Devices: route to the saved headset before serving; a headset removed elsewhere mid-install reaches nothing (review round 28)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/test_link.py

@@ -118,6 +118,27 @@ class Connecting(unittest.TestCase):
                             explain=explain)
         self.addCleanup(self.link.stop)
 
+    def test_start_routes_to_the_saved_headset_before_serving(self):
+        a = self.reg.add_device("frame", hosts=["192.0.2.1"])
+        b = self.reg.add_device("frame-2", hosts=["192.0.2.2"])
+        self.reg.set_active(b["id"])
+        with mock.patch.object(self.link, "run", lambda: None):  # no connector: only what start() applies
+            self.link.start()
+        self.assertEqual(self.routes[0][0], "frame-2")
+        self.assertIn("HostName=192.0.2.2", self.routes[0][1])
+        self.assertNotEqual(a["id"], b["id"])
+
+    def test_headset_removed_elsewhere_mid_install_reaches_nothing(self):
+        a = self.reg.add_device("frame", hosts=["192.0.2.1"])
+        self.reg.add_device("frame-2", hosts=["192.0.2.2"])
+        self.reg.set_active(a["id"])
+        other = fd.Registry(self.dir / "devices.json")  # another Frame Control server
+        other.remove_device(a["id"])
+        self.link.work = lambda: 1
+        self.assertTrue(self.link.active_device().get("none"))
+        self.link.work = lambda: 0
+        self.assertEqual(self.link.active_device()["alias"], "frame-2")  # idle: move on
+
     def listen6(self):
         """A "different device": the same port on IPv6 loopback."""
         try:

ui/frame_devices.py

@@ -464,8 +464,10 @@ class Registry:
                 # The headset in use is this server's own choice: another server picking a
                 # different one mustn't move commands (an install, say) under it. The file's
                 # choice is only where a server starts.
+                # Kept even if another server removed it, so the connector can see that
+                # (and not quietly move to another headset in the middle of an install).
                 mine = self.data.get("active")
-                if mine and any(d["id"] == mine for d in data["devices"]):
+                if mine:
                     data["active"] = mine
                 self.data = data
 

ui/frame_link.py

@@ -242,6 +242,11 @@ class Link:
 
     # ---- control from the server ----
     def start(self):
+        # Route to the saved headset before the server takes requests: until the connector
+        # has run, commands (an upload by scp, say) would otherwise go to the default alias.
+        device = self.active_device()
+        with self.route_lock:
+            self.apply(device["alias"], self.first_route(device))
         self.thread = threading.Thread(target=self.run, name="frame-link", daemon=True)
         self.thread.start()
 
@@ -348,7 +353,10 @@ class Link:
             try:
                 return self.reg.get(want)
             except frame_devices.DeviceError:
-                pass
+                # Removed (by another server). Mid-install, fail closed: the rest of the
+                # install, or its clean-up, mustn't land on whichever headset comes next.
+                if self.work():
+                    return self.NONE
         devices = self.reg.devices()
         if devices:
             return devices[0]