diff --git a/docs/canary/ai-review-writer-a.md b/docs/canary/ai-review-writer-a.md
new file mode 100644
index 00000000..c5994145
--- /dev/null
+++ b/docs/canary/ai-review-writer-a.md
@@ -0,0 +1,3 @@
+# AI review writer canary A
+
+Disposable content-free branch used by issue #357 to verify exact-head check serialization.