SC Lighting PC joined: VISTA key and Restart key, rtpMIDI watched on MIDI

- a helper program (rtpMIDI) on a computer that joins after the MIDI key exists is added to it
  (it was marked seen and never added)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_campus.py

@@ -559,3 +559,17 @@ class TestJoinWindowsAdmin(unittest.TestCase):
         check = text.index("IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)")
         self.assertLess(check, text.index("Get-WindowsCapability"))                # before anything needs it
         self.assertIn("Run as administrator", text)
+
+
+class TestHelperJoinsLater(unittest.TestCase):
+    def test_rtpmidi_on_a_pc_that_joins_later_lands_on_the_midi_key(self):
+        inv = small()
+        inv["computers"].pop("lighting_pc")
+        cfg, seen = ac.build(BASE, inv, {"id": "sc", "name": "Southcoast"}, "1234")
+        midi = next((t for t in cfg["tiles"] if any(c.get("type") == "midi_wired" for c in t.get("checks", []))), None)
+        self.assertIsNotNone(midi)                                                   # the MIDI key is there first
+        new, added, now_seen = ac.extend(cfg, small(), seen)
+        midi = next(t for t in new["tiles"] if any(c.get("type") == "midi_wired" for c in t.get("checks", [])))
+        self.assertTrue(any((c.get("params") or {}).get("exe") == "rtpMIDI.exe" for c in midi["checks"]), added)
+        self.assertTrue(any("RTPMIDI" in a for a in added), added)
+        self.assertEqual(schema.validate(new)[0], [])