fix(proxy): resolve pass-through endpoint type from the route, not just the host

get_endpoint_type only matched Anthropic and OpenAI by hostname, so a
pass-through endpoint pointed at a provider that speaks either API on any
other host resolved to GENERIC. GENERIC matches no branch in the streaming
logging dispatch, so the stream was recorded as "cannot parse chunks to
standard response object" with no usage and no cost.

Fall back to the request path once the existing host checks miss: a route
ending in /v1/messages is Anthropic, one ending in /v1/chat/completions is
OpenAI. The fallback can only fire where the function returns GENERIC today,
so nothing that already classifies can reclassify. Suffix matching keeps
routes like /v1/messages/count_tokens on the generic path.

Fixes #40117

litellm/proxy/pass_through_endpoints/pass_through_endpoints.py

@@ -369,6 +369,11 @@ class HttpPassThroughEndpointHelpers(BasePassthroughUtils):
             or (parsed_url.hostname and "openai.com" in parsed_url.hostname)
         ):
             return EndpointType.OPENAI
+        route: Final = parsed_url.path.rstrip("/")
+        if route.endswith("/v1/messages"):
+            return EndpointType.ANTHROPIC
+        elif route.endswith("/v1/chat/completions"):
+            return EndpointType.OPENAI
         return EndpointType.GENERIC
 
     @staticmethod

tests/test_litellm/proxy/pass_through_endpoints/test_pass_through_endpoints.py

@@ -5837,3 +5837,95 @@ def test_passthrough_client_cannot_forge_session_id_omission(client_metadata_key
         )
         == "per-call-random-trace-id"
     )
+
+
+ANTHROPIC_SSE_STREAM = (
+    "event: message_start",
+    'data: {"type":"message_start","message":{"id":"msg_01","type":"message","role":"assistant",'
+    '"model":"claude-sonnet-4-5-20250929","content":[],"stop_reason":null,"stop_sequence":null,'
+    '"usage":{"input_tokens":17,"cache_creation_input_tokens":0,"cache_read_input_tokens":0,'
+    '"output_tokens":5}}}',
+    "event: content_block_start",
+    'data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}',
+    "event: content_block_delta",
+    'data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"Hello there."}}',
+    "event: content_block_stop",
+    'data: {"type":"content_block_stop","index":0}',
+    "event: message_delta",
+    'data: {"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null},'
+    '"usage":{"output_tokens":40}}',
+    "event: message_stop",
+    'data: {"type":"message_stop"}',
+)
+
+
+def _log_passthrough_stream(url: str):
+    from datetime import datetime
+
+    from litellm.proxy.pass_through_endpoints.streaming_handler import (
+        PassThroughStreamingHandler,
+    )
+
+    logging_obj = MagicMock(spec=LiteLLMLoggingObj)
+    logging_obj.model_call_details = {}
+    logging_obj.optional_params = {}
+    logging_obj.litellm_call_id = "test-call-id"
+
+    return PassThroughStreamingHandler._build_passthrough_logging_result(
+        litellm_logging_obj=logging_obj,
+        passthrough_success_handler_obj=PassThroughEndpointLogging(),
+        url_route=url,
+        request_body={"model": "claude-sonnet-4-5-20250929"},
+        endpoint_type=HttpPassThroughEndpointHelpers.get_endpoint_type(url),
+        start_time=datetime.now(),
+        raw_bytes=[(line + "\n").encode("utf-8") for line in ANTHROPIC_SSE_STREAM],
+        end_time=datetime.now(),
+        model="claude-sonnet-4-5-20250929",
+    )
+
+
+def test_anthropic_compatible_passthrough_stream_is_billed_off_api_anthropic_com():
+    """
+    Regression for #40117: the endpoint type was resolved from the hostname alone, so a
+    stream from a provider that speaks the Anthropic Messages API on any other host fell
+    through to GENERIC, matched no branch in the streaming logging dispatch, and was
+    recorded as "cannot parse chunks to standard response object" with no usage and no
+    cost. The same bytes must produce the same accounting whatever host served them.
+    """
+    anthropic_result, anthropic_kwargs = _log_passthrough_stream("https://api.anthropic.com/v1/messages")
+    custom_result, custom_kwargs = _log_passthrough_stream("https://my-provider.example.com/v1/messages")
+
+    assert custom_kwargs["response_cost"] == anthropic_kwargs["response_cost"]
+    assert custom_kwargs["response_cost"] > 0
+    assert custom_result.usage.prompt_tokens == anthropic_result.usage.prompt_tokens == 17
+    assert custom_result.usage.completion_tokens == anthropic_result.usage.completion_tokens == 40
+
+
+def test_openai_compatible_passthrough_route_resolves_off_api_openai_com():
+    from litellm.types.passthrough_endpoints.pass_through_endpoints import EndpointType
+
+    assert (
+        HttpPassThroughEndpointHelpers.get_endpoint_type("https://my-provider.example.com/v1/chat/completions")
+        == EndpointType.OPENAI
+    )
+    assert (
+        HttpPassThroughEndpointHelpers.get_endpoint_type("https://my-provider.example.com/openai/v1/chat/completions/")
+        == EndpointType.OPENAI
+    )
+
+
+def test_passthrough_routes_outside_the_known_shapes_stay_generic():
+    """
+    The path fallback must only claim the two canonical routes. Sending a body the
+    Anthropic or OpenAI handler cannot parse into that handler drops the log row
+    entirely, which is the failure mode LIT-4527 fixed for Vertex.
+    """
+    from litellm.types.passthrough_endpoints.pass_through_endpoints import EndpointType
+
+    for url in (
+        "https://my-provider.example.com/v1/messages/count_tokens",
+        "https://my-provider.example.com/v1/messages/batches",
+        "https://my-provider.example.com/v1/embeddings",
+        "https://upstream.example.com/ml/api/v1/time-series-forecast/predict",
+    ):
+        assert HttpPassThroughEndpointHelpers.get_endpoint_type(url) == EndpointType.GENERIC