diff --git a/tests/setup/package-provenance-contract b/tests/setup/package-provenance-contract
index c016d1d..f2d253a 100755
--- a/tests/setup/package-provenance-contract
+++ b/tests/setup/package-provenance-contract
@@ -105,6 +105,13 @@ before_system_flatpak="$(snapshot_file_state /var/lib/flatpak/repo/config)"
 before_system_flathub_key="$(snapshot_file_state /var/lib/flatpak/repo/flathub.trustedkeys.gpg)"
 before_user_flatpak="$(snapshot_file_state "$HOME/.local/share/flatpak/repo/config")"
 before_bashrc="$(snapshot_file_state "$HOME/.bashrc")"
+# A runtime case that escapes its case_root writes a fixture node into the real
+# nvm tree, and the real installer then refuses that unreceipted directory on
+# every later update. Snapshot the listing so the escape fails here instead.
+snapshot_nvm_node() {
+    find "${NVM_DIR:-$HOME/.nvm}/versions/node" -printf '%P %s %T@\n' 2>/dev/null | sort
+}
+before_nvm_node="$(snapshot_nvm_node)"
 
 # Runtime and agent installs must consume the reviewed provenance table. Keep
 # this scan at the public script boundary because a command hidden elsewhere in
@@ -2064,5 +2071,7 @@ STUB_DNF_FAIL_MATCH=terra-release expect_failure run_installer_function terra-dn
     || fail 'repository cases changed the user Flatpak remote'
 [[ "$before_bashrc" == "$(snapshot_file_state "$HOME/.bashrc")" ]] \
     || fail 'repository cases changed the protected bashrc'
+[[ "$before_nvm_node" == "$(snapshot_nvm_node)" ]] \
+    || fail 'runtime cases wrote into the real nvm node tree'
 
 printf 'package provenance contract: PASS\n'