test(maint): add VM and nspawn remedy scenario harness

Nine break/fix/assert scenarios run the real maint fix inside the test VM. The runner batches non-conflicting scenarios into one VM boot, restores the snapshot only between groups, and leaves the base image pristine afterwards. A systemd-nspawn fast lane runs the pacman-level group against a cached pacstrap rootfs in seconds. The plan layer validates the scenario contract without a VM and carries a 19-test unit suite. make test-maint wires the VM lane in.

The zfs lane is filtered but unexercised: the FS_PROFILE=zfs base image fails to build (ZFS DKMS module not found on linux-lts 6.18). The failure is tracked in the todo.

1 files changed, 22 insertions, 0 deletions

diff --git a/scripts/testing/maint-scenarios/31-fstrim-enable.sh b/scripts/testing/maint-scenarios/31-fstrim-enable.sh
new file mode 100644
index 0000000..2d548a1
--- /dev/null
+++ b/scripts/testing/maint-scenarios/31-fstrim-enable.sh
@@ -0,0 +1,22 @@
+# shellcheck shell=bash disable=SC2034  # sourced by run-maint-scenarios.sh
+# Scenario: fstrim.timer enabled and started from the disabled default.
+#
+# The base image ships util-linux with fstrim.timer disabled — the exact
+# state the metric flags. The remedy is systemctl enable --now.
+SCENARIO_DESC="fstrim.timer enabled and started"
+SCENARIO_GROUP="systemd"
+SCENARIO_PROFILES="btrfs"
+
+scenario_break() {
+    # Default state, but pin it so the scenario stays honest if a future
+    # base image enables the timer.
+    mexec "systemctl disable --now fstrim.timer >/dev/null 2>&1 || true; ! systemctl is-enabled fstrim.timer >/dev/null 2>&1"
+}
+
+scenario_fix() {
+    mfix fstrim_enable
+}
+
+scenario_assert() {
+    mexec "systemctl is-enabled fstrim.timer && systemctl is-active fstrim.timer"
+}