fix(guardrails): key the streamed block decision on status, not detail shape

InvokeGuardrailChecks details a Mapping on its 500 for an unparseable response,
so a detail-shape test read that outage as a policy block and framed it as a 200
guardrail_error. Both block sites raise 400, so gate on the status too.

litellm/proxy/guardrails/guardrail_hooks/bedrock_guardrails.py

@@ -2626,10 +2626,10 @@ class BedrockGuardrail(CustomGuardrail, BaseAWSLLM):
                 )
             except HTTPException as block_exc:
                 block_detail: Final = block_exc.detail
-                # Only a policy block carries a dict detail; every API/transport failure details a
-                # plain string (see _is_input_too_large_error). Re-raising those keeps their real
-                # status instead of reporting an outage as a guardrail decision
-                if not raw_sse or not isinstance(block_detail, Mapping):
+                # A policy block is the only 400 carrying a structured detail; a service failure
+                # either details a plain string or reports a non-400 status, and re-raising those
+                # keeps their real status instead of reporting an outage as a guardrail decision
+                if not raw_sse or block_exc.status_code != 400 or not isinstance(block_detail, Mapping):
                     raise
                 # past the keepalive ping the headers are already flushed, so a raise cannot reach
                 # the client; the block travels as a frame

tests/test_litellm/proxy/guardrails/guardrail_hooks/test_bedrock_guardrails.py

@@ -2958,7 +2958,7 @@ async def test_streaming_hook_block_stream_keeps_upstream_identity():
 async def test_streaming_hook_reraises_guardrail_service_failures():
     """A Bedrock outage must keep its status, not be reported to the caller as a guardrail decision.
 
-    Only a policy block details a Mapping; every API/transport failure details a plain string.
+    A policy block is the only 400 detailing a Mapping.
     """
     guardrail = _sse_guardrail()
 
@@ -2972,6 +2972,22 @@ async def test_streaming_hook_reraises_guardrail_service_failures():
     assert exc.value.status_code == 500
 
 
+@pytest.mark.asyncio
+async def test_streaming_hook_reraises_a_service_failure_that_details_a_mapping():
+    """InvokeGuardrailChecks details a Mapping on its 500, so detail shape alone cannot mean "block"."""
+    guardrail = _sse_guardrail()
+
+    with patch.object(guardrail, "make_bedrock_api_request", new_callable=AsyncMock) as mock_api:
+        mock_api.side_effect = HTTPException(
+            status_code=500,
+            detail={"error": "Bedrock InvokeGuardrailChecks returned an unexpected response shape"},
+        )
+        with pytest.raises(HTTPException) as exc:
+            await _drain_streaming_hook(guardrail)
+
+    assert exc.value.status_code == 500
+
+
 @pytest.mark.asyncio
 async def test_streaming_block_error_frame_message_is_a_string():
     """AnthropicErrorDetail.message is typed str, built by the proxy's own detail serializer."""