fix(cohere): close async streaming spans on errors

[euisuh]

Summary

Fix Cohere v2 async streaming instrumentation so spans are exported when the async stream raises.

Previously, aprocess_chat_v2_streaming_response only ended the span after successful stream consumption. If the async iterator raised while streaming, the exception propagated but the span was never ended/exported, so failed Cohere streams disappeared from telemetry.

This is separate from #4375, which covers non-streaming async Cohere error handling.

Changes

• Wrap async v2 stream iteration in try/except/finally
• Record stream exceptions and mark the span ERROR
• Always end the span
• Add regression coverage for a failing async Cohere v2 stream

Verification

• uv run pytest tests/test_streaming_error_handling.py -q
• uv run pytest tests/test_chat.py::test_cohere_v2_chat_legacy_with_streaming_async -q
• uv run ruff check .
• uv run pytest tests/ -q

Summary by CodeRabbit

• Bug Fixes
  • Improved error handling for asynchronous streaming responses.
  • Streaming failures are now recorded with error details and reflected in tracing spans before being re-raised.
  • Ensures spans are properly finalized even when unexpected errors occur.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: e9431dca-7a39-49c2-a04a-855db6bd1ba7

📥 Commits

Reviewing files that changed from the base of the PR and between 93429cf and de8d1e8.

📒 Files selected for processing (2)

• packages/opentelemetry-instrumentation-cohere/opentelemetry/instrumentation/cohere/streaming.py
• packages/opentelemetry-instrumentation-cohere/tests/test_streaming_error_handling.py

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📝 Walkthrough

Walkthrough

The async Cohere Chat v2 streaming processor now records unexpected streaming exceptions on the active span, marks it as errored, re-raises the exception, and preserves span finalization. A new test validates status, description, and exception event attributes.

Changes

Cohere streaming error handling

Layer / File(s)	Summary
Async streaming exception handling packages/opentelemetry-instrumentation-cohere/opentelemetry/instrumentation/cohere/streaming.py, packages/opentelemetry-instrumentation-cohere/tests/test_streaming_error_handling.py	aprocess_chat_v2_streaming_response marks unexpected exceptions as ERROR, records them on recording spans, re-raises them, and is covered by an async failing-stream test.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: handling errors so async Cohere streaming spans close correctly.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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