diff --git a/tests/plausible/recipe_meta.py b/tests/plausible/recipe_meta.py
index 5a0633b..ff77f0a 100644
--- a/tests/plausible/recipe_meta.py
+++ b/tests/plausible/recipe_meta.py
@@ -20,3 +20,12 @@ EXTRA_ENV = {
     # 64-char stable value for CI — plausible (Phoenix) requires >= 64 chars
     "SECRET_KEY_BASE": "ccciplausibletestkeybase64charsexactlyforCIephemeral4567890123",
 }
+
+# The upgrade tier defaults its base to recipe_versions[-2]. For the 3.1.0 upgrade PR the
+# published tags end [..., 3.0.0+v2.0.0, 3.0.1+v2.0.0], so [-2] picks 3.0.0 — whose clickhouse
+# entrypoint has no x86_64 ARCH mapping (added in 3.0.1): on amd64 it wgets the nonexistent
+# clickhouse-backup-linux-x86_64.tar.gz (HTTP 404), exits 1 silently (set -e + silenced wget)
+# and crash-loops, so the base deploy can NEVER converge on this host. The PR adds its version
+# ABOVE the newest published tag — the documented case where the correct base is [-1], the
+# newest published version. Pin it.
+UPGRADE_BASE_VERSION = "3.0.1+v2.0.0"