Ignore empty text deltas when streaming gpt-oss on Bedrock (#3215)

Author: DouweM

pydantic_ai_slim/pydantic_ai/models/bedrock.py

@@ -701,8 +701,8 @@ async def _get_event_iterator(self) -> AsyncIterator[ModelResponseStreamEvent]:
                                 signature=signature,
                                 provider_name=self.provider_name if signature else None,
                             )
-                    if 'text' in delta:
-                        maybe_event = self._parts_manager.handle_text_delta(vendor_part_id=index, content=delta['text'])
+                    if text := delta.get('text'):
+                        maybe_event = self._parts_manager.handle_text_delta(vendor_part_id=index, content=text)
                         if maybe_event is not None:  # pragma: no branch
                             yield maybe_event
                     if 'toolUse' in delta:

tests/models/cassettes/test_bedrock/test_bedrock_model_stream_empty_text_delta.yaml

@@ -0,0 +1,66 @@
+interactions:
+- request:
+    body: '{"messages": [{"role": "user", "content": [{"text": "Hi"}]}], "system": [], "inferenceConfig": {}}'
+    headers:
+      amz-sdk-invocation-id:
+      - !!binary |
+        Zjg3NDYxYzEtZDQzZS00YThkLTkwNDMtNDcwOTNjMWZlMGM2
+      amz-sdk-request:
+      - !!binary |
+        YXR0ZW1wdD0x
+      content-length:
+      - '98'
+      content-type:
+      - !!binary |
+        YXBwbGljYXRpb24vanNvbg==
+    method: POST
+    uri: https://bedrock-runtime.us-east-1.amazonaws.com/model/openai.gpt-oss-120b-1%3A0/converse-stream
+  response:
+    body:
+      string: !!binary |
+        AAAAsgAAAFKKQLTFCzpldmVudC10eXBlBwAMbWVzc2FnZVN0YXJ0DTpjb250ZW50LXR5cGUHABBh
+        cHBsaWNhdGlvbi9qc29uDTptZXNzYWdlLXR5cGUHAAVldmVudHsicCI6ImFiY2RlZmdoaWprbG1u
+        b3BxcnN0dXZ3eHl6QUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVowIiwicm9sZSI6ImFzc2lzdGFu
+        dCJ9QP+CaAAAAKIAAABXmsrXyAs6ZXZlbnQtdHlwZQcAEWNvbnRlbnRCbG9ja0RlbHRhDTpjb250
+        ZW50LXR5cGUHABBhcHBsaWNhdGlvbi9qc29uDTptZXNzYWdlLXR5cGUHAAVldmVudHsiY29udGVu
+        dEJsb2NrSW5kZXgiOjAsImRlbHRhIjp7InRleHQiOiIifSwicCI6ImFiY2RlZmdoaSJ9NTLrNAAA
+        ALkAAABW+v1BzQs6ZXZlbnQtdHlwZQcAEGNvbnRlbnRCbG9ja1N0b3ANOmNvbnRlbnQtdHlwZQcA
+        EGFwcGxpY2F0aW9uL2pzb24NOm1lc3NhZ2UtdHlwZQcABWV2ZW50eyJjb250ZW50QmxvY2tJbmRl
+        eCI6MCwicCI6ImFiY2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6QUJDREVGR0hJSktMTU5PUFFSU1RV
+        VldYWVowIn2IAETUAAABWQAAAFducmUhCzpldmVudC10eXBlBwARY29udGVudEJsb2NrRGVsdGEN
+        OmNvbnRlbnQtdHlwZQcAEGFwcGxpY2F0aW9uL2pzb24NOm1lc3NhZ2UtdHlwZQcABWV2ZW50eyJj
+        b250ZW50QmxvY2tJbmRleCI6MSwiZGVsdGEiOnsicmVhc29uaW5nQ29udGVudCI6eyJ0ZXh0Ijoi
+        VGhlIHVzZXIganVzdCBzYXlzIFwiSGlcIi4gV2UgbmVlZCB0byByZXNwb25kIGFwcHJvcHJpYXRl
+        bHksIGZyaWVuZGx5IGdyZWV0aW5nLiBObyBzcGVjaWFsIGluc3RydWN0aW9ucy4gU2hvdWxkIGJl
+        IHNob3J0LiJ9fSwicCI6ImFiY2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6QUJDREVGR0hJSktMTU5P
+        UFFSU1RVVldYIn2DKrHfAAAAsQAAAFbKjQoMCzpldmVudC10eXBlBwAQY29udGVudEJsb2NrU3Rv
+        cA06Y29udGVudC10eXBlBwAQYXBwbGljYXRpb24vanNvbg06bWVzc2FnZS10eXBlBwAFZXZlbnR7
+        ImNvbnRlbnRCbG9ja0luZGV4IjoxLCJwIjoiYWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXpBQkNE
+        RUZHSElKS0xNTk9QUVJTIn1Cad1JAAAA5AAAAFdNeXohCzpldmVudC10eXBlBwARY29udGVudEJs
+        b2NrRGVsdGENOmNvbnRlbnQtdHlwZQcAEGFwcGxpY2F0aW9uL2pzb24NOm1lc3NhZ2UtdHlwZQcA
+        BWV2ZW50eyJjb250ZW50QmxvY2tJbmRleCI6MiwiZGVsdGEiOnsidGV4dCI6IkhlbGxvISBIb3cg
+        Y2FuIEkgaGVscCJ9LCJwIjoiYWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXpBQkNERUZHSElKS0xN
+        Tk9QUVJTVFVWV1hZWjAxIn2L4Y7bAAAAuwAAAFf3OiI7CzpldmVudC10eXBlBwARY29udGVudEJs
+        b2NrRGVsdGENOmNvbnRlbnQtdHlwZQcAEGFwcGxpY2F0aW9uL2pzb24NOm1lc3NhZ2UtdHlwZQcA
+        BWV2ZW50eyJjb250ZW50QmxvY2tJbmRleCI6MiwiZGVsdGEiOnsidGV4dCI6IiB5b3UgdG9kYXk/
+        In0sInAiOiJhYmNkZWZnaGlqa2xtbm9wcXJzdHV2dyJ9dKsF8AAAAI4AAABW6fwlWws6ZXZlbnQt
+        dHlwZQcAEGNvbnRlbnRCbG9ja1N0b3ANOmNvbnRlbnQtdHlwZQcAEGFwcGxpY2F0aW9uL2pzb24N
+        Om1lc3NhZ2UtdHlwZQcABWV2ZW50eyJjb250ZW50QmxvY2tJbmRleCI6MiwicCI6ImFiY2RlZmdo
+        aWoifbla37UAAACDAAAAUY8IdEkLOmV2ZW50LXR5cGUHAAttZXNzYWdlU3RvcA06Y29udGVudC10
+        eXBlBwAQYXBwbGljYXRpb24vanNvbg06bWVzc2FnZS10eXBlBwAFZXZlbnR7InAiOiJhYiIsInN0
+        b3BSZWFzb24iOiJlbmRfdHVybiJ9kFbppAAAAOQAAABOKRLS4Qs6ZXZlbnQtdHlwZQcACG1ldGFk
+        YXRhDTpjb250ZW50LXR5cGUHABBhcHBsaWNhdGlvbi9qc29uDTptZXNzYWdlLXR5cGUHAAVldmVu
+        dHsibWV0cmljcyI6eyJsYXRlbmN5TXMiOjc1M30sInAiOiJhYmNkZWZnaGlqa2xtbiIsInVzYWdl
+        Ijp7ImlucHV0VG9rZW5zIjo3MCwib3V0cHV0VG9rZW5zIjo0Mywic2VydmVyVG9vbFVzYWdlIjp7
+        fSwidG90YWxUb2tlbnMiOjExM319saJH4A==
+    headers:
+      connection:
+      - keep-alive
+      content-type:
+      - application/vnd.amazon.eventstream
+      transfer-encoding:
+      - chunked
+    status:
+      code: 200
+      message: OK
+version: 1

tests/models/test_bedrock.py

@@ -32,7 +32,9 @@
 )
 from pydantic_ai.agent import Agent
 from pydantic_ai.exceptions import ModelRetry
+from pydantic_ai.messages import AgentStreamEvent
 from pydantic_ai.models import ModelRequestParameters
+from pydantic_ai.run import AgentRunResult, AgentRunResultEvent
 from pydantic_ai.tools import ToolDefinition
 from pydantic_ai.usage import RequestUsage, RunUsage
 
@@ -1272,3 +1274,33 @@ async def test_bedrock_no_tool_choice(bedrock_provider: BedrockProvider):
             ]
         }
     )
+
+
+async def test_bedrock_model_stream_empty_text_delta(allow_model_requests: None, bedrock_provider: BedrockProvider):
+    model = BedrockConverseModel(model_name='openai.gpt-oss-120b-1:0', provider=bedrock_provider)
+    agent = Agent(model)
+
+    result: AgentRunResult | None = None
+    events: list[AgentStreamEvent] = []
+    async for event in agent.run_stream_events('Hi'):
+        if isinstance(event, AgentRunResultEvent):
+            result = event.result
+        else:
+            events.append(event)
+
+    assert result is not None
+    # The response stream contains `{'contentBlockDelta': {'delta': {'text': ''}, 'contentBlockIndex': 0}}`, but our response should not have any empty text parts.
+    assert not any(part.content == '' for part in result.response.parts if isinstance(part, TextPart))
+    assert events == snapshot(
+        [
+            PartStartEvent(
+                index=0,
+                part=ThinkingPart(
+                    content='The user just says "Hi". We need to respond appropriately, friendly greeting. No special instructions. Should be short.'
+                ),
+            ),
+            PartStartEvent(index=1, part=TextPart(content='Hello! How can I help')),
+            FinalResultEvent(tool_name=None, tool_call_id=None),
+            PartDeltaEvent(index=1, delta=TextPartDelta(content_delta=' you today?')),
+        ]
+    )