results (lines 288–356): accumulates content and tool_calls from deltas but ignores logprobs on each Choice; hardcodes output logprobs to None at line 353
              • Non-streaming path (line 204): logs log_response["choices"] which includes the full logprobs object — correct
            • py/src/braintrust/wrappers/test_openai.py: no test for logprobs=True with stream=True
            Metadata
            Metadata
            Assignees
            Labels
            bot-automationintegration: openai
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              No milestone
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              No branches or pull requests
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var __re = new RegExp('^' + ".*" + '
[BOT ISSUE] OpenAI: chat completions streaming discards `logprobs` from chunks · Issue #180 · braintrustdata/braintrust-sdk-python · GitHub
              Skip to content
              [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks #180
              Closed
              Feature
              #215
              Closed
              [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks#180
              Feature
              #215
              Assignees
              AbhiPrasad
              Labels
              bot-automationintegration: openai
              Description
              @braintrust-bot
              braintrust-bot
              bot
              opened on Mar 31, 2026
              Summary
              When chat.completions.create(logprobs=True, stream=True) is used, the logprobs data present in each streaming chunk is discarded. The span output hardcodes "logprobs": None instead of accumulating the per-token log probabilities across chunks.
              Non-streaming calls correctly capture logprobs because the full choices dict is logged directly (line 204 of oai.py). Streaming calls lose this data because _postprocess_streaming_results (lines 288–356) only accumulates content, tool_calls, role, and finish_reason from deltas, and then hardcodes logprobs to None at line 353.
              What is missing
              Each ChatCompletionChunk.choices[0].logprobs contains a ChoiceLogprobs object with:
              • content: list of per-token log probabilities and top alternatives
              • refusal: list of per-token log probabilities for refusal tokens
              These are available in every streaming chunk but never read by the wrapper. The assembled span output sets:
              "logprobs": None, # line 353 — hardcoded
              Users who set logprobs=True for confidence scoring, model evaluation, or token-level analysis get correct data in non-streaming mode but silently lose it when switching to stream=True.
              Braintrust docs status
              not_found — The OpenAI integration docs document wrap_openai() and streaming token usage, but do not mention logprobs capture.
              Upstream sources
              • OpenAI Python SDK type: ChatCompletionChunk.choices[0].logprobs → ChoiceLogprobs (source)
              • OpenAI API reference: logprobs parameter in chat completions
              Local files inspected
              • py/src/braintrust/oai.py:

                • _postprocess_streaming_results (lines 288–356): accumulates content and tool_calls from deltas but ignores logprobs on each Choice; hardcodes output logprobs to None at line 353
                • Non-streaming path (line 204): logs log_response["choices"] which includes the full logprobs object — correct
              • py/src/braintrust/wrappers/test_openai.py: no test for logprobs=True with stream=True
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[BOT ISSUE] OpenAI: chat completions streaming discards `logprobs` from chunks · Issue #180 · braintrustdata/braintrust-sdk-python · GitHub
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                [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks #180
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                [BOT ISSUE] OpenAI: chat completions streaming discards logprobs from chunks#180
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                #215
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                AbhiPrasad
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                bot-automationintegration: openai
                Description
                @braintrust-bot
                braintrust-bot
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                opened on Mar 31, 2026
                Summary
                When chat.completions.create(logprobs=True, stream=True) is used, the logprobs data present in each streaming chunk is discarded. The span output hardcodes "logprobs": None instead of accumulating the per-token log probabilities across chunks.
                Non-streaming calls correctly capture logprobs because the full choices dict is logged directly (line 204 of oai.py). Streaming calls lose this data because _postprocess_streaming_results (lines 288–356) only accumulates content, tool_calls, role, and finish_reason from deltas, and then hardcodes logprobs to None at line 353.
                What is missing
                Each ChatCompletionChunk.choices[0].logprobs contains a ChoiceLogprobs object with:
                • content: list of per-token log probabilities and top alternatives
                • refusal: list of per-token log probabilities for refusal tokens
                These are available in every streaming chunk but never read by the wrapper. The assembled span output sets:
                "logprobs": None, # line 353 — hardcoded
                Users who set logprobs=True for confidence scoring, model evaluation, or token-level analysis get correct data in non-streaming mode but silently lose it when switching to stream=True.
                Braintrust docs status
                not_found — The OpenAI integration docs document wrap_openai() and streaming token usage, but do not mention logprobs capture.
                Upstream sources
                • OpenAI Python SDK type: ChatCompletionChunk.choices[0].logprobs → ChoiceLogprobs (source)
                • OpenAI API reference: logprobs parameter in chat completions
                Local files inspected
                • py/src/braintrust/oai.py:

                  • _postprocess_streaming_results (lines 288–356): accumulates content and tool_calls from deltas but ignores logprobs on each Choice; hardcodes output logprobs to None at line 353
                  • Non-streaming path (line 204): logs log_response["choices"] which includes the full logprobs object — correct
                • py/src/braintrust/wrappers/test_openai.py: no test for logprobs=True with stream=True
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