fix(bedrock/claude_platform): warn when claude_platform_unsupported_params has an invalid type

A present but non-collection claude_platform_unsupported_params was silently
ignored, so an operator who mistyped the value (e.g. a string) got the default
filtering with no feedback. resolve_unsupported_override now logs a WARNING that
names the param in that case, mirroring the existing dropped-param warning. The
header-derivation pass passes log_invalid=False so the message is emitted once
per request rather than twice on the native /v1/messages path.

litellm/llms/bedrock/claude_platform/common_utils.py

@@ -78,18 +78,30 @@ def filter_claude_platform_request_body(
 
 def resolve_unsupported_override(
     litellm_params: Union[dict[str, object], GenericLiteLLMParams],
+    log_invalid: bool = True,
 ) -> Optional[frozenset[str]]:
     """Read ``claude_platform_unsupported_params`` from litellm_params.
 
-    Returns None (use default set) when the key is absent. Returns a
-    frozenset when present, allowing operators to override or clear the
-    unsupported-param list via proxy config without a code change.
+    Returns None (use the default set) when the key is absent or set to a
+    non-collection type; returns a frozenset when a list/set/tuple is given,
+    letting operators override or clear the unsupported-param list via proxy
+    config without a code change. A present but non-collection value is a
+    misconfiguration: it is ignored (defaults apply) and logged at WARNING when
+    ``log_invalid`` is set, so operators see the override had no effect. The
+    header-derivation pass disables it so the warning fires once per request.
     """
     raw = litellm_params.get("claude_platform_unsupported_params")
     if raw is None:
         return None
     if isinstance(raw, (list, set, frozenset, tuple)):
         return frozenset(str(item) for item in raw)
+    if log_invalid:
+        verbose_logger.warning(
+            "bedrock/claude_platform: ignoring claude_platform_unsupported_params "
+            "of unsupported type %s; expected a list/set/tuple of param names. "
+            "Using the default unsupported-param set.",
+            type(raw).__name__,
+        )
     return None
 
 

litellm/llms/bedrock/claude_platform/messages_transformation.py

@@ -52,7 +52,9 @@ class BedrockClaudePlatformMessagesConfig(
         if resolved_api_key and "x-api-key" not in headers:
             headers["x-api-key"] = resolved_api_key
 
-        unsupported_override = resolve_unsupported_override(litellm_params)
+        unsupported_override = resolve_unsupported_override(
+            litellm_params, log_invalid=False
+        )
         filtered_optional_params = filter_claude_platform_request_body(
             optional_params,
             unsupported_override=unsupported_override,

tests/test_litellm/llms/bedrock/test_claude_platform_provider.py

@@ -485,26 +485,31 @@ def test_claude_platform_unsupported_override_allows_context_management():
 def test_claude_platform_unsupported_override_ignores_invalid_type():
     """
     If claude_platform_unsupported_params is set to a non-collection type
-    (e.g. a string), the override is ignored and defaults apply.
+    (e.g. a string), the override is ignored, defaults apply, and a warning
+    naming the param is logged so the operator sees it had no effect.
     """
+    from litellm.llms.bedrock.claude_platform import common_utils
     from litellm.llms.bedrock.claude_platform.transformation import (
         BedrockClaudePlatformConfig,
     )
 
     config = BedrockClaudePlatformConfig()
-    request_body = config.transform_request(
-        model="claude-sonnet-4-6",
-        messages=[{"role": "user", "content": "hello"}],
-        optional_params={
-            "context_management": {"edits": [{"type": "clear_tool_uses_20250919"}]},
-            "max_tokens": 10,
-        },
-        litellm_params={"claude_platform_unsupported_params": "not_a_list"},
-        headers={},
-    )
+    with patch.object(common_utils.verbose_logger, "warning") as mock_warning:
+        request_body = config.transform_request(
+            model="claude-sonnet-4-6",
+            messages=[{"role": "user", "content": "hello"}],
+            optional_params={
+                "context_management": {"edits": [{"type": "clear_tool_uses_20250919"}]},
+                "max_tokens": 10,
+            },
+            litellm_params={"claude_platform_unsupported_params": "not_a_list"},
+            headers={},
+        )
 
     assert "context_management" not in request_body
     assert request_body["max_tokens"] == 10
+    warned = [call.args[0] for call in mock_warning.call_args_list]
+    assert any("claude_platform_unsupported_params" in message for message in warned)
 
 
 def test_claude_platform_messages_does_not_advertise_beta_for_stripped_context_management():