feat(llm): carry the upstream provider and error type as request-log event fields

LiteLLM drops OpenRouter's top-level `provider` from stream chunks (including error chunks) and the `metadata.provider_name` of non-2xx replies, so the request log could not say which provider served or failed an attempt. Record both, plus OpenRouter's `metadata.error_type`, per attempt and emit them as `upstream=` / `upstream_error=` on the llm_request line.

strix/config/models.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 import asyncio
 import contextlib
 import inspect
+import json
 import logging
 import os
 import time
@@ -745,6 +746,11 @@ def _install_openrouter_stream_cost_capture() -> None:
 
     class _StrixOpenRouterStreamingHandler(OpenRouterChatCompletionStreamingHandler):
         def chunk_parser(self, chunk: dict[str, Any]) -> Any:
+            # Before parsing: LiteLLM raises on an error chunk and drops its
+            # top-level ``provider``.
+            request_log.record_upstream_provider(
+                chunk.get("provider"), _openrouter_error_type(chunk.get("error"))
+            )
             stream = super().chunk_parser(chunk)
             usage = chunk.get("usage")
             response_id = chunk.get("id") or getattr(stream, "id", None)
@@ -763,12 +769,22 @@ def _install_openrouter_stream_cost_capture() -> None:
                 json_mode=json_mode,
             )
 
+        def get_error_class(self, error_message: str, status_code: int, headers: Any) -> Any:
+            # A non-2xx reply names the provider in ``error.metadata``.
+            with contextlib.suppress(Exception):
+                error = json.loads(error_message)["error"]
+                request_log.record_upstream_provider(
+                    error["metadata"].get("provider_name"), _openrouter_error_type(error)
+                )
+            return super().get_error_class(error_message, status_code, headers)
+
         def transform_response(self, *args: Any, **kwargs: Any) -> Any:
             # Non-streamed replies (LLM_DISABLE_STREAMING) skip the chunk parser.
             response = super().transform_response(*args, **kwargs)
             raw_response = kwargs.get("raw_response", args[1] if len(args) > 1 else None)
             with contextlib.suppress(Exception):
                 body = raw_response.json()  # type: ignore[union-attr]
+                request_log.record_upstream_provider(body.get("provider"))
                 if body.get("usage"):
                     record_openrouter_provider(body.get("provider"), body["usage"])
             return response
@@ -789,6 +805,14 @@ def _install_openrouter_stream_cost_capture() -> None:
     litellm.OpenrouterConfig = _StrixOpenrouterConfig  # type: ignore[misc]
 
 
+def _openrouter_error_type(error: object) -> object:
+    if isinstance(error, dict):
+        metadata = error.get("metadata")
+        if isinstance(metadata, dict):
+            return metadata.get("error_type")
+    return None
+
+
 OPENROUTER_ATTRIBUTION_HEADERS = {
     "HTTP-Referer": "https://strix.ai",
     "X-Title": "Strix",

strix/llm/request_log.py

@@ -109,6 +109,9 @@ class LlmRequestEvent:
     # Streamed calls only.
     time_to_first_token_ms: int | None = None
     finish_reason: str | None = None
+    # The provider a gateway (OpenRouter) routed the attempt to, and its error type.
+    upstream_provider: str | None = None
+    upstream_error_type: str | None = None
     # Every response header the provider sent, name-normalized, values capped.
     response_headers: dict[str, str] | None = None
     # Free-form: request parameters, full usage object, SDK hidden params,
@@ -159,11 +162,24 @@ class HttpReply:
 
     status_code: int | None = None
     headers: dict[str, str] | None = None
+    upstream_provider: str | None = None
+    upstream_error_type: str | None = None
 
 
 _http_reply: ContextVar[HttpReply | None] = ContextVar("strix_llm_http_reply", default=None)
 
 
+def record_upstream_provider(provider: object, error_type: object = None) -> None:
+    """Remember which provider behind a gateway served the attempt in flight."""
+    reply = _http_reply.get()
+    if reply is None:
+        return
+    if isinstance(provider, str) and provider:
+        reply.upstream_provider = provider
+    if isinstance(error_type, str) and error_type:
+        reply.upstream_error_type = error_type
+
+
 async def record_http_reply(response: Response) -> None:
     """httpx ``response`` event hook: remember the reply for the attempt in flight.
 
@@ -682,6 +698,7 @@ def event_from_litellm(
             ttft_ms = max(0, int((first_at - started).total_seconds() * 1000))
 
     context = current_call_context()
+    reply = _http_reply.get() or HttpReply()
     base = LlmRequestEvent(
         call_id=call_id,
         route="litellm",
@@ -704,6 +721,8 @@ def event_from_litellm(
         request_bytes=json_size(_litellm_request_body(kwargs)),
         time_to_first_token_ms=ttft_ms,
         response_headers=headers_from_response(reply_headers),
+        upstream_provider=reply.upstream_provider,
+        upstream_error_type=reply.upstream_error_type,
     )
     if outcome == "success":
         return _litellm_success(base, kwargs, response, hidden, slo)
@@ -897,12 +916,14 @@ def _log_line_sink(event: LlmRequestEvent) -> None:
     level = logging.DEBUG if event.outcome == "success" else logging.WARNING
     logger.log(
         level,
-        "llm_request route=%s provider=%s model=%s host=%s outcome=%s status=%s "
-        "request_id=%s response_id=%s stream=%s duration_ms=%d ttft_ms=%s "
+        "llm_request route=%s provider=%s upstream=%s upstream_error=%s model=%s host=%s "
+        "outcome=%s status=%s request_id=%s response_id=%s stream=%s duration_ms=%d ttft_ms=%s "
         "req_bytes=%s res_bytes=%s finish=%s "
         "in=%s out=%s cached=%s cost=%s agent=%s attempt=%d%s",
         event.route,
         event.provider or "-",
+        event.upstream_provider or "-",
+        event.upstream_error_type or "-",
         event.model,
         event.api_host or "-",
         event.outcome,
@@ -1050,6 +1071,8 @@ class RequestLoggingModel(Model):
             time_to_first_token_ms=ttft_ms,
             finish_reason=finish_reason,
             response_headers=headers_from_response(reply.headers),
+            upstream_provider=reply.upstream_provider,
+            upstream_error_type=reply.upstream_error_type,
         )
         if exc is None:
             usage = _openai_usage(response) if response is not None else {}

tests/test_cost_tracking.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import json
 import uuid
 from types import SimpleNamespace
 from typing import TYPE_CHECKING, Any
@@ -389,3 +390,67 @@ def test_openrouter_request_carries_agent_session_id() -> None:
             assert body()["session_id"] == session_id
     finally:
         request_log.reset_call_context(token)
+
+
+def _openrouter_config() -> Any:
+    _install_openrouter_stream_cost_capture()
+    config = ProviderConfigManager.get_provider_chat_config(
+        model="z-ai/glm-5.3", provider=LlmProviders.OPENROUTER
+    )
+    assert config is not None
+    return config
+
+
+def test_openrouter_records_upstream_of_stream_and_mid_stream_error() -> None:
+    handler = _openrouter_config().get_model_response_iterator(
+        streaming_response=iter([]), sync_stream=True
+    )
+    reply = request_log.HttpReply()
+    token = request_log._http_reply.set(reply)
+    try:
+        handler.chunk_parser(
+            {
+                "id": "gen-a",
+                "created": 1,
+                "model": "z-ai/glm-5.3",
+                "provider": "Relace",
+                "choices": [{"index": 0, "delta": {"content": "x"}}],
+            }
+        )
+        assert reply.upstream_provider == "Relace"
+        assert reply.upstream_error_type is None
+        with pytest.raises(Exception, match="incomplete tool call"):
+            handler.chunk_parser(
+                {
+                    "id": "gen-a",
+                    "provider": "Relace",
+                    "error": {
+                        "code": 400,
+                        "message": "Generation stopped with an incomplete tool call.",
+                        "metadata": {"error_type": "invalid_request"},
+                    },
+                }
+            )
+    finally:
+        request_log._http_reply.reset(token)
+    assert reply.upstream_provider == "Relace"
+    assert reply.upstream_error_type == "invalid_request"
+
+
+def test_openrouter_records_upstream_of_pre_stream_error() -> None:
+    body = {
+        "error": {
+            "message": "Provider returned error",
+            "code": 400,
+            "metadata": {"raw": "...", "provider_name": "InferenceNet"},
+        }
+    }
+    reply = request_log.HttpReply()
+    token = request_log._http_reply.set(reply)
+    try:
+        _openrouter_config().get_error_class(json.dumps(body), 400, {})
+        _openrouter_config().get_error_class("<html>502 Bad Gateway</html>", 502, {})
+    finally:
+        request_log._http_reply.reset(token)
+    assert reply.upstream_provider == "InferenceNet"
+    assert reply.upstream_error_type is None

tests/test_llm_request_log.py

@@ -394,9 +394,29 @@ def test_log_line_sink_formats_without_content(caplog: pytest.LogCaptureFixture)
     assert "request_id=req_line01" in line
     assert "status=400" in line
     assert "provider=anthropic" in line
+    assert "upstream=- upstream_error=-" in line
     assert "SECRET PROMPT" not in line
 
 
+def test_log_line_names_upstream_recorded_during_attempt(
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    exc = _anthropic_error(400, ANTHROPIC_BLOCK_BODY, {})
+    token = request_log._http_reply.set(request_log.HttpReply())
+    try:
+        request_log.record_upstream_provider("Together", "provider_unavailable")
+        event = request_log.event_from_litellm(
+            _anthropic_kwargs(exc), None, None, None, outcome="error"
+        )
+    finally:
+        request_log._http_reply.reset(token)
+    assert event.upstream_provider == "Together"
+    with caplog.at_level(logging.DEBUG, logger="strix.llm.request_log"):
+        request_log._log_line_sink(event)
+    line = caplog.records[-1].getMessage()
+    assert "upstream=Together upstream_error=provider_unavailable" in line
+
+
 # --------------------------------------------------------------------------- #
 # sizes, timing, finish reason, free-form headers and details                  #
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