fix(bedrock): don't send stopSequences to OpenAI GPT-6/GPT-5.6/gpt-oss (#7731)

OpenAI models on Bedrock reject inferenceConfig.stopSequences with a 400,
and crewAI adds the "\nObservation:" stop word to every agent call, so
Agent.kickoff() and Crew.kickoff() failed on GPT-6 Sol/Luna, GPT-5.6 and
gpt-oss.

supports_stop_words() now returns False for "openai." model ids and
_get_inference_config() only sends stopSequences when it returns True,
mirroring the Azure provider. Stop words are still applied client-side
by _apply_stop_words, and executors fall back to use_stop_words=False.

Co-authored-by: Claude <[email protected]>

lib/crewai/src/crewai/llms/providers/bedrock/completion.py

@@ -2056,7 +2056,7 @@ class BedrockCompletion(BaseLLM):
             config["temperature"] = float(self.temperature)
         if self.top_p is not None:
             config["topP"] = float(self.top_p)
-        if self.stop_sequences:
+        if self.stop_sequences and self.supports_stop_words():
             config["stopSequences"] = self.stop_sequences
 
         if self.is_claude_model and self.top_k is not None:
@@ -2130,8 +2130,13 @@ class BedrockCompletion(BaseLLM):
         return self.supports_tools
 
     def supports_stop_words(self) -> bool:
-        """Check if the model supports stop words."""
-        return True
+        """Check if the model supports stop words.
+
+        OpenAI models on Bedrock (gpt-oss, GPT-5.x, GPT-6) reject
+        ``stopSequences``. Stop words are still applied to their output
+        client-side by ``_apply_stop_words``.
+        """
+        return "openai." not in self.model.lower()
 
     def get_context_window_size(self) -> int:
         """Get the context window size for the model."""

lib/crewai/tests/llms/bedrock/test_bedrock.py

@@ -945,6 +945,43 @@ def test_bedrock_stop_sequences_sent_to_api():
         assert call_kwargs["inferenceConfig"]["stopSequences"] == ["\nObservation:", "\nThought:"]
 
 
+@pytest.mark.parametrize(
+    "model",
+    [
+        "bedrock/us.openai.gpt-6-sol",
+        "bedrock/global.openai.gpt-6-luna",
+        "bedrock/openai.gpt-oss-120b-1:0",
+    ],
+)
+def test_bedrock_openai_models_do_not_send_stop_sequences(model):
+    """Test that OpenAI models on Bedrock get stop words client-side, not as stopSequences."""
+    llm = LLM(model=model)
+    llm.stop = ["\nObservation:"]
+
+    with patch.object(llm._client, 'converse') as mock_converse:
+        mock_converse.return_value = {
+            'output': {
+                'message': {
+                    'role': 'assistant',
+                    'content': [{'text': 'Thought: done\nObservation: extra'}]
+                }
+            },
+            'usage': {
+                'inputTokens': 10,
+                'outputTokens': 5,
+                'totalTokens': 15
+            }
+        }
+
+        result = llm.call("Say hello in one word")
+
+        assert "stopSequences" not in mock_converse.call_args[1]["inferenceConfig"]
+        assert result == "Thought: done"
+
+    # Agent executors read this to fall back to client-side stop handling.
+    assert llm.supports_stop_words() is False
+
+
 # Agent Kickoff Structured Output Tests