fix: retry on RemoteProtocolError when retry_connection_errors is enabled

When a server crashes mid-request (e.g. SIGSEGV in core-product-api),
httpx raises RemoteProtocolError ("Server disconnected without sending
a response"). This error was falling through to the catch-all Exception
handler and being wrapped as PermanentError, bypassing retry even when
retry_connection_errors=True.

This adds RemoteProtocolError to the list of retriable exceptions
alongside ConnectError and TimeoutException, in both sync and async
retry paths.

Discovered during INC-10207 (40factory) where core-product-api pod
crashes caused cascading 504s in the partitioner plugin with no retry.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: fxdgear

_test_unstructured_client/unit/test_retries.py

@@ -0,0 +1,129 @@
+"""Tests for retry logic, specifically covering RemoteProtocolError retry behavior."""
+
+import asyncio
+from unittest.mock import MagicMock
+
+import httpx
+import pytest
+
+from unstructured_client.utils.retries import (
+    BackoffStrategy,
+    PermanentError,
+    Retries,
+    RetryConfig,
+    retry,
+    retry_async,
+)
+
+
+def _make_retries(retry_connection_errors: bool) -> Retries:
+    return Retries(
+        config=RetryConfig(
+            strategy="backoff",
+            backoff=BackoffStrategy(
+                initial_interval=100,
+                max_interval=200,
+                exponent=1.5,
+                max_elapsed_time=5000,
+            ),
+            retry_connection_errors=retry_connection_errors,
+        ),
+        status_codes=[],
+    )
+
+
+class TestRemoteProtocolErrorRetry:
+    """Test that RemoteProtocolError (e.g. 'Server disconnected without sending a response')
+    is retried when retry_connection_errors=True."""
+
+    def test_remote_protocol_error_retried_when_enabled(self):
+        """RemoteProtocolError should be retried and succeed on subsequent attempt."""
+        retries_config = _make_retries(retry_connection_errors=True)
+
+        mock_response = MagicMock(spec=httpx.Response)
+        mock_response.status_code = 200
+
+        call_count = 0
+
+        def func():
+            nonlocal call_count
+            call_count += 1
+            if call_count == 1:
+                raise httpx.RemoteProtocolError(
+                    "Server disconnected without sending a response."
+                )
+            return mock_response
+
+        result = retry(func, retries_config)
+        assert result.status_code == 200
+        assert call_count == 2
+
+    def test_remote_protocol_error_not_retried_when_disabled(self):
+        """RemoteProtocolError should raise PermanentError when retry_connection_errors=False."""
+        retries_config = _make_retries(retry_connection_errors=False)
+
+        def func():
+            raise httpx.RemoteProtocolError(
+                "Server disconnected without sending a response."
+            )
+
+        with pytest.raises(httpx.RemoteProtocolError):
+            retry(func, retries_config)
+
+    def test_connect_error_still_retried(self):
+        """Existing ConnectError retry behavior should be preserved."""
+        retries_config = _make_retries(retry_connection_errors=True)
+
+        mock_response = MagicMock(spec=httpx.Response)
+        mock_response.status_code = 200
+
+        call_count = 0
+
+        def func():
+            nonlocal call_count
+            call_count += 1
+            if call_count == 1:
+                raise httpx.ConnectError("Connection refused")
+            return mock_response
+
+        result = retry(func, retries_config)
+        assert result.status_code == 200
+        assert call_count == 2
+
+
+class TestRemoteProtocolErrorRetryAsync:
+    """Async versions of the RemoteProtocolError retry tests."""
+
+    def test_remote_protocol_error_retried_async(self):
+        """Async: RemoteProtocolError should be retried when retry_connection_errors=True."""
+        retries_config = _make_retries(retry_connection_errors=True)
+
+        mock_response = MagicMock(spec=httpx.Response)
+        mock_response.status_code = 200
+
+        call_count = 0
+
+        async def func():
+            nonlocal call_count
+            call_count += 1
+            if call_count == 1:
+                raise httpx.RemoteProtocolError(
+                    "Server disconnected without sending a response."
+                )
+            return mock_response
+
+        result = asyncio.run(retry_async(func, retries_config))
+        assert result.status_code == 200
+        assert call_count == 2
+
+    def test_remote_protocol_error_not_retried_async_when_disabled(self):
+        """Async: RemoteProtocolError should not be retried when retry_connection_errors=False."""
+        retries_config = _make_retries(retry_connection_errors=False)
+
+        async def func():
+            raise httpx.RemoteProtocolError(
+                "Server disconnected without sending a response."
+            )
+
+        with pytest.raises(httpx.RemoteProtocolError):
+            asyncio.run(retry_async(func, retries_config))

src/unstructured_client/utils/retries.py

@@ -88,6 +88,11 @@ def do_request() -> httpx.Response:
                 if retries.config.retry_connection_errors:
                     raise
 
+                raise PermanentError(exception) from exception
+            except httpx.RemoteProtocolError as exception:
+                if retries.config.retry_connection_errors:
+                    raise
+
                 raise PermanentError(exception) from exception
             except httpx.TimeoutException as exception:
                 if retries.config.retry_connection_errors:
@@ -137,6 +142,11 @@ async def do_request() -> httpx.Response:
                 if retries.config.retry_connection_errors:
                     raise
 
+                raise PermanentError(exception) from exception
+            except httpx.RemoteProtocolError as exception:
+                if retries.config.retry_connection_errors:
+                    raise
+
                 raise PermanentError(exception) from exception
             except httpx.TimeoutException as exception:
                 if retries.config.retry_connection_errors: