From 8692e42a6eeb63c71436a43272b60cb7776c9749 Mon Sep 17 00:00:00 2001
From: andrewwhitecdw <andrewwhitecdw@users.noreply.github.com>
Date: Tue, 11 Aug 2026 10:07:45 -0500
Subject: [PATCH] fix: content-filter responses raise instead of normalizing

## Summary
`_response()` raised `ValueError("LiteLLM returned no text content")` for any
response with empty `content`, including content-filter responses where empty
output is expected. This caused legitimate content-filter results to fail
instead of being normalized.

## Root cause
The guard at the end of `_response()` did not distinguish between a truly
empty/invalid response and a `content_filter` finish reason, which by design
returns no content.

## Fix
Allow empty `content` when the finish reason is `content_filter`; keep the
existing raise for all other empty-content cases so unexpected responses still
fail fast.

```diff
-    if not content:
-        raise ValueError("LiteLLM returned no text content")
+    if not content and choice.finish_reason != "content_filter":
+        raise ValueError("LiteLLM returned no text content")
```

## Testing
Added `test_response_content_filter_empty_content` to
`examples/experimental/litellm/tests/test_client.py` and verified the full
non-e2e suite passes:

```
uv run --project examples/experimental/litellm --python 3.12 \
  pytest examples/experimental/litellm/tests/test_client.py -m "not e2e" -v
# 34 passed
```

## Contributor guidelines
- DCO sign-off included.
- One focused commit per PR.

Signed-off-by: andrewwhitecdw <andrewwhitecdw@users.noreply.github.com>
---
 .../litellm/src/switchyard_litellm/client.py  |  2 +-
 .../experimental/litellm/tests/test_client.py | 22 +++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/examples/experimental/litellm/src/switchyard_litellm/client.py b/examples/experimental/litellm/src/switchyard_litellm/client.py
index dc0286c1f..04cc9a9a3 100644
--- a/examples/experimental/litellm/src/switchyard_litellm/client.py
+++ b/examples/experimental/litellm/src/switchyard_litellm/client.py
@@ -290,7 +290,7 @@ def _response(response: ModelResponse) -> dict[str, object]:
             "name": tool_call.function.name,
             "arguments": arguments,
         })
-    if not content:
+    if not content and choice.finish_reason != "content_filter":
         raise ValueError("LiteLLM returned no text content")
     return {
         "id": response.id,
diff --git a/examples/experimental/litellm/tests/test_client.py b/examples/experimental/litellm/tests/test_client.py
index 5e3654816..3fd821b7e 100644
--- a/examples/experimental/litellm/tests/test_client.py
+++ b/examples/experimental/litellm/tests/test_client.py
@@ -552,3 +552,25 @@ async def test_cached_token_count_preserves_explicit_zero() -> None:
         await client.aclose()
 
     assert response["usage"]["cached_input_tokens"] == 0
+
+
+def test_response_content_filter_empty_content() -> None:
+    """Empty content with a content_filter finish reason must be normalized."""
+    from types import SimpleNamespace
+
+    from switchyard_litellm.client import _response
+
+    response = SimpleNamespace(
+        id="chatcmpl-test",
+        model="openai/strong",
+        choices=[
+            SimpleNamespace(
+                message=SimpleNamespace(content=None, tool_calls=None),
+                finish_reason="content_filter",
+            )
+        ],
+        usage=None,
+    )
+    result = _response(response)
+    assert result["outputs"][0]["content"] == []
+    assert result["outputs"][0]["stop_reason"] == "content_filter"