diff --git a/router/main.py b/router/main.py
index 1b23603b..2487b4b6 100644
--- a/router/main.py
+++ b/router/main.py
@@ -1291,10 +1291,11 @@ async def classify_request(
             return "agent-advanced-core", latency, False, "advanced (exception)"
 
 
-def _read_json_file_sync(file_path: str) -> dict:
-    """Helper to read JSON files synchronously."""
-    with open(file_path, "r") as f:
-        return json.load(f)
+async def _read_json_file_async(file_path: str) -> dict:
+    """Helper to read JSON files asynchronously."""
+    async with aiofiles.open(file_path, "r", encoding="utf-8") as f:
+        content = await f.read()
+        return json.loads(content)
 
 
 
@@ -1307,7 +1308,7 @@ async def get_gemini_oauth_status() -> dict:
                 "detail": "No oauth_creds.json found",
                 "expiry_ms": 0,
             }
-        data = await asyncio.to_thread(_read_json_file_sync, GEMINI_OAUTH_CREDS_PATH)
+        data = await _read_json_file_async(GEMINI_OAUTH_CREDS_PATH)
         access_token = data.get("access_token")
         expiry_ms = data.get("expiry_date", 0)
         current_ms = int(time.time() * 1000)
diff --git a/router/tests/test_get_gemini_oauth_status.py b/router/tests/test_get_gemini_oauth_status.py
index 016b5356..89cfc3be 100644
--- a/router/tests/test_get_gemini_oauth_status.py
+++ b/router/tests/test_get_gemini_oauth_status.py
@@ -1,6 +1,6 @@
 import pytest
 import json
-from unittest.mock import patch, mock_open
+from unittest.mock import patch, AsyncMock
 
 from router import main
 
@@ -13,8 +13,11 @@ async def test_get_gemini_oauth_status_missing_file():
 @pytest.mark.asyncio
 async def test_get_gemini_oauth_status_no_access_token():
     mock_data = {"expiry_date": 1234567890000}
+    mock_file = AsyncMock()
+    mock_file.read.return_value = json.dumps(mock_data)
+    mock_file.__aenter__.return_value = mock_file
     with patch("os.path.exists", return_value=True), \
-         patch("builtins.open", mock_open(read_data=json.dumps(mock_data))):
+         patch("aiofiles.open", return_value=mock_file):
         result = await main.get_gemini_oauth_status()
         assert result == {"status": "missing", "detail": "No access token in file", "expiry_ms": 0}
 
@@ -31,8 +34,11 @@ async def test_get_gemini_oauth_status_scenarios(delta, expected_status, expecte
     current_time_ms = 1000000000000
     expiry_ms = current_time_ms + delta
     mock_data = {"access_token": "test_token", "expiry_date": expiry_ms}
+    mock_file = AsyncMock()
+    mock_file.read.return_value = json.dumps(mock_data)
+    mock_file.__aenter__.return_value = mock_file
     with patch("os.path.exists", return_value=True), \
-         patch("builtins.open", mock_open(read_data=json.dumps(mock_data))), \
+         patch("aiofiles.open", return_value=mock_file), \
          patch("time.time", return_value=current_time_ms / 1000.0):
         result = await main.get_gemini_oauth_status()
         assert result == {"status": expected_status, "detail": expected_detail, "expiry_ms": expiry_ms}
@@ -40,6 +46,6 @@ async def test_get_gemini_oauth_status_scenarios(delta, expected_status, expecte
 @pytest.mark.asyncio
 async def test_get_gemini_oauth_status_exception():
     with patch("os.path.exists", return_value=True), \
-         patch("builtins.open", side_effect=Exception("Test error")):
+         patch("aiofiles.open", side_effect=Exception("Test error")):
         result = await main.get_gemini_oauth_status()
         assert result == {"status": "error", "detail": "Test error", "expiry_ms": 0}
diff --git a/router/tests/test_read_json_file_sync.py b/router/tests/test_read_json_file_async.py
similarity index 51%
rename from router/tests/test_read_json_file_sync.py
rename to router/tests/test_read_json_file_async.py
index 4d385d6d..85ae0044 100644
--- a/router/tests/test_read_json_file_sync.py
+++ b/router/tests/test_read_json_file_async.py
@@ -1,14 +1,18 @@
 import json
-from unittest.mock import mock_open, patch
+from unittest.mock import patch, AsyncMock
 import pytest
 
 from router import main
 
 
-def test_read_json_file_sync_success():
+@pytest.mark.asyncio
+async def test_read_json_file_async_success():
     mock_data = '{"key": "value"}'
-    with patch("builtins.open", mock_open(read_data=mock_data)):
-        result = main._read_json_file_sync("dummy_path.json")
+    mock_file = AsyncMock()
+    mock_file.read.return_value = mock_data
+    mock_file.__aenter__.return_value = mock_file
+    with patch("aiofiles.open", return_value=mock_file):
+        result = await main._read_json_file_async("dummy_path.json")
         assert result == {"key": "value"}
 
 
@@ -16,7 +20,7 @@ def test_read_json_file_sync_success():
     "mock_kwargs, expected_exc, match_msg",
     [
         (
-            {"new": mock_open(read_data='{"key": "value"')},
+            {"return_value": AsyncMock(__aenter__=AsyncMock(return_value=AsyncMock(read=AsyncMock(return_value='{"key": "value"'))))},
             json.JSONDecodeError,
             r"Unterminated string starting at|Expecting",
         ),
@@ -32,7 +36,8 @@ def test_read_json_file_sync_success():
         ),
     ],
 )
-def test_read_json_file_sync_errors(mock_kwargs, expected_exc, match_msg):
-    with patch("builtins.open", **mock_kwargs):
+@pytest.mark.asyncio
+async def test_read_json_file_async_errors(mock_kwargs, expected_exc, match_msg):
+    with patch("aiofiles.open", **mock_kwargs):
         with pytest.raises(expected_exc, match=match_msg):
-            main._read_json_file_sync("dummy_path.json")
+            await main._read_json_file_async("dummy_path.json")