fix(openai): Handles Bedrock-style context overflow errors for OpenAI-compatible endpoints (strands-agents#1529)

Author: dinindunz

src/strands/models/openai.py

@@ -27,6 +27,15 @@
 
 T = TypeVar("T", bound=BaseModel)
 
+# Alternative context overflow error messages
+# These are commonly returned by OpenAI-compatible endpoints wrapping other providers
+# (e.g., Databricks serving Bedrock models)
+_CONTEXT_OVERFLOW_MESSAGES = [
+    "Input is too long for requested model",
+    "input length and `max_tokens` exceed context limit",
+    "too many total text bytes",
+]
+
 
 class Client(Protocol):
     """Protocol defining the OpenAI-compatible interface for the underlying provider client."""
@@ -600,6 +609,14 @@ async def stream(
                 # Rate limits (including TPM) require waiting/retrying, not context reduction
                 logger.warning("OpenAI threw rate limit error")
                 raise ModelThrottledException(str(e)) from e
+            except openai.APIError as e:
+                # Check for alternative context overflow error messages
+                error_message = str(e)
+                if any(overflow_msg in error_message for overflow_msg in _CONTEXT_OVERFLOW_MESSAGES):
+                    logger.warning("context window overflow error detected")
+                    raise ContextWindowOverflowException(error_message) from e
+                # Re-raise other APIError exceptions
+                raise
 
             logger.debug("got response from model")
             yield self.format_chunk({"chunk_type": "message_start"})
@@ -723,6 +740,14 @@ async def structured_output(
                 # Rate limits (including TPM) require waiting/retrying, not context reduction
                 logger.warning("OpenAI threw rate limit error")
                 raise ModelThrottledException(str(e)) from e
+            except openai.APIError as e:
+                # Check for alternative context overflow error messages
+                error_message = str(e)
+                if any(overflow_msg in error_message for overflow_msg in _CONTEXT_OVERFLOW_MESSAGES):
+                    logger.warning("context window overflow error detected")
+                    raise ContextWindowOverflowException(error_message) from e
+                # Re-raise other APIError exceptions
+                raise
 
         parsed: T | None = None
         # Find the first choice with tool_calls

tests/strands/models/test_openai.py

@@ -1035,6 +1035,92 @@ async def test_stream_context_overflow_exception(openai_client, model, messages)
     assert exc_info.value.__cause__ == mock_error
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "error_message",
+    [
+        "Input is too long for requested model",
+        "input length and `max_tokens` exceed context limit",
+        "too many total text bytes",
+    ],
+)
+async def test_stream_alternative_context_overflow_messages(openai_client, model, messages, error_message):
+    """Test that alternative context overflow messages in APIError are properly converted."""
+    # Create a mock OpenAI APIError with alternative context overflow message
+    mock_error = openai.APIError(
+        message=error_message,
+        request=unittest.mock.MagicMock(),
+        body={"error": {"message": error_message}},
+    )
+
+    # Configure the mock client to raise the APIError
+    openai_client.chat.completions.create.side_effect = mock_error
+
+    # Test that the stream method converts the error properly
+    with pytest.raises(ContextWindowOverflowException) as exc_info:
+        async for _ in model.stream(messages):
+            pass
+
+    # Verify the exception message contains the original error
+    assert error_message in str(exc_info.value)
+    assert exc_info.value.__cause__ == mock_error
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "error_message",
+    [
+        "Input is too long for requested model",
+        "input length and `max_tokens` exceed context limit",
+        "too many total text bytes",
+    ],
+)
+async def test_structured_output_alternative_context_overflow_messages(
+    openai_client, model, messages, test_output_model_cls, error_message
+):
+    """Test that alternative context overflow messages in APIError are properly converted in structured output."""
+    # Create a mock OpenAI APIError with alternative context overflow message
+    mock_error = openai.APIError(
+        message=error_message,
+        request=unittest.mock.MagicMock(),
+        body={"error": {"message": error_message}},
+    )
+
+    # Configure the mock client to raise the APIError
+    openai_client.beta.chat.completions.parse.side_effect = mock_error
+
+    # Test that the structured_output method converts the error properly
+    with pytest.raises(ContextWindowOverflowException) as exc_info:
+        async for _ in model.structured_output(test_output_model_cls, messages):
+            pass
+
+    # Verify the exception message contains the original error
+    assert error_message in str(exc_info.value)
+    assert exc_info.value.__cause__ == mock_error
+
+
+@pytest.mark.asyncio
+async def test_stream_api_error_passthrough(openai_client, model, messages):
+    """Test that APIError without overflow messages passes through unchanged."""
+    # Create a mock OpenAI APIError without overflow message
+    mock_error = openai.APIError(
+        message="Some other API error",
+        request=unittest.mock.MagicMock(),
+        body={"error": {"message": "Some other API error"}},
+    )
+
+    # Configure the mock client to raise the APIError
+    openai_client.chat.completions.create.side_effect = mock_error
+
+    # Test that APIError without overflow messages passes through
+    with pytest.raises(openai.APIError) as exc_info:
+        async for _ in model.stream(messages):
+            pass
+
+    # Verify the original exception is raised, not ContextWindowOverflowException
+    assert exc_info.value == mock_error
+
+
 @pytest.mark.asyncio
 async def test_stream_other_bad_request_errors_passthrough(openai_client, model, messages):
     """Test that other BadRequestError exceptions are not converted to ContextWindowOverflowException."""