test(net): add the doctor control-plane repair scenarios and runner

net Phase 1's three privileged fixes (unmask-nm, disable-rival, chmod-keyfile) can't be verified against fakes past the point where real sudo and a running NetworkManager matter, and the broken states they repair are too dangerous to stage on a daily driver. I added the live-verification harness they need.

Three scenario files encode the break/fix/assert for each: mask NetworkManager, enable a rival dhcpcd, and chmod a profile keyfile to 0644, then run the real net doctor --fix and assert the repair. Each also names the read-only diagnose verdict it expects, so a run that breaks catches whether the fault is in the diagnosis or the fix. run-net-scenarios.sh rsyncs the net and panelkit trees into a target VM over ssh and drives the scenarios there.

The target is a booted VM, not a container: NetworkManager needs a real kernel and network stack to actually run, so an nspawn container can only show the filesystem-level half (the mask symlink, the keyfile mode) and not "NM is active". A disposable VM you revert is the right environment.

The scenario break/fix/assert logic is the reviewed part. The ssh transport plumbing hasn't been exercised against a live target yet, so it's marked first-draft and may need a shakeout on the first real run. The by-hand equivalent already lives in the manual-testing checklist.

1 files changed, 27 insertions, 0 deletions

diff --git a/scripts/testing/net-scenarios/20-rival-manager.sh b/scripts/testing/net-scenarios/20-rival-manager.sh
new file mode 100644
index 0000000..0d7836b
--- /dev/null
+++ b/scripts/testing/net-scenarios/20-rival-manager.sh
@@ -0,0 +1,27 @@
+# shellcheck shell=bash disable=SC2034  # sourced by run-net-scenarios.sh
+# Scenario: a rival network manager active alongside NetworkManager is disabled.
+#
+# dhcpcd (or systemd-networkd / iwd) running next to NM fights it for the link.
+# Break by enabling dhcpcd; the fix disables it, and the chain resets to
+# reconnect. Requires dhcpcd installed in the target.
+SCENARIO_DESC="an active rival manager (dhcpcd) is disabled"
+SCENARIO_GROUP="control-plane"
+
+scenario_break() {
+    nexec "systemctl enable --now dhcpcd"
+}
+
+scenario_diagnose_expect() {
+    # The verdict fires only when the link is also failing; in a fresh target
+    # with no configured uplink that holds, so the rival should be named.
+    ndoctor_json ".report.control_plane.rivals | index(\"dhcpcd\")" \
+        | grep -vqx null
+}
+
+scenario_fix() {
+    nfix
+}
+
+scenario_assert() {
+    ! nexec "systemctl is-active dhcpcd >/dev/null 2>&1"
+}