fix(vertexai): record the accumulated text for async streaming responses

packages/opentelemetry-instrumentation-vertexai/opentelemetry/instrumentation/vertexai/__init__.py

@@ -175,7 +175,9 @@ async def _abuild_from_streaming_response(span, event_logger, response, llm_mode
 
         yield item_to_yield
 
-    handle_streaming_response(span, event_logger, llm_model, response, token_usage)
+    handle_streaming_response(
+        span, event_logger, llm_model, complete_response, token_usage
+    )
 
     span.set_status(Status(StatusCode.OK))
     span.end()

packages/opentelemetry-instrumentation-vertexai/tests/test_streaming_attributes.py

@@ -0,0 +1,56 @@
+import asyncio
+
+from opentelemetry.instrumentation.vertexai import _abuild_from_streaming_response
+from opentelemetry.instrumentation.vertexai.config import Config
+from opentelemetry.semconv._incubating.attributes import (
+    gen_ai_attributes as GenAIAttributes,
+)
+
+
+class _Chunk:
+    def __init__(self, text):
+        self.text = text
+        self.usage_metadata = None
+
+
+async def _stream(chunks):
+    for chunk in chunks:
+        yield chunk
+
+
+def _consume_async_stream(span, chunks):
+    async def consume():
+        async for _ in _abuild_from_streaming_response(
+            span, None, _stream(chunks), "gemini-2.5-flash"
+        ):
+            pass
+
+    asyncio.run(consume())
+
+
+def test_async_streaming_records_completion_text(tracer_provider, span_exporter, monkeypatch):
+    monkeypatch.setattr(Config, "use_legacy_attributes", True)
+    tracer = tracer_provider.get_tracer(__name__)
+    chunks = [_Chunk("Hello"), _Chunk(" world"), _Chunk("!")]
+
+    with tracer.start_as_current_span("generate_content") as span:
+        _consume_async_stream(span, chunks)
+
+    (finished,) = span_exporter.get_finished_spans()
+    content = finished.attributes[f"{GenAIAttributes.GEN_AI_COMPLETION}.0.content"]
+
+    assert content == "Hello world!"
+    assert "<async_generator" not in content
+
+
+def test_async_streaming_records_completion_role(tracer_provider, span_exporter, monkeypatch):
+    monkeypatch.setattr(Config, "use_legacy_attributes", True)
+    tracer = tracer_provider.get_tracer(__name__)
+
+    with tracer.start_as_current_span("generate_content") as span:
+        _consume_async_stream(span, [_Chunk("ok")])
+
+    (finished,) = span_exporter.get_finished_spans()
+    role_key = f"{GenAIAttributes.GEN_AI_COMPLETION}.0.role"
+
+    assert finished.attributes[role_key] == "assistant"