MIDI: STUDIO B KEY - the Waves Tune key the tracks send really arrives in Studio B

User 2026-10-26: make sure the key Ableton sends changes Waves Tune at FOH and in Studio B. Studio B's Pro
Tools can't report the plugin's key, so midi_witness.py (LaunchAgent there) logs every program change on
'Network Tracks Midi' and the watchdog checks it against the song ProPresenter shows (the program that
song's Waves Tune clip sends, from the READY look): wrong program, or none after 45 s of a running song,
is red. FOH's LiveBox has no network interface: a witness on NA Ingest logs whether it sends anything back.

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

tests/test_midi_witness.py

@@ -0,0 +1,40 @@
+"""midi_witness.py (2026-10-26, NA): the key changes Studio B really receives, through real CoreMIDI."""
+import json
+import os
+import sys
+import tempfile
+import time
+import unittest
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+import coremidi  # noqa: E402
+import midi_witness as mw  # noqa: E402
+
+
+class TestWitness(unittest.TestCase):
+    def test_parses_a_packet(self):
+        self.assertEqual(mw.messages(bytes([0xC0, 7, 0xF8, 0x90, 60, 100, 0xF0, 1, 2, 0xF7, 0xC1, 4])),
+                         [(0xC0, b"\x07"), (0x90, b"<d"), (0xC1, b"\x04")])
+
+    def test_writes_down_program_changes_it_really_receives(self):
+        src = coremidi.VirtualSource("witness-test")
+        out = os.path.join(tempfile.mkdtemp(), "w.json")
+        try:
+            w = mw.Witness(["witness-test"], out=out)
+            w.poll()
+            time.sleep(0.3)
+            src.send(bytes([0xC0, 7]))          # Ebmaj
+            src.send(bytes([0x90, 60, 100]))
+            src.send(bytes([0xC2, 11]))
+            time.sleep(0.5)
+            w.save()
+            d = json.load(open(out))
+            self.assertTrue(d["sources"]["witness-test"]["connected"])
+            self.assertEqual([p[2:] for p in d["pcs"]], [[1, 7], [3, 11]])
+            self.assertEqual(d["sources"]["witness-test"]["count"], 3)
+        finally:
+            src.close()
+
+
+if __name__ == "__main__":
+    unittest.main()