diff --git a/Documentation/baseos-reviewer-canary.txt b/Documentation/baseos-reviewer-canary.txt
new file mode 100644
index 000000000000..107fe3f380fa
--- /dev/null
+++ b/Documentation/baseos-reviewer-canary.txt
@@ -0,0 +1,7 @@
+BaseOS Reviewer progress-comment canary
+=======================================
+
+This temporary draft-PR change validates that BaseOS Reviewer creates its
+maintained GitHub comment as soon as a review is queued, before Boro finishes.
+
+This file is test-only and is not intended to be merged.