fix(fireworks): raise ContextOverflowError on prompt-too-long (#37458)

Co-authored-by: open-swe[bot] <open-swe@users.noreply.github.com>
Co-authored-by: ccurme <26529506+ccurme@users.noreply.github.com>

libs/partners/fireworks/langchain_fireworks/chat_models.py

@@ -21,6 +21,7 @@ from fireworks.client.error import (  # type: ignore[import-untyped]
     BadGatewayError,
     FireworksError,
     InternalServerError,
+    InvalidRequestError,
     RateLimitError,
     ServiceUnavailableError,
 )
@@ -28,6 +29,7 @@ from langchain_core.callbacks import (
     AsyncCallbackManagerForLLMRun,
     CallbackManagerForLLMRun,
 )
+from langchain_core.exceptions import ContextOverflowError
 from langchain_core.language_models import (
     LanguageModelInput,
     ModelProfile,
@@ -436,6 +438,17 @@ def _promote_http_status_error(exc: httpx.HTTPStatusError) -> NoReturn:
     raise exc
 
 
+class FireworksContextOverflowError(InvalidRequestError, ContextOverflowError):
+    """`InvalidRequestError` raised when input exceeds Fireworks's context limit."""
+
+
+def _handle_fireworks_invalid_request(e: InvalidRequestError) -> NoReturn:
+    """Promote prompt-too-long errors to `FireworksContextOverflowError`."""
+    if "prompt is too long" in str(e):
+        raise FireworksContextOverflowError(str(e)) from e
+    raise e
+
+
 def _raise_empty_stream() -> NoReturn:
     """Raise a descriptive error when the SDK returns a zero-chunk stream."""
     msg = "Received empty stream from Fireworks"
@@ -791,9 +804,13 @@ class ChatFireworks(BaseChatModel):
             params["stream_options"] = {"include_usage": True}
 
         default_chunk_class: type[BaseMessageChunk] = AIMessageChunk
-        for chunk in _completion_with_retry(
+        try:
+            stream = _completion_with_retry(
                 self, run_manager=run_manager, messages=message_dicts, **params
-        ):
+            )
+        except InvalidRequestError as e:
+            _handle_fireworks_invalid_request(e)
+        for chunk in stream:
             if not isinstance(chunk, dict):
                 chunk = chunk.model_dump()
             message_chunk = _convert_chunk_to_message_chunk(chunk, default_chunk_class)
@@ -837,9 +854,12 @@ class ChatFireworks(BaseChatModel):
             **({"stream": stream} if stream is not None else {}),
             **kwargs,
         }
+        try:
             response = _completion_with_retry(
                 self, run_manager=run_manager, messages=message_dicts, **params
             )
+        except InvalidRequestError as e:
+            _handle_fireworks_invalid_request(e)
         return self._create_chat_result(response)
 
     def _create_message_dicts(
@@ -899,9 +919,13 @@ class ChatFireworks(BaseChatModel):
             params["stream_options"] = {"include_usage": True}
 
         default_chunk_class: type[BaseMessageChunk] = AIMessageChunk
-        async for chunk in await _acompletion_with_retry(
+        try:
+            stream = await _acompletion_with_retry(
                 self, run_manager=run_manager, messages=message_dicts, **params
-        ):
+            )
+        except InvalidRequestError as e:
+            _handle_fireworks_invalid_request(e)
+        async for chunk in stream:
             if not isinstance(chunk, dict):
                 chunk = chunk.model_dump()
             message_chunk = _convert_chunk_to_message_chunk(chunk, default_chunk_class)
@@ -948,9 +972,12 @@ class ChatFireworks(BaseChatModel):
             **({"stream": stream} if stream is not None else {}),
             **kwargs,
         }
+        try:
             response = await _acompletion_with_retry(
                 self, run_manager=run_manager, messages=message_dicts, **params
             )
+        except InvalidRequestError as e:
+            _handle_fireworks_invalid_request(e)
         return self._create_chat_result(response)
 
     @property

libs/partners/fireworks/tests/unit_tests/test_chat_models.py

@@ -14,6 +14,7 @@ from fireworks.client.error import (  # type: ignore[import-untyped]
     RateLimitError,
     ServiceUnavailableError,
 )
+from langchain_core.exceptions import ContextOverflowError
 from langchain_core.messages import (
     AIMessage,
     AIMessageChunk,
@@ -25,6 +26,7 @@ from langchain_core.messages import (
 
 from langchain_fireworks import ChatFireworks
 from langchain_fireworks.chat_models import (
+    FireworksContextOverflowError,
     _acompletion_with_retry,
     _completion_with_retry,
     _convert_chunk_to_message_chunk,
@@ -1140,3 +1142,106 @@ class TestServiceTier:
         result = model.invoke("Hello")
         assert isinstance(result, AIMessage)
         assert "service_tier" not in result.response_metadata
+
+
+_CONTEXT_OVERFLOW_MESSAGE = (
+    '{"error": {"object": "error", "type": "invalid_request_error", '
+    '"code": "invalid_request_error", "message": "The prompt is too long: '
+    '500208, model maximum context length: 262143"}}'
+)
+
+
+def test_context_overflow_error_invoke_sync() -> None:
+    """Prompt-too-long errors surface as `ContextOverflowError` on invoke."""
+    llm = _make_llm(max_retries=0)
+    mock_client = MagicMock()
+    mock_client.create.side_effect = InvalidRequestError(_CONTEXT_OVERFLOW_MESSAGE)
+    llm.client = mock_client
+
+    with pytest.raises(ContextOverflowError) as exc_info:
+        llm.invoke([HumanMessage(content="test")])
+
+    assert "prompt is too long" in str(exc_info.value)
+    assert isinstance(exc_info.value, FireworksContextOverflowError)
+
+
+async def test_context_overflow_error_invoke_async() -> None:
+    """Prompt-too-long errors surface as `ContextOverflowError` on ainvoke."""
+    llm = _make_llm(max_retries=0)
+    mock_async = MagicMock()
+
+    async def _acreate(**_kwargs: Any) -> dict[str, Any]:
+        raise InvalidRequestError(_CONTEXT_OVERFLOW_MESSAGE)
+
+    mock_async.acreate = _acreate
+    llm.async_client = mock_async
+
+    with pytest.raises(ContextOverflowError) as exc_info:
+        await llm.ainvoke([HumanMessage(content="test")])
+
+    assert "prompt is too long" in str(exc_info.value)
+    assert isinstance(exc_info.value, FireworksContextOverflowError)
+
+
+def test_context_overflow_error_stream_sync() -> None:
+    """Prompt-too-long errors surface as `ContextOverflowError` on stream."""
+    llm = _make_llm(max_retries=0)
+    mock_client = MagicMock()
+    mock_client.create.side_effect = InvalidRequestError(_CONTEXT_OVERFLOW_MESSAGE)
+    llm.client = mock_client
+
+    with pytest.raises(ContextOverflowError) as exc_info:
+        list(llm.stream([HumanMessage(content="test")]))
+
+    assert "prompt is too long" in str(exc_info.value)
+    assert isinstance(exc_info.value, FireworksContextOverflowError)
+
+
+async def test_context_overflow_error_stream_async() -> None:
+    """Prompt-too-long errors surface as `ContextOverflowError` on astream."""
+    llm = _make_llm(max_retries=0)
+    mock_async = MagicMock()
+
+    def _acreate(**_kwargs: Any) -> Any:
+        async def _failing_agen() -> Any:
+            raise InvalidRequestError(_CONTEXT_OVERFLOW_MESSAGE)
+            yield  # pragma: no cover
+
+        return _failing_agen()
+
+    mock_async.acreate = _acreate
+    llm.async_client = mock_async
+
+    with pytest.raises(ContextOverflowError) as exc_info:
+        async for _ in llm.astream([HumanMessage(content="test")]):
+            pass
+
+    assert "prompt is too long" in str(exc_info.value)
+    assert isinstance(exc_info.value, FireworksContextOverflowError)
+
+
+def test_context_overflow_error_backwards_compatibility() -> None:
+    """`ContextOverflowError` is also catchable as `InvalidRequestError`."""
+    llm = _make_llm(max_retries=0)
+    mock_client = MagicMock()
+    mock_client.create.side_effect = InvalidRequestError(_CONTEXT_OVERFLOW_MESSAGE)
+    llm.client = mock_client
+
+    with pytest.raises(InvalidRequestError) as exc_info:
+        llm.invoke([HumanMessage(content="test")])
+
+    assert isinstance(exc_info.value, InvalidRequestError)
+    assert isinstance(exc_info.value, ContextOverflowError)
+
+
+def test_unrelated_invalid_request_error_not_promoted() -> None:
+    """Unrelated `InvalidRequestError`s should not be wrapped."""
+    llm = _make_llm(max_retries=0)
+    mock_client = MagicMock()
+    mock_client.create.side_effect = InvalidRequestError("some other bad request")
+    llm.client = mock_client
+
+    with pytest.raises(InvalidRequestError) as exc_info:
+        llm.invoke([HumanMessage(content="test")])
+
+    assert not isinstance(exc_info.value, ContextOverflowError)