Update oncall reviewer assignment

.github/scripts/oncall_manager.py

@@ -28,6 +28,7 @@
 ROTATION_TEAM_SLUG = "mcore-oncall-rotation"
 ACTIVE_ONCALL_TEAM_SLUG = "mcore-oncall"
 SLACK_USERGROUP_HANDLE = "mcore-oncall"
+COMMUNITY_REQUEST_LABEL = "community-request"
 TARGET_WEEKS = 12
 
 # Caches for email and Slack lookups
@@ -391,14 +392,44 @@ def ensure_schedule_filled(schedule, repo_owner):
         print(f"Appended: {new_entry}")
 
 def assign_reviewer(pr_number):
-    """Assigns the mcore-oncall team as the reviewer for the PR."""
+    """Assigns mcore-oncall if no reviewers are set or community-request is applied."""
     owner, repo = get_repo_info()
+
+    pr_url = f"{GITHUB_API_URL}/repos/{owner}/{repo}/pulls/{pr_number}"
+    pr_resp = requests.get(pr_url, headers=get_headers())
+
+    if pr_resp.status_code != 200:
+        print(f"Failed to fetch PR: {pr_resp.status_code} {pr_resp.text}")
+        sys.exit(1)
+
+    pr_data = pr_resp.json()
+    requested_reviewers = pr_data.get("requested_reviewers", [])
+    requested_teams = pr_data.get("requested_teams", [])
+    labels = {label.get("name") for label in pr_data.get("labels", [])}
+    requested_team_slugs = {team.get("slug") for team in requested_teams}
+    has_community_request_label = COMMUNITY_REQUEST_LABEL in labels
+
+    if ACTIVE_ONCALL_TEAM_SLUG in requested_team_slugs:
+        print(
+            f"Skipping reviewer request: team NVIDIA/{ACTIVE_ONCALL_TEAM_SLUG} "
+            "is already requested"
+        )
+        return
+
+    if not has_community_request_label and (requested_reviewers or requested_teams):
+        print(
+            "Skipping reviewer request: PR already has "
+            f"{len(requested_reviewers)} user reviewer(s) and "
+            f"{len(requested_teams)} team reviewer(s)"
+        )
+        return
+
     url = f"{GITHUB_API_URL}/repos/{owner}/{repo}/pulls/{pr_number}/requested_reviewers"
-    
+
     # Assign the oncall team as reviewer
     data = {"team_reviewers": [ACTIVE_ONCALL_TEAM_SLUG]}
     resp = requests.post(url, headers=get_headers(), json=data)
-    
+
     if resp.status_code in [201, 200]:
         print(f"Successfully requested review from team NVIDIA/{ACTIVE_ONCALL_TEAM_SLUG}")
     else:

tests/test_utils/python_scripts/test_oncall_manager.py

@@ -0,0 +1,125 @@
+# Copyright (c) 2026, NVIDIA CORPORATION.  All rights reserved.
+#
+# 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 importlib.util
+import sys
+import types
+from pathlib import Path
+
+import pytest
+
+REPO_ROOT = Path(__file__).resolve().parents[3]
+ONCALL_MANAGER_PATH = REPO_ROOT / ".github" / "scripts" / "oncall_manager.py"
+
+
+class FakeResponse:
+    def __init__(self, status_code, json_data=None, text=""):
+        self.status_code = status_code
+        self._json_data = json_data
+        self.text = text
+
+    def json(self):
+        return self._json_data
+
+
+class FakeRequests:
+    def __init__(self, pr_data):
+        self.pr_data = pr_data
+        self.posts = []
+
+    def get(self, url, headers=None):
+        return FakeResponse(200, self.pr_data)
+
+    def post(self, url, headers=None, json=None):
+        self.posts.append({"url": url, "headers": headers, "json": json})
+        return FakeResponse(201)
+
+
+@pytest.fixture
+def oncall_manager(monkeypatch):
+    slack_module = types.ModuleType("slack_sdk")
+    slack_module.WebClient = object
+
+    slack_errors_module = types.ModuleType("slack_sdk.errors")
+    slack_errors_module.SlackApiError = Exception
+    requests_module = types.ModuleType("requests")
+
+    monkeypatch.setitem(sys.modules, "requests", requests_module)
+    monkeypatch.setitem(sys.modules, "slack_sdk", slack_module)
+    monkeypatch.setitem(sys.modules, "slack_sdk.errors", slack_errors_module)
+    monkeypatch.setenv("GITHUB_REPOSITORY", "NVIDIA/Megatron-LM")
+    monkeypatch.setenv("GH_TOKEN", "token")
+
+    spec = importlib.util.spec_from_file_location("oncall_manager", ONCALL_MANAGER_PATH)
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+@pytest.mark.parametrize(
+    "pr_data",
+    [
+        {
+            "user": {"login": "maintainer"},
+            "requested_reviewers": [{"login": "alice"}],
+            "requested_teams": [],
+        },
+        {
+            "user": {"login": "maintainer"},
+            "requested_reviewers": [],
+            "requested_teams": [{"slug": "mcore"}],
+        },
+        {
+            "requested_reviewers": [{"login": "alice"}],
+            "requested_teams": [{"slug": "mcore-oncall"}],
+            "labels": [{"name": "community-request"}],
+        },
+    ],
+)
+def test_assign_reviewer_skips_when_oncall_is_not_needed(
+    oncall_manager, monkeypatch, capsys, pr_data
+):
+    fake_requests = FakeRequests(pr_data)
+    monkeypatch.setattr(oncall_manager, "requests", fake_requests)
+
+    oncall_manager.assign_reviewer(123)
+
+    assert fake_requests.posts == []
+    assert "Skipping reviewer request" in capsys.readouterr().out
+
+
+@pytest.mark.parametrize(
+    "pr_data",
+    [
+        {"user": {"login": "maintainer"}, "requested_reviewers": [], "requested_teams": []},
+        {
+            "requested_reviewers": [{"login": "alice"}],
+            "requested_teams": [{"slug": "mcore"}],
+            "labels": [{"name": "community-request"}],
+        },
+    ],
+)
+def test_assign_reviewer_requests_oncall_when_needed(oncall_manager, monkeypatch, pr_data):
+    fake_requests = FakeRequests(pr_data)
+    monkeypatch.setattr(oncall_manager, "requests", fake_requests)
+
+    oncall_manager.assign_reviewer(123)
+
+    assert fake_requests.posts == [
+        {
+            "url": "https://api.github.com/repos/NVIDIA/Megatron-LM/pulls/123/requested_reviewers",
+            "headers": {"Authorization": "token token", "Accept": "application/vnd.github.v3+json"},
+            "json": {"team_reviewers": ["mcore-oncall"]},
+        }
+    ]