diff --git a/template/stacks/ci-sizer/gitlab-webhook.yaml b/template/stacks/ci-sizer/gitlab-webhook.yaml
index c0b1bce..c92cae5 100644
--- a/template/stacks/ci-sizer/gitlab-webhook.yaml
+++ b/template/stacks/ci-sizer/gitlab-webhook.yaml
@@ -1,3 +1,7 @@
+# Optional: GitLab CI integration
+# Only hydrate this app for clusters that run GitLab Runner.
+# For Forgejo/GitHub-only deployments, omit this app from stacks-instances.
+# See: ci-sizer/docs/deployment-modes.md
 apiVersion: argoproj.io/v1alpha1
 kind: Application
 metadata: