diff --git a/pyproject.toml b/pyproject.toml
index ed89d3b4c0a172..818d9a4ce620f9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -372,6 +372,7 @@ module = [
     "sentry.issues.endpoints.group_events",
     "sentry.issues.endpoints.group_notes",
     "sentry.issues.endpoints.group_notes_details",
+    "sentry.issues.endpoints.group_open_periods",
     "sentry.issues.endpoints.group_similar_issues_embeddings",
     "sentry.issues.endpoints.group_tombstone",
     "sentry.issues.endpoints.group_tombstone_details",
@@ -412,6 +413,7 @@ module = [
     "sentry.issues.status_change",
     "sentry.issues.status_change_consumer",
     "sentry.issues.status_change_message",
+    "sentry.issues.streamline",
     "sentry.issues.update_inbox",
     "sentry.lang.java.processing",
     "sentry.llm.*",
@@ -557,6 +559,7 @@ module = [
     "tests.sentry.issues.endpoints.test_group_hashes",
     "tests.sentry.issues.endpoints.test_group_notes",
     "tests.sentry.issues.endpoints.test_group_notes_details",
+    "tests.sentry.issues.endpoints.test_group_open_periods",
     "tests.sentry.issues.endpoints.test_group_similar_issues_embeddings",
     "tests.sentry.issues.endpoints.test_group_tombstone",
     "tests.sentry.issues.endpoints.test_group_tombstone_details",
diff --git a/src/sentry/issues/streamline.py b/src/sentry/issues/streamline.py
index 5f069eaf6ba6c6..84c1d90631e1c5 100644
--- a/src/sentry/issues/streamline.py
+++ b/src/sentry/issues/streamline.py
@@ -4,7 +4,7 @@
 from sentry.models.organization import Organization
 
 
-def apply_streamline_rollout_group(organization: Organization):
+def apply_streamline_rollout_group(organization: Organization) -> None:
     # This shouldn't run multiple times, but if it does, don't re-sort the organization.
     # If they're already in the experiment, we ignore them.
     if organization.get_option("sentry:streamline_ui_only") is not None: