From 7c026bdbd68486c3360a51854a6f7421a3ae9e42 Mon Sep 17 00:00:00 2001
From: Charan Rathore <charan-rathore@users.noreply.github.com>
Date: Mon, 28 Sep 2026 10:45:22 +0530
Subject: [PATCH] fix(proxy): retain user-config router through call and stream

---
 litellm/proxy/common_request_processing.py    |   6 +-
 litellm/proxy/route_llm_request.py            |  68 +++++++-
 .../proxy/test_user_config_router_lifetime.py | 162 ++++++++++++++++++
 3 files changed, 230 insertions(+), 6 deletions(-)
 create mode 100644 tests/test_litellm/proxy/test_user_config_router_lifetime.py

diff --git a/litellm/proxy/common_request_processing.py b/litellm/proxy/common_request_processing.py
index 15610da9aec..9322901e537 100644
--- a/litellm/proxy/common_request_processing.py
+++ b/litellm/proxy/common_request_processing.py
@@ -3453,9 +3453,13 @@ class ProxyBaseLLMRequestProcessing:
         unwrapped inner iterator.
         """
         from litellm.litellm_core_utils.streaming_handler import CustomStreamWrapper
+        from litellm.proxy.route_llm_request import _RouterOwnedStream
         from litellm.router_utils.add_retry_fallback_headers import HiddenParamsAsyncIteratorWrapper
 
-        unwrapped: Final = response._inner if isinstance(response, HiddenParamsAsyncIteratorWrapper) else response
+        owned_stream: Final = response._stream if isinstance(response, _RouterOwnedStream) else response
+        unwrapped: Final = (
+            owned_stream._inner if isinstance(owned_stream, HiddenParamsAsyncIteratorWrapper) else owned_stream
+        )
 
         if isinstance(unwrapped, CustomStreamWrapper):
             # Intentionally a live reference (not a copy) — mirrors
diff --git a/litellm/proxy/route_llm_request.py b/litellm/proxy/route_llm_request.py
index 536c58df65a..9309de387f4 100644
--- a/litellm/proxy/route_llm_request.py
+++ b/litellm/proxy/route_llm_request.py
@@ -1,6 +1,7 @@
 import asyncio
-from collections.abc import Mapping
-from typing import TYPE_CHECKING, Any, Final, Literal
+from collections.abc import AsyncIterator, Mapping
+from contextlib import suppress
+from typing import TYPE_CHECKING, Any, Final, Literal, cast
 
 import httpx
 from fastapi import HTTPException, status
@@ -35,6 +36,46 @@ else:
     LitellmRouter = Any
 
 
+class _RouterOwnedStream:
+    """Keep per-request router callbacks until the stream ends or is closed."""
+
+    def __init__(self, stream: AsyncIterator[object], router: LitellmRouter):
+        self._stream = stream
+        self._router = router
+        self._discarded = False
+
+    def __getattr__(self, name: str) -> object:
+        return getattr(self._stream, name)
+
+    def __aiter__(self) -> "_RouterOwnedStream":
+        return self
+
+    def _discard(self) -> None:
+        if not self._discarded:
+            self._discarded = True
+            self._router.discard()
+
+    async def __anext__(self) -> object:
+        try:
+            return await anext(self._stream)
+        except BaseException:
+            # A failed or cancelled stream still owns an upstream connection.
+            # Preserve the original exception if closing also fails.
+            with suppress(BaseException):
+                await self.aclose()
+            raise
+
+    async def aclose(self) -> None:
+        if self._discarded:
+            return
+        try:
+            closer = getattr(self._stream, "aclose", None)
+            if closer is not None:
+                await closer()
+        finally:
+            self._discard()
+
+
 def _route_user_config_request(data: dict, route_type: str):
     """Route a request using the user-provided router config."""
     router_config: Final = data.pop("user_config")
@@ -45,9 +86,26 @@ def _route_user_config_request(data: dict, route_type: str):
     filtered_config: Final = {k: v for k, v in router_config.items() if k in valid_args}
 
     user_router: Final = litellm.Router(**filtered_config)
-    ret_val: Final = getattr(user_router, f"{route_type}")(**data)
-    user_router.discard()
-    return ret_val
+    try:
+        call = getattr(user_router, route_type)(**data)
+    except BaseException:
+        user_router.discard()
+        raise
+
+    async def _run():
+        stream_returned = False
+        try:
+            response = await call
+            if isinstance(response, AsyncIterator):
+                wrapped = _RouterOwnedStream(cast("AsyncIterator[object]", response), user_router)
+                stream_returned = True
+                return wrapped
+            return response
+        finally:
+            if not stream_returned:
+                user_router.discard()
+
+    return _run()
 
 
 def _is_a2a_agent_model(model_name: object) -> bool:
diff --git a/tests/test_litellm/proxy/test_user_config_router_lifetime.py b/tests/test_litellm/proxy/test_user_config_router_lifetime.py
new file mode 100644
index 00000000000..28a59b00218
--- /dev/null
+++ b/tests/test_litellm/proxy/test_user_config_router_lifetime.py
@@ -0,0 +1,162 @@
+import asyncio
+
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_user_config_router_stays_live_until_await_and_discards_after(monkeypatch):
+    import litellm
+    from litellm.proxy.route_llm_request import _route_user_config_request
+
+    routers = []
+
+    class FakeRouter:
+        @staticmethod
+        def get_valid_args():
+            return ["model_list"]
+
+        def __init__(self, **kwargs):
+            self.discarded = False
+            routers.append(self)
+
+        async def acompletion(self, **kwargs):
+            assert not self.discarded
+            return "done"
+
+        def discard(self):
+            assert not self.discarded
+            self.discarded = True
+
+    monkeypatch.setattr(litellm, "Router", FakeRouter)
+    call = _route_user_config_request({"user_config": {"model_list": []}}, "acompletion")
+    assert not routers[0].discarded
+    assert await call == "done"
+    assert routers[0].discarded
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("failure", [ValueError("provider failed"), asyncio.CancelledError()])
+async def test_user_config_router_discards_on_provider_error(monkeypatch, failure):
+    import litellm
+    from litellm.proxy.route_llm_request import _route_user_config_request
+
+    routers = []
+
+    class FakeRouter:
+        @staticmethod
+        def get_valid_args():
+            return []
+
+        def __init__(self):
+            self.discarded = False
+            routers.append(self)
+
+        async def acompletion(self):
+            assert not self.discarded
+            raise failure
+
+        def discard(self):
+            self.discarded = True
+
+    monkeypatch.setattr(litellm, "Router", FakeRouter)
+    with pytest.raises(type(failure)):
+        await _route_user_config_request({"user_config": {}}, "acompletion")
+    assert routers[0].discarded
+
+
+@pytest.mark.asyncio
+async def test_user_config_stream_keeps_router_until_exhaustion_or_close(monkeypatch):
+    import litellm
+    from litellm.proxy.route_llm_request import _route_user_config_request
+
+    routers = []
+
+    class FakeStream:
+        def __init__(self, router):
+            self.router = router
+            self.count = 0
+            self.closed = False
+            self._hidden_params = {"model_id": "test"}
+
+        def __aiter__(self):
+            return self
+
+        async def __anext__(self):
+            assert not self.router.discarded
+            self.count += 1
+            if self.count > 1:
+                raise StopAsyncIteration
+            return "chunk"
+
+        async def aclose(self):
+            assert not self.router.discarded
+            self.closed = True
+
+    class FakeRouter:
+        @staticmethod
+        def get_valid_args():
+            return []
+
+        def __init__(self):
+            self.discarded = False
+            self.discards = 0
+            routers.append(self)
+
+        async def acompletion(self, **kwargs):
+            return FakeStream(self)
+
+        def discard(self):
+            self.discarded = True
+            self.discards += 1
+
+    monkeypatch.setattr(litellm, "Router", FakeRouter)
+    for close_early in (False, True):
+        stream = await _route_user_config_request({"user_config": {}, "stream": True}, "acompletion")
+        router = routers[-1]
+        assert not router.discarded
+        assert stream._hidden_params == {"model_id": "test"}
+        assert await anext(stream) == "chunk"
+        assert not router.discarded
+        if close_early:
+            await stream.aclose()
+            assert stream._stream.closed
+        else:
+            with pytest.raises(StopAsyncIteration):
+                await anext(stream)
+        assert router.discards == 1
+        await stream.aclose()
+        assert router.discards == 1
+
+
+@pytest.mark.asyncio
+async def test_user_config_stream_discards_when_iteration_raises(monkeypatch):
+    import litellm
+    from litellm.proxy.route_llm_request import _route_user_config_request
+
+    routers = []
+
+    class FakeRouter:
+        @staticmethod
+        def get_valid_args():
+            return []
+
+        def __init__(self):
+            self.discards = 0
+            routers.append(self)
+
+        async def acompletion(self):
+            async def stream():
+                assert self.discards == 0
+                raise ValueError("stream failed")
+                yield "unreachable"
+
+            return stream()
+
+        def discard(self):
+            self.discards += 1
+
+    monkeypatch.setattr(litellm, "Router", FakeRouter)
+    stream = await _route_user_config_request({"user_config": {}}, "acompletion")
+    with pytest.raises(ValueError, match="stream failed"):
+        await anext(stream)
+    assert routers[0].discards == 1