ATEM: alarm when ATEM Software Control's MIDI control is turned on

New 'pref' check reads an app setting on NA Ingest (defaults read) every
10 s; ATEM shows ATEM SW MIDI ON if midiEnabled is not 0.

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

status_panel.py

@@ -149,6 +149,7 @@ class Snapshot:
         self.remote_midi_time = {}  # host -> when it last reported
         self.peer_addr = {}      # (host or "", session, peer) -> address it was last seen at
         self.conn_hosts = {}     # Companion connection label -> its "host" setting
+        self.prefs = {}          # (preferences domain, key) -> value as "defaults read" prints it
         self.midi_time = 0.0
         self.mdns = set()        # Bonjour _apple-midi._udp instance names
         self.mdns_time = 0.0
@@ -415,6 +416,14 @@ def check_http(chk, snap, ctx):
     return [("http", Result(OK))]
 
 
+def check_pref(chk, snap, ctx):
+    """An app setting on NA Ingest, e.g. ATEM Software Control's "Enable MIDI control" must stay off."""
+    value = snap.prefs.get((chk["domain"], chk["key"]))
+    if value is None or value == str(chk["want"]):
+        return [("pref", Result(OK))]                    # not read yet, or as it should be
+    return [("pref", Result(ERR, chk["msg"], named=True))]
+
+
 def check_disk(chk, snap, ctx):
     free = snap.disk.get(chk["path"])
     if free is None:
@@ -496,7 +505,7 @@ def check_remote(chk, snap, ctx):
 CHECKS = {
     "conn": check_conn, "hyperdeck": check_hyperdeck, "dante": check_dante, "shure": check_shure,
     "psm": check_psm, "tascam": check_tascam, "ping": check_ping, "launchd": check_launchd,
-    "process": check_process, "http": check_http, "disk": check_disk, "midi_peer": check_midi_peer,
+    "process": check_process, "http": check_http, "disk": check_disk, "midi_peer": check_midi_peer, "pref": check_pref,
     "mdns": check_mdns, "midi_rx": check_midi_rx, "remote": check_remote, "artnet": check_artnet,
 }
 
@@ -1451,6 +1460,10 @@ def poll_system(snap, cfg):
         elif c["type"] == "disk":
             usage = shutil.disk_usage(c["path"])
             snap.disk = dict(snap.disk, **{c["path"]: int(usage.free / 1e9)})
+        elif c["type"] == "pref":
+            r = subprocess.run(["/usr/bin/defaults", "read", c["domain"], c["key"]], capture_output=True,
+                               text=True, timeout=5)
+            snap.prefs[(c["domain"], c["key"])] = r.stdout.strip() if r.returncode == 0 else None
     snap.procs = procs