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Chat Completions streaming can emit function calls with an empty call_id #4560

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Chat Completions streaming can emit function calls with an empty call_id #4560

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22 changes: 17 additions & 5 deletions src/agents/models/chatcmpl_stream_handler.py
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Original file line number Diff line number Diff line change
Expand Up @@ -339,19 +339,30 @@ def _accumulate_tool_call_delta(
)

@staticmethod
def _buffered_tool_call_delta(
buffered_call: _BufferedToolCall,
) -> ChoiceDeltaToolCall:
if not buffered_call.call_id:
def _validate_completed_tool_call(call_id: str | None, name: str | None) -> None:
"""Reject a finalized tool call with a missing id or name.

Shared by the buffered path (`_buffered_tool_call_delta()`) and the unbuffered
fallback path in `handle_stream()`, so both fail with the same diagnostics instead
of the unbuffered path silently emitting a `call_id=""` function call.
"""
if not call_id:
raise ModelBehaviorError(
"Buffered Chat Completions tool call stream ended without a tool call id."
)

if not buffered_call.name:
if not name:
raise ModelBehaviorError(
"Buffered Chat Completions tool call stream ended without a function name."
)

@classmethod
def _buffered_tool_call_delta(
cls,
buffered_call: _BufferedToolCall,
) -> ChoiceDeltaToolCall:
cls._validate_completed_tool_call(buffered_call.call_id, buffered_call.name)

tool_call_delta = ChoiceDeltaToolCall(
index=buffered_call.index,
id=buffered_call.call_id,
Expand Down Expand Up @@ -1259,6 +1270,7 @@ async def handle_stream(
else:
# Function call was not streamed (fallback to old behavior)
# This handles edge cases where function name never arrived
cls._validate_completed_tool_call(function_call.call_id, function_call.name)

@chatgpt-codex-connector chatgpt-codex-connector Bot Aug 21, 2026

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P2 Badge Preserve usage before rejecting the malformed call

When an unbuffered stream reports CompletionUsage and then ends with a missing call ID or function name, this new validation raises while the usage remains only in handle_stream()'s local variable. OpenAIChatCompletionsModel.stream_response() catches ModelBehaviorError and populates its generation span from the base response (openai_chatcompletions.py lines 508-512), which has not received that usage, so the failed request and its tokens disappear from tracing. Copy the built usage and raw-usage snapshot to response—or mark the request completed when usage is absent—before raising.

AGENTS.md reference: AGENTS.md:L167-L167

Useful? React with 👍 / 👎.

output_index = output_layout.function_call_output_index(state, index)
fallback_func_call_item = cls._function_call_item(
state,
Expand Down
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