Record headset results for sideloading and devkit pairing

Tested on a Frame (BUILD_ID 20260922.6101926):

- Devkit pairing: the service runs and answers properties.json, but /register
  refuses with "please put the Steam client in pairing mode" unless Steam is on
  Settings > Developer > Pair new host. Both setup paths now say so and keep
  asking for 2 minutes before falling back to the password.
- Sideloading: registering, launching, quoted start paths and Remove work; a
  Windows exe runs under Proton 11 through FEX. An aarch64 build starts but
  outside the runtime container, and an x86-64 Linux build doesn't start
  because the x86-64 Steam Linux Runtime 4.0 isn't installed. The inspect note
  for x86-64 Linux builds now says so.

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

tests/test_connect.py

@@ -22,6 +22,7 @@ PUB = "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQC+/x= frame-control@old\n"
 class StubDevkit(BaseHTTPRequestHandler):
     """Answers like steamos-devkit-service; `reply` picks the /register outcome."""
     reply = (200, b"Registered\n")
+    replies = []  # if set, each /register takes the next one instead of `reply`
     properties = {"txtvers": 1, "login": "steamos", "settings": "{}", "devkit1": ["devkit-1"]}
     bodies = []
 
@@ -41,7 +42,7 @@ class StubDevkit(BaseHTTPRequestHandler):
     def do_POST(self):
         body = self.rfile.read(int(self.headers["Content-Length"]))
         StubDevkit.bodies.append((self.path, self.headers["Content-Type"], body))
-        code, text = self.reply
+        code, text = StubDevkit.replies.pop(0) if StubDevkit.replies else self.reply
         self.send_response(code)
         self.send_header("Content-type", "text/plain")
         self.end_headers()
@@ -63,6 +64,7 @@ class DevkitPairing(unittest.TestCase):
     def setUp(self):
         StubDevkit.reply = (200, b"Registered\n")
         StubDevkit.bodies = []
+        StubDevkit.replies = []
         self.said = []
         self._say, fc.say = fc.say, self.said.append
 
@@ -104,7 +106,31 @@ class DevkitPairing(unittest.TestCase):
         path, ctype, body = StubDevkit.bodies[0]
         self.assertEqual((path, ctype), ("/register", "text/plain"))
         self.assertEqual(body.decode(), fc.register_body(PUB, "frame-control@test"))
-        self.assertTrue(any("Approve the pairing request" in s for s in self.said))
+        self.assertTrue(any("Pair new host" in s for s in self.said))
+
+    NOT_PAIRING = (403, b'{"error": "devkit approve-ssh-key: please put the Steam client in pairing mode: '
+                        b'Settings -> Developer -> Pair new host"}')
+
+    def test_pair_waits_for_pairing_mode(self):
+        # The headset refuses until Steam is on "Pair new host", then prompts.
+        StubDevkit.replies = [self.NOT_PAIRING, self.NOT_PAIRING, (200, b"Registered\n")]
+        sleep, fc.time.sleep = fc.time.sleep, lambda s: None
+        try:
+            reason = fc.devkit_pair("127.0.0.1", PUB, "c", self.port)
+        finally:
+            fc.time.sleep = sleep
+        self.assertIsNone(reason)
+        self.assertEqual(len(StubDevkit.bodies), 3)
+
+    def test_pair_gives_up_without_pairing_mode(self):
+        StubDevkit.reply = self.NOT_PAIRING
+        wait, fc.PAIRING_MODE_WAIT = fc.PAIRING_MODE_WAIT, 0
+        try:
+            reason = fc.devkit_pair("127.0.0.1", PUB, "c", self.port)
+        finally:
+            fc.PAIRING_MODE_WAIT = wait
+        self.assertIn("pairing mode", reason)
+        self.assertEqual(len(StubDevkit.bodies), 1)
 
     def test_pair_refused_falls_back(self):
         StubDevkit.reply = (403, b'{"error": "timeout - Steam did not respond to the pairing request"}')

tests/test_frame_titles.py

@@ -109,10 +109,10 @@ class Targets(unittest.TestCase):
         self.assertEqual((p['target'], p['runtime']), ('game.arm64', 'SteamLinuxRuntime_4-arm64'))
         self.assertEqual(p['runtimes'], ['SteamLinuxRuntime_4-arm64'])
 
-    def test_x86_64_linux_build_is_marked_inferred(self):
+    def test_x86_64_linux_build_warns_it_may_not_start(self):
         p = self.plan({'game.x86_64': elf(0x3E)}, 'game')
         self.assertEqual(p['runtime'], 'SteamLinuxRuntime_4')
-        self.assertIn('inferred', p['note'])
+        self.assertIn("won't start", p['note'])
 
     def test_native_arm64_beats_x86_64(self):
         p = self.plan({'game.x86_64': elf(0x3E, pad=900), 'game.arm64': elf(0xB7)}, 'game')