fix(api): preserve base URL paths in Twirp requests

Author: Kayvan-Zahiri

livekit-api/livekit/api/twirp_client.py

@@ -202,8 +202,8 @@ def __init__(
         if scheme.startswith("ws"):
             scheme = scheme.replace("ws", "http")
 
-        host = f"{scheme}://{parse_res.netloc}/{parse_res.path}"
-        self.host = host.rstrip("/")
+        self._base_path = parse_res.path.rstrip("/")
+        self.host = f"{scheme}://{parse_res.netloc}{self._base_path}"
         self.pkg = pkg
         self.prefix = prefix
         self._session = session
@@ -251,7 +251,7 @@ async def request(
 
         for attempt in range(max_attempts):
             is_last = attempt + 1 >= max_attempts
-            url = f"{current_origin}/{path}"
+            url = f"{current_origin}{self._base_path}/{path}"
 
             transport_exc: Optional[BaseException] = None
             retryable_status: Optional[int] = None

tests/api/test_twirp_client.py

@@ -0,0 +1,96 @@
+# Copyright 2026 LiveKit, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import asyncio
+from unittest.mock import AsyncMock
+
+import aiohttp
+import pytest
+from aiohttp import web
+from aiohttp.test_utils import TestServer
+
+from livekit.api import CreateRoomRequest, LiveKitAPI, Room
+from livekit.api import twirp_client
+from livekit.api.twirp_client import REQUEST_ID_HEADER, TwirpClient
+
+
+@pytest.mark.parametrize("base_path", ["", "/", "/livekit", "/proxy/livekit/"])
+@pytest.mark.parametrize("scheme", ["http", "ws"])
+def test_api_request_preserves_base_path(base_path: str, scheme: str) -> None:
+    async def run() -> None:
+        async def create_room(request: web.Request) -> web.Response:
+            message = CreateRoomRequest.FromString(await request.read())
+            assert message.name == "test-room"
+            assert request.headers["Authorization"] == "Bearer test-token"
+            return web.Response(body=Room(name=message.name).SerializeToString())
+
+        app = web.Application()
+        app.router.add_post(
+            f"{base_path.rstrip('/')}/twirp/livekit.RoomService/CreateRoom", create_room
+        )
+        async with TestServer(app) as server:
+            url = str(server.make_url(base_path)).replace("http://", f"{scheme}://", 1)
+            async with LiveKitAPI.with_token("test-token", url, failover=False) as api:
+                room = await api.room.create_room(CreateRoomRequest(name="test-room"))
+            assert room.name == "test-room"
+
+    asyncio.run(run())
+
+
+@pytest.mark.parametrize("prefix", ["twirp", "custom/twirp"])
+def test_failover_preserves_base_path(monkeypatch: pytest.MonkeyPatch, prefix: str) -> None:
+    async def run() -> None:
+        requests = []
+
+        async def record_request(request: web.Request) -> None:
+            requests.append(
+                (request.path, request.headers[REQUEST_ID_HEADER], await request.read())
+            )
+
+        async def primary(request: web.Request) -> web.Response:
+            await record_request(request)
+            return web.json_response({"code": "unavailable", "msg": "retry"}, status=503)
+
+        async def fallback(request: web.Request) -> web.Response:
+            await record_request(request)
+            return web.Response(body=Room(name="test-room").SerializeToString())
+
+        route = f"/proxy/livekit/{prefix}/livekit.RoomService/CreateRoom"
+        primary_app = web.Application()
+        primary_app.router.add_post(route, primary)
+        fallback_app = web.Application()
+        fallback_app.router.add_post(route, fallback)
+        async with TestServer(primary_app) as first, TestServer(fallback_app) as second:
+            discover = AsyncMock(return_value=[str(second.make_url("")).rstrip("/")])
+            monkeypatch.setattr(twirp_client._REGION_CACHE, "region_origins", discover)
+            async with aiohttp.ClientSession() as session:
+                client = TwirpClient(
+                    session,
+                    str(first.make_url("/proxy/livekit/")),
+                    "livekit",
+                    prefix=prefix,
+                    _failover_force=True,
+                    _failover_backoff=0,
+                )
+                room = await client.request(
+                    "RoomService", "CreateRoom", CreateRoomRequest(name="test-room"), {}, Room
+                )
+            assert room.name == "test-room"
+            assert len(requests) == 2
+            assert requests[0] == requests[1]
+            assert requests[0][0] == route
+            assert requests[0][1]
+            discover.assert_awaited_once()
+
+    asyncio.run(run())