From 430d931ff841fb39356d68c658095fa0cbf473c1 Mon Sep 17 00:00:00 2001
From: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
Date: Thu, 1 Oct 2026 17:31:16 -0700
Subject: [PATCH] refactor(router): read a deployment's declared prefill
 support without an empty except

---
 .../continuation_prefill_check.py             | 19 ++++++++++++-------
 .../test_continuation_prefill_check.py        |  2 ++
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/litellm/router_utils/pre_call_checks/continuation_prefill_check.py b/litellm/router_utils/pre_call_checks/continuation_prefill_check.py
index 0d6d462d417..2bde8ca920d 100644
--- a/litellm/router_utils/pre_call_checks/continuation_prefill_check.py
+++ b/litellm/router_utils/pre_call_checks/continuation_prefill_check.py
@@ -24,18 +24,23 @@ MID_STREAM_CONTINUATION_MARKER: Final = _ContinuationMarker()
 _STR_KEYED_DICT_ADAPTER: Final = TypeAdapter(dict[str, object])
 
 
+def _declared_prefill_support(deployment_map: Mapping[str, object]) -> bool | None:
+    try:
+        model_info: Final = _STR_KEYED_DICT_ADAPTER.validate_python(deployment_map.get("model_info"))
+    except ValidationError:
+        return None
+    declared: Final = model_info.get("supports_assistant_prefill")
+    return declared if isinstance(declared, bool) else None
+
+
 def _deployment_supports_prefill(deployment: object) -> bool:
     try:
         deployment_map: Final = _STR_KEYED_DICT_ADAPTER.validate_python(deployment)
     except ValidationError:
         return False
-    try:
-        model_info: Final = _STR_KEYED_DICT_ADAPTER.validate_python(deployment_map.get("model_info"))
-        declared: Final = model_info.get("supports_assistant_prefill")
-        if isinstance(declared, bool):
-            return declared
-    except ValidationError:
-        pass
+    declared: Final = _declared_prefill_support(deployment_map)
+    if declared is not None:
+        return declared
     try:
         litellm_params: Final = _STR_KEYED_DICT_ADAPTER.validate_python(deployment_map.get("litellm_params"))
     except ValidationError:
diff --git a/tests/unit/router_utils/pre_call_checks/test_continuation_prefill_check.py b/tests/unit/router_utils/pre_call_checks/test_continuation_prefill_check.py
index bf3ff3c6b4f..4cbe48eda54 100644
--- a/tests/unit/router_utils/pre_call_checks/test_continuation_prefill_check.py
+++ b/tests/unit/router_utils/pre_call_checks/test_continuation_prefill_check.py
@@ -32,6 +32,8 @@ def _deployment(model: str, dep_id: str) -> dict:
 def test_deployment_supports_prefill_reads_capability():
     assert _deployment_supports_prefill(_deployment(PREFILL_MODEL, "a")) is True
     assert _deployment_supports_prefill(_deployment(NON_PREFILL_MODEL, "b")) is False
+    assert _deployment_supports_prefill({"litellm_params": {"model": PREFILL_MODEL}}) is True
+    assert _deployment_supports_prefill({"litellm_params": {"model": PREFILL_MODEL}, "model_info": "bogus"}) is True
 
 
 def test_deployment_model_info_override_wins_over_cost_map():